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Sample records for extrasolar planetary atmospheres

  1. The Atmospheres of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Richardson, L. J.; Seager, S.

    2007-01-01

    In this chapter we examine what can be learned about extrasolar planet atmospheres by concentrating on a class of planets that transit their parent stars. As discussed in the previous chapter, one way of detecting an extrasolar planet is by observing the drop in stellar intensity as the planet passes in front of the star. A transit represents a special case in which the geometry of the planetary system is such that the planet s orbit is nearly edge-on as seen from Earth. As we will explore, the transiting planets provide opportunities for detailed follow-up observations that allow physical characterization of extrasolar planets, probing their bulk compositions and atmospheres.

  2. Extrasolar Planetary Imaging Coronagraph (EPIC)

    NASA Astrophysics Data System (ADS)

    Clampin, Mark

    2009-01-01

    The Extrasolar Planetary Imaging Coronagraph (EPIC) is a proposed NASA Exoplanet Probe mission to image and characterize extrasolar giant planets. EPIC will provide insights into the physical nature and architecture of a variety of planets in other solar systems. Initially, it will detect and characterize the atmospheres of planets identified by radial velocity surveys, determine orbital inclinations and masses and characterize the atmospheres around A and F type stars which cannot be found with RV techniques. It will also observe the inner spatial structure of exozodiacal disks. EPIC has a heliocentric Earth trailing drift-away orbit, with a 5 year mission lifetime. The robust mission design is simple and flexible ensuring mission success while minimizing cost and risk. The science payload consists of a heritage optical telescope assembly (OTA), and visible nulling coronagraph (VNC) instrument. The instrument achieves a contrast ratio of 10^9 over a 5 arcsecond field-of-view with an unprecedented inner working angle of 0.13 arcseconds over the spectral range of 440-880 nm. The telescope is a 1.65 meter off-axis Cassegrain with an OTA wavefront error of lambda/9, which when coupled to the VNC greatly reduces the requirements on the large scale optics.

  3. Extrasolar Planetary Imaging Coronagraph (EPIC)

    NASA Astrophysics Data System (ADS)

    Clampin, Mark; Melnick, Gary; Lyon, Richard; Kenyon, Scott; Sasselov, Dimitar; Tolls, Volker; Ford, Holland; Golimowski, David; Petro, Larry; Hartig, George; Sparks, William; Illingworth, Garth; Lin, Doug; Seager, Sara; Weinberger, Alycia; Harwit, Martin; Marley, Mark; Schneider, Jean; Shao, Michael; Levine, Marty; Ge, Jian; Woodruff, Robert

    2006-06-01

    The Extrasolar Planetary Imaging Coronagraph (EPIC) is a proposed NASA Discovery mission to image and characterize extrasolar giant planets in orbits with semi-major axes between 2 and 10 AU. EPIC will provide insights into the physical nature of a variety of planets in other solar systems complimenting radial velocity (RV) and astrometric planet searches. It will detect and characterize the atmospheres of planets identified by radial velocity surveys, determine orbital inclinations and masses, characterize the atmospheres around A and F type stars which cannot be found with RV techniques, and observe the inner spatial structure and colors of debris disks. EPIC has a proposed launch date of 2012 to heliocentric Earth trailing drift-away orbit, with a 3 year mission lifetime (5 year goal), and will revisit planets at least three times at intervals of 9 months. The robust mission design is simple and flexible ensuring mission success while minimizing cost and risk. The science payload consists of a heritage optical telescope assembly (OTA), and visible nulling coronagraph (VNC) instrument. The instrument achieves a contrast ratio of 109 over a 4.84 arcsecond field-of-view with an unprecedented inner working angle of 0.14 arcseconds over the spectral range of 440-880 nm, with spectral resolutions from 10 - 150. The telescope is a 1.5 meter offaxis Cassegrain with an OTA wavefront error of λ/9, which when coupled to the VNC greatly reduces the requirements on the large scale optics, compressing them to stability requirements within the relatively compact VNC optical chain. The VNC features two integrated modular nullers, a spatial filter array (SFA), and an E2V-L3 photon counting CCD. Direct null control is accomplished from the science focal mitigating against complex wavefront and amplitude sensing and control strategies.

  4. Extrasolar Planetary Systems

    NASA Astrophysics Data System (ADS)

    Ksanfomaliti, L. V.

    2000-11-01

    The discovery of planetary systems around alien stars is an outstanding achievement of recent years. The idea that the Solar System may be representative of planetary systems in the Galaxy in general develops upon the knowledge, current until the last decade of the 20th century, that it is the only object of its kind. Studies of the known planets gave rise to a certain stereotype in theoretical research. Therefore, the discovery of exoplanets, which are so different from objects of the Solar System, alters our basic notions concerning the physics and very criteria of normal planets. A substantial factor in the history of the Solar System was the formation of Jupiter. Two waves of meteorite bombardment played an important role in that history. Ultimately there arose a stable low-entropy state of the Solar System, in which Jupiter and the other giants in stable orbits protect the inner planets from impacts by dangerous celestial objects, reducing this danger by many orders of magnitude. There are even variants of the anthropic principle maintaining that life on Earth owes its genesis and development to Jupiter. Some 20 companions more or less similar to Jupiter in mass and a few ``infrared dwarfs,'' have been found among the 500 solar-type stars belonging to the main sequence. Approximately half of the exoplanets discovered are of the ``hot-Jupiter'' type. These are giants, sometimes of a mass several times that of Jupiter, in very low orbits and with periods of 3-14 days. All of their parent stars are enriched with heavy elements, [Fe/H] = 0.1-0.2. This may indicate that the process of exoplanet formation depends on the chemical composition of the protoplanetary disk. The very existence of exoplanets of the hot-Jupiter type considered in the context of new theoretical work comes up against the problem of the formation of Jupiter in its real orbit. All the exoplanets in orbits with a semimajor axis of more than 0.15-0.20 astronomical units (AU) have orbital

  5. Tidal Dynamics of Transiting Extrasolar Planetary Systems

    NASA Astrophysics Data System (ADS)

    Fabrycky, Daniel C.

    2008-05-01

    The transits of extrasolar planets have revealed a wealth of information about their structures and atmospheres. Because of increased transit likelihood, these planets have small semi-major axes; therefore the planets we know the best are those which are tidally evolved. Transiting planets have not yet been found in multiple-planet systems, but will eventually be an excellent probe of their dynamics. This talk addresses both sides of the coin: theories of tidal dynamics on the one side, clever observations to constrain those theories on the other. On the theory side: Small orbits may be established via eccentricity pumping by a third body (e.g., Kozai cycles) plus tidal dissipation; (b) Oblique spins (Cassini states) may be created and maintained through a secular resonance between orbital precession and spin precession; and (c) Second planets may evolve out of coorbital configurations (near Lagrange points) and mean motion resonance (e.g., the Laplace resonance among Jupiter's satellites) by tidal dissipation. On the observation side: (a) Spectroscopic transit measurements assess the spin orientation of the host star relative to the orbit of the transiting planet; (b) Transit timing measurements can discover second planets and characterize the dynamics of resonant planetary systems; (c) The instantaneous orbital configuration of two-planet systems can indicate the precession rate of the transiting planet, yielding its Love number and probing its internal structure. I gratefully acknowledge funding by the Michelson Fellowship, supported by the National Aeronautics and Space Administration and administered by the Michelson Science Center.

  6. Atmospheres of Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Marley, Mark

    2006-01-01

    The next decade will almost certainly see the direct imaging of extrasolar giant planets around nearby stars. Unlike purely radial velocity detections, direct imaging will open the door to characterizing the atmosphere and interiors of extrasola planets and ultimately provide clues on their formation and evolution through time. This process has already begun for the transiting planets, placing new constraints on their atmospheric structure, composition, and evolution. Indeed the key to understanding giant planet detectability, interpreting spectra, and constraining effective temperature and hence evolution-is the atmosphere. I will review the universe of extrasolar giant planet models, focusing on what we have already learned from modeling and what we will likely be able to learn from the first generation of direct detection data. In addition to these theoretical considerations, I will review the observations and interpretation of the - transiting hot Jupiters. These objects provide a test of our ability to model exotic atmospheres and challenge our current understanding of giant planet evolution.

  7. Detectability of extrasolar planetary transits

    NASA Technical Reports Server (NTRS)

    Borucki, W. J.; Scargle, J. D.; Hudson, H. S.

    1985-01-01

    Precise stellar photometry can be used to detect other planetary systems. However, the intrinsic variability of stellar luminosity imposes a fundamental limit on the sensitivity of this method. Based on recent precise solar observations made from the Solar Maximum Mission satellite, it appears that the detection of earth-sized planets will be marginal during periods of high stellar activity. However, with a suitable photometer larger planets should be readily detectable even in the presence of stellar activity equal to that of the sun at the peak of its sunspot cycle. The high precision, multiple-star photometric system required to detect planets in other stellar systems could be used to monitor flares, starspots, and global oscillations.

  8. Extrasolar Planetary Imaging Coronagraph: Visible Nulling Coronagraph Testbed Results

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.

    2008-01-01

    The Extrasolar Planetary Imaging Coronagraph (EPIC) is a proposed NASA Discovery mission to image and characterize extrasolar giant planets in orbits with semi-major axes between 2 and 10 AU. EPIC will provide insights into the physical nature of a variety of planets in other solar systems complimenting radial velocity (RV) and astrometric planet searches. It will detect and characterize the atmospheres of planets identified by radial velocity surveys, determine orbital inclinations and masses, characterize the atmospheres around A and F stars, observed the inner spatial structure and colors of inner Spitzer selected debris disks. EPIC would be launched to heliocentric Earth trailing drift-away orbit, with a 3-year mission lifetime ( 5 year goal) and will revisit planets at least three times at intervals of 9 months. The starlight suppression approach consists of a visible nulling coronagraph (VNC) that enables high order starlight suppression in broadband light. To demonstrate the VNC approach and advance it's technology readiness the NASA Goddard Space Flight Center and Lockheed-Martin have developed a laboratory VNC and have demonstrated white light nulling. We will discuss our ongoing VNC work and show the latest results from the VNC testbed,

  9. Dead zones and extrasolar planetary properties

    NASA Astrophysics Data System (ADS)

    Matsumura, Soko; Pudritz, Ralph E.

    2006-01-01

    Most low-mass protostellar discs evolve in clustered environments where they are affected by external radiation fields, while others evolve in more isolated star-forming regions. Assuming that the magnetorotational instability (MRI) is the main source of viscosity, we calculate the size of a poorly ionized, MRI inactive and hence low viscosity region - the `dead zone'- in these protostellar discs. We include disc ionization by X-rays, cosmic rays, radioactive elements and thermal collisions, recombination by molecules, metals and grains, as well as the effect of turbulence stimulation in the dead zone by the active layers lying above it. We also calculate the gap-opening masses of planets, which are determined by a disc's viscosity and a disc aspect ratio, for discs in these environments and compare them with each other. We find that the dead zone is a robust feature of the protostellar discs that is largely independent of their environment, typically stretching out to ~15 au. We analyse the possible effects of dead zones on planet formation, migration and eccentricity evolution. We show that the gap-opening mass inside the dead zone is expected to be of the order of terrestrial and ice giant mass planets while that outside the dead zone is Jovian or super-Jovian mass planets, largely independent of the star-forming environment. We show that dead zones can significantly slow down both type I and type II planetary migration due to their lower viscosity. We also find that the growth of eccentricity of massive extrasolar planets is particularly favourable through the planet-disc interaction inside the dead zones due to the large gaps expected to be opened by planets.

  10. Exploring Extrasolar Planetary Systems: New Observations of Extrasolar Planets Enabled by the James Webb Space Telescope

    NASA Technical Reports Server (NTRS)

    Clampin, Mark

    2012-01-01

    The search for extrasolar planets has been increasingly success over the last few years. In excess of 700 systems are now known, and Kepler has approx.2500 additional candidate systems, yet to be confirmed. Recently, progress has also been made in directly imaging extrasolar planets, both from the ground and in space. In this presentation will discuss the techniques employed to discover planetary systems, and highlight the capabilities, enabled by the James Webb Space Telescope (JWST). JWST is a large 6.5 meter aperture infrared telescope that is scheduled for launch in 2018, and will allow us to transition to characterizing the properties of these extrasolar planets and the planetary systems in which they reside.

  11. Hydrodynamic escape from planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Tian, Feng

    Hydrodynamic escape is an important process in the formation and evolution of planetary atmospheres. Due to the existence of a singularity point near the transonic point, it is difficult to find transonic steady state solutions by solving the time-independent hydrodynamic equations. In addition to that, most previous works assume that all energy driving the escape flow is deposited in one narrow layer. This assumption not only results in less accurate solutions to the hydrodynamic escape problem, but also makes it difficult to include other chemical and physical processes in the hydrodynamic escape models. In this work, a numerical model describing the transonic hydrodynamic escape from planetary atmospheres is developed. A robust solution technique is used to solve the time dependent hydrodynamic equations. The method has been validated in an isothermal atmosphere where an analytical solution is available. The hydrodynamic model is applied to 3 cases: hydrogen escape from small orbit extrasolar planets, hydrogen escape from a hydrogen rich early Earth's atmosphere, and nitrogen/methane escape from Pluto's atmosphere. Results of simulations on extrasolar planets are in good agreement with the observations of the transiting extrasolar planet HD209458b. Hydrodynamic escape of hydrogen from other hypothetical close-in extrasolar planets are simulated and the influence of hydrogen escape on the long-term evolution of these extrasolar planets are discussed. Simulations on early Earth suggest that hydrodynamic escape of hydrogen from a hydrogen rich early Earth's atmosphere is about two orders magnitude slower than the diffusion limited escape rate. A hydrogen rich early Earth's atmosphere could have been maintained by the balance between the hydrogen escape and the supply of hydrogen into the atmosphere by volcanic outgassing. Origin of life may have occurred in the organic soup ocean created by the efficient formation of prebiotic molecules in the hydrogen rich early

  12. Limits of photosynthesis in extrasolar planetary systems for earth-like planets.

    PubMed

    Franck, S; von Bloh, W; Bounama, C; Steffen, M; Schonberner, D; Schellnhuber, H J

    2001-01-01

    We present a general modeling scheme for investigating the possibility of photosynthesis-based life on extrasolar planets. The scheme focuses on the identification of the habitable zone in main-sequence-star planetary systems with planets of Earth mass and size. Our definition of habitability is based on the long-term possibility of photosynthetic biomass production as a function of mean planetary surface temperature and atmospheric CO2-content. All the astrophysical, climatological, biogeochemical, and geodynamic key processes involved in the generation of photosynthesis-driven life conditions are taken into account. Implicitly, a co-genetic origin of the central star and the orbiting planet is assumed. The numerical solution of an advanced geodynamic model yields realistic look-up diagrams for determining the limits of photosynthesis in extrasolar planetary systems, assuming minimum CO2 levels set by the demand of C4 photosynthesis.

  13. Stellar Ablation of Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Moore, Thomas E.; Horwitz, J. L.

    2007-01-01

    We review observations and theories of the solar ablation of planetary atmospheres, focusing on the terrestrial case where a large magnetosphere holds off the solar wind, so that there is little direct atmospheric impact, but also couples the solar wind electromagnetically to the auroral zones. We consider the photothermal escape flows known as the polar wind or refilling flows, the enhanced mass flux escape flows that result from localized solar wind energy dissipation in the auroral zones, and the resultant enhanced neutral atom escape flows. We term these latter two escape flows the "auroral wind." We review observations and theories of the heating and acceleration of auroral winds, including energy inputs from precipitating particles, electromagnetic energy flux at magnetohydrodynamic and plasma wave frequencies, and acceleration by parallel electric fields and by convection pickup processes also known as "centrifugal acceleration." We consider also the global circulation of ionospheric plasmas within the magnetosphere, their participation in magnetospheric disturbances as absorbers of momentum and energy, and their ultimate loss from the magnetosphere into the downstream solar wind, loading reconnection processes that occur at high altitudes near the magnetospheric boundaries. We consider the role of planetary magnetization and the accumulating evidence of stellar ablation of extrasolar planetary atmospheres. Finally, we suggest and discuss future needs for both the theory and observation of the planetary ionospheres and their role in solar wind interactions, to achieve the generality required for a predictive science of the coupling of stellar and planetary atmospheres over the full range of possible conditions.

  14. Extrasolar Planetary Systems and the Principle of Mediocrity

    NASA Astrophysics Data System (ADS)

    Franck, S.; von Bloh, W.; Bounama, C.

    2007-03-01

    We estimate the likelihood to find habitable Earth-like planets on stable orbits for 86 selected extrasolar planetary systems, where luminosity, effective temperature and stellar age are known. For determining the habitable zone (HZ) an integrated system approach is used taking into account a variety of climatological, biogeochemical, and geodynamical processes. Habitability is linked to the photosynthetic activity on the planetary surface. We find that habitability strongly depends on the age of the stellar system and the characteristics of a virtual Earth-like planet. In particular the portion of land / ocean coverages plays an important role. We approximated the conditions for orbital stability using a method based on the Hill radius. Almost 60% of the investigated systems could harbour habitable Earth-like planets on stable orbits. In 18 extrasolar systems we find even better prerequisites for dynamic habitability than in our own solar system.

  15. Atmospheric dynamics of tidally synchronized extrasolar planets.

    PubMed

    Cho, James Y-K

    2008-12-13

    Tidally synchronized planets present a new opportunity for enriching our understanding of atmospheric dynamics on planets. Subject to an unusual forcing arrangement (steady irradiation on the same side of the planet throughout its orbit), the dynamics on these planets may be unlike that on any of the Solar System planets. Characterizing the flow pattern and temperature distribution on the extrasolar planets is necessary for reliable interpretation of data currently being collected, as well as for guiding future observations. In this paper, several fundamental concepts from atmospheric dynamics, likely to be central for characterization, are discussed. Theoretical issues that need to be addressed in the near future are also highlighted.

  16. Extrasolar Planetary Complex Biosphere Organization as Exemplified

    NASA Astrophysics Data System (ADS)

    Heath, Martin; Williams, Darren; Doyle, Laurence

    Planetary habitability has usually been defined with reference to the physiological tolerances of human beings, or, in a more general sense, in terms of a modelled planet's ability to retain liquid water (essential for life as we know it) on its surface for a few Gyr. Another way of investigating habitability is with regard to the global mode of biosphere organization. Every combination of stellar composition and main sequence luminosity evolution, planetary characteristics and history, and biosphere organisation is unique, and will have its own specific inner and outer Habitable Zone radii. We illustrate this with modelled equilibrium partial pressures of CO_2. Although, as pointed out by previous workers, plants' CO_2 compensation points (where respiration exactly balances photosynthetic production) are just a few p.p.m. for some species, plants in the real world need to grow, repair tissue loss, reproduce and colonise new areas as they become available. This means that Earth-type forest ecosystems will require CO_2 levels comparable to those of the present day Earth. Reductions in equilibrium CO_2 with progressievely higher insolation, will define different inner margins for the Forest H.Z. with different axial obliquities and continential configurations.

  17. IONIZATION OF EXTRASOLAR GIANT PLANET ATMOSPHERES

    SciTech Connect

    Koskinen, Tommi T.; Cho, James Y-K.; Achilleos, Nicholas; Aylward, Alan D.

    2010-10-10

    Many extrasolar planets orbit close in and are subject to intense ionizing radiation from their host stars. Therefore, we expect them to have strong, and extended, ionospheres. Ionospheres are important because they modulate escape in the upper atmosphere and can modify circulation, as well as leave their signatures, in the lower atmosphere. In this paper, we evaluate the vertical location Z{sub I} and extent D{sub I} of the EUV ionization peak layer. We find that Z{sub I{approx}}1-10 nbar-for a wide range of orbital distances (a = 0.047-1 AU) from the host star-and D{sub I}/H{sub p{approx}}>15, where H{sub p} is the pressure scale height. At Z{sub I}, the plasma frequency is {approx}80-450 MHz, depending on a. We also study global ion transport, and its dependence on a, using a three-dimensional thermosphere-ionosphere model. On tidally synchronized planets with weak intrinsic magnetic fields, our model shows only a small, but discernible, difference in electron density from the dayside to the nightside ({approx}9 x 10{sup 13} m{sup -3} to {approx}2 x 10{sup 12} m{sup -3}, respectively) at Z{sub I}. On asynchronous planets, the distribution is essentially uniform. These results have consequences for hydrodynamic modeling of the atmospheres of close-in extrasolar giant planets.

  18. On Orbital Elements of Extrasolar Planetary Candidates and Spectroscopic Binaries

    NASA Technical Reports Server (NTRS)

    Stepinski, T. F.; Black, D. C.

    2001-01-01

    We estimate probability densities of orbital elements, periods, and eccentricities, for the population of extrasolar planetary candidates (EPC) and, separately, for the population of spectroscopic binaries (SB) with solar-type primaries. We construct empirical cumulative distribution functions (CDFs) in order to infer probability distribution functions (PDFs) for orbital periods and eccentricities. We also derive a joint probability density for period-eccentricity pairs in each population. Comparison of respective distributions reveals that in all cases EPC and SB populations are, in the context of orbital elements, indistinguishable from each other to a high degree of statistical significance. Probability densities of orbital periods in both populations have P(exp -1) functional form, whereas the PDFs of eccentricities can he best characterized as a Gaussian with a mean of about 0.35 and standard deviation of about 0.2 turning into a flat distribution at small values of eccentricity. These remarkable similarities between EPC and SB must be taken into account by theories aimed at explaining the origin of extrasolar planetary candidates, and constitute an important clue us to their ultimate nature.

  19. Investigations on physics of planetary atmospheres and small bodies of the Solar system, extrasolar planets and disk structures around the stars

    NASA Astrophysics Data System (ADS)

    Vidmachenko, A. P.; Delets, O. S.; Dlugach, J. M.; Zakhozhay, O. V.; Kostogryz, N. M.; Krushevska, V. M.; Kuznyetsova, Y. G.; Morozhenko, O. V.; Nevodovskyi, P. V.; Ovsak, O. S.; Rozenbush, O. E.; Romanyuk, Ya. O.; Shavlovskiy, V. I.; Yanovitskij, E. G.

    2015-12-01

    The history and main becoming stages of Planetary system physics Department of the Main astronomical observatory of National academy of Sciences of Ukraine are considered. Fundamental subjects of department researches and science achievements of employees are presented. Fields of theoretical and experimental researches are Solar system planets and their satellites; vertical structures of planet atmospheres; radiative transfer in planet atmospheres; exoplanet systems of Milky Way; stars having disc structures; astronomical engineering. Employees of the department carry out spectral, photometrical and polarimetrical observations of Solar system planets, exoplanet systems and stars with disc structures. 1. From the history of department 2. The main directions of department research 3. Scientific instrumentation 4. Telescopes and observation stations 5. Theoretical studies 6. The results of observations of planets and small Solar system bodies and their interpretation 7. The study of exoplanets around the stars of our galaxy 8. Spectral energy distribution of fragmenting protostellar disks 9. Cooperation with the National Technical University of Ukraine (KPI) and National University of Ukraine "Lviv Polytechnic" to study the impact of stratospheric aerosol changes on weather and climate of the Earth 10. International relations. Scientific and organizational work. Scientific conferences, congresses, symposia 11. The main achievements of the department 12. Current researches 13. Anniversaries and awards

  20. Predicting the Atmospheric Composition of Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Sharp, A. G.; Moses, J. I.; Friedson, A. J.; Fegley, B., Jr.; Marley, M. S.; Lodders, K.

    2004-01-01

    To date, approximately 120 planet-sized objects have been discovered around other stars, mostly through the radial-velocity technique. This technique can provide information about a planet s minimum mass and its orbital period and distance; however, few other planetary data can be obtained at this point in time unless we are fortunate enough to find an extrasolar giant planet that transits its parent star (i.e., the orbit is edge-on as seen from Earth). In that situation, many physical properties of the planet and its parent star can be determined, including some compositional information. Our prospects of directly obtaining spectra from extrasolar planets may improve in the near future, through missions like NASA's Terrestrial Planet Finder. Most of the extrasolar giant planets (EGPs) discovered so far have masses equal to or greater than Jupiter's mass, and roughly 16% have orbital radii less than 0.1 AU - extremely close to the parent star by our own Solar-System standards (note that Mercury is located at a mean distance of 0.39 AU and Jupiter at 5.2 AU from the Sun). Although all EGPs are expected to have hydrogen-dominated atmospheres similar to Jupiter, the orbital distance can strongly affect the planet's temperature, physical, chemical, and spectral properties, and the abundance of minor, detectable atmospheric constituents. Thermochemical equilibrium models can provide good zero-order predictions for the atmospheric composition of EGPs. However, both the composition and spectral properties will depend in large part on disequilibrium processes like photochemistry, chemical kinetics, atmospheric transport, and haze formation. We have developed a photochemical kinetics, radiative transfer, and 1-D vertical transport model to study the atmospheric composition of EGPs. The chemical reaction list contains H-, C-, O-, and N-bearing species and is designed to be valid for atmospheric temperatures ranging from 100-3000 K and pressures up to 50 bar. Here we examine

  1. Extra-solar Oort cloud encounters and planetary impact rates

    SciTech Connect

    Stern, A.

    1987-01-01

    Upper limits are estimated to the number density of extra-solar Oort clouds (ESOC) through which the solar system might pass and to the probable number of attendant planetary impacts by comets. All stars are assumed to have Oort clouds. The model is based on the observed stellar spatial density and the ratio of the total number density to the observed number density. It is estimated that 486 close stellar passages and 12,160 ESOC encounters may have occurred. Each encounter would have produced a shower of hyperbolic comets, with the results of 1-3 ESOC impacts with the earth. It is concluded that the great majority of terrestrial cratering events by comets have and will come from solar Oort cloud comets. 19 references.

  2. Transiting extrasolar planetary candidates in the Galactic bulge.

    PubMed

    Sahu, Kailash C; Casertano, Stefano; Bond, Howard E; Valenti, Jeff; Smith, T Ed; Minniti, Dante; Zoccali, Manuela; Livio, Mario; Panagia, Nino; Piskunov, Nikolai; Brown, Thomas M; Brown, Timothy; Renzini, Alvio; Rich, R Michael; Clarkson, Will; Lubow, Stephen

    2006-10-01

    More than 200 extrasolar planets have been discovered around relatively nearby stars, primarily through the Doppler line shifts owing to reflex motions of their host stars, and more recently through transits of some planets across the faces of the host stars. The detection of planets with the shortest known periods, 1.2-2.5 days, has mainly resulted from transit surveys which have generally targeted stars more massive than 0.75 M(o), where M(o) is the mass of the Sun. Here we report the results from a planetary transit search performed in a rich stellar field towards the Galactic bulge. We discovered 16 candidates with orbital periods between 0.4 and 4.2 days, five of which orbit stars of masses in the range 0.44-0.75 M(o). In two cases, radial-velocity measurements support the planetary nature of the companions. Five candidates have orbital periods below 1.0 day, constituting a new class of ultra-short-period planets, which occur only around stars of less than 0.88 M(o). This indicates that those orbiting very close to more-luminous stars might be evaporatively destroyed or that jovian planets around stars of lower mass might migrate to smaller radii.

  3. Transiting extrasolar planetary candidates in the Galactic bulge.

    PubMed

    Sahu, Kailash C; Casertano, Stefano; Bond, Howard E; Valenti, Jeff; Smith, T Ed; Minniti, Dante; Zoccali, Manuela; Livio, Mario; Panagia, Nino; Piskunov, Nikolai; Brown, Thomas M; Brown, Timothy; Renzini, Alvio; Rich, R Michael; Clarkson, Will; Lubow, Stephen

    2006-10-01

    More than 200 extrasolar planets have been discovered around relatively nearby stars, primarily through the Doppler line shifts owing to reflex motions of their host stars, and more recently through transits of some planets across the faces of the host stars. The detection of planets with the shortest known periods, 1.2-2.5 days, has mainly resulted from transit surveys which have generally targeted stars more massive than 0.75 M(o), where M(o) is the mass of the Sun. Here we report the results from a planetary transit search performed in a rich stellar field towards the Galactic bulge. We discovered 16 candidates with orbital periods between 0.4 and 4.2 days, five of which orbit stars of masses in the range 0.44-0.75 M(o). In two cases, radial-velocity measurements support the planetary nature of the companions. Five candidates have orbital periods below 1.0 day, constituting a new class of ultra-short-period planets, which occur only around stars of less than 0.88 M(o). This indicates that those orbiting very close to more-luminous stars might be evaporatively destroyed or that jovian planets around stars of lower mass might migrate to smaller radii. PMID:17024085

  4. Remote sensing of planetary properties and biosignatures on extrasolar terrestrial planets.

    PubMed

    Des Marais, David J; Harwit, Martin O; Jucks, Kenneth W; Kasting, James F; Lin, Douglas N C; Lunine, Jonathan I; Schneider, Jean; Seager, Sara; Traub, Wesley A; Woolf, Neville J

    2002-01-01

    The major goals of NASA's Terrestrial Planet Finder (TPF) and the European Space Agency's Darwin missions are to detect terrestrial-sized extrasolar planets directly and to seek spectroscopic evidence of habitable conditions and life. Here we recommend wavelength ranges and spectral features for these missions. We assess known spectroscopic molecular band features of Earth, Venus, and Mars in the context of putative extrasolar analogs. The preferred wavelength ranges are 7-25 microns in the mid-IR and 0.5 to approximately 1.1 microns in the visible to near-IR. Detection of O2 or its photolytic product O3 merits highest priority. Liquid H2O is not a bioindicator, but it is considered essential to life. Substantial CO2 indicates an atmosphere and oxidation state typical of a terrestrial planet. Abundant CH4 might require a biological source, yet abundant CH4 also can arise from a crust and upper mantle more reduced than that of Earth. The range of characteristics of extrasolar rocky planets might far exceed that of the Solar System. Planetary size and mass are very important indicators of habitability and can be estimated in the mid-IR and potentially also in the visible to near-IR. Additional spectroscopic features merit study, for example, features created by other biosignature compounds in the atmosphere or on the surface and features due to Rayleigh scattering. In summary, we find that both the mid-IR and the visible to near-IR wavelength ranges offer valuable information regarding biosignatures and planetary properties; therefore both merit serious scientific consideration for TPF and Darwin. PMID:12469366

  5. Remote sensing of planetary properties and biosignatures on extrasolar terrestrial planets

    NASA Technical Reports Server (NTRS)

    Des Marais, David J.; Harwit, Martin O.; Jucks, Kenneth W.; Kasting, James F.; Lin, Douglas N C.; Lunine, Jonathan I.; Schneider, Jean; Seager, Sara; Traub, Wesley A.; Woolf, Neville J.

    2002-01-01

    The major goals of NASA's Terrestrial Planet Finder (TPF) and the European Space Agency's Darwin missions are to detect terrestrial-sized extrasolar planets directly and to seek spectroscopic evidence of habitable conditions and life. Here we recommend wavelength ranges and spectral features for these missions. We assess known spectroscopic molecular band features of Earth, Venus, and Mars in the context of putative extrasolar analogs. The preferred wavelength ranges are 7-25 microns in the mid-IR and 0.5 to approximately 1.1 microns in the visible to near-IR. Detection of O2 or its photolytic product O3 merits highest priority. Liquid H2O is not a bioindicator, but it is considered essential to life. Substantial CO2 indicates an atmosphere and oxidation state typical of a terrestrial planet. Abundant CH4 might require a biological source, yet abundant CH4 also can arise from a crust and upper mantle more reduced than that of Earth. The range of characteristics of extrasolar rocky planets might far exceed that of the Solar System. Planetary size and mass are very important indicators of habitability and can be estimated in the mid-IR and potentially also in the visible to near-IR. Additional spectroscopic features merit study, for example, features created by other biosignature compounds in the atmosphere or on the surface and features due to Rayleigh scattering. In summary, we find that both the mid-IR and the visible to near-IR wavelength ranges offer valuable information regarding biosignatures and planetary properties; therefore both merit serious scientific consideration for TPF and Darwin.

  6. Remote sensing of planetary properties and biosignatures on extrasolar terrestrial planets.

    PubMed

    Des Marais, David J; Harwit, Martin O; Jucks, Kenneth W; Kasting, James F; Lin, Douglas N C; Lunine, Jonathan I; Schneider, Jean; Seager, Sara; Traub, Wesley A; Woolf, Neville J

    2002-01-01

    The major goals of NASA's Terrestrial Planet Finder (TPF) and the European Space Agency's Darwin missions are to detect terrestrial-sized extrasolar planets directly and to seek spectroscopic evidence of habitable conditions and life. Here we recommend wavelength ranges and spectral features for these missions. We assess known spectroscopic molecular band features of Earth, Venus, and Mars in the context of putative extrasolar analogs. The preferred wavelength ranges are 7-25 microns in the mid-IR and 0.5 to approximately 1.1 microns in the visible to near-IR. Detection of O2 or its photolytic product O3 merits highest priority. Liquid H2O is not a bioindicator, but it is considered essential to life. Substantial CO2 indicates an atmosphere and oxidation state typical of a terrestrial planet. Abundant CH4 might require a biological source, yet abundant CH4 also can arise from a crust and upper mantle more reduced than that of Earth. The range of characteristics of extrasolar rocky planets might far exceed that of the Solar System. Planetary size and mass are very important indicators of habitability and can be estimated in the mid-IR and potentially also in the visible to near-IR. Additional spectroscopic features merit study, for example, features created by other biosignature compounds in the atmosphere or on the surface and features due to Rayleigh scattering. In summary, we find that both the mid-IR and the visible to near-IR wavelength ranges offer valuable information regarding biosignatures and planetary properties; therefore both merit serious scientific consideration for TPF and Darwin.

  7. The signature of hot hydrogen in the atmosphere of the extrasolar planet HD 209458b.

    PubMed

    Ballester, Gilda E; Sing, David K; Herbert, Floyd

    2007-02-01

    About ten per cent of the known extrasolar planets are gas giants that orbit very close to their parent stars. The atmospheres of these 'hot Jupiters' are heated by the immense stellar irradiation. In the case of the planet HD 209458b, this energy deposition results in a hydrodynamic state in the upper atmosphere, allowing for sizeable expansion and escape of neutral hydrogen gas. HD 209458b was the first extrasolar planet discovered that transits in front of its parent star. The size of the planet can be measured using the total optical obscuration of the stellar disk during an observed transit, and the structure and composition of the planetary atmosphere can be studied using additional planetary absorption signatures in the stellar spectrum. Here we report the detection of absorption by hot hydrogen in the atmosphere of HD 209458b. Previously, the lower atmosphere and the full extended upper atmosphere of HD 209458b have been observed, whereas here we probe a layer where the escaping gas forms in the upper atmosphere of HD 209458b.

  8. The signature of hot hydrogen in the atmosphere of the extrasolar planet HD 209458b.

    PubMed

    Ballester, Gilda E; Sing, David K; Herbert, Floyd

    2007-02-01

    About ten per cent of the known extrasolar planets are gas giants that orbit very close to their parent stars. The atmospheres of these 'hot Jupiters' are heated by the immense stellar irradiation. In the case of the planet HD 209458b, this energy deposition results in a hydrodynamic state in the upper atmosphere, allowing for sizeable expansion and escape of neutral hydrogen gas. HD 209458b was the first extrasolar planet discovered that transits in front of its parent star. The size of the planet can be measured using the total optical obscuration of the stellar disk during an observed transit, and the structure and composition of the planetary atmosphere can be studied using additional planetary absorption signatures in the stellar spectrum. Here we report the detection of absorption by hot hydrogen in the atmosphere of HD 209458b. Previously, the lower atmosphere and the full extended upper atmosphere of HD 209458b have been observed, whereas here we probe a layer where the escaping gas forms in the upper atmosphere of HD 209458b. PMID:17268463

  9. Infrared spectra of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Townes, C. H.

    1975-01-01

    The development of high spectral resolution and highly sensitive long infrared wavelength instruments is reported. This instrumentation is used to examine molecular lines in planetary atmospheres in enough detail to obtain new information about these atmospheres. Such information includes (1) pressure and temperature relations in planetary atmospheres, and (2) molecular and isotopic composition.

  10. Planetary atmosphere modeling and predictions

    NASA Technical Reports Server (NTRS)

    Berman, A. L.

    1977-01-01

    The capability to generate spacecraft frequency predictions which include the refractive bending effects induced during signal passage through a planetary atmosphere is a pivotal element of the DSN Radio Science System. This article describes the current implementation effort to develop planetary atmosphere modeling and prediction capability.

  11. Radial Velocity Detection of Extra-Solar Planetary Systems

    NASA Technical Reports Server (NTRS)

    Cochran, William D.

    1998-01-01

    The McDonald Observatory Planetary Search (MOPS) was designed to search for Jovian-mass planets in orbit around solar-type stars by making high-precision measurements of the Radial Velocity (RV) of a star, to attempt to detect the reflex orbital motion of the star around the star-planet barycenter. In our solar system, the velocity of the Sun around the Sun-Jupiter barycenter averages 12.3 m/ s. The MOPS survey started operation in September 1987, and searches 36 bright, nearby, solar-type dwarfs to 10 m/s precision. The survey was started using telluric O2 absorption lines as the velocity reference metric. Observations use the McDonald Observatory 2.7-m Harlan Smith Telescope coude spectrograph with the six-foot camera. This spectrograph configuration isolates a single order of the echelle grating on a Texas Instruments 800 x 800 CCD. The telluric line method gave us a routine radial velocity precision of about 15 m/s for stars down to about 5-th magnitude. However, the data obtained with this technique suffered from some source of long-term systematic errors, which was probably the intrinsic velocity variability of the terrestrial atmosphere, i.e. winds. In order to eliminate this systematic error and to improve our overall measurement precision, we installed a stabilized I2 gas absorption cell as the velocity metric for the MOPS in October 1990. In use at the telescope, the cell is placed directly in front of the spectrograph entrance slit, with starlight passing through the cell. The use of this sealed stabilized I2 cell removes potential problems with possible long-term drifts in the velocity metric. The survey now includes a sample of 36 nearby F, G, and K type stars of luminosity class V or IV-V.

  12. Planetary Sciences

    NASA Astrophysics Data System (ADS)

    de Pater, Imke; Lissauer, Jack J.

    2015-01-01

    1. Introduction; 2. Dynamics; 3. Solar heating and energy transport; 4. Planetary atmospheres; 5. Planetary surfaces; 6. Planetary interiors; 7. Magnetic fields and plasmas; 8. Meteorites; 9. Minor planets; 10. Comets; 11. Planetary rings; 12. Extrasolar planets; 13. Planet formation; 14. Planets and life; Appendixes; References; Index.

  13. The chemistry of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Huntress, W. T., Jr.

    1976-01-01

    Present knowledge concerning the chemistry of planetary atmospheres is reviewed along with the theories which attempt to explain observational data. The known gross atmospheric compositions of the terrestrial and giant planets are listed, differences between the atmospheres of earth and Venus are discussed, and the atmospheres of the giant planets are described. The origin and evolution of the atmospheres of earth, Venus, Mars, Jupiter, Saturn, and Uranus are outlined, and chemical processes in the atmospheres are examined, particularly cloud formation. The question of organic synthesis and evolution in the reducing atmospheres of the giant planets is considered. It is noted that laboratory work on the individual chemical processes and reactions involved in the evolution of organic compounds in planetary atmospheres, comets, and interstellar space points to the inevitability of organic-compound synthesis in all these situations and to the pervasiveness of organic chemistry throughout the universe.

  14. An extrasolar planetary system with three Neptune-mass planets.

    PubMed

    Lovis, Christophe; Mayor, Michel; Pepe, Francesco; Alibert, Yann; Benz, Willy; Bouchy, François; Correia, Alexandre C M; Laskar, Jacques; Mordasini, Christoph; Queloz, Didier; Santos, Nuno C; Udry, Stéphane; Bertaux, Jean-Loup; Sivan, Jean-Pierre

    2006-05-18

    Over the past two years, the search for low-mass extrasolar planets has led to the detection of seven so-called 'hot Neptunes' or 'super-Earths' around Sun-like stars. These planets have masses 5-20 times larger than the Earth and are mainly found on close-in orbits with periods of 2-15 days. Here we report a system of three Neptune-mass planets with periods of 8.67, 31.6 and 197 days, orbiting the nearby star HD 69830. This star was already known to show an infrared excess possibly caused by an asteroid belt within 1 au (the Sun-Earth distance). Simulations show that the system is in a dynamically stable configuration. Theoretical calculations favour a mainly rocky composition for both inner planets, while the outer planet probably has a significant gaseous envelope surrounding its rocky/icy core; the outer planet orbits within the habitable zone of this star.

  15. Can The Periods of Some Extra-Solar Planetary Systems be Quantized?

    NASA Astrophysics Data System (ADS)

    El Fady Morcos, Abd

    A simple formula was derived before by Morcos (2013 ), to relate the quantum numbers of planetary systems and their periods. This formula is applicable perfectly for the solar system planets, and some extra-solar planets , of stars of approximately the same masses like the Sun. This formula has been used to estimate the periods of some extra-solar planet of known quantum numbers. The used quantum numbers were calculated previously by other authors. A comparison between the observed and estimated periods, from the given formula has been done. The differences between the observed and calculated periods for the extra-solar systems have been calculated and tabulated. It is found that there is an error of the range of 10% The same formula has been also used to find the quantum numbers, of some known periods, exo-planet. Keywords: Quantization; Periods; Extra-Planetary; Extra-Solar Planet REFERENCES [1] Agnese, A. G. and Festa, R. “Discretization on the Cosmic Scale Inspirred from the Old Quantum Mechanics,” 1998. http://arxiv.org/abs/astro-ph/9807186 [2] Agnese, A. G. and Festa, R. “Discretizing ups-Andro- medae Planetary System,” 1999. http://arxiv.org/abs/astro-ph/9910534. [3] Barnothy, J. M. “The Stability of the Solar Systemand of Small Stellar Systems,” Proceedings of the IAU Sympo-sium 62, Warsaw, 5-8 September 1973, pp. 23-31. [4] Morcos, A.B. , “Confrontation between Quantized Periods of Some Extra-Solar Planetary Systems and Observations”, International Journal of Astronomy and Astrophysics, 2013, 3, 28-32. [5] Nottale, L. “Fractal Space-Time and Microphysics, To-wards a Theory of Scale Relativity,” World Scientific, London, 1994. [6] Nottale , L., “Scale-Relativity and Quantization of Extra- Solar Planetary Systems,” Astronomy & Astrophysics, Vol. 315, 1996, pp. L9-L12 [7] Nottale, L., Schumacher, G. and Gay, J. “Scale-Relativity and Quantization of the Solar Systems,” Astronomy & Astrophysics letters, Vol. 322, 1997, pp. 1018-10 [8

  16. Planetary Formation: From The Earth And Moon To Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, Donald (Technical Monitor)

    1999-01-01

    An overview of current theories of planetary growth, emphasizing the formation of habitable planets, is presented. These models are based upon observations of the Solar System and of young stars and their environments. They predict that rocky planets should form around most single stars, although it is possible that in some cases such planets are lost - to orbital decay within the protoplanetary disk. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth like terrestrial planets, but if they become massive enough before the protoplanetary disk dissipates, then they are able to accumulate substantial amounts of gas. Specific issues to be discussed include: (1) how do giant planets influence the formation and habitability of terrestrial planets? (2) could a giant impact leading to lunar formation have occurred - 100 million years after the condensation of the oldest meteorites?

  17. The search for extra-solar planetary systems.

    PubMed

    Paresce, F

    1992-01-01

    I review the observational evidence for planetary systems around nearby stars and, using our own solar system as a guide, assess the stringent requirements that new searches need to meet in order to unambiguously establish the presence of another planetary system. Basically, these requirements are: 1 milliarcsecond or better positional accuracy for astrometric techniques, 9 orders of magnitude or better star to planet luminosity ratio discrimination at 0.5 to 1" separation in the optical for direct imaging techniques, 10 meters sec-1 or better radial velocity accuracy for reflex motion techniques and +/-1% or better brightness fluctuation accuracy for planet/star occultation measurements. The astrometric accuracy is in reach of HST, direct imaging will require much larger telescopes and/or a 50 times smoother mirror than HST while the reflex motion and occultation techniques best performed on the ground are just becoming viable and promise exciting new discoveries. On the other band, new indirect evidence on the existence of other planetary systems also comes from the observation of large dusty disks around nearby main sequence stars not too dissimilar from our sun. In one particular case, that of Beta Pictoris, a flattened disk seen nearly edge-on has been imaged in the optical and near IR down to almost 70 AU of the star. It probably represents a young planetary system in its clearing out phase as planetesimals collide, erode and are swept out of the inner system by radiation pressure. The hypothesized Kuiper belt around our solar system may be the analogous structure in a later evolutionary stage. Features of this type have been detected in the far IR and sub-millimeter wavelength regions around 50-100 nearby main sequence and pre-main sequence stars. I discuss a battery of new accurate observations planned in the near future of these objects some of which may actually harbour planets or planetesimals that will certainly dramatically improve our knowledge of

  18. Carbon Monoxide Affecting Planetary Atmospheric Chemistry

    NASA Astrophysics Data System (ADS)

    He, Chao; Horst, Sarah

    2016-10-01

    Atmospheric hazes are present in a range of solar system and extrasolar planetary atmospheres, and organic hazes, such as that in Titan's atmosphere, could be a source of prebiotic molecules.1 However, the chemistry occurring in planetary atmospheres and the resulting chemical structures are still not clear. Numerous experimental simulations2 have been carried out in the laboratory to understand the chemistry in N2/CH4 atmospheres, but very few simulations4 have included CO in their initial gas mixtures, which is an important component in many N2/CH4 atmospheres including Titan, Triton, and Pluto.3 Here we have conducted a series of atmosphere simulation experiments using AC glow discharge (cold plasma) as energy source to irradiate reactions in gas mixtures of CO, CH4, and N2 with a range of CO mixing ratios (from 0, 0.05%, 0.2%, 0.5%, 1%, 2.5%, to 5%) at low temperature (~100 K). Gas phase products are monitored during the reaction by quadrupole mass spectrometer (MS), and solid phase products are analyzed by solution-state nuclear magnetic resonance spectroscopy (NMR). MS results show that with the increase of CO in the initial gases, the production of nitrogenous organic molecules increases while the production of hydrogen molecules decreases in the gas phase. NMR measurements of the solid phase products show that with the increase of CO, hydrogen atoms bonded to nitrogen or oxygen in unsaturated structures increase while those bonded to saturated carbon decrease, which means more unsaturated species and less saturated species formed with the addition of CO. MS and NMR results demonstrate that the inclusion of CO affects the compositions of both gas and solid phase products, indicating that CO has an important impact on the chemistry occurring in our experiments and probably in planetary atmospheres.1. Hörst, S. M., et al. 2012, AsBio, 12, 8092. Cable, M. L., et al. 2012, Chem. Rev., 112, 18823. Lutz, B. L., et al. 1983, Sci, 220, 1374; Greaves, J. S., et al

  19. Studies of Tenuous Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Combi, Michael R.

    1997-01-01

    In order to understand the physical and chemical processes which produce the dust comae in comets and various tenuous planetary and planetary satellite (upper) atmospheres through interactions with their particle, field, and radiation environs, it is necessary analyze remotely observed and spacecraft data with physically meaningful models. With this in mind, we have undertaken a coupled program of theoretical modeling and complementary data analysis regarding the distribution of dust in comets, and the global distributions of neutral and ionized gases in, and escape from, tenuous planetary atmospheres. The nature of the atmospheres and ionospheres of Jupiter's natural satellites Io and Europa and their interactions with their surrounding radiation, and particles and fields environments is a very active and timely field of study. Various kinds of work, depending on different regime-dependent approaches have been adopted in recent years, with the hope of understanding the basic global structure of the atmospheres, and their interactions with solar radiation and with the Jovian plasma torus environment. Io's interaction with Jupiter's corotating plasma torus has been studied for over 25 years. Io has a neutral atmosphere which is probably locally thick but rather uneven across its surface. (See Lellouch 1996 for an excellent review of pre-1996 literature.) The ultimate source for atmospheric gases appears to be the numerous active volcanoes on the surface, moderated by condensation and sublimation from the surface. The energetic particle environment near Io is responsible for the balance of the plasma heating, Joule heating, ionization, and surface d responsible I an atmospheric sputtering, and in some form drives the escape of the neutral atmosphere. The tenuous atmosphere portion of our work involves developing and applying coupled three-dimensional magnetohydrodynamic (MHD) and fully kinetic ion and neutral Direct Simulation Monte Carlo models to describe the upper

  20. Clouds in Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    West, R.

    1999-01-01

    In the terrestrial atmosphere clouds are familiar as vast collections of small water drops or ice cyrstals suspended in the air. The study of clouds touches on many facets of armospheric science. The chemistry of clouds is tied to the chemistry of the surrounding atmosphere.

  1. Dynamical Instabilities and the Formation of Extrasolar Planetary Systems

    PubMed

    Rasio; Ford

    1996-11-01

    The existence of a dominant massive planet, Jupiter, in our solar system, although perhaps essential for long-term dynamical stability and the development of life, may not be typical of planetary systems that form around other stars. In a system containing two Jupiter-like planets, the possibility exists that a dynamical instability will develop. Computer simulations suggest that in many cases this instability leads to the ejection of one planet while the other is left in a smaller, eccentric orbit. In extreme cases, the eccentric orbit has a small enough periastron distance that it may circularize at an orbital period as short as a few days through tidal dissipation. This may explain the recently detected Jupiter-mass planets in very tight circular orbits and wider eccentric orbits around nearby stars.

  2. Deciphering the Hot Giant Atmospheres Orbiting Nearby Extrasolar Systems with JWST

    NASA Astrophysics Data System (ADS)

    Afrin Badhan, Mahmuda; Batalha, Natasha; Deming, Drake; Domagal-Goldman, Shawn; HEBRARD, Eric; Kopparapu, Ravi Kumar; Irwin, Patrick Gerard Joseph

    2016-10-01

    Unique and exotic planets give us an opportunity to understand how planetary systems form and evolve over their lifetime, by placing our own planetary system in the context of the vastly different extrasolar systems that are being continually discovered by present space missions. With orbital separations that are less than one-tenth of the Mercury-Sun distance, these close-in planets provide us with valuable insights about the host stellar atmosphere and planetary atmospheres subjected to their enormous stellar insolation. Observed spectroscopic signatures reveal all spectrally active species in a planet, along with information about its thermal structure and dynamics, allowing us to characterize the planet's atmosphere. NASA's upcoming missions will give us the high-resolution spectra necessary to constrain the atmospheric properties with unprecedented accuracy. However, to interpret the observed signals from exoplanetary transit events with any certainty, we need reliable atmospheric retrieval tools that can model the expected observables adequately. In my work thus far, I have built a Markov Chain Monte Carlo (MCMC) convergence scheme, with an analytical radiative equilibrium formulation for the thermal structures, within the NEMESIS atmospheric modeling tool, to allow sufficient (and efficient) exploration of the parameter space. I also augmented the opacity tables to improve the speed and reliability of retrieval models. I then utilized this upgraded version to infer the pressure-temperature (P-T) structures and volume-mixing ratios (VMRs) of major gas species in hot Jupiter dayside atmospheres, from their emission spectra. I have employed a parameterized thermal structure to retrieve plausible P-T profiles, along with altitude-invariant VMRs. Here I show my retrieval results on published datasets of HD189733b, and compare them with both medium and high spectral resolution JWST/NIRSPEC simulations. In preparation for the upcoming JWST mission, my current work

  3. The Role of Carbon in Extrasolar Planetary Geodynamics and Habitability

    NASA Astrophysics Data System (ADS)

    Unterborn, Cayman T.; Kabbes, Jason E.; Pigott, Jeffrey S.; Reaman, Daniel M.; Panero, Wendy R.

    2014-10-01

    The proportions of oxygen, carbon, and major rock-forming elements (e.g., Mg, Fe, Si) determine a planet's dominant mineralogy. Variation in a planet's mineralogy subsequently affects planetary mantle dynamics as well as any deep water or carbon cycle. Through thermodynamic models and high pressure diamond anvil cell experiments, we demonstrate that the oxidation potential of C is above that of Fe at all pressures and temperatures, indicative of 0.1-2 Earth-mass planets. This means that for a planet with (Mg+2Si+Fe+2C)/O > 1, excess C in the mantle will be in the form of diamond. We find that an increase in C, and thus diamond, concentration slows convection relative to a silicate-dominated planet, due to diamond's ~3 order of magnitude increase in both viscosity and thermal conductivity. We assert then that in the C-(Mg+2Si+Fe)-O system, there is a compositional range in which a planet can be habitable. Planets outside of this range will be dynamically sluggish or stagnant, thus having limited carbon or water cycles leading to surface conditions inhospitable to life as we know it.

  4. The role of carbon in extrasolar planetary geodynamics and habitability

    SciTech Connect

    Unterborn, Cayman T.; Kabbes, Jason E.; Pigott, Jeffrey S.; Panero, Wendy R.; Reaman, Daniel M.

    2014-10-01

    The proportions of oxygen, carbon, and major rock-forming elements (e.g., Mg, Fe, Si) determine a planet's dominant mineralogy. Variation in a planet's mineralogy subsequently affects planetary mantle dynamics as well as any deep water or carbon cycle. Through thermodynamic models and high pressure diamond anvil cell experiments, we demonstrate that the oxidation potential of C is above that of Fe at all pressures and temperatures, indicative of 0.1-2 Earth-mass planets. This means that for a planet with (Mg+2Si+Fe+2C)/O > 1, excess C in the mantle will be in the form of diamond. We find that an increase in C, and thus diamond, concentration slows convection relative to a silicate-dominated planet, due to diamond's ∼3 order of magnitude increase in both viscosity and thermal conductivity. We assert then that in the C-(Mg+2Si+Fe)-O system, there is a compositional range in which a planet can be habitable. Planets outside of this range will be dynamically sluggish or stagnant, thus having limited carbon or water cycles leading to surface conditions inhospitable to life as we know it.

  5. Dynamics of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Ingersoll, Andrew P.

    1989-01-01

    The overall goal is to illuminate the mechanisms that control weather and climate on the Earth and other planets. Each planet presents its own puzzling behavior - the stability of jets and vortices in Jupiter's otherwise turbulent atmosphere, the superrotation of the Venus atmosphere, the interplay of dust, polar volatiles, and climate change in Mars, the supersonic meteorology of Io, and the counterintuitive equator-to-pole temperature gradients on the outer planets. The data sets are generally those obtained from spacecraft - cloud-tracked winds, radiometrically inferred temperatures, and the results of in situ observations where appropriate. The approach includes both data analysis and modeling, ranging from analytic modeling to time-dependent numerical modeling of atmospheric dynamics. The latter approach involves the use of supercomputers such as the San Diego Cray. Progress is generally made when a model with a small number of free parameters either fits a data set that has a large number of independent observations or applies to several planets at once.

  6. Theoretical spectra and atmospheres of extrasolar giant planets

    NASA Astrophysics Data System (ADS)

    Sudarsky, David L.

    This work is a detailed study of extrasolar giant planet (EGP) atmospheres and spectra. Models representative of the full range of systems known today are included, from the extreme close-in EGPs to Jovian-like planets at large orbital radii. Using a self-consistent planar atmosphere code along with the latest atomic and molecular cross sections, cloud models, Mie theory treatment of grain scattering and absorption, and incident stellar fluxes, I produce an extensive set of theoretical EGP atmosphere models and emergent spectra. The emergent spectra of EGPs strongly depend upon their outer atmospheric chemical compositions, which in turn depend upon the run of temperature and pressure with atmospheric depth. Because of qualitative similarities in the compositions and spectra of objects within several broad temperature ranges, EGPs fall naturally into five groups, or composition classes. Such a classification scheme, however preliminary, brings a degree of order to the rich variety of EGP systems known to exist today. Generic models that represent the EGP classes, as well as a set of specific models for a number of important systems that have been detected, are provided. Furthermore, the effects on emergent EGP spectra of varying key parameters such as surface gravity, cloud particle sizes, orbital distance, etc. are modeled. A discussion of current and future ground-based and space- based missions to detect and characterize EGPs in light of theoretical spectral models is included to facilitate an understanding of which systems are most likely to be studied successfully.

  7. Spectroscopy of planetary atmospheres in our Galaxy

    NASA Astrophysics Data System (ADS)

    Tinetti, Giovanna; Encrenaz, Thérèse; Coustenis, Athena

    2013-10-01

    About 20 years after the discovery of the first extrasolar planet, the number of planets known has grown by three orders of magnitude, and continues to increase at neck breaking pace. For most of these planets we have little information, except for the fact that they exist and possess an address in our Galaxy. For about one third of them, we know how much they weigh, their size and their orbital parameters. For less than 20, we start to have some clues about their atmospheric temperature and composition. How do we make progress from here? We are still far from the completion of a hypothetical Hertzsprung-Russell diagram for planets comparable to what we have for stars, and today we do not even know whether such classification will ever be possible or even meaningful for planetary objects. But one thing is clear: planetary parameters such as mass, radius and temperature alone do not explain the diversity revealed by current observations. The chemical composition of these planets is needed to trace back their formation history and evolution, as happened for the planets in our Solar System. As in situ measurements are and will remain off-limits for exoplanets, to study their chemical composition we will have to rely on remote sensing spectroscopic observations of their gaseous envelopes. In this paper, we critically review the key achievements accomplished in the study of exoplanet atmospheres in the past ten years. We discuss possible hurdles and the way to overcome those. Finally, we review the prospects for the future. The knowledge and the experience gained with the planets in our solar system will guide our journey among those faraway worlds.

  8. ROCKY EXTRASOLAR PLANETARY COMPOSITIONS DERIVED FROM EXTERNALLY POLLUTED WHITE DWARFS

    SciTech Connect

    Klein, B.; Jura, M.; Zuckerman, B.; Koester, D. E-mail: jura@astro.ucla.edu E-mail: koester@astrophysik.uni-kiel.de

    2011-11-01

    We report Keck High Resolution Echelle Spectrometer data and model atmosphere analysis of two helium-dominated white dwarfs, PG1225-079 and HS2253+8023, whose heavy pollutions most likely derive from the accretion of terrestrial-type planet(esimal)s. For each system, the minimum accreted mass is {approx}10{sup 22} g, that of a large asteroid. In PG1225-079, Mg, Cr, Mn, Fe, and Ni have abundance ratios similar to bulk Earth values, while we measure four refractory elements, Ca, Sc, Ti, and V, all at a factor of {approx}2-3 higher abundance than in the bulk Earth. For HS2253+8023 the swallowed material was compositionally similar to bulk Earth in being more than 85% by mass in the major element species, O, Mg, Si, and Fe, and with abundances in the distinctive proportions of mineral oxides-compelling evidence for an origin in a rocky parent body. Including previous studies we now know of four heavily polluted white dwarfs where the measured oxygen and hydrogen are consistent with the view that the parents' bodies formed with little ice, interior to any snow line in their nebular environments. The growing handful of polluted white dwarf systems with comprehensive abundance measurements form a baseline for characterizing rocky exoplanet compositions that can be compared with bulk Earth.

  9. Rapid heating of the atmosphere of an extrasolar planet.

    PubMed

    Laughlin, Gregory; Deming, Drake; Langton, Jonathan; Kasen, Daniel; Vogt, Steve; Butler, Paul; Rivera, Eugenio; Meschiari, Stefano

    2009-01-29

    Near-infrared observations of more than a dozen 'hot-Jupiter' extrasolar planets have now been reported. These planets display a wide diversity of properties, yet all are believed to have had their spin periods tidally spin-synchronized with their orbital periods, resulting in permanent star-facing hemispheres and surface flow patterns that are most likely in equilibrium. Planets in significantly eccentric orbits can enable direct measurements of global heating that are largely independent of the details of the hydrodynamic flow. Here we report 8-microm photometric observations of the planet HD 80606b during a 30-hour interval bracketing the periastron passage of its extremely eccentric 111.4-day orbit. As the planet received its strongest irradiation (828 times larger than the flux received at apastron) its maximum 8-microm brightness temperature increased from approximately 800 K to approximately 1,500 K over a six-hour period. We also detected a secondary eclipse for the planet, which implies an orbital inclination of i approximately 90 degrees , fixes the planetary mass at four times the mass of Jupiter, and constrains the planet's tidal luminosity. Our measurement of the global heating rate indicates that the radiative time constant at the planet's 8-microm photosphere is approximately 4.5 h, in comparison with 3-5 days in Earth's stratosphere.

  10. Rapid heating of the atmosphere of an extrasolar planet

    NASA Astrophysics Data System (ADS)

    Laughlin, Gregory; Deming, Drake; Langton, Jonathan; Kasen, Daniel; Vogt, Steve; Butler, Paul; Rivera, Eugenio; Meschiari, Stefano

    2009-01-01

    Near-infrared observations of more than a dozen `hot-Jupiter' extrasolar planets have now been reported. These planets display a wide diversity of properties, yet all are believed to have had their spin periods tidally spin-synchronized with their orbital periods, resulting in permanent star-facing hemispheres and surface flow patterns that are most likely in equilibrium. Planets in significantly eccentric orbits can enable direct measurements of global heating that are largely independent of the details of the hydrodynamic flow. Here we report 8-μm photometric observations of the planet HD80606b during a 30-hour interval bracketing the periastron passage of its extremely eccentric 111.4-day orbit. As the planet received its strongest irradiation (828 times larger than the flux received at apastron) its maximum 8-μm brightness temperature increased from ~800K to ~1,500K over a six-hour period. We also detected a secondary eclipse for the planet, which implies an orbital inclination of i~90°, fixes the planetary mass at four times the mass of Jupiter, and constrains the planet's tidal luminosity. Our measurement of the global heating rate indicates that the radiative time constant at the planet's 8-μm photosphere is ~4.5 h, in comparison with 3-5 days in Earth's stratosphere.

  11. The HARPS search for southern extra-solar planets. XXVII. Seven new planetary systems

    NASA Astrophysics Data System (ADS)

    Moutou, C.; Mayor, M.; Lo Curto, G.; Ségransan, D.; Udry, S.; Bouchy, F.; Benz, W.; Lovis, C.; Naef, D.; Pepe, F.; Queloz, D.; Santos, N. C.; Sousa, S. G.

    2011-03-01

    We are conducting a planet search survey with HARPS since seven years. The volume-limited stellar sample includes all F2 to M0 main-sequence stars within 57.5 pc, where extrasolar planetary signatures are systematically searched for with the radial-velocity technics. In this paper, we report the discovery of new substellar companions of seven main-sequence stars and one giant star, detected through multiple Doppler measurements with the instrument HARPS installed on the ESO 3.6 m telescope, La Silla, Chile. These extrasolar planets orbit the stars HD 1690, HD 25171, HD 33473A, HD 89839, HD 113538, HD 167677, and HD 217786. The already-published giant planet around HD 72659 is also analysed here, and its elements are better determined by the addition of HARPS and Keck data. The other discoveries are giant planets in distant orbits, ranging from 0.3 to 29 MJup in mass and between 0.7 and 10 years in orbital period. The low metallicity of most of these new planet-hosting stars reinforces the current trend for long-distance planets around metal-poor stars. Long-term radial-velocity surveys allow probing the outskirts of extrasolar planetary systems, although confidence in the solution may be low until more than one orbital period is fully covered by the observations. For many systems discussed in this paper, longer baselines are necessary to refine the radial-velocity fit and derive planetary parameters. The radial-velocity time series of stars BD -114672 and HIP 21934 are also analysed and their behaviour interpreted in terms of the activity cycle of the star, rather than long-period planetary companions. Based on observations made with the HARPS instrument on the ESO 3.6 m telescope at La Silla Observatory under programme IDs 072.C-0488(E) and 085.C-0019.RV data are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/527/A63

  12. Water vapour in the atmosphere of a transiting extrasolar planet.

    PubMed

    Tinetti, Giovanna; Vidal-Madjar, Alfred; Liang, Mao-Chang; Beaulieu, Jean-Philippe; Yung, Yuk; Carey, Sean; Barber, Robert J; Tennyson, Jonathan; Ribas, Ignasi; Allard, Nicole; Ballester, Gilda E; Sing, David K; Selsis, Franck

    2007-07-12

    Water is predicted to be among the most abundant (if not the most abundant) molecular species after hydrogen in the atmospheres of close-in extrasolar giant planets ('hot Jupiters'). Several attempts have been made to detect water on such planets, but have either failed to find compelling evidence for it or led to claims that should be taken with caution. Here we report an analysis of recent observations of the hot Jupiter HD 189733b (ref. 6) taken during the transit, when the planet passed in front of its parent star. We find that absorption by water vapour is the most likely cause of the wavelength-dependent variations in the effective radius of the planet at the infrared wavelengths 3.6 mum, 5.8 mum (both ref. 7) and 8 mum (ref. 8). The larger effective radius observed at visible wavelengths may arise from either stellar variability or the presence of clouds/hazes. We explain the report of a non-detection of water on HD 189733b (ref. 4) as being a consequence of the nearly isothermal vertical profile of the planet's atmosphere.

  13. Modelling the formation of atmospheric dust in brown dwarfs and planetary atmospheres.

    PubMed

    Helling, Christiane; Fomins, Aleksejs

    2013-07-13

    Atmospheric dust from volcanoes, sand storms and biogenic products provides condensation seeds for water cloud formation on the Earth. Extrasolar planetary objects such as brown dwarfs and extrasolar giant planets have no comparable sources of condensation seeds. Hence, understanding cloud formation and further its implications for the climate requires a modelling effort that includes the treatment of seed formation (nucleation), growth and evaporation, in addition to rain-out, mixing and gas-phase depletion. This paper discusses nucleation in the ultra-cool atmospheres of brown dwarfs and extrasolar giant planets whose chemical gas-phase composition differs largely from the terrestrial atmosphere. A kinetic model for atmospheric dust formation is described, which, in recent work, has become part of a cloud-formation model. For the first time, diffusive replenishment of the upper atmosphere is introduced as a source term into our model equations. This paper further aims to show how experimental and computational chemistry work links into our dust-formation model, which is driven by applications in extraterrestrial environments. PMID:23734048

  14. Spectral Signatures of Photosynthesis. II. Coevolution with Other Stars And The Atmosphere on Extrasolar Worlds

    NASA Astrophysics Data System (ADS)

    Kiang, Nancy Y.; Segura, Antígona; Tinetti, Giovanna; Govindjee; Blankenship, Robert E.; Cohen, Martin; Siefert, Janet; Crisp, David; Meadows, Victoria S.

    2007-02-01

    As photosynthesis on Earth produces the primary signatures of life that can be detected astronomically at the global scale, a strong focus of the search for extrasolar life will be photosynthesis, particularly photosynthesis that has evolved with a different parent star. We take previously simulated planetary atmospheric compositions for Earth-like planets around observed F2V and K2V, modeled M1V and M5V stars, and around the active M4.5V star AD Leo; our scenarios use Earth's atmospheric composition as well as very low O2 content in case anoxygenic photosynthesis dominates. With a line-by-line radiative transfer model, we calculate the incident spectral photon flux densities at the surface of the planet and under water. We identify bands of available photosynthetically relevant radiation and find that photosynthetic pigments on planets around F2V stars may peak in absorbance in the blue, K2V in the red-orange, and M stars in the near-infrared, in bands at 0.93-1.1 μm, 1.1-1.4 μm, 1.5-1.8 μ m, and 1.8-2.5 μm. However, underwater organisms will be restricted to wavelengths shorter than 1.4 μm and more likely below 1.1 μm. M star planets without oxygenic photosynthesis will have photon fluxes above 1.6 μm curtailed by methane. Longer-wavelength, multi-photo-system series would reduce the quantum yield but could allow for oxygenic photosystems at longer wavelengths. A wavelength of 1.1 μm is a possible upper cutoff for electronic transiprotions versus only vibrational energy; however, this cutoff is not strict, since such energetics depend on molecular configuration. M star planets could be a half to a tenth as productive as Earth in the visible, but exceed Earth if useful photons extend to 1.1 μm for anoxygenic photosynthesis. Under water, organisms would still be able to survive ultraviolet flares from young M stars and acquire adequate light for growth. Key Words: Photosynthesis-Astrobiology - Photosynthetic pigments - Oxygenic photosynthesis - Anoxygenic

  15. On the Abundance of Water in Extrasolar Planetary Systems as a Function of Stellar Metallicity

    NASA Astrophysics Data System (ADS)

    Dominguez, Gerardo

    2016-06-01

    The discovery, to date, of several hundred confirmed extra solar planets and a statistical analysis of their properties has revealed intriguing patterns in the abundance and types of extrasolar planets. The metallicity of the host star appears to be a driver in determining extrasolar planetary system characteristics, although a mechanistic understanding of these relationships is not currently available. Understanding the broad relationship(s) between the characteristics of extrasolar planets and stellar metallicity thus appears timely.Recent work examining the timescales for water production in protoplanetary disks suggest that ionizing radiation required to drive surface chemistry in protoplanetary disks is insufficient and production timescales too slow to account for a significant amount of water in protoplanetary disks. Here we focus on the timescales for water production in cold molecular clouds and examine the relationship of this timescale as a function of molecular cloud metallicity. To do this, we consider the distribution of surface area concentration (dA/dV) in molecular clouds as a function of their metallicity and various MRN-like dust grain size distributions. We find that molecular cloud metallicity is a significant factor in determining upper-limits to the availability of water in molecular clouds and by extension, protoplanetary disks. The spectral index of the MRN distribution affects the upper-limits to H2O abundance, but the effect is not as significant as metallicity. We find that the ratio of H2O/SiO2 produced in a molecular cloud of solar metallicity can easily account for Earth’s present day ratio , supporting the “wet” hypothesis for the origins of Earth’s water. Future studies will focus on the retention of water on interstellar dust grain surfaces in protoplanetary disk environments inside the water line, the abundance of other volatile species, more detailed estimates of H2O destruction timescales in molecular clouds, and

  16. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. III. BREAKDOWN CONDITIONS FOR MINERAL CLOUDS

    SciTech Connect

    Helling, Ch.; Jardine, M.; Stark, C.; Diver, D.

    2013-04-20

    Electric discharges were detected directly in the cloudy atmospheres of Earth, Jupiter, and Saturn, are debatable for Venus, and indirectly inferred for Neptune and Uranus in our solar system. Sprites (and other types of transient luminous events) have been detected only on Earth, and are theoretically predicted for Jupiter, Saturn, and Venus. Cloud formation is a common phenomenon in ultra-cool atmospheres such as in brown dwarf and extrasolar planetary atmospheres. Cloud particles can be expected to carry considerable charges which may trigger discharge events via small-scale processes between individual cloud particles (intra-cloud discharges) or large-scale processes between clouds (inter-cloud discharges). We investigate electrostatic breakdown characteristics, like critical field strengths and critical charge densities per surface, to demonstrate under which conditions mineral clouds undergo electric discharge events which may trigger or be responsible for sporadic X-ray emission. We apply results from our kinetic dust cloud formation model that is part of the DRIFT-PHOENIX model atmosphere simulations. We present a first investigation of the dependence of the breakdown conditions in brown dwarf and giant gas exoplanets on the local gas-phase chemistry, the effective temperature, and primordial gas-phase metallicity. Our results suggest that different intra-cloud discharge processes dominate at different heights inside mineral clouds: local coronal (point discharges) and small-scale sparks at the bottom region of the cloud where the gas density is high, and flow discharges and large-scale sparks near, and maybe above, the cloud top. The comparison of the thermal degree of ionization and the number density of cloud particles allows us to suggest the efficiency with which discharges will occur in planetary atmospheres.

  17. Chemical kinetics on extrasolar planets.

    PubMed

    Moses, Julianne I

    2014-04-28

    Chemical kinetics plays an important role in controlling the atmospheric composition of all planetary atmospheres, including those of extrasolar planets. For the hottest exoplanets, the composition can closely follow thermochemical-equilibrium predictions, at least in the visible and infrared photosphere at dayside (eclipse) conditions. However, for atmospheric temperatures approximately <2000K, and in the uppermost atmosphere at any temperature, chemical kinetics matters. The two key mechanisms by which kinetic processes drive an exoplanet atmosphere out of equilibrium are photochemistry and transport-induced quenching. I review these disequilibrium processes in detail, discuss observational consequences and examine some of the current evidence for kinetic processes on extrasolar planets. PMID:24664912

  18. Chemical kinetics on extrasolar planets.

    PubMed

    Moses, Julianne I

    2014-04-28

    Chemical kinetics plays an important role in controlling the atmospheric composition of all planetary atmospheres, including those of extrasolar planets. For the hottest exoplanets, the composition can closely follow thermochemical-equilibrium predictions, at least in the visible and infrared photosphere at dayside (eclipse) conditions. However, for atmospheric temperatures approximately <2000K, and in the uppermost atmosphere at any temperature, chemical kinetics matters. The two key mechanisms by which kinetic processes drive an exoplanet atmosphere out of equilibrium are photochemistry and transport-induced quenching. I review these disequilibrium processes in detail, discuss observational consequences and examine some of the current evidence for kinetic processes on extrasolar planets.

  19. PLANET-PLANET SCATTERING IN PLANETESIMAL DISKS. II. PREDICTIONS FOR OUTER EXTRASOLAR PLANETARY SYSTEMS

    SciTech Connect

    Raymond, Sean N.; Armitage, Philip J.; Gorelick, Noel

    2010-03-10

    We develop an idealized dynamical model to predict the typical properties of outer extrasolar planetary systems, at radii comparable to the Jupiter-to-Neptune region of the solar system. The model is based upon the hypothesis that dynamical evolution in outer planetary systems is controlled by a combination of planet-planet scattering and planetary interactions with an exterior disk of small bodies ('planetesimals'). Our results are based on 5000 long duration N-body simulations that follow the evolution of three planets from a few to 10 AU, together with a planetesimal disk containing 50 M{sub +} from 10 to 20 AU. For large planet masses (M {approx}> M{sub Sat}), the model recovers the observed eccentricity distribution of extrasolar planets. For lower-mass planets, the range of outcomes in models with disks is far greater than that which is seen in isolated planet-planet scattering. Common outcomes include strong scattering among massive planets, sudden jumps in eccentricity due to resonance crossings driven by divergent migration, and re-circularization of scattered low-mass planets in the outer disk. We present the distributions of the eccentricity and inclination that result, and discuss how they vary with planet mass and initial system architecture. In agreement with other studies, we find that the currently observed eccentricity distribution (derived primarily from planets at a {approx}< 3 AU) is consistent with isolated planet-planet scattering. We explain the observed mass dependence-which is in the opposite sense from that predicted by the simplest scattering models-as a consequence of strong correlations between planet masses in the same system. At somewhat larger radii, initial planetary mass correlations and disk effects can yield similar modest changes to the eccentricity distribution. Nonetheless, strong damping of eccentricity for low-mass planets at large radii appears to be a secure signature of the dynamical influence of disks. Radial velocity

  20. Planetary Atmospheres at High Resolution

    NASA Astrophysics Data System (ADS)

    Gurwell, M.; Butler, B.; Moullet, A.

    2013-10-01

    The long millimeter through submillimeter bands are particularly well suited for studying the wide variety of planetary atmospheres in our solar system. Temperatures ranging from a few 10s to hundreds of degrees, coupled with typically high densities (relative to the ISM) mean that thermal ‘continuum’ emission can be strong and molecular rotational transitions can be well-populated. Large bodies (Jovian and terrestrial planets) can be reasonably well studied by current interferometers such as the Submillimeter Array, IRAM Plateau de Bure Interferometer, and Combined Array for Research in Millimeter-wave Astronomy, yet many smaller bodies with atmospheres can only be crudely studied, primarily due to lack of sensitivity on baselines long enough to well resolve the object. Newly powerful interferometers such as the Atacama Large Millimeter/Submillimeter Array will usher in a new era of planetary atmospheric exploration. The vast sensitivity and spatial resolution of these arrays will increase our ability to image all bodies with extremely fine fidelity (due to the large number of antennas), and for study of smaller objects by resolving their disks into many pixels while providing the sensitivity necessary to detect narrow and/or weak line emission. New science topics will range from detailed mapping of HDO, ClO, and sulfur species in the mesosphere of Venus and PH3 and H2S in the upper tropospheres of the gas and ice giants, high SNR mapping of winds on Mars, Neptune and Titan, down to spectroscopic imaging of volcanic eruptions within the tenuous atmosphere on Io, resolved imaging of CO and other species in the atmosphere of Pluto, and even potentially detection of gases within the plumes of Enceladus.

  1. Fundamental Planetary Science

    NASA Astrophysics Data System (ADS)

    Lissauer, Jack J.; de Pater, Imke

    2013-10-01

    1. Introduction; 2. Dynamics; 3. Solar heating and energy transport; 4. Planetary atmospheres; 5. Planetary surfaces; 6. Planetary interiors; 7. Magnetic fields and plasmas; 8. Meteorites; 9. Minor planets; 10. Comets; 11. Planetary rings; 12. Extrasolar planets; 13. Planet formation; 14. Planets and life; Index.

  2. The role of planetary formation and evolution in shaping the composition of exoplanetary atmospheres

    NASA Astrophysics Data System (ADS)

    Turrini, D.; Nelson, R. P.; Barbieri, M.

    2015-12-01

    Over the last twenty years, the search for extrasolar planets has revealed the rich diversity of outcomes from the formation and evolution of planetary systems. In order to fully understand how these extrasolar planets came to be, however, the orbital and physical data we possess are not enough, and they need to be complemented with information about the composition of the exoplanets. Ground-based and space-based observations provided the first data on the atmospheric composition of a few extrasolar planets, but a larger and more detailed sample is required before we can fully take advantage of it. The primary goal of a dedicated space mission like the Exoplanet Characterization Observatory (EChO) proposal is to fill this gap and to expand the limited data we possess by performing a systematic survey of extrasolar planets. The full exploitation of the data that space-based and ground-based facilities will provide in the near future, however, requires knowledge about the sources and sinks of the chemical species and molecules that will be observed. Luckily, the study of the past history of the Solar System provides several indications about the effects of processes like migration, late accretion and secular impacts, and on the time they occur in the life of planetary systems. In this work we will review what is already known about the factors influencing the composition of planetary atmospheres, focusing on the case of gaseous giant planets, and what instead still need to be investigated.

  3. Physics of planetary atmospheres and ionospheres

    NASA Technical Reports Server (NTRS)

    Bauer, S. J.

    1981-01-01

    The traditional atmospheric regions, the distinction between homosphere and heterosphere, and changing atmospheric composition are discussed. The validity of the barometric law based on a Maxwell-Boltzmann distribution, for the major part of a planetary atmosphere and its breakdown in the exosphere due to escape of atmospheric particles is considered. The formation and maintenance of photochemical and diffusion-controlled ionospheric layers are treated. Their applicability to planetary ionospheres is dealt with. The spatial extent of magnetic and nonmagnetic planet ionospheres is investigated. Thermal and nonthermal processes responsible for the mass loss of planetary atmospheres are surveyed.

  4. Impact erosion of terrestrial planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Ahrens, Thomas J.

    1992-01-01

    I review current ideas about the nature of the planetesimals - composition, size distribution, and the planetary encounter velocity. Previous papers on accretion and erosion of planetary atmospheres as a result of multiple impacts are reviewed. Finally, the effects of blowing off a substantial fraction of the atmosphere from a terrestrial planet due to a single giant body impact are discussed.

  5. A SEARCH FOR WIDE COMPANIONS TO THE EXTRASOLAR PLANETARY SYSTEM HR 8799

    SciTech Connect

    Close, Laird M.; Males, Jared R.

    2010-01-20

    The extrasolar planetary system around HR 8799 is the first multiplanet system ever imaged. It is also, by a wide margin, the highest mass system with >27 Jupiters of planetary mass past 25 AU. This is a remarkable system with no analog in any other known planetary system. In the first part of this paper, we investigated the nature of two faint objects imaged near the system. These objects are considerably fainter (H = 20.4 and 21.6 mag) and more distant (projected separations of 612 and 534 AU) than the three known planetary companions b, c, and d (68-24 AU). It is possible that these two objects could be lower mass planets (of mass approx5M{sub Jup} and approx3M{sub Jup}) that have been scattered to wider orbits. We make the first direct comparison of newly reduced archival Gemini adaptive optics images to archival Hubble Space Telescope/NICMOS images. With nearly a decade between these epochs, we can accurately assess the proper motion nature of each candidate companion. We find that both objects are unbound to HR 8799 and are background. We estimate that HR 8799 has no companions of H < 22 from approx5'' to 15''. Any scattered giant planets in the HR 8799 system are >600 AU or less than 3 M{sub Jup} in mass. In the second part of this paper, we search for any sign of a 'reverse parallax signature' in the astrometric residuals of HR 8799b. No such signal was found and we conclude, as expected, that HR 8799b has the same parallax as HR 8799A. In the third part of this paper, we carry out a search for wider common proper motion objects. We found one object within 1 deg{sup 2} in the Palomar Observatory Sky Survey-Digitized Sky Survey images with similar (<2sigma) proper motions to HR 8799 at a separation of 4.'0. We conclude that it is not likely a bound companion to HR 8799 based on available photometry.

  6. Characterizing extrasolar planets

    NASA Astrophysics Data System (ADS)

    Brown, Timothy M.

    Transiting extrasolar planets provide the best current opportunities for characterizing the physical properties of extrasolar planets. In this review, I first describe the geometry of planetary transits, and methods for detecting and refining the observations of such transits. I derive the methods by which transit light curves and radial velocity data can be analyzed to yield estimates of the planetary radius, mass, and orbital parameters. I also show how visible-light and infrared spectroscopy can be valuable tools for understanding the composition, temperature, and dynamics of the atmospheres of transiting planets. Finally, I relate the outcome of a participatory lecture-hall exercise relating to one term in the Drake equation, namely the lifetime of technical civilizations.

  7. Cryptic photosynthesis--extrasolar planetary oxygen without a surface biological signature.

    PubMed

    Cockell, Charles S; Kaltenegger, Lisa; Raven, John A

    2009-09-01

    On Earth, photosynthetic organisms are responsible for the production of virtually all the oxygen in the atmosphere. On land, vegetation reflects in the visible and leads to a "red edge," which developed about 450 million years ago on Earth and has been proposed as a biosignature for life on extrasolar planets. However, in many regions on Earth, particularly where surface conditions are extreme--in hot and cold deserts, for example--photosynthetic organisms can be driven into and under substrates where light is still sufficient for photosynthesis. These communities exhibit no detectable surface spectral signature to indicate life. The same is true of the assemblages of photosynthetic organisms at more than a few meters' depth in water bodies. These communities are widespread and dominate local photosynthetic productivity. We review known cryptic photosynthetic communities and their productivity. We have linked geomicrobiology with observational astronomy by calculating the disk-averaged spectra of cryptic habitats and identifying detectable features on an exoplanet dominated by such a biota. The hypothetical cryptic photosynthesis worlds discussed here are Earth analogues that show detectable atmospheric biosignatures like our own planet but do not exhibit a discernable biological surface feature in the disc-averaged spectrum.

  8. The photochemistry of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Dalgarno, A.

    1988-01-01

    Recent theoretical and observational investigations of photochemical processes in the atmospheres of the planets and their satellites are reviewed. Particular attention is given to the CO2-dominated atmospheres of Mars and Venus, the hydrogen-dominated atmospheres of the Jovian planets, the SO2 atmosphere of Io, and the massive atmospheres of Titan and Triton. The principal reaction paths involved are listed and briefly characterized, and numerical data on atmospheric compositions are given in tables.

  9. Extrasolar planets

    PubMed Central

    Lissauer, Jack J.; Marcy, Geoffrey W.; Ida, Shigeru

    2000-01-01

    The first known extrasolar planet in orbit around a Sun-like star was discovered in 1995. This object, as well as over two dozen subsequently detected extrasolar planets, were all identified by observing periodic variations of the Doppler shift of light emitted by the stars to which they are bound. All of these extrasolar planets are more massive than Saturn is, and most are more massive than Jupiter. All orbit closer to their stars than do the giant planets in our Solar System, and most of those that do not orbit closer to their star than Mercury is to the Sun travel on highly elliptical paths. Prevailing theories of star and planet formation, which are based on observations of the Solar System and of young stars and their environments, predict that planets should form in orbit about most single stars. However, these models require some modifications to explain the properties of the observed extrasolar planetary systems. PMID:11035782

  10. Extrasolar planets.

    PubMed

    Lissauer, J J; Marcy, G W; Ida, S

    2000-11-01

    The first known extrasolar planet in orbit around a Sun-like star was discovered in 1995. This object, as well as over two dozen subsequently detected extrasolar planets, were all identified by observing periodic variations of the Doppler shift of light emitted by the stars to which they are bound. All of these extrasolar planets are more massive than Saturn is, and most are more massive than Jupiter. All orbit closer to their stars than do the giant planets in our Solar System, and most of those that do not orbit closer to their star than Mercury is to the Sun travel on highly elliptical paths. Prevailing theories of star and planet formation, which are based on observations of the Solar System and of young stars and their environments, predict that planets should form in orbit about most single stars. However, these models require some modifications to explain the properties of the observed extrasolar planetary systems.

  11. Extrasolar planets.

    PubMed

    Lissauer, J J; Marcy, G W; Ida, S

    2000-11-01

    The first known extrasolar planet in orbit around a Sun-like star was discovered in 1995. This object, as well as over two dozen subsequently detected extrasolar planets, were all identified by observing periodic variations of the Doppler shift of light emitted by the stars to which they are bound. All of these extrasolar planets are more massive than Saturn is, and most are more massive than Jupiter. All orbit closer to their stars than do the giant planets in our Solar System, and most of those that do not orbit closer to their star than Mercury is to the Sun travel on highly elliptical paths. Prevailing theories of star and planet formation, which are based on observations of the Solar System and of young stars and their environments, predict that planets should form in orbit about most single stars. However, these models require some modifications to explain the properties of the observed extrasolar planetary systems. PMID:11035782

  12. Detection techniques for tenuous planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hoenig, S. A. (Principal Investigator)

    1975-01-01

    Electrostatic charging of dust and its effect on planetary atmospheres is discussed, along with its applications to Martian atmosphere. Laboratory and field experiments in dust storms indicate that the major atmospheric parameters on Mars include: (1) pressure, temperature, and relative humidity; (2) wind velocity and direction; (3) particulate size and composition; and (4) electrostatic charge and field gradient. Various instrumentation techniques adapted for a Mars Lander are briefly reviewed. The effect of exoelectron emission on surface catalysis is studied.

  13. Work on Planetary Atmospheres and Planetary Atmosphere Probes

    NASA Astrophysics Data System (ADS)

    Lester, Peter

    1999-01-01

    A summary final report of work accomplished is presented. Work was performed in the following areas: (1) Galileo Probe science analysis, (2) Galileo probe Atmosphere Structure Instrument, (3) Mars Pathfinder Atmosphere Structure/Meteorology instrument, (4) Mars Pathfinder data analysis, (5) Science Definition for future Mars missions, (6) Viking Lander data analysis, (7) winds in Mars atmosphere Venus atmospheric dynamics, (8) Pioneer Venus Probe data analysis, (9) Pioneer Venus anomaly analysis, (10) Discovery Venus Probe Titan probe instrument design, and (11) laboratory studies of Titan probe impact phenomena. The work has resulted in more than 10 articles published in archive journals, 2 encyclopedia articles, and many working papers. This final report is organized around the four planets on which there was activity, Jupiter, Mars, Venus, and Titan, with a closing section on Miscellaneous Activities. A major objective was to complete the fabrication, test, and evaluation of the atmosphere structure experiment on the Galileo probe, and to receive, analyze and interpret data received from the spacecraft. The instrument was launched on April 14, 1989. Calibration data were taken for all experiment sensors. The data were analyzed, fitted with algorithms, and summarized in a calibration report for use in analyzing and interpreting data returned from Jupiter's atmosphere. The sensors included were the primary science pressure, temperature and acceleration sensors, and the supporting engineering temperature sensors. Computer programs were written to decode the Experiment Data Record and convert the digital numbers to physical quantities, i.e., temperatures, pressures, and accelerations. The project office agreed to obtain telemetry of checkout data from the probe. Work to extend programs written for use on the Pioneer Venus project included: (1) massive heat shield ablation leading to important mass loss during entry; and (2) rapid planet rotation, which introduced

  14. Convective storms in planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Hueso, R.; Sánchez-Lavega, A.

    2013-05-01

    The atmospheres of the planets in the Solar System have different physical properties that in some cases can be considered as extreme when compared with our own planet's more familiar atmosphere. From the tenuous and cold atmosphere of Mars to the dense and warm atmosphere of Venus in the case of the terrestrial planets, to the gigantic atmospheres of the outer planets, or the nitrogen and methane atmosphere of Saturn's moon Titan, we can find a large variety of physical environments. The comparative study of these atmospheres provides a better understanding of the physics of a geophysical fluid. In many of these worlds convective storms of different intensity appear. They are analogous to terrestrial atmospheres fed by the release of latent heat when one of the gases in the atmosphere condenses and they are therefore called moist convective storms. In many of these planets they can produce severe meteorological phenomena and by studying them in a comparative way we can aspire to get a further insight in the dynamics of these atmospheres even beyond the scope of moist convection. A classical example is the structure of the complex systems of winds in the giant planets Jupiter and Saturn. These winds are zonal and alternate in latitude but their deep structure is not accessible to direct observation. However the behaviour of large--scale convective storms vertically extending over the "weather layer" allows to study the buried roots of these winds. Another interesting atmosphere with a rather different structure of convection is Titan, a world where methane is close to its triple point in the atmosphere and can condense in bright clouds with large precipitation fluxes that may model part of the orography of the surface making Titan a world with a methane cycle similar to the hydrological cycle of Earth's atmosphere.

  15. Dynamics and Origin of Extra-solar Planetary Systems and Microlensing Detection of Extra-solar Planets

    NASA Technical Reports Server (NTRS)

    Peale, S. J.

    2003-01-01

    We compare a space-based microlensing search for planets, with a ground based microlensing search originally proposed by D. Tytler (Beichman, et al. 1996). Perturbations of microlensing light curves when the lens star has a planetary companion are sought by one wide angle survey telescope and an array of three or four followup narrow angle telescopes distributed in longitude that follow events with high precision, high time resolution photometry. Alternative ground based programs are considered briefly. With the four 2 meter telescopes distributed in longitude in the southern hemisphere in the Tytler proposal, observational constraints on a ground-based search for planets during microlensing events toward the center of the galaxy are severe. Probably less than 100 events could be monitored per year with high precision, high time resolution photometry with only about 42% coverage on the average regardless of how many events were discovered by the survey telescope. Statistics for the occurrence and properties for Jupiter-mass planets would be meaningful but relatively meager four years after the program was started, and meaningful statistics for Earth-mass planets would be non existent. In contrast, the 14,500 events in a proposed 4 year space based program (GEST = Galactic Exoplanet Survey Telescope) would yield very sound statistics on the occurrence, masses and separations of Jupiter-mass planets, and significant constraints on similar properties for Earth-mass planets. The significance of the Jupiter statistics would be to establish the frequency of planetary systems like our own, where terrestrial planets could exist inside the orbits of the giants.

  16. Work on Planetary Atmospheres and Planetary Atmosphere Probes

    NASA Technical Reports Server (NTRS)

    Lester, Peter

    1999-01-01

    A summary final report of work accomplished is presented. Work was performed in the following areas: (1) Galileo Probe science analysis, (2) Galileo probe Atmosphere Structure Instrument, (3) Mars Pathfinder Atmosphere Structure/Meteorology instrument, (4) Mars Pathfinder data analysis, (5) Science Definition for future Mars missions, (6) Viking Lander data analysis, (7) winds in Mars atmosphere Venus atmospheric dynamics, (8) Pioneer Venus Probe data analysis, (9) Pioneer Venus anomaly analysis, (10) Discovery Venus Probe Titan probe instrument design, and (11) laboratory studies of Titan probe impact phenomena. The work has resulted in more than 10 articles published in archive journals, 2 encyclopedia articles, and many working papers. This final report is organized around the four planets on which there was activity, Jupiter, Mars, Venus, and Titan, with a closing section on Miscellaneous Activities. A major objective was to complete the fabrication, test, and evaluation of the atmosphere structure experiment on the Galileo probe, and to receive, analyze and interpret data received from the spacecraft. The instrument was launched on April 14, 1989. Calibration data were taken for all experiment sensors. The data were analyzed, fitted with algorithms, and summarized in a calibration report for use in analyzing and interpreting data returned from Jupiter's atmosphere. The sensors included were the primary science pressure, temperature and acceleration sensors, and the supporting engineering temperature sensors. Computer programs were written to decode the Experiment Data Record and convert the digital numbers to physical quantities, i.e., temperatures, pressures, and accelerations. The project office agreed to obtain telemetry of checkout data from the probe. Work to extend programs written for use on the Pioneer Venus project included: (1) massive heat shield ablation leading to important mass loss during entry; and (2) rapid planet rotation, which introduced

  17. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. I. THE ROLE OF ELECTRON AVALANCHE

    SciTech Connect

    Helling, Ch.; Jardine, M.; Witte, S.; Diver, D. A.

    2011-01-20

    Brown dwarf and extrasolar planet atmospheres form clouds which strongly influence the local chemistry and physics. These clouds are globally neutral obeying dust-gas charge equilibrium which is, on short timescales, inconsistent with the observation of stochastic ionization events of the solar system planets. We argue that a significant volume of the clouds in brown dwarfs and extrasolar planets is susceptible to local discharge events. These are electron avalanches triggered by charged dust grains. Such intra-cloud discharges occur on timescales shorter than the time needed to neutralize the dust grains by collisional processes. An ensemble of discharges is likely to produce enough free charges to suggest a partial and stochastic coupling of the atmosphere to a large-scale magnetic field.

  18. Chemical kinetics and modeling of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Yung, Yuk L.

    1990-01-01

    A unified overview is presented for chemical kinetics and chemical modeling in planetary atmospheres. The recent major advances in the understanding of the chemistry of the terrestrial atmosphere make the study of planets more interesting and relevant. A deeper understanding suggests that the important chemical cycles have a universal character that connects the different planets and ultimately link together the origin and evolution of the solar system. The completeness (or incompleteness) of the data base for chemical kinetics in planetary atmospheres will always be judged by comparison with that for the terrestrial atmosphere. In the latter case, the chemistry of H, O, N, and Cl species is well understood. S chemistry is poorly understood. In the atmospheres of Jovian planets and Titan, the C-H chemistry of simple species (containing 2 or less C atoms) is fairly well understood. The chemistry of higher hydrocarbons and the C-N, P-N chemistry is much less understood. In the atmosphere of Venus, the dominant chemistry is that of chlorine and sulfur, and very little is known about C1-S coupled chemistry. A new frontier for chemical kinetics both in the Earth and planetary atmospheres is the study of heterogeneous reactions. The formation of the ozone hole on Earth, the ubiquitous photochemical haze on Venus and in the Jovian planets and Titan all testify to the importance of heterogeneous reactions. It remains a challenge to connect the gas phase chemistry to the production of aerosols.

  19. Work on Planetary Atmospheres and Planetary Atmosphere Probes

    NASA Technical Reports Server (NTRS)

    Seiff, Alvin; Lester, Peter

    1999-01-01

    A major objective of the grant was to complete the fabrication, test, and evaluation of the atmosphere structure experiment on the Galileo Probe, and to receive, analyze, and interpret data received from the spacecraft. The grantee was competitively selected to be Principal Investigator of Jupiter's atmosphere structure on the Galileo Probe. His primary motivation was to learn as much as possible about Jupiter's atmosphere by means of a successful atmosphere structure experiment, and to support the needs and schedule of the Galileo Project. After a number of launch delays, the Flight instrument was shipped to Kennedy Space Center 2 years after the start of this collaboration, on April 14, 1989, at which time it was determined from System level tests of the ASI on the Probe that the instrument was in good working order and ready for flight. The spacecraft was launched on October 18, 1989. Data analysis of test and calibration data taken over a period of years of instrument testing was continued in preparation for the encounter. The initial instrument checkout in space was performed on October 26, 1989. The data set received by telemetry was thoroughly analyzed, and a report of the findings was transmitted to the Probe Operations Office on Feb. 28, 1990. Key findings reported were that the accelerometer biases had shifted by less than 1 mg through launch and since calibration at Bell Aerospace in 1983; accelerometer scale factors, evaluated by means of calibration currents, fell on lines of variation with temperature established in laboratory calibrations; pressure sensor offsets, correlated as a function of temperature, fell generally within the limits of several years of ground test data; atmospheric and engineering temperature sensor data were internally consistent within a few tenths of a degree; and the instrument electronics performed all expected functions without any observable fault. Altogether, this checkout was highly encouraging of the prospects of

  20. Infrared laboratory studies of synthetic planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Williams, D.

    1973-01-01

    Previous research dealing with telluric gases is briefly reviewed. Current research concerning absorption-line broadening, and particulate constituents of planetary atmospheres are discussed. Two articles are included: optical constants of liquid ammonia in the infrared, and broadening of infrared absorption lines at reduced temperatures for nitrous oxide.

  1. Detection techniques for tenuous planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hoenig, S. A.

    1972-01-01

    The research for the development of new types of detectors for analysis of planetary atmospheres is summarized. Topics discussed include: corona discharge humidity detector, surface catalysis and exo-electron emission, and analysis of soil samples by means of exo-electron emission. A report on the exo-electron emission during heterogeneous catalysis is included.

  2. Submillimeter Planetary Atmospheric Chemistry Exploration Sounder

    NASA Technical Reports Server (NTRS)

    Schlecht, Erich T.; Allen, Mark A.; Gill, John J.; Choonsup, Lee; Lin, Robert H.; Sin, Seth; Mehdi, Imran; Siegel, Peter H.; Maestrini, Alain

    2013-01-01

    Planetary Atmospheric Chemistry Exploration Sounder (SPACES), a high-sensitivity laboratory breadboard for a spectrometer targeted at orbital planetary atmospheric analysis. The frequency range is 520 to 590 GHz, with a target noise temperature sensitivity of 2,500 K for detecting water, sulfur compounds, carbon compounds, and other atmospheric constituents. SPACES is a prototype for a powerful tool for the exploration of the chemistry and dynamics of any planetary atmosphere. It is fundamentally a single-pixel receiver for spectral signals emitted by the relevant constituents, intended to be fed by a fixed or movable telescope/antenna. Its front-end sensor translates the received signal down to the 100-MHz range where it can be digitized and the data transferred to a spectrum analyzer for processing, spectrum generation, and accumulation. The individual microwave and submillimeter wave components (mixers, LO high-powered amplifiers, and multipliers) of SPACES were developed in cooperation with other programs, although with this type of instrument in mind. Compared to previous planetary and Earth science instruments, its broad bandwidth (approx. =.13%) and rapid tunability (approx. =.10 ms) are new developments only made possible recently by the advancement in submillimeter circuit design and processing at JPL.

  3. Life on the Edge: Planetary Atmospheres in Extreme Environments

    NASA Astrophysics Data System (ADS)

    Knutson, Heather; Deming, Drake; Todorov, Kamen; Desert, Jean-Michel; Agol, Eric; Cowan, Nicolas; Burrows, Adam; Fortney, Jonathan; Howard, Andrew; Laughlin, Gregory; Langton, Jonathan; Showman, Adam; Lewis, Nikole

    2011-05-01

    Studies of extrasolar planets have been moving at an ever-accelerating pace, with more than one hundred known transiting planet systems and hundreds of new planet candidates from missions such as Kepler and CoRoT waiting in the wings. Ongoing efforts with the Hubble and Spitzer Space Telescopes, as well as from the ground, have allowed us to characterize the atmospheres of these planets in unprecedented detail and have revealed a surprisingly diverse array of atmosphere properties. We propose to address some of the most hotly debated questions in the field using a subset of bright, recently discovered transiting planet systems, which provide the most optimal targets for detailed characterization. These questions include: What is the mechanism responsible for maintaining the large day-night temperature gradients observed for some tidally locked hot Jupiters? Are MHD effects such as Lorentz braking and Ohmic dissipation important in the hottest planetary atmospheres? What sets the balance between methane and CO in cooler atmospheres, and how important is photochemistry and other non-equilibrium processes? Although it would be natural to extend these same studies down into the super-Earth (< 10 M_earth) mass range, there is currently only one system (GJ 1214) that is suitable for detailed characterization. We therefore propose to carry out a search for transits of known, low-mass radial velocity planets orbiting bright stars, with a 52% probability of finding a new transiting super-Earth. Because the vast majority of Kepler- and CoRoT-detected planets in this mass range are too faint for detailed atmosphere studies, such systems will be crucial in allowing us to characterize the atmospheres of smaller and more earth-like worlds.

  4. Studies of Tenuous Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Combi, Michael R.

    1998-01-01

    The final report includes an overall project overview as well as scientific background summaries of dust and sodium in comets, and tenuous atmospheres of Jupiter's natural satellites. Progress and continuing work related to dust coma and tenuous atmospheric studies are presented. Also included are published articles written during the course of the report period. These are entitled: (1) On Europa's Magnetospheric Interaction: An MHD Simulation; (2) Dust-Gas Interrelations in Comets: Observations and Theory; and (3) Io's Plasma Environment During the Galileo Flyby: Global Three Dimensional MHD Modeling with Adaptive Mesh Refinement.

  5. Atmospheric escape, redox evolution, and planetary habitability

    NASA Astrophysics Data System (ADS)

    Catling, D. C.; Zahnle, K. J.

    2011-12-01

    Through the greenhouse effect, the presence and composition of an atmosphere is critical for defining a (conventional) circumstellar habitable zone in terms of planetary surface temperatures suitable for liquid water. Lack of knowledge of planetary atmospheres is likely to frustrate attempts to say with any certainty whether detected terrestrial-sized exoplanets may or may not be habitable. Perhaps an underappreciated role in such considerations is the evolutionary effect of atmospheric escape for determining atmospheric composition or whether an atmosphere exists in the first place. Whether atmospheres exist at all on planets is demonstrably connected to the effect of integrated atmospheric escape. When we observe our own Solar System and transiting exoplanets, the existence of an atmosphere is clearly delineated by a relative vulnerability to thermal escape and impact erosion. The prevalence of thermal escape as a key evolutionary determinant for the presence of planetary atmosphere is shown by a relationship between the relative solar (or stellar) heating and the escape velocity. Those bodies with too much stellar heating and too smaller escape velocity end up devoid of atmospheres. Impact erosion is evident in the relationship between impact velocity and escape velocity. Escape due to impacts is particularly important for understanding the large differences in the atmospheres of giant planet moons, such as Ganymede versus Titan. It is also significant for Mars-sized planets. The oxidation state of atmospheres is important for some theories of the origin of life (where an early reducing atmosphere is helpful for organic synthesis) and the evolution of advanced life (where free molecular oxygen is the best source of high energy metabolism). Surfaces on some relatively small planets and moons are observed to have evolved to an oxidized state, which theory and observation can explain through atmospheric escape. There are several examples in the Solar System where a

  6. Spectral signatures of photosynthesis. II. Coevolution with other stars and the atmosphere on extrasolar worlds.

    PubMed

    Kiang, Nancy Y; Segura, Antígona; Tinetti, Giovanna; Govindjee; Blankenship, Robert E; Cohen, Martin; Siefert, Janet; Crisp, David; Meadows, Victoria S

    2007-02-01

    As photosynthesis on Earth produces the primary signatures of life that can be detected astronomically at the global scale, a strong focus of the search for extrasolar life will be photosynthesis, particularly photosynthesis that has evolved with a different parent star. We take previously simulated planetary atmospheric compositions for Earth-like planets around observed F2V and K2V, modeled M1V and M5V stars, and around the active M4.5V star AD Leo; our scenarios use Earth's atmospheric composition as well as very low O2 content in case anoxygenic photosynthesis dominates. With a line-by-line radiative transfer model, we calculate the incident spectral photon flux densities at the surface of the planet and under water. We identify bands of available photosynthetically relevant radiation and find that photosynthetic pigments on planets around F2V stars may peak in absorbance in the blue, K2V in the red-orange, and M stars in the near-infrared, in bands at 0.93-1.1 microm, 1.1-1.4 microm, 1.5-1.8 microm, and 1.8-2.5 microm. However, underwater organisms will be restricted to wavelengths shorter than 1.4 microm and more likely below 1.1 microm. M star planets without oxygenic photosynthesis will have photon fluxes above 1.6 microm curtailed by methane. Longer-wavelength, multi-photo-system series would reduce the quantum yield but could allow for oxygenic photosystems at longer wavelengths. A wavelength of 1.1 microm is a possible upper cutoff for electronic transitions versus only vibrational energy; however, this cutoff is not strict, since such energetics depend on molecular configuration. M star planets could be a half to a tenth as productive as Earth in the visible, but exceed Earth if useful photons extend to 1.1 microm for anoxygenic photosynthesis. Under water, organisms would still be able to survive ultraviolet flares from young M stars and acquire adequate light for growth.

  7. Comparative Planetary Atmospheres of Pluto and Triton

    NASA Astrophysics Data System (ADS)

    Strobel, D. F.; Zhu, X.

    2015-10-01

    Both atmospheres of Pluto and Neptune's largest satellite Triton have cold surfaces with similar surface gravities and atmospheric surface pressures. We have updated the Zhu et al.Icarus 228 , 301, 2014) model for Pluto's atmosphere by adopting Voigt line profiles in the radiation code with the latest spectral database and extended the model to Triton's atmosphere by including additional parameterized heating due to the magnetospheric electron energy deposition. Numerical experiments show that the escape rate of an atmosphere for an icy planetary body similar to Pluto or Triton is quite sensitive to the methane abundance and planetary surface gravity. Together this leads to a cumulative effect on the density variation with the altitude that significantly changes the atmospheric scale height at the exobase together with the exobase altitude. The atmospheric thermal structure near the exobase is sensitive to the atmospheric escape rate only when it is significantly greater than 10 26 molecules s-1 above which an enhanced escape rate corresponds to a stronger radial velocity that adiabatically cools the atmosphere to a lower temperature.

  8. Radiative transfer in realistic planetary atmospheres. [bibliographies

    NASA Technical Reports Server (NTRS)

    Plass, G. N.; Kattawar, G. W.

    1982-01-01

    Some 40 publications that appeared in scientific journals from 1973 to 1981 as well as 45 scientific reports issued during the grant period are listed by title. Topics cover the development of a matrix operator theory of radiative transfer which made possible the exact model calculations of the radiance as a function of height in planetary atmospheres; calculation of the Mie phase matrix for various types of particles as well as for radiance and polarization in planetary atmospheres; analysis of high dispersion spectroscopic observations of Venus; calculation of curves of growth for Venus; the development of a theory for calculating radiative transfer in spherical shell atmospheres; investigations of zonal winds on Venus; and examination of Rayleigh scattering.

  9. The Next Generation of Planetary Atmospheric Probes

    NASA Technical Reports Server (NTRS)

    Houben, Howard

    2005-01-01

    Entry probes provide useful insights into the structures of planetary atmospheres, but give only one-dimensional pictures of complex four-dimensional systems that vary on all temporal and spatial scales. This makes the interpretation of the results quite challenging, especially as regards atmospheric dynamics. Here is a planetary meteorologist's vision of what the next generation of atmospheric entry probe missions should be: Dedicated sounding instruments get most of the required data from orbit. Relatively simple and inexpensive entry probes are released from the orbiter, with low entry velocities, to establish ground truth, to clarify the vertical structure, and for adaptive observations to enhance the dataset in preparation for sensitive operations. The data are assimilated onboard in real time. The products, being immediately available, are of immense benefit for scientific and operational purposes (aerobraking, aerocapture, accurate payload delivery via glider, ballooning missions, weather forecasts, etc.).

  10. Atmospheric planetary wave response to external forcing

    NASA Technical Reports Server (NTRS)

    Stevens, D. E.; Reiter, E. R.

    1985-01-01

    The tools of observational analysis, complex general circulation modeling, and simpler modeling approaches were combined in order to attack problems on the largest spatial scales of the earth's atmosphere. Two different models were developed and applied. The first is a two level, global spectral model which was designed primarily to test the effects of north-south sea surface temperature anomaly (SSTA) gradients between the equatorial and midlatitude north Pacific. The model is nonlinear, contains both radiation and a moisture budget with associated precipitation and surface evaporation, and utilizes a linear balance dynamical framework. Supporting observational analysis of atmospheric planetary waves is briefly summarized. More extensive general circulation models have also been used to consider the problem of the atmosphere's response, especially in the horizontal propagation of planetary scale waves, to SSTA.

  11. Extrasolar Cosmochemistry

    NASA Astrophysics Data System (ADS)

    Jura, M.; Young, E. D.

    2014-05-01

    Evidence is now compelling that elements heavier than helium in many white dwarf atmospheres have accumulated by accretion from orbiting rocky bodies, often larger than 100 km in diameter, such as asteroids. Consequently, we now possess a powerful tool to measure the elemental constituents of extrasolar minor planets. To zeroth order, the accreted extrasolar parent bodies resemble bulk Earth: They are at least 85% by mass composed of oxygen, magnesium, silicon, and iron; carbon and ice are only trace constituents. Assembled data for white dwarf pollutions suggest that differentiation of extrasolar planetesimals, leading to iron-rich cores and aluminum-rich crusts, is common. Except for instances of unexpectedly high calcium abundances, the compositions of extrasolar planetesimals can be understood as resulting from processes similar to those controlling the formation and evolution of objects in the inner Solar System.

  12. Metal Hydride and Alkali Halide Opacities in Extrasolar Giant Planets and Cool Stellar Atmospheres

    NASA Technical Reports Server (NTRS)

    Weck, Philippe F.; Stancil, Phillip C.; Kirby, Kate; Schweitzer, Andreas; Hauschildt, Peter H.

    2006-01-01

    The lack of accurate and complete molecular line and continuum opacity data has been a serious limitation to developing atmospheric models of cool stars and Extrasolar Giant Planets (EGPs). We report our recent calculations of molecular opacities resulting from the presence of metal hydrides and alkali halides. The resulting data have been included in the PHOENIX stellar atmosphere code (Hauschildt & Baron 1999). The new models, calculated using spherical geometry for all gravities considered, also incorporate our latest database of nearly 670 million molecular lines, and updated equations of state.

  13. A stability limit for the atmospheres of giant extrasolar planets.

    PubMed

    Koskinen, Tommi T; Aylward, Alan D; Miller, Steve

    2007-12-01

    Recent observations of the planet HD209458b indicate that it is surrounded by an expanded atmosphere of atomic hydrogen that is escaping hydrodynamically. Theoretically, it has been shown that such escape is possible at least inside an orbit of 0.1 au (refs 4 and 5), and also that H3+ ions play a crucial role in cooling the upper atmosphere. Jupiter's atmosphere is stable, so somewhere between 5 and 0.1 au there must be a crossover between stability and instability. Here we show that there is a sharp breakdown in atmospheric stability between 0.14 and 0.16 au for a Jupiter-like planet orbiting a solar-type star. These results are in contrast to earlier modelling that implied much higher thermospheric temperatures and more significant evaporation farther from the star. (We use a three-dimensional, time-dependent coupled thermosphere-ionosphere model and properly include cooling by H3+ ions, allowing us to model globally the redistribution of heat and changes in molecular composition.) Between 0.2 and 0.16 au cooling by H3+ ions balances heating by the star, but inside 0.16 au molecular hydrogen dissociates thermally, suppressing the formation of H3+ and effectively shutting down that mode of cooling. PMID:18064005

  14. A stability limit for the atmospheres of giant extrasolar planets.

    PubMed

    Koskinen, Tommi T; Aylward, Alan D; Miller, Steve

    2007-12-01

    Recent observations of the planet HD209458b indicate that it is surrounded by an expanded atmosphere of atomic hydrogen that is escaping hydrodynamically. Theoretically, it has been shown that such escape is possible at least inside an orbit of 0.1 au (refs 4 and 5), and also that H3+ ions play a crucial role in cooling the upper atmosphere. Jupiter's atmosphere is stable, so somewhere between 5 and 0.1 au there must be a crossover between stability and instability. Here we show that there is a sharp breakdown in atmospheric stability between 0.14 and 0.16 au for a Jupiter-like planet orbiting a solar-type star. These results are in contrast to earlier modelling that implied much higher thermospheric temperatures and more significant evaporation farther from the star. (We use a three-dimensional, time-dependent coupled thermosphere-ionosphere model and properly include cooling by H3+ ions, allowing us to model globally the redistribution of heat and changes in molecular composition.) Between 0.2 and 0.16 au cooling by H3+ ions balances heating by the star, but inside 0.16 au molecular hydrogen dissociates thermally, suppressing the formation of H3+ and effectively shutting down that mode of cooling.

  15. Ionization in atmospheres of brown dwarfs and extrasolar planets VI: Properties of large-scale discharge events

    SciTech Connect

    Bailey, R. L.; Helling, Ch.; Hodosán, G.; Bilger, C.; Stark, C. R.

    2014-03-20

    Mineral clouds in substellar atmospheres play a special role as a catalyst for a variety of charge processes. If clouds are charged, the surrounding environment becomes electrically activated, and ensembles of charged grains are electrically discharging (e.g., by lightning), which significantly influences the local chemistry creating conditions similar to those thought responsible for life in early planetary atmospheres. We note that such lightning discharges contribute also to the ionization state of the atmosphere. We apply scaling laws for electrical discharge processes from laboratory measurements and numerical experiments to DRIFT-PHOENIX model atmosphere results to model the discharge's propagation downward (as lightning) and upward (as sprites) through the atmospheric clouds. We evaluate the spatial extent and energetics of lightning discharges. The atmospheric volume affected (e.g., by increase of temperature or electron number) is larger in a brown dwarf atmosphere (10{sup 8}-10{sup 10} m{sup 3}) than in a giant gas planet (10{sup 4}-10{sup 6} m{sup 3}). Our results suggest that the total dissipated energy in one event is <10{sup 12} J for all models of initial solar metallicity. First attempts to show the influence of lightning on the local gas phase indicate an increase of small carbohydrate molecules like CH and CH{sub 2} at the expense of CO and CH{sub 4}. Dust-forming molecules are destroyed and the cloud particle properties are frozen in unless enough time is available for complete evaporation. We summarize instruments potentially suitable to observe lightning on extrasolar objects.

  16. Chemistry of Planetary Atmospheres: Insights and Prospects

    NASA Astrophysics Data System (ADS)

    Yung, Yuk

    2015-11-01

    Using observations from the Mariners, Pioneers, Vikings, Voyagers, Pioneer Venus, Galileo, Venus Express, Curiosity, Cassini, New Horizons, and numerous observatories both in orbit of Earth and on the ground, I will give a survey of the major chemical processes that control the composition of planetary atmospheres. For the first time since the beginning of the space age, we understand the chemistry of planetary atmospheres ranging from the primitive atmospheres of the giant planets to the highly evolved atmospheres of terrestrial planets and small bodies. Our understanding can be distilled into three important ideas: (1) The stability of planetary atmospheres against escape of their constituents to space, (2) the role of equilibrium chemistry in determining the partitioning of chemical species, and (3) the role of disequilibrium chemistry, which produces drastic departures from equilibrium chemistry. To these three ideas we must also add a fourth: the role of biochemistry at Earth's surface, which makes its atmospheric chemistry unique in the cosmochemical environment. Only in the Earth's atmosphere do strong reducing and oxidizing species coexist to such a degree. For example, nitrogen species in the Earth's atmosphere span eight oxidation states from ammonia to nitric acid. Much of the Earth's atmospheric chemistry consists of reactions initiated by the degradation of biologically produced molecules. Life uses solar energy to drive chemical reactions that would otherwise not occur; it represents a kind of photochemistry that is special to Earth, at least within the Solar System. It remains to be seen how many worlds like Earth there are beyond the Solar System, especially as we are now exploring the exoplanets using Kepler, TESS, HST, Spitzer, soon to be launched missions such as JWST and WFIRST, and ground-based telescopes. The atmospheres of the Solar System provide a benchmark for studying exoplanets, which in turn serve to test and extend our current

  17. Moon formation and orbital evolution in extrasolar planetary systems - A literature review

    NASA Astrophysics Data System (ADS)

    Lewis, K.

    2011-02-01

    With over 450 extrasolar planets detected, the possibility of searching for moons of these planets is starting to be investigated. In order to make efficient use of limited observing resources, it would be useful if the types of moons that a given planet is likely to host was known prior to detection. Fortunately, informed by simulations of moon formation in our own solar system, as well as more general theoretical investigations of moon orbital evolution, such information is now available. I present a review of literature results concerning the likely physical and orbital properties of extra-solar moons, and how these properties are predicted to vary with the properties of their host planet.

  18. Relativistic breakdown in planetary atmospheres

    SciTech Connect

    Dwyer, J. R.

    2007-04-15

    In 2003, a new electrical breakdown mechanism involving the production of runaway avalanches by positive feedback from runaway positrons and energetic photons was introduced. This mechanism, which shall be referred to as 'relativistic feedback', allows runaway discharges in gases to become self-sustaining, dramatically increasing the flux of runaway electrons, the accompanying high-energy radiation, and resulting ionization. Using detailed Monte Carlo calculations, properties of relativistic feedback are investigated. It is found that once relativistic feedback fully commences, electrical breakdown will occur and the ambient electric field, extending over cubic kilometers, will be discharged in as little as 2x10{sup -5} s. Furthermore, it is found that the flux of energetic electrons and x rays generated by this mechanism can exceed the flux generated by the standard relativistic runaway electron model by a factor of 10{sup 13}, making relativistic feedback a good candidate for explaining terrestrial gamma-ray flashes and other high-energy phenomena observed in the Earth's atmosphere.

  19. Atmospheric Excitation of Planetary Normal Modes

    NASA Technical Reports Server (NTRS)

    Tanimoto, Toshiro

    2001-01-01

    The objectives of this study were to: (1) understand the phenomenon of continuous free oscillations of the Earth and (2) examine the idea of using this phenomenon for planetary seismology. We first describe the results on (1) and present our evaluations of the idea (2) in the final section. In 1997, after almost forty years since the initial attempt by Benioff et al, continuous free oscillations of the Earth were discovered. Spheroidal fundamental modes between 2 and 7 millihertz are excited continuously with acceleration amplitudes of about 0.3-0.5 nanogals. The signal is now commonly found in virtually all data recorded by STS-1 type broadband seismometers at quiet sites. Seasonal variation in amplitude and the existence of two coupled modes between the atmosphere and the solid Earth support that these oscillations are excited by the atmosphere. Stochastic excitation due to atmospheric turbulence is a favored mechanism, providing a good match between theory and data. The atmosphere has ample energy to support this theory because excitation of these modes require only 500-10000 W whereas the atmosphere contains about 117 W of kinetic energy. An application of this phenomenon includes planetary seismology, because other planets may be oscillating due to atmospheric excitation. The interior structure of planets could be learned by determining the eigenfrequencies in the continuous free oscillations. It is especially attractive to pursue this idea for tectonically quiet planets, since quakes may be too infrequent to be recorded by seismic instruments.

  20. Diurnal Forcing of Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Houben, Howard C.

    1997-01-01

    Much progress has been made on calculations of the Martian seasonal water cycle using the Mars Climate Model developed for this purpose. Two papers, documenting the model and the water transport results obtained with it have been published in the Journal of Geophysical Research - Planets. An additional paper describing results related to the evolution of the seasonal water cycle as a result of orbital changes was published in Advances in Space Research. Since that time, further studies have concentrated on the consequences of the soil adsorption required to match the observed water cycle and its relation to the stability of ground ice and other potential water reservoirs. Earth-related studies have concentrated on incorporating an efficient and realistic microphysical model into the Ames Stratospheric General Circulation Model used to simulate the spread of the ML Pinatubo and other volcanic clouds in the stratosphere. In addition, visualizations of the simulations are being incorporated into a video describing the UARS mission. A paper describing the new stratospheric aerosol microphysics package (and its consequences for volcanic cloud evolution) will be submitted in the near future. The paper will discuss the relative importance of condensation and coagulation to early particle growth and the separation of the cloud by sedimentation of the larger particles. A more general paper which highlights the observation that particle number densities did not increase dramatically after the ML Pinatubo eruption is planned. Simulations of atmospheric transport will be extended to include studies of terrestrial tropospheric tracers using the Fifth-Generation Penn State/NCAR Mesoscale Model.

  1. Constraints on planetary formation from the discovery & study of transiting Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Triaud, A. H. M. J.

    2011-08-01

    Earth-Sun distance. In Astronomy, we cannot do experiments; we are a part of it. Instead, we search and characterise several similar objects in order to extract information out of them statistically. To answer our question, we needed to find several objects and detect the clues from their past history bringing us back to the processes that led to their formation. There are several manners with which one can find planets. For this thesis, the so-called transit method was used. It consists in detecting a periodic loss of light from a star in front of which a planet passes: a transit. This method is particularly sensitive to the presence of hot Jupiters. During this thesis, about fifty planets of such type have been discovered, about a third of the known hot Jupiters. Those planets are confirmed thanks to radial velocity measurements, the same technique that led to the discovery of the first extrasolar planet, around the star 51 Pegasi. The analysis of the stellar light affected by the presence of a planet around it, notably the light received during transit, allows us to know about the mass, the size of the planet, its orbital period, the shape of its orbit, its temperature, even the chemical composition of its atmosphere. Furthermore, these observations give us the occasion to study the star around which is found the planet, such as its mass, its size, its rotation speed, as well as give estimates on its age. One type of observations was employed in particular: the Rossiter-McLaughlin effect. During transit, this effect creates an anomaly compared to the expected radial velocities. Through a modelisation of this anomaly, it is possible to measure the projection of the angle between the orbital plane of the planet and the equatorial plane of the star, on the sky. In our System, all planets are located more or less in a same plane : the ecliptic. The equatorial plane of the Sun is also almost aligned with the ecliptic. This observation led Kant and Laplace to postulate on

  2. Atmosphere Models for the Brown Dwarf Gliese 229 B and the Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Marley, Mark S.

    1996-01-01

    Brown dwarfs inhabit a realm intermediate between the more massive stars and the less massive planets. Their thermal infrared emission is powered by the release of gravitational potential energy as regulated by their atmospheres. Long known only as theoretical constructs. the discovery of the first unimpeachable brown dwarf. Gliese 229 has opened up a new field: the study of brown dwarf atmospheres. The subsequent discoverv of numerous extrasolar giant planets circling nearby stars, further demonstrated the need for a comprehensive modeling effort to understand this new class of jovian atmospheres. Although no spectra are yet available of the new planets, the next generation of groundbased and spacebased telescopes will return such data. Here author report on the effort with Ames collaborator Dr. Christopher McKay to better understand these new atmospheres.

  3. Origin and evolution of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Lewis, John S.

    1992-01-01

    This report concerns several research tasks related to the origin and evolution of planetary atmospheres and the large-scale distribution of volatile elements in the Solar System. These tasks and their present status are as follows: (1) we have conducted an analysis of the volatility and condensation behavior of compounds of iron, aluminum, and phosphorus in the atmosphere of Venus in response to publish interpretations of the Soviet Venera probe XRF experiment data, to investigate the chemistry of volcanic gases, injection of volatiles by cometary and asteroidal impactors, and reactions in the troposphere; (2) we have completed and are now writing up our research on condensation-accretion modeling of the terrestrial planets; (3) we have laid the groundwork for a detailed study of the effects of water transport in the solar nebula on the bulk composition, oxidation state, and volatile content of preplanetary solids; (4) we have completed an extensive laboratory study of cryovolcanic materials in the outer solar system; (5) we have begun to study the impact erosion and shock alteration of the atmosphere of Mars resulting from cometary and asteroidal bombardment; and (6) we have developed a new Monte Carlo model of the cometary and asteroidal bombardment flux on the terrestrial planets, including all relevant chemical and physical processes associated with atmospheric entry and impact, to assess both the hazards posed by this bombardment to life on Earth and the degree of cross-correlation between the various phenomena (NO(x) production, explosive yield, crater production, iridium signature, etc.) that characterize this bombardment. The purpose of these investigations has been to contribute to the developing understanding of both the dynamics of long-term planetary atmosphere evolution and the short-term stability of planetary surface environments.

  4. Molecular Line and Continuum Opacities for Modeling of Extrasolar Giant Planet and Cool Stellar Atmospheres

    NASA Technical Reports Server (NTRS)

    Weck, P. F.; Schweitzer, A.; Stancil, P. C.; Hauschildt, P. H.; Kirby, K.; Yamaguchi, Y.; Allen, W. D.

    2002-01-01

    The molecular line and continuum opacities are investigated in the atmospheres of cool stars and Extrasolar Giant Planets (EGPs). Using a combination of ab inito and experimentally derived potential curves and dipole transition moments, accurate data have been calculated for rovibrationally-resolved oscillator strengths and photodissociation cross sections in the B' (sup 2)Sigma+ (left arrow) X (sup 2)Sigma+ and A (sup 2)Pi (left arrow) X (sup 2)Sigma+ band systems in MgH. We also report our progress on the study of the electronic structure of LiCl and FeH.

  5. Molecular Line and Continuum Opacities for Modeling of Extrasolar Giant Planet and Cool Stellar Atmospheres

    NASA Astrophysics Data System (ADS)

    Weck, P. F.; Stancil, P. C.; Schweitzer, A.; Hauschildt, P. H.; Kirby, K.; Yamaguchi, Y.; Allen, W.

    2002-11-01

    The molecular hue and continuum opacities are investigated in the atmospheres of cool stars and Extrasolar Giant Planets (EGPs). Using a combination of ab inito and experimentally derived potential curves and dipole transition moments, accurate data have been calculated for rovibrationally-resolved oscillator strengths and photodissociation cross sections in the B' 2∑+ ← X 2∑+ and A 2II ← X 2∑+ baud systems in MgH. We also report our progress on the study of the electronic structure of LiCl and FeH.

  6. The Undiscovered Country: Can We Estimate the Likelihood of Extrasolar Planetary Habitability?

    NASA Astrophysics Data System (ADS)

    Unterborn, C. T.; Panero, W. R.; Hull, S. D.

    2015-12-01

    Plate tectonics have operated on Earth for a majority of its lifetime. Tectonics regulates atmospheric carbon and creates a planetary-scale water cycle, and is a primary factor in the Earth being habitable. While the mechanism for initiating tectonics is unknown, as we expand our search for habitable worlds, understanding which planetary compositions produce planets capable of supporting long-term tectonics is of paramount importance. On Earth, this sustentation of tectonics is a function of both its structure and composition. Currently, however, we have no method to measure the interior composition of exoplanets. In our Solar system, though, Solar abundances for refractory elements mirror the Earth's to within ~10%, allowing the adoption of Solar abundances as proxies for Earth's. It is not known, however, whether this mirroring of stellar and terrestrial planet abundances holds true for other star-planet systems without determination of the composition of initial planetesimals via condensation sequence calculations. Currently, all code for ascertaining these sequences are commercially available or closed-source. We present, then, the open-source Arbitrary Composition Condensation Sequence calculator (ArCCoS) for converting the elemental composition of a parent star to that of the planet-building material as well as the extent of oxidation within the planetesimals. These data allow us to constrain the likelihood for one of the main drivers for plate tectonics: the basalt to eclogite transition subducting plates. Unlike basalt, eclogite is denser than the surrounding mantle and thus sinks into the mantle, pulling the overlying slab with it. Without this higher density relative to the mantle, plates stagnate at shallow depths, shutting off plate tectonics. Using the results of ArCCoS as abundance inputs into the MELTS and HeFESTo thermodynamic models, we calculate phase relations for the first basaltic crust and depleted mantle of a terrestrial planet produced from

  7. Origin and evolution of planetary and satellite atmospheres

    SciTech Connect

    Atreya, S.K.; Pollack, J.B.; Matthews, M.S.

    1989-01-01

    The present volume on the origin and evolution of planet and satellite atmospheres discusses the chemistry of interstellar gas and grains, planetary accretion, cometary composition, the inventories of asteroid volatiles, key similarities and differences among the terrestrial planets' atmospheric compositions, and planets' atmospheric escape and water loss. Also discussed are planetary atmosphere-planetary interior evolutionary coupling, the atmospheric composition of the outer planets, the structure and composition of giant planet interiors, the tenuous atmosphere of Io, the sources of the atmospheres of the outer solar system's satellites, the present state and chemical evolution of the Titan, Triton, and Pluto atmospheres, and the thermal structure and heat balance of the outer planets.

  8. Planetary Atmospheres and Evolution of Complex Life

    NASA Astrophysics Data System (ADS)

    Catling, D.

    2014-04-01

    Let us define "complex life" as actively mobile organisms exceeding tens of centimeter size scale with specialized, differentiated anatomy comparable to advanced metazoans. Such organisms on any planet will need considerable energy for growth and metabolism, and an atmosphere is likely to play a key role. The history of life on Earth suggests that there were at least two major hurdles to overcome before complex life developed. The first was biological. Large, three-dimensional multicellular animals and plants are made only of eukaryotic cells, which are the only type that can develop into a large, diverse range of cell types unlike the cells of microbes. Exactly how eukaryotes allow 3D multicellularity and how they originated are matters of debate. But the internal structure and bigger and more modular genomes of eukaryotes are important factors. The second obstacle for complex life was having sufficient free, diatomic oxygen (O2). Aerobic metabolism provides about an order of magnitude more energy for a given intake of food than anaerobic metabolism, so anaerobes don't grow multicellular beyond filaments because of prohibitive growth efficiencies. A precursor to a 2.4 Ga rise of oxygen was the evolution of water-splitting, oxygen-producing photosynthesis. But although the atmosphere became oxidizing at 2.4 Ga, sufficient atmospheric O2 did not occur until about 0.6 Ga. Earth-system factors were involved including planetary outgassing (as affected by size and composition), hydrogen escape, and processing of organic carbon. An atmosphere rich in O2 provides the largest feasible energy source per electron transfer in the Periodic Table, which suggests that O2 would be important for complex life on exoplanets. But plentiful O2 is unusual in a planetary atmosphere because O2 is easily consumed in chemical reactions with reducing gases or surface materials. Even with aerobic metabolism, the partial pressure of O2 (pO2) must exceed ~10^3 Pa to allow organisms that rely

  9. Detection techniques for tenuous planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hoenig, S. A.; Summerton, J. E.; Kirchner, J. D.; Allred, J. B.

    1974-01-01

    The development of new types of detectors for analysis of planetary atmospheres is discussed. Initially, the interest was in detectors for use under partial vacuum conditions; recently, the program has been extended to include detectors for use at one atmosphere and adsorption systems for control and separation of gases. Results to date have included detector for O2 and H2 under partial vacuum conditions. Experiments on detectors for use at high pressures began in 1966; and systems for CO, H2, and O2 were reported in 1967 and 1968. In 1968 studies began on an electrically controlled adsorbent. It was demonstrated that under proper conditions a thin film of semiconductor material could be electrically cycled to absorb and desorb a specific gas. This work was extended to obtain quantitative data on the use of semiconductors as controllable adsorbents.

  10. Detection techniques for tenuous planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hoenig, S. A.

    1971-01-01

    The development of new types of detectors for analysis of planetary atmospheres is discussed. Initially, the interest was in detectors for use under partial vacuum conditions. The program has been extended to include detectors for use at one atmosphere and adsorption system for control and separation of gases. Results to date have included detectors for O2 and H2 under partial vacuum conditions. Experiments on detectors for use at high pressures began in 1966, and systems for CO, H2, and O2, were reported. Electrically controlled adsorbent was developed. It was demonstrated that under proper conditions a thin film of semiconductor material could be electrically cycled to adsorb and desorb a specific gas. This work was extended to obtain quantitative data on the use of semiconductors as controllable adsorbents.

  11. The Blue Dot Workshop: Spectroscopic Search for Life on Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Des Marais, David J. (Editor)

    1997-01-01

    This workshop explored the key questions and challenges associated with detecting life on an extrasolar planet. The final product will be a NASA Conference Publication which includes the abstracts from 21 talks, summaries of key findings, and recommendations for future research. The workshop included sessions on three related topics: the biogeochemistry of biogenic gases in the atmosphere, the chemistry and spectroscopy of planetary atmospheres, and the remote sensing of planetary atmospheres and surfaces. With the observation that planetary formation is probably a common phenomenon, together with the advent of the technical capability to locate and describe extrasolar planets, this research area indeed has an exciting future.

  12. Galactic cosmic rays on extrasolar Earth-like planets. II. Atmospheric implications

    NASA Astrophysics Data System (ADS)

    Grießmeier, J.-M.; Tabataba-Vakili, F.; Stadelmann, A.; Grenfell, J. L.; Atri, D.

    2016-03-01

    Context. Theoretical arguments indicate that close-in terrestial exoplanets may have weak magnetic fields. As described in the companion article (Paper I), a weak magnetic field results in a high flux of galactic cosmic rays to the top of the planetary atmosphere. Aims: We investigate effects that may result from a high flux of galactic cosmic rays both throughout the atmosphere and at the planetary surface. Methods: Using an air shower approach, we calculate how the atmospheric chemistry and temperature change under the influence of galactic cosmic rays for Earth-like (N2-O2 dominated) atmospheres. We evaluate the production and destruction rate of atmospheric biosignature molecules. We derive planetary emission and transmission spectra to study the influence of galactic cosmic rays on biosignature detectability. We then calculate the resulting surface UV flux, the surface particle flux, and the associated equivalent biological dose rates. Results: We find that up to 20% of stratospheric ozone is destroyed by cosmic-ray protons. The effect on the planetary spectra, however, is negligible. The reduction of the planetary ozone layer leads to an increase in the weighted surface UV flux by two orders of magnitude under stellar UV flare conditions. The resulting biological effective dose rate is, however, too low to strongly affect surface life. We also examine the surface particle flux: For a planet with a terrestrial atmosphere (with a surface pressure of 1033 hPa), a reduction of the magnetic shielding efficiency can increase the biological radiation dose rate by a factor of two, which is non-critical for biological systems. For a planet with a weaker atmosphere (with a surface pressure of 97.8 hPa), the planetary magnetic field has a much stronger influence on the biological radiation dose, changing it by up to two orders of magnitude. Conclusions: For a planet with an Earth-like atmospheric pressure, weak or absent magnetospheric shielding against galactic cosmic

  13. Observations and Modeling of Tropical Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Laraia, Anne

    2016-01-01

    This thesis is a comprised of three different projects within the topic of tropical atmospheric dynamics. First, I analyze observations of thermal radiation from Saturn's atmosphere and from them, determine the latitudinal distribution of ammonia vapor near the 1.5-bar pressure level. The most prominent feature of the observations is the high brightness temperature of Saturn's subtropical latitudes on either side of the equator. After comparing the observations to a microwave radiative transfer model, I find that these subtropical bands require very low ammonia relative humidity below the ammonia cloud layer in order to achieve the high brightness temperatures observed. We suggest that these bright subtropical bands represent dry zones created by a meridionally overturning circulation. Second, I use a dry atmospheric general circulation model to study equatorial superrotation in terrestrial atmospheres. A wide range of atmospheres are simulated by varying three parameters: the pole-equator radiative equilibrium temperature contrast, the convective lapse rate, and the planetary rotation rate. A scaling theory is developed that establishes conditions under which superrotation occurs in terrestrial atmospheres. The scaling arguments show that superrotation is favored when the off-equatorial baroclinicity and planetary rotation rates are low. Similarly, superrotation is favored when the convective heating strengthens, which may account for the superrotation seen in extreme global-warming simulations. Third, I use a moist slab-ocean general circulation model to study the impact of a zonally-symmetric continent on the distribution of monsoonal precipitation. I show that adding a hemispheric asymmetry in surface heat capacity is sufficient to cause symmetry breaking in both the spatial and temporal distribution of precipitation. This spatial symmetry breaking can be understood from a large-scale energetic perspective, while the temporal symmetry breaking requires

  14. Dynamical Simulations of Extrasolar Planetary Systems with Debris Disks Using a GPU Accelerated N-Body Code

    NASA Astrophysics Data System (ADS)

    Moore, Alexander

    This thesis begins with a description of a hybrid symplectic integrator named QYMSYM which is capable of planetary system simulations. This integrator has been programmed with the Compute Unified Device Architecture (CUDA) language which allows for implementation on Graphics Processing Units (GPUs). With the enhanced compute performance made available by this choice, QYMSYM was used to study the effects debris disks have on the dynamics of the extrasolar planetary systems HR 8799 and KOI-730. The four planet system HR 8799 was chosen because it was known to have relatively small regions of stability in orbital phase space. Using this fact, it can be shown that a simulated debris disk of moderate mass around HR 8799 can easily pull this system out of these regions of stability. In other cases it is possible to migrate the system to a region of stability - although this requires significantly more mass and a degree of fine tuning. These findings suggest that previous studies on the stability of HR 8799 which do not include a debris disk may not accurately report on the size and location of the stable orbital phase space available for the planets. This insight also calls into question the practice of using dynamical simulations to help constrain observed planetary orbital data. Next, by studying the stability of another four planet system, KOI-730, whose planets are in an 8:6:4:3 mean motion resonance, we were additionally able to determine mass constraints on debris disks for KOI-730 like Kepler objects. Noting that planet inclinations increase by a couple of degrees when migrating through a Neptune mass debris disk, and that planet candidates discovered by the Kepler Space Telescope are along the line of site, it is concluded that significant planetary migration did not occur among the Kepler objects. This result indicates that Kepler objects like KOI-730 have relatively small or stable debris disks which did not cause migration of their planets - ruling out late

  15. AN ALUMINUM/CALCIUM-RICH, IRON-POOR, WHITE DWARF STAR: EVIDENCE FOR AN EXTRASOLAR PLANETARY LITHOSPHERE?

    SciTech Connect

    Zuckerman, B.; Klein, B.; Jura, M.; Koester, D.; Dufour, P.; Melis, Carl

    2011-10-01

    The presence of elements heavier than helium in white dwarf atmospheres is often a signpost for the existence of rocky objects that currently or previously orbited these stars. We have measured the abundances of various elements in the hydrogen-atmosphere white dwarfs G149-28 and NLTT 43806. In comparison with other white dwarfs with atmospheres polluted by heavy elements, NLTT 43806 is substantially enriched in aluminum but relatively poor in iron. We compare the relative abundances of Al and eight other heavy elements seen in NLTT 43806 with the elemental composition of bulk Earth, with simulated extrasolar rocky planets, with solar system meteorites, with the atmospheric compositions of other polluted white dwarfs, and with the outer layers of the Moon and Earth. The best agreement is found with a model that involves accretion of a mixture of terrestrial crust and upper mantle material onto NLTT 43806. The implication is that NLTT 43806 is orbited by a differentiated rocky planet, perhaps quite similar to Earth, that has suffered a collision that stripped away some of its outer layers.

  16. Constraining Oxygen False Positives in Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Harman, C. E.; Schottelkotte, J. C.; Kasting, J. F.

    2014-03-01

    Oxygen (O2) and ozone (O3) in the present Earth's atmosphere are byproducts of oxygenic photosynthesis coupled with organic carbon burial. On Earth, no known abiotic surface process would be able to generate such an atmosphere, and by extension, lifeless exoplanets are expected to be devoid of O2. As a result, molecular oxygen and ozone are often seen as convincing signposts for life. Recently, however, a number of authors have demonstrated the abiotic generation of molecular oxygen in a planetary atmosphere, either under oxidizing conditions (Hu et al., 2013) or around an M star (Tian et al., 2013). This èfalse positive', if verified, would remove oxygen and ozone from an already short list of easily detectable biosignatures. We explore oxygen false positives with our 1-D photochemical model, updated from Segura et al. (2007). Preliminary results show that if water vapor photolysis longward of ~200 nm is neglected, substantial amounts of CO and O2 can build up in the lower part of the atmosphere. Additionally, the ultimate fate of CO and O2 produced in such atmospheres is strongly dependent on the imposed lower boundary condition, with low depositional velocities corresponding to higher mixing ratios in the lower atmosphere. The deposition velocity of a gas depends on it dissolved concentration, however, and so one needs to consider the chemistry of these gases in solution. Ongoing work seeks to test the conclusions of Tian et al., (2013) by exploring this dependence on ocean chemistry and by including spectra from AD Leo (an active M-dwarf, used by Domagal-Goldman et al., (2011)) to compare with the M-dwarf spectra used by Tian et al.

  17. Ionisation and discharge in cloud-forming atmospheres of brown dwarfs and extrasolar planets

    NASA Astrophysics Data System (ADS)

    Helling, Ch; Rimmer, P. B.; Rodriguez-Barrera, I. M.; Wood, Kenneth; Robertson, G. B.; Stark, C. R.

    2016-07-01

    Brown dwarfs and giant gas extrasolar planets have cold atmospheres with rich chemical compositions from which mineral cloud particles form. Their properties, like particle sizes and material composition, vary with height, and the mineral cloud particles are charged due to triboelectric processes in such dynamic atmospheres. The dynamics of the atmospheric gas is driven by the irradiating host star and/or by the rotation of the objects that changes during its lifetime. Thermal gas ionisation in these ultra-cool but dense atmospheres allows electrostatic interactions and magnetic coupling of a substantial atmosphere volume. Combined with a strong magnetic field \\gg {{B}\\text{Earth}} , a chromosphere and aurorae might form as suggested by radio and x-ray observations of brown dwarfs. Non-equilibrium processes like cosmic ray ionisation and discharge processes in clouds will increase the local pool of free electrons in the gas. Cosmic rays and lighting discharges also alter the composition of the local atmospheric gas such that tracer molecules might be identified. Cosmic rays affect the atmosphere through air showers in a certain volume which was modelled with a 3D Monte Carlo radiative transfer code to be able to visualise their spacial extent. Given a certain degree of thermal ionisation of the atmospheric gas, we suggest that electron attachment to charge mineral cloud particles is too inefficient to cause an electrostatic disruption of the cloud particles. Cloud particles will therefore not be destroyed by Coulomb explosion for the local temperature in the collisional dominated brown dwarf and giant gas planet atmospheres. However, the cloud particles are destroyed electrostatically in regions with strong gas ionisation. The potential size of such cloud holes would, however, be too small and might occur too far inside the cloud to mimic the effect of, e.g. magnetic field induced star spots.

  18. Arctic Climate and Atmospheric Planetary Waves

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Haekkinen, S.; Zukor, Dorothy J. (Technical Monitor)

    2001-01-01

    Analysis of a fifty-year record (1946-1995) of monthly-averaged sea level pressure data provides a link between the phases of planetary-scale sea level pressure waves and Arctic Ocean and ice variability. Results of this analysis show: (1) a breakdown of the dominant wave 1 pattern in the late 1960's, (2) shifts in the mean phase of waves 1 and 2 since this breakdown, (3) an eastward shift in the phases of both waves 1 and 2 during the years of simulated cyclonic Arctic Ocean circulation relative to their phases during the years of anticyclonic circulation, (4) a strong decadal variability of wave phase associated with simulated Arctic Ocean circulation changes. Finally, the Arctic atmospheric circulation patterns that emerge when waves 1 and 2 are in their extreme eastern and western positions suggest an alternative approach for determining significant forcing patterns of sea ice and high-latitude variability.

  19. Arctic Climate and Atmospheric Planetary Waves

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Haekkinen, S.

    2000-01-01

    Analysis of a fifty-year record (1946-1995) of monthly-averaged sea level pressure data provides a link between the phases of planetary-scale sea level pressure waves and Arctic Ocean and ice variability. Results of this analysis show: (1) a breakdown of the dominant wave I pattern in the late 1960's, (2) shifts in the mean phase of waves 1 and 2 since this breakdown, (3) an eastward shift in the phases of both waves 1 and 2 during the years of simulated cyclonic Arctic Ocean circulation relative to their phases during the years of anticyclonic circulation, (4) a strong decadal variability of wave phase associated with simulated Arctic Ocean circulation changes. Finally, the Arctic atmospheric circulation patterns that emerge when waves 1 and 2 are in their extreme eastern and western positions suggest an alternative approach to determine significant forcing patterns of sea ice and high-latitude variability.

  20. Measurement of Spin-Orbit Alignment in an Extrasolar Planetary System

    NASA Astrophysics Data System (ADS)

    Winn, Joshua N.; Noyes, Robert W.; Holman, Matthew J.; Charbonneau, David; Ohta, Yasuhiro; Taruya, Atsushi; Suto, Yasushi; Narita, Norio; Turner, Edwin L.; Johnson, John A.; Marcy, Geoffrey W.; Butler, R. Paul; Vogt, Steven S.

    2005-10-01

    We determine the stellar, planetary, and orbital properties of the transiting planetary system HD 209458 through a joint analysis of high-precision radial velocities, photometry, and timing of the secondary eclipse. Of primary interest is the strong detection of the Rossiter-McLaughlin effect, the alteration of photospheric line profiles that occurs because the planet occults part of the rotating surface of the star. We develop a new technique for modeling this effect and use it to determine the inclination of the planetary orbit relative to the apparent stellar equator (λ=-4.4d+/-1.4d), and the line-of-sight rotation speed of the star (vsinI*=4.70+/-0.16 km s-1). The uncertainty in these quantities has been reduced by an order of magnitude relative to the pioneering measurements by Queloz and collaborators. The small but nonzero misalignment is probably a relic of the planet formation epoch, because the expected timescale for tidal coplanarization is larger than the age of the star. Our determination of vsinI* is a rare case in which rotational line broadening has been isolated from other broadening mechanisms.

  1. The Presence of Methane in the Atmosphere of an Extrasolar Planet

    NASA Technical Reports Server (NTRS)

    Swain, Mark R.; Vasisht, Gautam; Tinetti, Giovanna

    2008-01-01

    Molecules present in the atmospheres of extrasolar planets are expected to influence strongly the balance of atmospheric radiation, to trace dynamical and chemical processes, and to indicate the presence of disequilibrium effects. As molecules have the potential to reveal atmospheric conditions and chemistry, searching for them is a high priority. The rotational-vibrational transition bands of water, carbon monoxide and methane are anticipated to be the primary sources of non-continuum opacity in hot-Jupiter planets. As these bands can overlap in wavelength, and the corresponding signatures from them are weak, decisive identification requires precision infrared spectroscopy. Here we report a near-infrared transmission spectrum of the planet HD 189733b that shows the presence of methane. Additionally, a resolved water vapour band at 1.9 (micro)m confirms the recent claim4 of water in this object. On thermochemical grounds, carbon monoxide is expected to be abundant in the upper atmosphere of hot-Jupiter planets, but is not identifiable here; therefore the detection of methane rather than carbon monoxide in such a hot planet could signal the presence of a horizontal chemical gradient away from the permanent dayside, or it may imply an ill-understood photochemical mechanism that leads to an enhancement of methane.

  2. The presence of methane in the atmosphere of an extrasolar planet.

    PubMed

    Swain, Mark R; Vasisht, Gautam; Tinetti, Giovanna

    2008-03-20

    Molecules present in the atmospheres of extrasolar planets are expected to influence strongly the balance of atmospheric radiation, to trace dynamical and chemical processes, and to indicate the presence of disequilibrium effects. As molecules have the potential to reveal atmospheric conditions and chemistry, searching for them is a high priority. The rotational-vibrational transition bands of water, carbon monoxide and methane are anticipated to be the primary sources of non-continuum opacity in hot-Jupiter planets. As these bands can overlap in wavelength, and the corresponding signatures from them are weak, decisive identification requires precision infrared spectroscopy. Here we report a near-infrared transmission spectrum of the planet HD 189733b that shows the presence of methane. Additionally, a resolved water vapour band at 1.9 mum confirms the recent claim of water in this object. On thermochemical grounds, carbon monoxide is expected to be abundant in the upper atmosphere of hot-Jupiter planets, but is not identifiable here; therefore the detection of methane rather than carbon monoxide in such a hot planet could signal the presence of a horizontal chemical gradient away from the permanent dayside, or it may imply an ill-understood photochemical mechanism that leads to an enhancement of methane.

  3. Insights into Planet Formation from Debris Disks - II. Giant Impacts in Extrasolar Planetary Systems

    NASA Astrophysics Data System (ADS)

    Wyatt, Mark C.; Jackson, Alan P.

    2016-03-01

    Giant impacts refer to collisions between two objects each of which is massive enough to be considered at least a planetary embryo. The putative collision suffered by the proto-Earth that created the Moon is a prime example, though most Solar System bodies bear signatures of such collisions. Current planet formation models predict that an epoch of giant impacts may be inevitable, and observations of debris around other stars are providing mounting evidence that giant impacts feature in the evolution of many planetary systems. This chapter reviews giant impacts, focussing on what we can learn about planet formation by studying debris around other stars. Giant impact debris evolves through mutual collisions and dynamical interactions with planets. General aspects of this evolution are outlined, noting the importance of the collision-point geometry. The detectability of the debris is discussed using the example of the Moon-forming impact. Such debris could be detectable around another star up to 10 Myr post-impact, but model uncertainties could reduce detectability to a few 100 yr window. Nevertheless the 3 % of young stars with debris at levels expected during terrestrial planet formation provide valuable constraints on formation models; implications for super-Earth formation are also discussed. Variability recently observed in some bright disks promises to illuminate the evolution during the earliest phases when vapour condensates may be optically thick and acutely affected by the collision-point geometry. The outer reaches of planetary systems may also exhibit signatures of giant impacts, such as the clumpy debris structures seen around some stars.

  4. A theoretical framework for volcanic degassing chemistry in a comparative planetology perspective and implications for planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Gaillard, Fabrice; Scaillet, Bruno

    2014-10-01

    Magmatic degassing is ubiquitous and enduring, yet its impact on both planetary surficial chemistry and how it may have varied among planetary systems remains imprecise. A large number of factors are likely to be involved in the control of magmatic gas compositions, leading roles being given to the redox state and volatile abundances in planetary interiors, and the fate of the latter during mantle melting. We however show that the pressure at which degassing occurs, that is the atmospheric pressure in most sensible cases, has a prime influence on the composition of subaerial volcanic gases on planets: high surface pressure produces N2- and CO2-rich and dry volcanic gases, while low pressure promotes sulfur-rich gases. In-between, atmospheric pressures close to 1 bar trigger volcanic gases dominated by H2O. This simple pattern broadly mirrors the atmospheres of Venus-Earth-Mars-Io planetary suite and constitutes benchmarks for the prediction and interpretation of atmospheric features of extra-solar planets. Volatile abundances within the planetary body interiors also matter but they play a secondary role. Furthermore, our analysis shows that any difference in redox conditions prevailing during partial melting tends to disappear with the degassing process itself, converging toward a unique - planetary oxygen fugacity - at the venting pressure. A feedback relationship between volcanic gas compositions and atmospheric pressure implies a runaway drying during atmospheric growth; that is volcanic gases must become CO2 richer as the atmospheric mass increases. This may explain some features of the Venusian atmosphere. On Earth, impact ejection of the atmosphere and CO2-sink mechanisms, such as carbonate precipitation and plate tectonics, must have decreased atmospheric pressure allowing the reestablishment of water-rich volcanic gases.

  5. Extra-solar planetary systems. III - Potential sites for the origin and evolution of technical civilisations

    NASA Astrophysics Data System (ADS)

    Fogg, M. J.

    1986-07-01

    A series of runs of the Silicon Creation' computer model developed by Fogg (1985) has been analyzed in order to evaluate the probable abundance of planets possessing suitable conditions for the evolution of technologically adept forms of life. The evolutionary simulation encompassed 100,000 disk stars of varying mass, metallicity, and age, and focused on civilizations that may have come into existence on planets over the past 10 to the 10th years of planetary disk history. The frequency of such sites is determined to be 0.00292, and the frequency of planets developing a technological civilization is 0.00009; these figures are two orders of magnitude lower than the most optimistic manipulations of the Drake equation, but not low enough to resolve the Fermi paradox, according to which an alien civilization, if existent, should long ago have colonized the entire Galaxy.

  6. Meteoric Material: An Important Component of Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Grebowsky, Joseph M.; Moses, Julianne I.; Pesnell, W. Dean; Vondrak, Richard R. (Technical Monitor)

    2001-01-01

    Interplanetary dust particles (IDPs) interact with all planetary atmospheres and leave their imprint as perturbations of the background atmospheric chemistry and structure. They lead to layers of metal ions that can become the dominant positively charged species in lower ionospheric regions. Theoretical models and radio occultation measurements provide compelling evidence that such layers exist in all planetary atmospheres. In addition IDP ablation products can affect neutral atmospheric chemistry, particularly at the outer planets where the IDPs supply oxygen compounds like water and carbon dioxide to the upper atmospheres. Aerosol or smoke particles from incomplete ablation or recondensation of ablated IDP vapors may also have a significant impact on atmospheric properties.

  7. Cloudless Atmospheres for L/T Dwarfs and Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Tremblin, P.; Amundsen, D. S.; Chabrier, G.; Baraffe, I.; Drummond, B.; Hinkley, S.; Mourier, P.; Venot, O.

    2016-01-01

    The admitted, conventional scenario to explain the complex spectral evolution of brown dwarfs (BDs) since their first detection 20 years ago has always been the key role played by micron-size condensates, called "dust" or "clouds," in their atmosphere. This scenario, however, faces major problems, in particular the J-band brightening and the resurgence of FeH absorption at the L to T transition, and a physical first-principle understanding of this transition is lacking. In this Letter, we propose a new, completely different explanation for BD and extrasolar giant planet (EGP) spectral evolution, without the need to invoke clouds. We show that, due to the slowness of the CO/ CH4 and N2/NH3 chemical reactions, brown dwarf (L and T, respectively) and EGP atmospheres are subject to a thermo-chemical instability similar in nature to the fingering or chemical convective instability present in Earth oceans and at the Earth core/mantle boundary. The induced small-scale turbulent energy transport reduces the temperature gradient in the atmosphere, explaining the observed increase in near-infrared J-H and J-K colors of L dwarfs and hot EGPs, while a warming up of the deep atmosphere along the L to T transition, as the CO/CH4 instability vanishes, naturally solves the two aforementioned puzzles, and provides a physical explanation of the L to T transition. This new picture leads to a drastic revision of our understanding of BD and EGP atmospheres and their evolution.

  8. Cloudless Atmospheres for L/T Dwarfs and Extrasolar Giant Planets

    NASA Astrophysics Data System (ADS)

    Tremblin, P.; Amundsen, D. S.; Chabrier, G.; Baraffe, I.; Drummond, B.; Hinkley, S.; Mourier, P.; Venot, O.

    2016-02-01

    The admitted, conventional scenario to explain the complex spectral evolution of brown dwarfs (BDs) since their first detection 20 years ago has always been the key role played by micron-size condensates, called “dust” or “clouds,” in their atmosphere. This scenario, however, faces major problems, in particular the J-band brightening and the resurgence of FeH absorption at the L to T transition, and a physical first-principle understanding of this transition is lacking. In this Letter, we propose a new, completely different explanation for BD and extrasolar giant planet (EGP) spectral evolution, without the need to invoke clouds. We show that, due to the slowness of the CO/CH4 and N2/NH3 chemical reactions, brown dwarf (L and T, respectively) and EGP atmospheres are subject to a thermo-chemical instability similar in nature to the fingering or chemical convective instability present in Earth oceans and at the Earth core/mantle boundary. The induced small-scale turbulent energy transport reduces the temperature gradient in the atmosphere, explaining the observed increase in near-infrared J-H and J-K colors of L dwarfs and hot EGPs, while a warming up of the deep atmosphere along the L to T transition, as the CO/CH4 instability vanishes, naturally solves the two aforementioned puzzles, and provides a physical explanation of the L to T transition. This new picture leads to a drastic revision of our understanding of BD and EGP atmospheres and their evolution.

  9. Planetary Formation: From the Earth and Moon to Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, Donald (Technical Monitor)

    1999-01-01

    An overview of current theories of star and planet formation is presented. These models are based upon observations of the Solar System and of young stars and their environments. They predict that rocky planets should form around most single stars, although it is possible that in some cases-such planets are lost to orbital decay within the protoplanetary disk. The frequency of formation of gas giant planets is more difficult to predict theoretically. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth like terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. Specific issues to be discussed include: (1) how large a solid core is needed to initiate rapid accumulation of gas? (2) can giant planets form very close to stars? (3) could a giant impact leading to lunar formation have occurred approx. 100 million years after the condensation of the oldest meteorites?

  10. Planetary Formation: From the Earth and Moon to Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack; DeVincenzi, Donald (Technical Monitor)

    1999-01-01

    An overview of current theories of star and planet formation is presented. These models are based upon observations of the Solar System and of young stars and their environments. They predict that rocky planets should form around most single stars, although it is possible that in some cases such planets are lost to orbital decay within the protoplanetary disk. The frequency of formation of gas giant planets is more difficult to predict theoretically. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth like terrestrial planets, but they become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. Specific issues to be discussed include: (1) how large a solid core is needed to initiate rapid accumulation of gas? (2) can giant planets form very close to stars? (3) could a giant impact leading to lunar formation have occurred approximately 100 million years after the condensation of the oldest meteorites?

  11. Planetary Atmosphere Dynamics and Radiative Transfer

    NASA Astrophysics Data System (ADS)

    Atkinson, David H.

    1996-01-01

    This research program has dealt with two projects in the field of planetary atmosphere dynamics and radiative energy transfer, one theoretical and one experimental. The first project, in radiative energy transfer, incorporated the capability to isolate and quantify the contribution of individual atmospheric components to the Venus radiative balance and thermal structure to greatly improve the current understanding of the radiative processes occurring within the Venus atmosphere. This is possible by varying the mixing ratios of each gas species, and the location, number density and aerosol size distributions of the clouds. This project was a continuation of the work initiated under a 1992 University Consortium Agreement. Under the just completed grant, work has continued on the use of a convolution-based algorithm that provided the capability to calculate the k coefficients of a gas mixture at different temperatures, pressures and spectral intervals from the separate k-distributions of the individual gas species. The second primary goal of this research dealt with the Doppler wind retrieval for the Successful Galileo Jupiter probe mission in December, 1995. In anticipation of the arrival of Galileo at Jupiter, software development continued to read the radioscience and probe/orbiter trajectory data provided by the Galileo project and required for Jupiter zonal wind measurements. Sample experiment radioscience data records and probe/orbiter trajectory data files provided by the Galileo Radioscience and Navigation teams at the Jet Propulsion Laboratory, respectively, were used for the first phase of the software development. The software to read the necessary data records was completed in 1995. The procedure by which the wind retrieval takes place begins with initial consistency checks of the raw data, preliminary data reductions, wind recoveries, iterative reconstruction of the probe descent profile, and refined wind recoveries. At each stage of the wind recovery

  12. A Novel Diagnosis of Chemical Disequilibrium in Extrasolar Planet and Substellar Object Atmospheres

    NASA Astrophysics Data System (ADS)

    Line, Michael R.; Yung, Y. L.

    2013-10-01

    With recent advancements in spectroscopic capabilities, characterization of the temperatures and compositions of extra-solar planets is becoming more prevalent. One outstanding issue one can address with temperature and abundance determinations is the role that disequilibrium plays in sculpting the atmospheric compositions. A variety of disequilibrium models now exist in the literature to explore various planets and the effects that photochemistry and vertical mixing have on the molecular abundances. In this investigation we introduce a novel approach to diagnosing disequilibrium without the need of sophisticated photochemical/kinetics models. In short, we define an “equilibrium” line as a function of a representative planet temperature. If we can determine the abundances of H2O, CH4, CO, and H2, we can evaluate a simple analytic formula to quickly assess whether or not the atmospheric composition is in disequilibrium. We verify the usefulness of this approach with state-of-the-art chemistry-transport models and find that, as expected, cooler planets tend to show the strongest signs of disequilibrium.

  13. Calculating the Tidal, Spin, and Dynamical Evolution of Extrasolar Planetary Systems

    NASA Astrophysics Data System (ADS)

    Mardling, Rosemary A.; Lin, D. N. C.

    2002-07-01

    Based on formulations by Heggie and by Eggleton, we present an efficient method for calculating self-consistently the tidal, spin, and dynamical evolution of a many-body system, here with particular emphasis on planetary systems. The star and innermost planet (or in general the closest pair of bodies in the system) are endowed with structure while the other bodies are treated as point masses. The evolution of the spin rates and obliquities of the extended bodies are calculated (for arbitrary initial obliquities), as is the tidal evolution of the innermost orbit. In addition, the radius of the innermost planet is evolved according to its ability to efficiently dissipate tidal energy. Relativistic effects are included to post-Newtonian order. For resonant systems such as GJ 876, the evolution equations must be integrated directly to allow for variation of the semimajor axes (other than from tidal damping) and for the possibility of instability. For systems such as Upsilon Andromedae in which the period ratio of the two inner planets is small, the innermost orbit may be averaged producing (in this case) a 50-fold reduction in the calculation time. In order to illustrate the versatility of the formulation, we consider three hypothetical primitive Earth-Moon-Sun-Jupiter systems. The parameters and initial conditions are identical in the first two models except for the Love number of the Earth, which results in dramatically different evolutionary paths. The third system is one studied by Touma & Wisdom and serves as a test of the numerical formulations presented here by reproducing two secular mean motion resonances (the evection and eviction resonances). The methods may be used for any system of bodies.

  14. Atmospheric planetary-wave response to external forcing

    NASA Technical Reports Server (NTRS)

    Stevens, D. E.; Reiter, E. R.

    1983-01-01

    A summary of the progress report is given, covering the following areas: atmospheric circulation, planetary waves, adaption of the model to the Cyber 205, continental heat flux anomalies, and nonlinear evolution of inertial instabilities in the tropics.

  15. Astronomical, physical, and meteorological parameters for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Allison, Michael; Travis, Larry D.

    1986-01-01

    A newly compiled table of astronomical, physical, and meteorological parameters for planetary atmospheres is presented. Formulae and explanatory notes for their application and a complete listing of sources are also given.

  16. Vibrational-Rotational Spectroscopy For Planetary Atmospheres, volume 1

    NASA Technical Reports Server (NTRS)

    Mumma, M. J. (Editor); Fox, K. (Editor); Hornstein, J. (Editor)

    1982-01-01

    Comprehensive information on the composition and dynamics of the varied planetary atmospheres is summarized. New observations resulted in new demands for supporting laboratory studies. Spectra observed from spacecraft used to interpret planetary atmospheric structure measurements, to aid in greenhouse and cloud physics calculations, and to plan future experiments are discussed. Current findings and new ideas of physicists, chemists, and planetry astronomers relating to the knowledge of the structure of things large and small, of planets and of molecules are summarized.

  17. First International Conference on Laboratory Research for Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Fox, Kenneth (Editor); Allen, John E., Jr. (Editor); Stief, Louis J. (Editor); Quillen, Diana T. (Editor)

    1990-01-01

    Proceedings of the First International Conference on Laboratory Research for Planetary Atmospheres are presented. The covered areas of research include: photon spectroscopy, chemical kinetics, thermodynamics, and charged particle interactions. This report contains the 12 invited papers, 27 contributed poster papers, and 5 plenary review papers presented at the conference. A list of attendees and a reprint of the Report of the Subgroup on Strategies for Planetary Atmospheres Exploration (SPASE) are provided in two appendices.

  18. Electrodynamics on extrasolar giant planets

    SciTech Connect

    Koskinen, T. T.; Yelle, R. V.; Lavvas, P.; Cho, J. Y-K.

    2014-11-20

    Strong ionization on close-in extrasolar giant planets (EGPs) suggests that their atmospheres may be affected by ion drag and resistive heating arising from wind-driven electrodynamics. Recent models of ion drag on these planets, however, are based on thermal ionization only and do not include the upper atmosphere above the 1 mbar level. These models are also based on simplified equations of resistive magnetohydrodynamics that are not always valid in extrasolar planet atmospheres. We show that photoionization dominates over thermal ionization over much of the dayside atmosphere above the 100 mbar level, creating an upper ionosphere dominated by ionization of H and He and a lower ionosphere dominated by ionization of metals such as Na, K, and Mg. The resulting dayside electron densities on close-in exoplanets are higher than those encountered in any planetary ionosphere of the solar system, and the conductivities are comparable to the chromosphere of the Sun. Based on these results and assumed magnetic fields, we constrain the conductivity regimes on close-in EGPs and use a generalized Ohm's law to study the basic effects of electrodynamics in their atmospheres. We find that ion drag is important above the 10 mbar level where it can also significantly alter the energy balance through resistive heating. Due to frequent collisions of the electrons and ions with the neutral atmosphere, however, ion drag is largely negligible in the lower atmosphere below the 10 mbar level for a reasonable range of planetary magnetic moments. We find that the atmospheric conductivity decreases by several orders of magnitude in the night side of tidally locked planets, leading to a potentially interesting large-scale dichotomy in electrodynamics between the day and night sides. A combined approach that relies on UV observations of the upper atmosphere, phase curve and Doppler measurements of global dynamics, and visual transit observations to probe the alkali metals can potentially be

  19. Atmospheric circulation of brown dwarfs and directly imaged extrasolar giant planets with active clouds

    NASA Astrophysics Data System (ADS)

    Tan, Xianyu; Showman, Adam

    2016-10-01

    Observational evidence have suggested active meteorology in the atmospheres of brown dwarfs (BDs) and directly imaged extrasolar giant planets (EGPs). In particular, a number of surveys for brown dwarfs showed that near-IR brightness variability is common for L and T dwarfs. Directly imaged EGPs share similar observations, and can be viewed as low-gravity versions of BDs. Clouds are believed to play the major role in shaping the thermal structure, dynamics and near-IR flux of these atmospheres. So far, only a few studies have been devoted to atmospheric circulation and the implications for observations of BDs and directly EGPs, and yet no global model includes a self-consistent active cloud formation. Here we present preliminary results from the first global circulation model applied to BDs and directly imaged EGPs that can properly treat absorption and scattering of radiation by cloud particles. Our results suggest that horizontal temperature differences on isobars can reach up to a few hundred Kelvins, with typical horizontal length scale of the temperature and cloud patterns much smaller than the radius of the object. The combination of temperature anomaly and cloud pattern can result in moderate disk-integrated near-IR flux variability. Wind speeds can reach several hundred meters per second in cloud forming layers. Unlike Jupiter and Saturn, we do not observe stable zonal jet/banded patterns in our simulations. Instead, our simulated atmospheres are typically turbulent and dominated by transient vortices. The circulation is sensitive to the parameterized cloud microphysics. Under some parameter combinations, global-scale atmospheric waves can be triggered and maintained. These waves induce global-scale temperature anomalies and cloud patterns, causing large (up to several percent) disk-integrated near-IR flux variability. Our results demonstrate that the commonly observed near-IR brightness variability for BDs and directly imaged EGPs can be explained by the

  20. Infrared experiments for spaceborne planetary atmospheres research. Full report

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The role of infrared sensing in atmospheric science is discussed and existing infrared measurement techniques are reviewed. Proposed techniques for measuring planetary atmospheres are criticized and recommended instrument developments for spaceborne investigations are summarized for the following phenomena: global and local radiative budget; radiative flux profiles; winds; temperature; pressure; transient and marginal atmospheres; planetary rotation and global atmospheric activity; abundances of stable constituents; vertical, lateral, and temporal distribution of abundances; composition of clouds and aerosols; radiative properties of clouds and aerosols; cloud microstructure; cloud macrostructure; and non-LTE phenomena.

  1. A systematic retrieval analysis of secondary eclipse spectra. III. Diagnosing chemical disequilibrium in planetary atmospheres

    SciTech Connect

    Line, Michael R.; Yung, Yuk L.

    2013-12-10

    Chemical disequilibrium has recently become a relevant topic in the study of the atmospheres of transiting extrasolar planets, brown dwarfs, and directly imaged exoplanets. We present a new way of assessing whether or not a Jovian-like atmosphere is in chemical disequilibrium from observations of detectable or inferred gases such as H{sub 2}O, CH{sub 4}, CO, and H{sub 2}. Our hypothesis, based on previous kinetic modeling studies, is that cooler atmospheres will show stronger signs of disequilibrium than hotter atmospheres. We verify this with chemistry-transport models and show that planets with temperatures less than ∼1200 K are likely to show the strongest signs of disequilibrium due to the vertical quenching of CO, and that our new approach is able to capture this process. We also find that in certain instances a planetary composition may appear in equilibrium when it actually is not due to the degeneracy in the shape of the vertical mixing ratio profiles. We determine the state of disequilibrium in eight exoplanets using the results from secondary eclipse temperature and abundance retrievals. We find that all of the planets in our sample are consistent with thermochemical equilibrium to within 3σ. Future observations are needed to further constrain the abundances in order to definitively identify disequilibrium in exoplanet atmospheres.

  2. MEP and planetary climates: insights from a two-box climate model containing atmospheric dynamics

    PubMed Central

    Jupp, Tim E.; Cox, Peter M.

    2010-01-01

    A two-box model for equator-to-pole planetary heat transport is extended to include simple atmospheric dynamics. The surface drag coefficient CD is treated as a free parameter and solutions are calculated analytically in terms of the dimensionless planetary parameters η (atmospheric thickness), ω (rotation rate) and ξ (advective capability). Solutions corresponding to maximum entropy production (MEP) are compared with solutions previously obtained from dynamically unconstrained two-box models. As long as the advective capability ξ is sufficiently large, dynamically constrained MEP solutions are identical to dynamically unconstrained MEP solutions. Consequently, the addition of a dynamical constraint does not alter the previously obtained MEP results for Earth, Mars and Titan, and an analogous result is presented here for Venus. The rate of entropy production in an MEP state is shown to be independent of rotation rate if the advective capability ξ is sufficiently large (as for the four examples in the solar system), or if the rotation rate ω is sufficiently small. The model indicates, however, that the dynamical constraint does influence the MEP state when ξ is small, which might be the case for some extrasolar planets. Finally, results from the model developed here are compared with previous numerical simulations in which the effect of varying surface drag coefficient on entropy production was calculated. PMID:20368254

  3. MEP and planetary climates: insights from a two-box climate model containing atmospheric dynamics.

    PubMed

    Jupp, Tim E; Cox, Peter M

    2010-05-12

    A two-box model for equator-to-pole planetary heat transport is extended to include simple atmospheric dynamics. The surface drag coefficient CD is treated as a free parameter and solutions are calculated analytically in terms of the dimensionless planetary parameters eta (atmospheric thickness), omega (rotation rate) and xi (advective capability). Solutions corresponding to maximum entropy production (MEP) are compared with solutions previously obtained from dynamically unconstrained two-box models. As long as the advective capability xi is sufficiently large, dynamically constrained MEP solutions are identical to dynamically unconstrained MEP solutions. Consequently, the addition of a dynamical constraint does not alter the previously obtained MEP results for Earth, Mars and Titan, and an analogous result is presented here for Venus. The rate of entropy production in an MEP state is shown to be independent of rotation rate if the advective capability xi is sufficiently large (as for the four examples in the solar system), or if the rotation rate omega is sufficiently small. The model indicates, however, that the dynamical constraint does influence the MEP state when xi is small, which might be the case for some extrasolar planets. Finally, results from the model developed here are compared with previous numerical simulations in which the effect of varying surface drag coefficient on entropy production was calculated. PMID:20368254

  4. MEP and planetary climates: insights from a two-box climate model containing atmospheric dynamics.

    PubMed

    Jupp, Tim E; Cox, Peter M

    2010-05-12

    A two-box model for equator-to-pole planetary heat transport is extended to include simple atmospheric dynamics. The surface drag coefficient CD is treated as a free parameter and solutions are calculated analytically in terms of the dimensionless planetary parameters eta (atmospheric thickness), omega (rotation rate) and xi (advective capability). Solutions corresponding to maximum entropy production (MEP) are compared with solutions previously obtained from dynamically unconstrained two-box models. As long as the advective capability xi is sufficiently large, dynamically constrained MEP solutions are identical to dynamically unconstrained MEP solutions. Consequently, the addition of a dynamical constraint does not alter the previously obtained MEP results for Earth, Mars and Titan, and an analogous result is presented here for Venus. The rate of entropy production in an MEP state is shown to be independent of rotation rate if the advective capability xi is sufficiently large (as for the four examples in the solar system), or if the rotation rate omega is sufficiently small. The model indicates, however, that the dynamical constraint does influence the MEP state when xi is small, which might be the case for some extrasolar planets. Finally, results from the model developed here are compared with previous numerical simulations in which the effect of varying surface drag coefficient on entropy production was calculated.

  5. Planetary Research Center. [astronomical photography of planetary surfaces and atmospheres

    NASA Technical Reports Server (NTRS)

    Baum, W. A.; Millis, R. L.; Bowell, E. L. G.

    1974-01-01

    Extensive Earth-based photography of Mars, Jupiter, and Venus is presented which monitors the atmospheric and/or surface changes that take place day to day. Color pictures are included of the 1973 dust storm on Mars, showing the daily cycle of the storm's regeneration. Martian topography, and the progress of the storm is examined. Areas most affected by the storm are summarized.

  6. Infrared experiments for spaceborne planetary atmospheres research. Executive summary

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The role of 0.5 to 300 micron remote sensing in planetary atmospheres exploration was evaluated by examining a broad range of measurement techniques including quantitative intercomparisons of existing and planned instruments by the phenomenological method. Key areas of infrared instrumentation requiring development for the investigations of atmospheres were identified.

  7. Time-dependent simulations of disk-embedded planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Stökl, A.; Dorfi, E. A.

    2014-03-01

    At the early stages of evolution of planetary systems, young Earth-like planets still embedded in the protoplanetary disk accumulate disk gas gravitationally into planetary atmospheres. The established way to study such atmospheres are hydrostatic models, even though in many cases the assumption of stationarity is unlikely to be fulfilled. Furthermore, such models rely on the specification of a planetary luminosity, attributed to a continuous, highly uncertain accretion of planetesimals onto the surface of the solid core. We present for the first time time-dependent, dynamic simulations of the accretion of nebula gas into an atmosphere around a proto-planet and the evolution of such embedded atmospheres while integrating the thermal energy budget of the solid core. The spherical symmetric models computed with the TAPIR-Code (short for The adaptive, implicit RHD-Code) range from the surface of the rocky core up to the Hill radius where the surrounding protoplanetary disk provides the boundary conditions. The TAPIR-Code includes the hydrodynamics equations, gray radiative transport and convective energy transport. The results indicate that diskembedded planetary atmospheres evolve along comparatively simple outlines and in particular settle, dependent on the mass of the solid core, at characteristic surface temperatures and planetary luminosities, quite independent on numerical parameters and initial conditions. For sufficiently massive cores, this evolution ultimately also leads to runaway accretion and the formation of a gas planet.

  8. Planetary Atmospheres and the Search for Life.

    ERIC Educational Resources Information Center

    Owen, Tobias

    1982-01-01

    Different ways in which the atmospheres of different planets have originated and evolved are discussed. Includes tables on the atmospheric composition of: (1) Earth; (2) Mars; (3) Venus; (4)Titan (Saturn's Satellite); and (5) the outer planets. (SK)

  9. NASA Planetary Astronomy Lunar Atmospheric Imaging Study

    NASA Technical Reports Server (NTRS)

    Stern, S. Alan

    1996-01-01

    Authors have conducted a program of research focused on studies of the lunar atmosphere. Also present preliminary results of an ongoing effort to determine the degree that metal abundances in the lunar atmosphere are stoichiometric, that is, reflective of the lunar surface composition. We make the first-ever mid-ultraviolet spectroscopic search for emission from the lunar atmosphere.

  10. Planetary Radio Interferometry and Doppler Experiment (PRIDE) for Planetary Atmospheric Studies

    NASA Astrophysics Data System (ADS)

    Bocanegra Bahamon, Tatiana; Cimo, Giuseppe; Duev, Dmitry; Gurvits, Leonid; Molera Calves, Guifre; Pogrebenko, Sergei

    2015-04-01

    The Planetary Radio Interferometry and Doppler Experiment (PRIDE) is a technique that allows the determination of the radial velocity and lateral coordinates of planetary spacecraft with very high accuracy (Duev, 2012). The setup of the experiment consists of several ground stations from the European VLBI Network (EVN) located around the globe, which simultaneously perform Doppler tracking of a spacecraft carrier radio signal, and are subsequently processed in a VLBI-style in phase referencing mode. Because of the accurate examination of the changes in phase and amplitude of the radio signal propagating from the spacecraft to the multiple stations on Earth, the PRIDE technique can be used for several fields of planetary research, among which planetary atmospheric studies, gravimetry and ultra-precise celestial mechanics of planetary systems. In the study at hand the application of this technique for planetary atmospheric investigations is demonstrated. As a test case, radio occultation experiments were conducted with PRIDE having as target ESA's Venus Express, during different observing sessions with multiple ground stations in April 2012 and March 2014. Once each of the stations conducts the observation, the raw data is delivered to the correlation center at the Joint Institute for VLBI in Europe (JIVE) located in the Netherlands. The signals are processed with a high spectral resolution and phase detection software package from which Doppler observables of each station are derived. Subsequently the Doppler corrected signals are correlated to derive the VLBI observables. These two sets of observables are used for precise orbit determination. The reconstructed orbit along with the Doppler observables are used as input for the radio occultation processing software, which consists of mainly two modules, the geometrical optics module and the ray tracing inversion module, from which vertical density profiles, and subsequently, temperature and pressure profiles of Venus

  11. A spectrum of an extrasolar planet.

    PubMed

    Richardson, L Jeremy; Deming, Drake; Horning, Karen; Seager, Sara; Harrington, Joseph

    2007-02-22

    Of the over 200 known extrasolar planets, 14 exhibit transits in front of their parent stars as seen from Earth. Spectroscopic observations of the transiting planets can probe the physical conditions of their atmospheres. One such technique can be used to derive the planetary spectrum by subtracting the stellar spectrum measured during eclipse (planet hidden behind star) from the combined-light spectrum measured outside eclipse (star + planet). Although several attempts have been made from Earth-based observatories, no spectrum has yet been measured for any of the established extrasolar planets. Here we report a measurement of the infrared spectrum (7.5-13.2 microm) of the transiting extrasolar planet HD 209458b. Our observations reveal a hot thermal continuum for the planetary spectrum, with an approximately constant ratio to the stellar flux over this wavelength range. Superposed on this continuum is a broad emission peak centred near 9.65 microm that we attribute to emission by silicate clouds. We also find a narrow, unidentified emission feature at 7.78 microm. Models of these 'hot Jupiter' planets predict a flux peak near 10 microm, where thermal emission from the deep atmosphere emerges relatively unimpeded by water absorption, but models dominated by water fit the observed spectrum poorly.

  12. Atmospheric circulation modeling of super Earths and terrestrial extrasolar planets using the SPARC/MITgcm

    NASA Astrophysics Data System (ADS)

    Kataria, T.; Showman, A. P.; Haberle, R. M.; Marley, M. S.; Fortney, J. J.; Freedman, R. S.

    2013-12-01

    The field of exoplanets continues to be a booming field of research in astronomy and planetary science, with numerous ground-based (e.g., SuperWASP, HARPS-N and S) and space-based surveys (e.g., Kepler) that detect and characterize planets ranging from hot Jupiters, Jovian-sized planets orbiting less than 0.1 AU from their star, to super Earths and terrestrial exoplanets, planets that have masses equal to or less than 10 times that of Earth with a range of orbital distances. Atmospheric circulation modeling plays an important role in the characterization of these planets, helping to constrain observations that probe their atmospheres. These models have proven successful in understanding observations of transiting exoplanets (when the planet passes in front of the star along our line of sight) particularly when the planet is passing through secondary eclipse (when the planet's dayside is visible). In modeling super Earths and terrestrial exoplanets, we must consider not only planets with thick fluid envelopes, but also traditional terrestrial planets with solid surfaces and thinner atmospheres. To that end, we present results from studies investigating the atmospheric circulation of these classes of planets using the SPARC/MITgcm, a state-of-the-art model which couples the MIT General Circulation Model with a plane-parallel, two-stream, non-gray radiative transfer model. We will present results from two studies, the first focusing on the circulation of GJ 1214b, a super-Earth detected by the MEarth ground-based survey, and a second study which explores the circulation of terrestrial exoplanets orbiting M-dwarfs.

  13. The runaway greenhouse: implications for future climate change, geoengineering and planetary atmospheres.

    PubMed

    Goldblatt, Colin; Watson, Andrew J

    2012-09-13

    The ultimate climate emergency is a 'runaway greenhouse': a hot and water-vapour-rich atmosphere limits the emission of thermal radiation to space, causing runaway warming. Warming ceases only after the surface reaches approximately 1400 K and emits radiation in the near-infrared, where water is not a good greenhouse gas. This would evaporate the entire ocean and exterminate all planetary life. Venus experienced a runaway greenhouse in the past, and we expect that the Earth will in around 2 billion years as solar luminosity increases. But could we bring on such a catastrophe prematurely, by our current climate-altering activities? Here, we review what is known about the runaway greenhouse to answer this question, describing the various limits on outgoing radiation and how climate will evolve between these. The good news is that almost all lines of evidence lead us to believe that is unlikely to be possible, even in principle, to trigger full a runaway greenhouse by addition of non-condensible greenhouse gases such as carbon dioxide to the atmosphere. However, our understanding of the dynamics, thermodynamics, radiative transfer and cloud physics of hot and steamy atmospheres is weak. We cannot therefore completely rule out the possibility that human actions might cause a transition, if not to full runaway, then at least to a much warmer climate state than the present one. High climate sensitivity might provide a warning. If we, or more likely our remote descendants, are threatened with a runaway greenhouse, then geoengineering to reflect sunlight might be life's only hope. Injecting reflective aerosols into the stratosphere would be too short-lived, and even sunshades in space might require excessive maintenance. In the distant future, modifying Earth's orbit might provide a sustainable solution. The runaway greenhouse also remains relevant in planetary sciences and astrobiology: as extrasolar planets smaller and nearer to their stars are detected, some will be in

  14. The runaway greenhouse: implications for future climate change, geoengineering and planetary atmospheres.

    PubMed

    Goldblatt, Colin; Watson, Andrew J

    2012-09-13

    The ultimate climate emergency is a 'runaway greenhouse': a hot and water-vapour-rich atmosphere limits the emission of thermal radiation to space, causing runaway warming. Warming ceases only after the surface reaches approximately 1400 K and emits radiation in the near-infrared, where water is not a good greenhouse gas. This would evaporate the entire ocean and exterminate all planetary life. Venus experienced a runaway greenhouse in the past, and we expect that the Earth will in around 2 billion years as solar luminosity increases. But could we bring on such a catastrophe prematurely, by our current climate-altering activities? Here, we review what is known about the runaway greenhouse to answer this question, describing the various limits on outgoing radiation and how climate will evolve between these. The good news is that almost all lines of evidence lead us to believe that is unlikely to be possible, even in principle, to trigger full a runaway greenhouse by addition of non-condensible greenhouse gases such as carbon dioxide to the atmosphere. However, our understanding of the dynamics, thermodynamics, radiative transfer and cloud physics of hot and steamy atmospheres is weak. We cannot therefore completely rule out the possibility that human actions might cause a transition, if not to full runaway, then at least to a much warmer climate state than the present one. High climate sensitivity might provide a warning. If we, or more likely our remote descendants, are threatened with a runaway greenhouse, then geoengineering to reflect sunlight might be life's only hope. Injecting reflective aerosols into the stratosphere would be too short-lived, and even sunshades in space might require excessive maintenance. In the distant future, modifying Earth's orbit might provide a sustainable solution. The runaway greenhouse also remains relevant in planetary sciences and astrobiology: as extrasolar planets smaller and nearer to their stars are detected, some will be in

  15. Crossing the Boundaries in Planetary Atmospheres - From Earth to Exoplanets

    NASA Technical Reports Server (NTRS)

    Simon-Miller, Amy A.; Genio, Anthony Del

    2013-01-01

    The past decade has been an especially exciting time to study atmospheres, with a renaissance in fundamental studies of Earths general circulation and hydrological cycle, stimulated by questions about past climates and the urgency of projecting the future impacts of humankinds activities. Long-term spacecraft and Earth-based observation of solar system planets have now reinvigorated the study of comparative planetary climatology. The explosion in discoveries of planets outside our solar system has made atmospheric science integral to understanding the diversity of our solar system and the potential habitability of planets outside it. Thus, the AGU Chapman Conference Crossing the Boundaries in Planetary Atmospheres From Earth to Exoplanets, held in Annapolis, MD from June 24-27, 2013 gathered Earth, solar system, and exoplanet scientists to share experiences, insights, and challenges from their individual disciplines, and discuss areas in which thinking broadly might enhance our fundamental understanding of how atmospheres work.

  16. Consequences of planetary migration: Kuiper belt dynamics and atmospheric escape from hot Jupiters

    NASA Astrophysics Data System (ADS)

    Murray-Clay, Ruth Ann

    The current resonance structure of the Kuiper belt suggests that during the late stages of planet formation, Neptune migrated outward as it scattered residual planetesimal debris. Extrasolar planetary systems also show evidence for planetary migration. Approximately 1/5 of the extrasolar planets discovered to date are "hot Jupiters," which likely exchanged angular momentum with gas disks, migrating large distances inward to reach their current semi-major axes of ~0.05 AU. In this thesis, I discuss three consequences of planetary migration. (1) During its migration, Neptune captured Kuiper belt objects (KBOs) into mean motion resonances. The current spatial distribution of KBOs in a particular resonance, the 2:1, acts as a celestial speedometer--fast planetary migration generates a larger population of 2:1 resonant KBOs trailing rather than leading Neptune on the sky. We provide an explanation of this phenomenon for the first time. Central to our understanding is how planetary migration shifts the equilibrium points of the superposed direct and indirect potentials felt by a KBO. The currently observed distribution of 2:1 KBOs excludes total migration times < 20 Myr with >99.65% confidence and is statistically consistent with the even population generated by slow migration. However, these observations are beset by systematic uncertainties. Observations with new telescopes such as PanSTARRS or LSST will tell us how quickly Neptune could have migrated. (2) Neptune's migration, powered by scattering planetesimal debris, was stochastic ("noisy"). Extreme stochasticity defeats resonance capture. We construct a theory analogous to Brownian motion for how a planet's orbital semi-major axis fluctuates in response to random planetesimal scatterings. The degree of stochasticity in Neptune's migration depends both on the sizes of the planetesimals driving migration and on their orbital elements and cannot currently be computed using N-body simulations. We find that capture of

  17. An application of gas chromatography to planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Oyama, V.

    1974-01-01

    A gas chromatography developed for the Viking experiment is described. The instrument is designed to measure gases in planetary atmospheres and head space in a chamber. It is hoped that the chromatograph will also measure any biological activity present in these environments.

  18. In situ observations of the atmospheres of terrestrial planetary bodies

    NASA Astrophysics Data System (ADS)

    Harri, Ari-Matti

    2005-11-01

    Direct observations of planetary atmospheres are scarce and significantly more data are needed for the understanding of their behavior. The principal theme of this dissertation is the exploration of planetary atmospheres by means of in situ observations, focusing on investigations performed by payloads operating on the planetary surface. The contextual frame includes the whole palette of planetary exploration including definition of scientific objectives, observational strategies, scientific payload and data analysis, as well as development of technological solutions and simulation models for planetary missions. Thus approach also led to the initiation of the planetary missions MetNet and NetLander to Mars. This work contributes to both in situ atmospheric observations and atmospheric modeling, which are strongly intertwined. Modeling efforts require observations to give solid background and foundation for the simulations, and on the other hand, definition of observational strategies and instrumentation gets guidance from modeling efforts to optimize the use of mission resources, as is successfully demonstrated in this dissertation. The dissertation consists of Summary and nine original scientific publications. Publications 1 to 7 and Summary address the development of new atmospheric science payloads for exploration missions to Mars and Titan, a Saturnian moon. Actual and planned missions included are the Mars-96 Program and its Small Surface Stations and Penetrators during the years 1988-1996, PPI/HASI onboard the Cassini/Huygens spacecraft to Saturn and its moon Titan in 1989-2005, the MET-P payload onboard the Mars Polar Lander in 1997-1999, the BAROBIT instrument for the Beagle 2 lander in 2001-2003, the NetLander Mars Mission in 1997-2001 and the ongoing Mars MetNet Mission, started in 2000. Specifically, Publication 4 reviews the sensor qualification process that facilitated the use of new type of atmospheric sensors at Mars, while Publications 2 and 7, as

  19. Composition of early planetary atmospheres - I. Connecting disc astrochemistry to the formation of planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Cridland, A. J.; Pudritz, R. E.; Alessi, M.

    2016-09-01

    We present a model of the early chemical composition and elemental abundances of planetary atmospheres based on the cumulative gaseous chemical species that are accreted on to planets forming by core accretion from evolving protoplanetary discs. The astrochemistry of the host disc is computed using an ionization-driven, non-equilibrium chemistry network within viscously evolving disc models. We accrete gas giant planets whose orbital evolution is controlled by planet traps using the standard core accretion model and track the chemical composition of the material that is accreted on to the protoplanet. We choose a fiducial disc model and evolve planets in three traps - water ice line, dead zone and heat transition. For a disc with a lifetime of 4.1 Myr, we produce two hot Jupiters (M = 1.43, 2.67 MJupiter, r = 0.15, 0.11 au) in the heat transition and ice line trap and one failed core (M = 0.003 MJupiter, r = 3.7 au) in the dead zone. These planets are found with mixing ratios for CO and H2O of 1.99 × 10-4 and 5.0 × 10-4, respectively, for both hot Jupiters. Additionally, for these planets we find CO2 and CH4, with mixing ratios of 1.8 × 10-6 → 9.8 × 10-10 and 1.1 × 10-8 → 2.3 × 10-10, respectively. These ranges correspond well with the mixing ratio ranges that have been inferred through the detection of emission spectra from hot Jupiters by multiple authors. We compute a carbon-to-oxygen ratio of 0.227 for the ice line planet and 0.279 for the heat transition planet. These planets accreted their gas inside the ice line, hence the sub-solar C/O.

  20. Understanding the formation and composition of hazes in planetary atmospheres that contain carbon monoxide

    NASA Astrophysics Data System (ADS)

    Hörst, S. M.; Yoon, Y. H.; Hicks, R. K.; Tolbert, M. A.

    2012-09-01

    Measurements from the Cassini Plasma Spectrometer (CAPS) have revealed the presence of molecules in Titan's ionosphere with masses in excess of hundreds of amu. Negative ions with mass/charge (m/z) up to 10,000 amu/q [1] and positive ions with m/z up to 400 amu/q [2] have been detected. CAPS has also observed O+ flowing into Titan's upper atmosphere [3], which appears to originate from Enceladus and is likely the source of oxygen bearing molecules in Titan's atmosphere [4]. The observed O+ is deposited in the region now known to contain large organic molecules. A recent Titan atmosphere simulation experiment has shown that incorporation of oxygen into Titan aerosol analogues results in the formation of all five nucleotide bases and the two smallest amino acids, glycine and alanine [5]. Similar chemical processes may have occurred in the atmosphere of the early Earth, or in the atmospheres of extrasolar planets; atmospheric aerosols may be an important source of the building blocks of life. Atmospheric aerosols play an important role in determining the radiation budget of an atmosphere and can also provide a wealth of organic material to the surface. The presence of atmospheric aerosols has been invoked to explain the relatively featureless spectrum of HD 189773b, including the lack of predicted atmospheric Na and K spectral lines [9]. The majority of the O+ precipitating into Titan's atmosphere forms CO (O(3P)+CH3 -> CO+H2+H) [4]. CO has also been detected in the atmospheres of a number of exoplanets including HD 189733b, HD 209458b, and WASP-12b [6-8]. It is therefore important to understand the role CO plays in the formation and composition of hazes in planetary atmospheres. Using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) (see e.g. [10]) we have obtained in situ composition measurements of aerosol particles (so-called "tholins") produced in N2/CH4/CO gas mixtures subjected to either FUV radiation (deuterium lamp, 115-400 nm) or a

  1. Interstellar cloud material: contribution to planetary atmospheres.

    PubMed

    Butler, D M; Newman, M J; Talbot, R J

    1978-08-11

    A statistical analysis of the properties of dense interstellar clouds indicates that the solar system has encountered at least a dozen clouds of sufficient density to cause planets to accumulate nonnegligible amounts of some isotopes. The effect is most pronounced for neon. This mechanism could be responsible for much of the neon in Earth's atmosphere. For Mars, the predicted amount of neon added by cloud encounters greatly exceeds the present abundance.

  2. SOIR and NOMAD: Characterization of Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Robert, S.; Chamberlain, S.; Mahieux, A.; Thomas, I.; Wilquet, V.; Vandaele, A. C.

    2014-06-01

    The Belgian Institute for Space Aeronomy is involved in the Venus Express mission (VeX), launched in 2006 and in the ExoMars Trace Gas Orbiter mission (TGO), due for launch in 2016. BISA is responsible for one instrument in each mission, SOIR onboard VeX and NOMAD onboard TGO respectively. The SOIR instrument onboard Venus Express allows observations of trace gases in the Venus atmosphere, at the terminator for both the morning and evening sides of the planet and for almost all latitudes. It has been designed to measure spectra in the IR region (2.2 - 4.3 µm) of the Venus atmosphere using the solar occultation technique1. This method derives unique information on the vertical composition and structure of the mesosphere and lower thermosphere2,3,4,5. It is unique in terms of spectral coverage and spectral resolution (0.15 cm-1), and is ideally designed to probe the Venus atmosphere for CO2 as well as trace gases, such as H2O, CO, HCl and HF. SOIR is capable of (1) providing vertical information on a broad series of species, such as CO2, CO, H2O, HCl, HF, SO26 and aerosols 7, covering the so far sparsely known region located above the clouds, (2) contributing to a better understanding of the dynamics and stability of the atmosphere by delivering total density and kinetic temperature profiles at the terminator, an up-to-now still unchartered region, and (3) detecting weak absorption bands of rare CO2 isotopologues8, due to the sensitivity of SOIR, the high concentration of CO2 on Venus and the long absorption paths sounded during solar occultations.

  3. Conservation of Total Escape from Hydrodynamic Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Tian, F.

    2013-12-01

    Atmosphere escape is one key process controlling the evolution of planets. However, estimating the escape rate in any detail is difficult because there are many physical processes contributing to the total escape rate. Here we show that as a result of energy conservation the total escape rate from hydrodynamic planetary atmospheres where the outflow remains subsonic is nearly constant under the same stellar XUV photon flux when increasing the escape efficiency from the exobase level, consistent with the energy limited escape approximation. Thus the estimate of atmospheric escape in a planet's evolution history can be greatly simplified.

  4. Tectonic implications of radiogenic noble gases in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Turcotte, D. L.; Schubert, G.

    1988-01-01

    An account is given of the ways in which the He-4 and Ar-40 radiogenic isotopes furnish important constraints on planetary interior tectonics. In the case of the earth, where there are such independent constraints on radiogenic isotope concentrations as observed surface heat flow, the specification of radiogenic isotope concentration allows the interpretation of data on the Ar-40 atmospheric mass and mantle He-4 in terms of models for the entire mantle and of layered mantle convection. He loss rate estimates through the Venus atmosphere indicate a flux that is nearly equal to that through the earth atmosphere.

  5. A Study on Planetary Atmospheric Circulations using THOR

    NASA Astrophysics Data System (ADS)

    Mendonça, João; Grosheintz, Luc; Lukas Grimm, Simon; Heng, Kevin

    2015-12-01

    The large variety of planetary parameters observed leads us to think that exoplanets may show a large range of possible climates. It is therefore of the uttermost importance to investigate the influence of astronomical and planetary bulk parameters in driving the atmospheric circulations. In the solar system the results from planetary spacecraft missions have demonstrated how different the planetary climate and atmospheric circulations can be. The study of exoplanets will require probing a far wider range of physical and orbital parameters than the ones of our neighbor planets. For this reason, such a study will involve exploring an even larger diversity of circulation and climate regimes. Our new atmospheric model, THOR, is intended to be extremely flexible and to explore the large diversity of planetary atmospheres.THOR is part of the Exoclimes Simulation Platform, and is a project of the Exoplanet and Exoclimes Group (see www.exoclime.org). THOR solves the complex atmospheric fluid equations in a rotating sphere (fully compressible - nonhydrostatic system) using an icosahedral grid. The main advantages of using our new platform against other recent exoplanet models is that 1) The atmospheric fluid equations are completely represented and no approximations are used that could compromise the physics of the problem; 2) The model uses for the first time in exoplanet studies, a specific icosahedral grid that solves the pole problem; 3) The interface is user friendly and can be easily adapted to a multitude of atmospheric conditions; 4) By using GPU computation, our code greatly improves the typical code running time.We will present and discuss the first detailed results of our simulations, more specifically of two benchmark tests that are a representative sample of the large range of exoplanetary parameters: Earth-like conditions (the Held-Suarez test) and a tidally locked hot-Jupiter. THOR has successfully passed these tests and is able to determine the main

  6. Detecting the polarization signatures of extra-solar planets

    NASA Astrophysics Data System (ADS)

    Hough, J. H.; Lucas, P. W.; Bailey, J. A.; Tamura, M.; Hirst, E.

    2006-06-01

    Direct detection of the light scattered from extra-solar planets is important in establishing the planet's mass, radius, albedo and nature of the particles in the planetary atmosphere. We describe, and present results from, a new optical polarimeter (PlanetPol) designed to reach fractional polarizations of 10 -6 or better from ground-based telescopes, necessary to detect the polarization signature of unresolved hot-Jupiters.

  7. Biomarkers of extrasolar planets and their observability

    NASA Astrophysics Data System (ADS)

    Selsis, Franck; Paillet, Jimmy; Allard, France

    The first space-borne instruments able to detect and characterize extrasolar terrestrial planets, Darwin (ESA) and TPF-C (Terrestrial Planet Finder-Coronograph, NASA), should be launched at the end of the next decade. Beyond the challenge of planet detection itself, the ability to measure mid-infrared (Darwin) and visible (TPF-C) spectra at low resolution will allow us to characterize the exoplanets discovered. The spectral analysis of these planets will extend the field of planetary science beyond the Solar System to the nearby Universe: It will give access to certain planetary properties (albedo, brightness temperature, radius) and reveal the presence of atmospheric compounds, which, together with the radiative budget of the planet, will provide the keys to understanding how the climate system works on these worlds. If terrestrial planets are sufficiently abundant, these missions will collect data for numerous planetary systems of different ages and orbiting different types of stars. Theories for the formation, evolution and habitability of the terrestrial planets will at last face the test observation. The most fascinating perspective offered by these space observatories is the ability to detect spectral signatures indicating biological activity. In this chapter, we review and discuss the concept of extrasolar biosignatures or biomarkers. We focus mainly on the identification of oxygen-rich atmospheres through the detection of O2 and O3 features, addressing also the case of other possible biomarkers and indicators of habitability.

  8. Volcanic Degassing and the Atmosphere of Planetary Suites

    NASA Astrophysics Data System (ADS)

    Gaillard, F.; Scaillet, B.

    2012-12-01

    How unique the Earth is requires an urgent definition in front of the myriad of spatial observations revealing extra solar planets with variable spectral signatures. In the close solar system, high water abundance, atmospheric pressure at 1 bar and an O2-rich atmosphere constitute the main features of the Earth surface. This contrasts with dry Venus and its nearly 100 bar of reduced atmosphere dominated by CO2. This also contrasts with Mars, once flowed by water, today dominated by sulphate deposits, with 0.01 bar of atmospheric pressure and its oxidized surface. Such diversity in the physic and chemistry of planetary surfaces constitutes our most robust observation and benchmark for deciphering the remote exoplanets and defining the possible development of clement conditions for extra-terrestrial life. Volcanic degassing is a fundamental planetary process that conveys igneous volatiles species regulating important physical and chemical features of the exosphere. Understanding the planetary chemical fix supplied by volcanoes and how it can vary is therefore critical for a better definition of systems favorable to life emergence. We show that the atmospheric pressure, defining the minimum pressure of volcanic degassing, is the chief parameter controlling the composition of volcanic gases. On Venus, volcanic degassing occurring at minimum pressure of 100 bar can only be composed of CO2, whereas water and sulfur remain dissolved in the lavas. This explains the dry Venusian atmosphere. Degassing at 1 bar (minimum) on Earth produces mixtures dominated by water, explaining the Earth's wet surface. On Mars, gases produced at less than 0.05 bar contain more sulfur than water and Jupiter moon, Io, emits, in vacuum, gases that are dominated by sulfite. The composition of volcanic gases is therefore merely regulated by the atmospheric pressure. The latter is, in turn, mainly controlled by the size of the planet, even if little certitude exists about the most influential

  9. Searching for extra-solar planets and probing the atmosphere of Bulge giant stars through gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Cassan, Arnaud

    2005-12-01

    A galactic microlensing effect occurs when a luminous object (the source) located in the Bulge of the Milky Way is temporarily magnified by an intervening star (the "microlens'') passing close to its line of sight. This phenomenom is used for searching extra-solar planets and constraining their abundance, as well as probing the atmosphere of Bulge giant stars. The PLANET collaboration (Probing Lensing Anomalies NETwork) monitors carefully chosen ongoing microlensing events on a round-the-clock basis from observatories in the southern hemisphere. Mathematical and numerical methods are developed to deal with both the highly non-linear equations and the wide parameter space plagued with many local minima. Microlensing exoplanet detection is possible because planets can induce perturbations to the standard lensing light curves. Its sensitivity can go down to Earth-mass planets, thanks to gravitational caustics that arise from a binary lens. If crossed by the source, additional secondary magnification peaks in the light curve can occur. OGLE 2005-BLG-390Lb is the third extra-solar planet detected by this method so far, and its discovery is reported here. It is the lightest exoplanet to date - about five Earth masses - located at a rather large distance of its star, that is about three astronomical units. A selection of microlensing events monitored during the 1995-2004 period was used to derive limits on exoplanets abundance around red dwarf stars. The method is described and detection efficiency diagrams are provided as a basis of the statistical analysis. Last, a differential magnification effect over the disk of the source star is used as a tool to probe Bulge giants stellar atmospheres. Limb-darkening parameters of a set of stars have been measured and compared to atmosphere models. Moreover, a high-resolution spectroscopic monitoring of a Bulge G5III giant at 9 kpc made possible both the measurement of the individual lines equivalent width and the direct detection

  10. Atmospheric planetary waves induced by solar rotation

    NASA Technical Reports Server (NTRS)

    Krivolutsky, A. A.

    1989-01-01

    It is known that there are variations in the atmospheric processes with a period close to that of the rotation of the Sun (27 days). The variations are discovered in tropospheric processes, rainfalls, geopotential and in stratosphere. The main theoretical problem is the identification of the physical process by which these heterogeneous solar and meteorological phenomena are connected. Ivanovsky and Krivolutsky proposed that the periodic heating of the ozone layer by the short wave radiation would be the reason of excitation the 27-day oscillations. It was also assumed that excitement takes place in condition of resonance with an excited mode corresponding to the conditions present in the stratospheric circulations. The possibility is discussed of the resonant excitation and presentation is made of the data analysis results which support this idea.

  11. A Department of Atmospheric and Planetary Sciences at Hampton University

    NASA Astrophysics Data System (ADS)

    Paterson, W. R.; McCormick, M. P.; Russell, J. M.; Anderson, J.; Kireev, S.; Loughman, R. P.; Smith, W. L.

    2006-12-01

    With this presentation we discuss the status of plans for a Department of Atmospheric and Planetary Sciences at Hampton University. Hampton University is a privately endowed, non-profit, non-sectarian, co-educational, and historically black university with 38 baccalaureate, 14 masters, and 4 doctoral degree programs. The graduate program in physics currently offers advanced degrees with concentration in Atmospheric Science. The 10 students now enrolled benefit substantially from the research experience and infrastructure resident in the university's Center for Atmospheric Sciences (CAS), which is celebrating its tenth anniversary. Promoting a greater diversity of participants in geosciences is an important objective for CAS. To accomplish this, we require reliable pipelines of students into the program. One such pipeline is our undergraduate minor in Space, Earth, and Atmospheric Sciences (SEAS minor). This minor concentraton of study is contributing to awareness of geosciences on the Hampton University campus, and beyond, as our students matriculate and join the workforce, or pursue higher degrees. However, the current graduate program, with its emphasis on physics, is not necessarily optimal for atmospheric scientists, and it limits our ability to recruit students who do not have a physics degree. To increase the base of candidate students, we have proposed creation of a Department of Atmospheric and Planetary Sciences, which could attract students from a broader range of academic disciplines. The revised curriculum would provide for greater concentration in atmospheric and planetary sciences, yet maintain a degree of flexibility to allow for coursework in physics or other areas to meet the needs of individual students. The department would offer the M.S. and Ph.D. degrees, and maintain the SEAS minor. The university's administration and faculty have approved our plan for this new department pending authorization by the university's board of trustees, which will

  12. Photochemical hazes in planetary atmospheres: solar system bodies and beyond

    NASA Astrophysics Data System (ADS)

    Imanaka, Hiroshi; Cruikshank, Dale P.; McKay, Christopher P.

    2015-11-01

    Recent transit observations of exoplanets have demonstrated the possibility of a wide prevalence of haze/cloud layers at high altitudes. Hydrocarbon photochemical haze could be the candidate for such haze particles on warm sub-Neptunes, but the lack of evidence for methane poses a puzzle for such hydrocarbon photochemical haze. The CH4/CO ratios in planetary atmospheres vary substantially from their temperature and dynamics. An understanding of haze formation rates and plausible optical properties in a wide diversity of planetary atmospheres is required to interpret the current and future observations.Here, we focus on how atmospheric compositions, specifically CH4/CO ratios, affect the haze production rates and their optical properties. We have conducted a series of cold plasma experiments to constrain the haze mass production rates from gas mixtures of various CH4/CO ratios diluted either in H2 or N2 atmosphere. The mass production rates in the N2-CH4-CO system are much greater than those in the H2-CH4-CO system. They are rather insensitive to the CH4/CO ratios larger than at 0.3. Significant formation of solid material is observed both in H2-CO and N2-CO systems without CH4 in the initial gas mixtures. The complex refractive indices were derived for haze samples from N2-CH4, H2-CH4, and H2-CO gas mixtures. These are the model atmospheres for Titan, Saturn, and exoplanets, respectively. The imaginary part of the complex refractive indices in the UV-Vis region are distinct among these samples, which can be utilized for modeling these planetary atmospheres.

  13. Detection of the Magnetospheric Emissions from Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Lazio, J.

    2014-12-01

    Planetary-scale magnetic fields are a window to a planet's interior and provide shielding of the planet's atmosphere. The Earth, Mercury, Ganymede, and the giant planets of the solar system all contain internal dynamo currents that generate planetary-scale magnetic fields. These internal dynamo currents arise from differential rotation, convection, compositional dynamics, or a combination of these. If coupled to an energy source, such as the incident kinetic or magnetic energy from the solar wind, a planet's magnetic field can produce electron cyclotron masers in its magnetic polar regions. The most well known example of this process is the Jovian decametric emission, but all of the giant planets and the Earth contain similar electron cyclotron masers within their magnetospheres. Extrapolated to extrasolar planets, the remote detection of the magnetic field of an extrasolar planet would provide a means of obtaining constraints on the thermal state, composition, and dynamics of its interior as well as improved understanding of the basic planetary dynamo process. The magnetospheric emissions from solar system planets and the discovery of extrasolar planets have motivated both theoretical and observational work on magnetospheric emissions from extrasolar planets. Stimulated by these advances, the W.M. Keck Institute for Space Studies hosted a workshop entitled "Planetary Magnetic Fields: Planetary Interiors and Habitability." I summarize the current observational status of searches for magnetospheric emissions from extrasolar planets, based on observations from a number of ground-based radio telescopes, and future prospects for ground-based studies. Using the solar system planetary magnetic fields as a guide, future space-based missions will be required to study planets with magnetic field strengths lower than that of Jupiter. I summarize mission concepts identified in the KISS workshop, with a focus on the detection of planetary electron cyclotron maser emission. The

  14. Studies of Excited Species in Planetary Upper Atmospheres

    NASA Technical Reports Server (NTRS)

    Fox, J. L.

    1999-01-01

    During the period of this portion of the on-going project, we investigated aspects of the upper atmospheres of Venus, Mars, Titan and Jupiter. During this period, we published four journal articles and one book chapter, copies of which are attached. The work reported in these manuscripts was in almost all cases begun under previous projects in the Planetary Atmospheres Program with the same title. I will summarize the papers, and another project that we worked on during this time period for which the papers will be published later.

  15. Disequilibrium in planetary atmospheres and the search for habitability

    NASA Astrophysics Data System (ADS)

    Simoncini, E.

    It has long been observed that Earth's atmosphere is uniquely far from its thermochemical equilibrium state in terms of its chemical composition. Studying this state of disequilibrium is important for its potential role in the detection of life on other suitable planets \\citep{Lovelock_1965,Kleidon_2010,Simoncini_2015}. We developed a methodology to calculate the extent of atmospheric chemical disequilibrium\\citep{Simoncini_2015,Kondepudi_1996}. This tool allows us to understand, on a thermodynamic basis, how life affected - and still affects - geochemical processes on Earth, and if other planetary atmospheres are habitable or have a disequilibrium similar to the Earth's one. A new computational framework called KROME has been applied to atmospheric models in order to give a correct computation of reactions´ kinetics \\citep{Grassi_2015}. In this work we present a first computation of the extent of disequilibrium for the present Earth atmosphere, considering the specific contribution of the different atmospheric processes, such as thermochemical reactions, eddy diffusion, photochemistry, deposition, and the effect of the biosphere. We then assess the effect of life on atmospheric disequilibrium of the Earth and provide a useful discussion about how the study of atmospheric disequilibrium can help in finding habitable (exo)planets. We finally compare the chemical disequilibrium of Earth and Mars atmospheres, for present and early conditions.

  16. Modeling Planetary Atmospheric Energy Deposition By Energetic Ions

    NASA Astrophysics Data System (ADS)

    Parkinson, Christopher; Bougher, Stephen; Gronoff, Guillaume; Barthelemy, Mathieu

    2016-07-01

    The structure, dynamics, chemistry, and evolution of planetary upper atmospheres are in large part determined by the available sources of energy. In addition to the solar EUV flux, the solar wind and solar energetic particle (SEP) events are also important sources. Both of these particle populations can significantly affect an atmosphere, causing atmospheric loss and driving chemical reactions. Attention has been paid to these sources from the standpoint of the radiation environment for humans and electronics, but little work has been done to evaluate their impact on planetary atmospheres. At unmagnetized planets or those with crustal field anomalies, in particular, the solar wind and SEPs of all energies have direct access to the atmosphere and so provide a more substantial energy source than at planets having protective global magnetic fields. Additionally, solar wind and energetic particle fluxes should be more significant for planets orbiting more active stars, such as is the case in the early history of the solar system for paleo-Venus and Mars. Therefore quantification of the atmospheric energy input from the solar wind and SEP events is an important component of our understanding of the processes that control their state and evolution. We have applied a full Lorentz motion particle transport model to study the effects of particle precipitation in the upper atmospheres of Mars and Venus. Such modeling has been previously done for Earth and Mars using a guiding center precipitation model. Currently, this code is only valid for particles with small gyroradii in strong uniform magnetic fields. There is a clear necessity for a Lorentz formulation, hence, a systematic study of the ionization, excitation, and energy deposition has been conducted, including a comparison of the influence relative to other energy sources (namely EUV photons). The result is a robust examination of the influence of energetic ion transport on the Venus and Mars upper atmosphere which

  17. Formation of spectral lines in planetary atmospheres. I - Theory for cloudy atmospheres: Application to Venus.

    NASA Technical Reports Server (NTRS)

    Hunt, G. E.

    1972-01-01

    The theory of the formation of spectral lines in a cloudy planetary atmosphere is studied in detail. It is shown that models based upon homogeneous, isotropically scattering atmospheres cannot be used to reproduce observed spectroscopic features of phase effect and the shape of spectral lines for weak and strong bands. The theory must, therefore, be developed using an inhomogeneous (gravitational) model of a planetary atmosphere, accurately incorporating all the physical processes of radiative transfer. Such a model of the lower Venus atmosphere, consistent with our present knowledge, is constructed. The results discussed in this article demonstrate the effects of the parameters that describe the atmospheric model on the spectroscopic features of spectral line profile and phase effect, at visible and near infrared wavelengths. This information enables us to develop a comprehensive theory of line formation in a Venus atmosphere.

  18. Dications and thermal ions in planetary atmospheric escape

    NASA Astrophysics Data System (ADS)

    Lilensten, J.; Simon Wedlund, C.; Barthélémy, M.; Thissen, R.; Ehrenreich, D.; Gronoff, G.; Witasse, O.

    2013-01-01

    In the recent years, the presence of dications in the atmospheres of Mars, Venus, Earth and Titan has been modeled and assessed. These studies also suggested that these ions could participate to the escape of the planetary atmospheres because a large fraction of them is unstable and highly energetic. When they dissociate, their internal energy is transformed into kinetic energy which may be larger than the escape energy. The goal of this study is to assess the impact of the doubly-charged ions in the escape of CO2-dominated planetary atmospheres and to compare it to the escape of thermal photo-ions. We solve a Boltzmann transport equation at daytime taking into account the dissociative states of CO2++ for a simplified single constituent atmosphere of a case-study planet. We compute the escape of fast ions using a Beer-Lambert approach. We study three test-cases. On a Mars-analog planet in today's conditions, we retrieve the measured electron escape flux. When comparing the two mechanisms (i.e. excluding solar wind effects, sputtering, etc.), the escape due to the fast ions issuing from the dissociation of dications may account for up to 6% of the total and the escape of thermal ions for the remaining. We show that these two mechanisms cannot explain the escape of the atmosphere since the magnetic field vanished and even contribute only marginally to this loss. We show that with these two mechanisms, the atmosphere of a Mars analog planet would empty in another giga years and a half. At Venus orbit, the contribution of the dications in the escape rate is negligible. When simulating the hot Jupiter HD 209458 b, the two processes cannot explain the measured escape flux of C+. This study shows that the dications may constitute a source of the escape of planetary atmospheres which had not been taken into account until now. This source, although marginal, is not negligible. The influence of the photoionization is of course large, but cannot explain alone the loss of Mars

  19. Studies on possible propagation of microbial contamination in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Dimmick, R. L.; Wolochow, H.; Chatigny, M. A.

    1975-01-01

    Maintained aerosols were studied to demonstrate the metabolism and propagation of microbes in clouds which could occur in the course of a probe of a planetary atmosphere. Bacteriophage was used as a tool to test whether the mechanisms for DNA production remain intact and functional within the airborne bacterial cell. In one test method, bacteria were mixed with coliphage in an atomizer to allow attachment before aerosolization; in another, two suspensions were atomized saperately into a common air stream prior to aerosolization. Results show that biochemical and physiological mechanisms to allow aerobic microbes to propagate in the airborne state do exist.

  20. AN ANALYTIC RADIATIVE-CONVECTIVE MODEL FOR PLANETARY ATMOSPHERES

    SciTech Connect

    Robinson, Tyler D.; Catling, David C.

    2012-09-20

    We present an analytic one-dimensional radiative-convective model of the thermal structure of planetary atmospheres. Our model assumes that thermal radiative transfer is gray and can be represented by the two-stream approximation. Model atmospheres are assumed to be in hydrostatic equilibrium, with a power-law scaling between the atmospheric pressure and the gray thermal optical depth. The convective portions of our models are taken to follow adiabats that account for condensation of volatiles through a scaling parameter to the dry adiabat. By combining these assumptions, we produce simple, analytic expressions that allow calculations of the atmospheric-pressure-temperature profile, as well as expressions for the profiles of thermal radiative flux and convective flux. We explore the general behaviors of our model. These investigations encompass (1) worlds where atmospheric attenuation of sunlight is weak, which we show tend to have relatively high radiative-convective boundaries; (2) worlds with some attenuation of sunlight throughout the atmosphere, which we show can produce either shallow or deep radiative-convective boundaries, depending on the strength of sunlight attenuation; and (3) strongly irradiated giant planets (including hot Jupiters), where we explore the conditions under which these worlds acquire detached convective regions in their mid-tropospheres. Finally, we validate our model and demonstrate its utility through comparisons to the average observed thermal structure of Venus, Jupiter, and Titan, and by comparing computed flux profiles to more complex models.

  1. Molecular beam simulation of planetary atmospheric entry - Some recent results.

    NASA Technical Reports Server (NTRS)

    French, J. B.; Reid, N. M.; Nier, A. O.; Hayden, J. L.

    1972-01-01

    Progress is reported in the development of molecular beam techniques to simulate entry into planetary atmospheres. Molecular beam sources for producing fast beams containing CO2 and atomic oxygen are discussed. Results pertinent to the design and calibration of a mass spectrometer ion source for measurement of the Martian atmosphere during the free molecule portion of the entry trajectory are also presented. The shortcomings and advantages of this simulation technique are discussed, and it is demonstrated that even with certain inadequacies much information useful to the ion source design was obtained. Particularly, it is shown that an open-cavity configuration retains sensitivity to atomic oxygen, provides reasonable signal enhancement from the stagnation effect, is not highly sensitive to pitch and yaw effects, and presents no unforeseen problems in measuring CO2 or atomic oxygen.

  2. Constructing an advanced software tool for planetary atmospheric modeling

    NASA Technical Reports Server (NTRS)

    Keller, Richard M.; Sims, Michael; Podolak, Ester; Mckay, Christopher

    1990-01-01

    Scientific model building can be an intensive and painstaking process, often involving the development of large and complex computer programs. Despite the effort involved, scientific models cannot be easily distributed and shared with other scientists. In general, implemented scientific models are complex, idiosyncratic, and difficult for anyone but the original scientist/programmer to understand. We believe that advanced software techniques can facilitate both the model building and model sharing process. In this paper, we describe a prototype for a scientific modeling software tool that serves as an aid to the scientist in developing and using models. This tool includes an interactive intelligent graphical interface, a high level domain specific modeling language, a library of physics equations and experimental datasets, and a suite of data display facilities. Our prototype has been developed in the domain of planetary atmospheric modeling, and is being used to construct models of Titan's atmosphere.

  3. Composition/Structure/Dynamics of comet and planetary satellite atmospheres

    NASA Technical Reports Server (NTRS)

    Combi, Michael R. (Principal Investigator)

    1995-01-01

    This research program addresses two cases of tenuous planetary atmospheres: comets and Io. The comet atmospheric research seeks to analyze a set of spatial profiles of CN in comet Halley taken in a 7.4-day period in April 1986; to apply a new dust coma model to various observations; and to analyze observations of the inner hydrogen coma, which can be optically thick to the resonance scattering of Lyman-alpha radiation, with the newly developed approach that combines a spherical radiative transfer model with our Monte Carlo H coma model. The Io research seeks to understand the atmospheric escape from Io with a hybrid-kinetic model for neutral gases and plasma given methods and algorithms developed for the study of neutral gas cometary atmospheres and the earth's polar wind and plasmasphere. Progress is reported on cometary Hydrogen Lyman-alpha studies; time-series analysis of cometary spatial profiles; model analysis of the dust comae of comets; and a global kinetic atmospheric model of Io.

  4. Magnetic Field Influence on Atmospheric Escape and Planetary Evolution

    NASA Astrophysics Data System (ADS)

    Driscoll, P. E.; Bercovici, D.

    2012-12-01

    Planetary magnetic fields are maintained by a convective dynamo within the deep interior but their influence extends all the way up to the magnetopause, where the solar wind is deflect around the planet. The presence of a magnetic field is thought to influence the atmosphere-solar wind interaction in a variety of ways, but there is no clear consensus as to whether it impedes or facilitates volatile loss to space. Escape of planetary atmospheres to space is of central importance to studying the evolution of planetary climates, volatile exchange with the interior, and interaction with the space environment. Out of the terrestrial planets Earth has by far the largest surface hydrogen inventory (mainly in the form of liquid water) and furthest magnetopause at ~10 Earth radii. Evidence from volatile concentrations and isotopic ratios imply that Mars and Venus have both lost a significant amount of H over their history, and have maintained little to no magnetic barrier, respectively, to hold off the erosive solar wind. Venus is a particularly interesting case because it is most similar to Earth in mass and density, yet has no detectable magnetic field and an isotopic D/H ratio that implies the loss of a significant amount of water in the past. Is the decline of Venus' dynamo related to the loss of hydrogen from its atmosphere? Is the stability of Earth's unusually large volatile reservoir over billions of years related to the presence of a strong magnetic field over that period of time? We explore conditions under which the presence of a magnetic barrier at the top of the atmosphere may operate as an additional limit to escape. We derive a model for magnetic field limited escape that depends on the terrestrial number density, area, scale height, and loss time scale at the magnetopause. This model predicts rapid escape when magnetic field is weak and magnetopause altitude is low, and a decrease in escape as magnetic field strength increases. This coupling between field

  5. The HARPS search for southern extra-solar planets. XXXVI. Planetary systems and stellar activity of the M dwarfs GJ 3293, GJ 3341, and GJ 3543

    NASA Astrophysics Data System (ADS)

    Astudillo-Defru, N.; Bonfils, X.; Delfosse, X.; Ségransan, D.; Forveille, T.; Bouchy, F.; Gillon, M.; Lovis, C.; Mayor, M.; Neves, V.; Pepe, F.; Perrier, C.; Queloz, D.; Rojo, P.; Santos, N. C.; Udry, S.

    2015-03-01

    Context. Planetary companions of a fixed mass induce reflex motions with a larger amplitude around lower-mass stars, which adds to making M dwarfs excellent targets for extra-solar planet searches. The most recent velocimeters with a stability of ~1 m s-1 can detect very low-mass planets out to the habitable zone of these stars. Low-mass small planets are abundant around M dwarfs, and most of the known potentially habitable planets orbit one of these cool stars. Aims: Our M-dwarf radial velocity monitoring with HARPS on the ESO 3.6 m telescope at La Silla observatory makes a major contribution to this sample. Methods: We present here dense radial velocity (RV) time series for three M dwarfs observed over ~five years: GJ 3293 (0.42 M⊙), GJ 3341 (0.47 M⊙), and GJ 3543 (0.45 M⊙). We extracted these RVs through minimum χ2-matching of each spectrum against a stack of all observed spectra for the same star that has a high signal-to-noise ratio. We then compared potential orbital signals against several stellar activity indicators to distinguish the Keplerian variations induced by planets from the spurious signals that result from rotational modulation of stellar surface inhomogeneities and from activity cycles. Results: Two Neptune-mass planets - msin(i) = 1.4 ± 0.1 and 1.3 ± 0.1Mnept - orbit GJ 3293 with periods P = 30.60 ± 0.02 d and P = 123.98 ± 0.38 d, possibly together with a super-Earth - msin(i) ~ 7.9 ± 1.4 M⊕ - with period P = 48.14 ± 0.12d. A super-Earth - msin(i) ~ 6.1 M⊕ - orbits GJ 3341 with P = 14.207 ± 0.007d. The RV variations of GJ 3543, on the other hand, reflect its stellar activity rather than planetary signals. Based on observations made with the HARPS instrument on the ESO 3.6 m telescope under the program IDs 072.C-0488, 082.C-0718 and 183.C-0437 at Cerro La Silla (Chile).Tables A.1-A.3 (radial velocity data) are available in electronic form at http://www.aanda.org and at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp

  6. Data Assimilation and Data Fusion for Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Houben, Howard

    2005-01-01

    The overarching goal of this Cooperative Agreement was to develop a model and procedures for the data assimilation of planetary spacecraft atmospheric observations. Data assimilation - in its application to weather analysis and prediction - is the process of finding an initial state of the meteorological variables (winds, temperatures, pressures, etc.) of an atmosphere, which, when propagated forward in time using a deterministic general circulation model, reproduces all of the available observations over that time to within the measurement and computational errors. With this definition, data assimilation is seen to be a natural extension of well-known least-squares minimization techniques. The primary complication arises from the scale of the problem: For the Martian atmosphere with the available nadir-viewing Thermal Emission Spectrometer data from Mars Global Surveyor, approximately 1,000,000 individual measurements of channel radiances (in the 15-micrometer region, where these radiances relate directly to the surface and atmospheric temperature) were made per day. A suitable general circulation model for dealing with this data set has on the order of 20,000 independent variables. After some spatial and temporal averaging of the data - which provides a necessary statistical estimate of the representativeness of the measurements, a crucial issue in data assimilation - the problem reduces in scale to the solution of approximately 50,000 equations for the 20,000 variables.

  7. Towards a Carbon Nanotube Ionization Source for Planetary Atmosphere Exploration

    NASA Astrophysics Data System (ADS)

    Oza, A. V.; Leblanc, F.; Berthelier, J. J.; Becker, J.; Coulomb, R.; Gilbert, P.; Hong, N. T.; Lee, S.; Vettier, L.

    2015-12-01

    The characterization of planetary exospheres today, relies on the development of a highly efficient ionization source, due to the scant neutral molecules (n < 108 cm -3) present in diffuse planetary coronae. These tenuous atmospheres provide insight on to physical processes known to occur such as: space weathering, magneto-atmosphere interactions, as well as atmospheric escape mechanisms, all of which are being heavily investigated via current 3D Monte Carlo simulations (Turc et al. 2014, Leblanc et al. 2016 in prep) at LATMOS. Validation of these studies will rely on in-situ observations in the coming decades. Neutral detection strongly depends on electron-impact ionization which via conventional cathode-sources, such as thermal filaments (heated up to 2000 K), may only produce the target ionization essential for energy-measurements with large power consumption. Carbon nanotubes (CNTs) however are ideal low-power, cold cathodes, when subject to moderate electric fields (E ~ 1 MV / m). We present our current device, a small CNT chip, of emission area 15 mm2, emitting electrons that pass through an anode grid and subsequent electrostatic analyzer. The device currently extracts hundreds of µAmperes with applied external voltages ~ -150 Volts, approaching minimum power consumption < 0.1 Watts. The 3D modeling of field effect electrons ionizing a standard influx of neutrals is shown, using the multiphysics suite COMSOL. To better anticipate the species an ideal in-situ spacecraft equipped with such an ionization source would observe, we discuss Europa's exosphere. Europa's environment is largely shaped by the Jovian plasma sputtering the icy regolith with heavy ions and electrons (keV < E < MeV), producing predominately molecular oxygen (Johnson et al. 2002).

  8. Continuing Studies in Support of Ultraviolet Observations of Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Clark, John

    1997-01-01

    This program was a one-year extension of an earlier Planetary Atmospheres program grant, covering the period 1 August 1996 through 30 September 1997. The grant was for supporting work to complement an active program observing planetary atmospheres with Earth-orbital telescopes, principally the Hubble Space Telescope (HST). The recent concentration of this work has been on HST observations of Jupiter's upper atmosphere and aurora, but it has also included observations of Io, serendipitous observations of asteroids, and observations of the velocity structure in the interplanetary medium. The observations of Jupiter have been at vacuum ultraviolet wavelengths, including imaging and spectroscopy of the auroral and airglow emissions. The most recent HST observations have been at the same time as in situ measurements made by the Galileo orbiter instruments, as reflected in the meeting presentations listed below. Concentrated efforts have been applied in this year to the following projects: The analysis of HST WFPC 2 images of Jupiter's aurora, including the Io footprint emissions. We have performed a comparative analysis of the lo footprint locations with two magnetic field models, studied the statistical properties of the apparent dawn auroral storms on Jupiter, and found various other repeated patterns in Jupiter's aurora. Analysis and modeling of airglow and auroral Ly alpha emission line profiles from Jupiter. This has included modeling the aurora] line profiles, including the energy degradation of precipitating charged particles and radiative transfer of the emerging emissions. Jupiter's auroral emission line profile is self-absorbed, since it is produced by an internal source, and the resulting emission with a deep central absorption from the overlying atmosphere permits modeling of the depth of the emissions, plus the motion of the emitting layer with respect to the overlying atmospheric column from the observed Doppler shift of the central absorption. By contrast

  9. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. IV. THE EFFECT OF COSMIC RAYS

    SciTech Connect

    Rimmer, P. B.; Helling, Ch.

    2013-09-10

    Cosmic rays provide an important source for free electrons in Earth's atmosphere and also in dense interstellar regions where they produce a prevailing background ionization. We utilize a Monte Carlo cosmic ray transport model for particle energies of 10{sup 6} eV atmospheres of free-floating objects. The cosmic ray calculations are applied to DRIFT-PHOENIX model atmospheres of an example brown dwarf with effective temperature T{sub eff} = 1500 K, and two example giant gas planets (T{sub eff} = 1000 K, 1500 K). For the model brown dwarf atmosphere, the electron fraction is enhanced significantly by cosmic rays when the pressure p{sub gas} < 10{sup -2} bar. Our example giant gas planet atmosphere suggests that the cosmic ray enhancement extends to 10{sup -4}-10{sup -2} bar, depending on the effective temperature. For the model atmosphere of the example giant gas planet considered here (T{sub eff} = 1000 K), cosmic rays bring the degree of ionization to f{sub e} {approx}> 10{sup -8} when p{sub gas} < 10{sup -8} bar, suggesting that this part of the atmosphere may behave as a weakly ionized plasma. Although cosmic rays enhance the degree of ionization by over three orders of magnitude in the upper atmosphere, the effect is not likely to be significant enough for sustained coupling of the magnetic field to the gas.

  10. Studies of Pressure-Broadening of Alkali Atom Resonance Lines for Modeling Atmospheres of Extrasolar Giant Planets and Brown Dwarfs

    NASA Technical Reports Server (NTRS)

    Kirby, Kate; Babb, J.; Yoshino, K.

    2004-01-01

    In L-dwarfs and T-dwarfs the resonance lines of sodium and potassium are so profoundly pressure-broadened that their wings extend several hundred nanometers from line center. With accurate knowledge of the line profiles as a function of temperature and pressure: such lines can prove to be valuable diagnostics of the atmospheres of such objects. We have initiated a joint program of theoretical and experimental research to study the line-broadening of alkali atom resonance lines due to collisions with species such as helium and molecular hydrogen. Although potassium and sodium are the alkali species of most interest in the atmospheres of cool brown dwarfs and extrasolar giant planets, some of our theoretical focus this year has involved the calculation of pressure-broadening of lithium resonance lines by He, as a test of a newly developed suite of computer codes. In addition, theoretical calculations have been carried out to determine the leading long range van der Waals coefficients for the interactions of ground and excited alkali metal atoms with helium atoms, to within a probable error of 2%. Such data is important in determining the behavior of the resonance line profiles in the far wings. Important progress has been made on the experimental aspects of the program since the arrival of a postdoctoral fellow in September. A new absorption cell has been designed, which incorporates a number of technical improvements over the previous cell, including a larger cell diameter to enhance the signal, and fittings which allow for easier cleaning, thereby significantly reducing the instrument down-time.

  11. Ionization in Atmospheres of Brown Dwarfs and Extrasolar Planets. V. Alfvén Ionization

    NASA Astrophysics Data System (ADS)

    Stark, C. R.; Helling, Ch.; Diver, D. A.; Rimmer, P. B.

    2013-10-01

    Observations of continuous radio and sporadic X-ray emission from low-mass objects suggest they harbor localized plasmas in their atmospheric environments. For low-mass objects, the degree of thermal ionization is insufficient to qualify the ionized component as a plasma, posing the question: what ionization processes can efficiently produce the required plasma that is the source of the radiation? We propose Alfvén ionization as a mechanism for producing localized pockets of ionized gas in the atmosphere, having sufficient degrees of ionization (>=10-7) that they constitute plasmas. We outline the criteria required for Alfvén ionization and demonstrate its applicability in the atmospheres of low-mass objects such as giant gas planets, brown dwarfs, and M dwarfs with both solar and sub-solar metallicities. We find that Alfvén ionization is most efficient at mid to low atmospheric pressures where a seed plasma is easier to magnetize and the pressure gradients needed to drive the required neutral flows are the smallest. For the model atmospheres considered, our results show that degrees of ionization of 10-6-1 can be obtained as a result of Alfvén ionization. Observable consequences include continuum bremsstrahlung emission, superimposed with spectral lines from the plasma ion species (e.g., He, Mg, H2, or CO lines). Forbidden lines are also expected from the metastable population. The presence of an atmospheric plasma opens the door to a multitude of plasma and chemical processes not yet considered in current atmospheric models. The occurrence of Alfvén ionization may also be applicable to other astrophysical environments such as protoplanetary disks.

  12. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. V. ALFVÉN IONIZATION

    SciTech Connect

    Stark, C. R.; Helling, Ch.; Rimmer, P. B.; Diver, D. A.

    2013-10-10

    Observations of continuous radio and sporadic X-ray emission from low-mass objects suggest they harbor localized plasmas in their atmospheric environments. For low-mass objects, the degree of thermal ionization is insufficient to qualify the ionized component as a plasma, posing the question: what ionization processes can efficiently produce the required plasma that is the source of the radiation? We propose Alfvén ionization as a mechanism for producing localized pockets of ionized gas in the atmosphere, having sufficient degrees of ionization (≥10{sup –7}) that they constitute plasmas. We outline the criteria required for Alfvén ionization and demonstrate its applicability in the atmospheres of low-mass objects such as giant gas planets, brown dwarfs, and M dwarfs with both solar and sub-solar metallicities. We find that Alfvén ionization is most efficient at mid to low atmospheric pressures where a seed plasma is easier to magnetize and the pressure gradients needed to drive the required neutral flows are the smallest. For the model atmospheres considered, our results show that degrees of ionization of 10{sup –6}-1 can be obtained as a result of Alfvén ionization. Observable consequences include continuum bremsstrahlung emission, superimposed with spectral lines from the plasma ion species (e.g., He, Mg, H{sub 2}, or CO lines). Forbidden lines are also expected from the metastable population. The presence of an atmospheric plasma opens the door to a multitude of plasma and chemical processes not yet considered in current atmospheric models. The occurrence of Alfvén ionization may also be applicable to other astrophysical environments such as protoplanetary disks.

  13. Plasma Flow Past Cometary and Planetary Satellite Atmospheres

    NASA Technical Reports Server (NTRS)

    Combi, Michael R.; Gombosi, Tamas I.; Kabin, Konstantin

    2000-01-01

    The tenuous atmospheres and ionospheres of comets and outer planet satellites share many common properties and features. Such similarities include a strong interaction with their outer radiation, fields and particles environs. For comets the interaction is with the magnetized solar wind plasma, whereas for satellites the interaction is with the strongly magnetized and corotating planetary magnetospheric plasma. For this reason there are many common or analogous physical regimes, and many of the same modeling techniques are used to interpret remote sensing and in situ measurements in order to study the important underlying physical phenomena responsible for their appearances. We present here a review of various modeling approaches which are used to elucidate the basic properties and processes shaping the energetics and dynamics of these systems which are similar in many respects.

  14. Hydrogen atom initiated chemistry. [chemical evolution in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hong, J. H.; Becker, R. S.

    1979-01-01

    H Atoms have been created by the photolysis of H2S. These then initiated reactions in mixtures involving acetylene-ammonia-water and ethylene-ammonia-water. In the case of the acetylene system, the products consisted of two amino acids, ethylene and a group of primarily cyclic thio-compounds, but no free sulfur. In the case of the ethylene systems, seven amino acids, including an aromatic one, ethane, free sulfur, and a group of solely linear thio-compounds were produced. Total quantum yields for the production of amino acids were about 3 x 10 to the -5th and about 2 x 10 to the -4th with ethylene and acetylene respectively as carbon substrates. Consideration is given of the mechanism for the formation of some of the products and implications regarding planetary atmosphere chemistry, particularly that of Jupiter, are explored.

  15. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. II. DUST-INDUCED COLLISIONAL IONIZATION

    SciTech Connect

    Helling, Ch.; Jardine, M.; Mokler, F.

    2011-08-10

    Observations have shown that continuous radio emission and also sporadic H{alpha} and X-ray emission are prominent in singular, low-mass objects later than spectral class M. These activity signatures are interpreted as being caused by coupling of an ionized atmosphere to the stellar magnetic field. What remains a puzzle, however, is the mechanism by which such a cool atmosphere can produce the necessary level of ionization. At these low temperatures, thermal gas processes are insufficient, but the formation of clouds sets in. Cloud particles can act as seeds for electron avalanches in streamers that ionize the ambient gas, and can lead to lightning and indirectly to magnetic field coupling, a combination of processes also expected for protoplanetary disks. However, the precondition is that the cloud particles are charged. We use results from DRIFT-PHOENIX model atmospheres to investigate collisional processes that can lead to the ionization of dust grains inside clouds. We show that ionization by turbulence-induced dust-dust collisions is the most efficient kinetic process. The efficiency is highest in the inner cloud where particles grow quickly and, hence, the dust-to-gas ratio is high. Dust-dust collisions alone are not sufficient to improve the magnetic coupling of the atmosphere inside the cloud layers, but the charges supplied either on grains or within the gas phase as separated electrons can trigger secondary nonlinear processes. Cosmic rays are likely to increase the global level of ionization, but their influence decreases if a strong, large-scale magnetic field is present as on brown dwarfs. We suggest that although thermal gas ionization declines in objects across the fully convective boundary, dust charging by collisional processes can play an important role in the lowest mass objects. The onset of atmospheric dust may therefore correlate with the anomalous X-ray and radio emission in atmospheres that are cool, but charged more than expected by pure

  16. Thermal escape from extrasolar giant planets

    PubMed Central

    Koskinen, Tommi T.; Lavvas, Panayotis; Harris, Matthew J.; Yelle, Roger V.

    2014-01-01

    The detection of hot atomic hydrogen and heavy atoms and ions at high altitudes around close-in extrasolar giant planets (EGPs) such as HD209458b implies that these planets have hot and rapidly escaping atmospheres that extend to several planetary radii. These characteristics, however, cannot be generalized to all close-in EGPs. The thermal escape mechanism and mass loss rate from EGPs depend on a complex interplay between photochemistry and radiative transfer driven by the stellar UV radiation. In this study, we explore how these processes change under different levels of irradiation on giant planets with different characteristics. We confirm that there are two distinct regimes of thermal escape from EGPs, and that the transition between these regimes is relatively sharp. Our results have implications for thermal mass loss rates from different EGPs that we discuss in the context of currently known planets and the detectability of their upper atmospheres. PMID:24664923

  17. Thermal escape from extrasolar giant planets.

    PubMed

    Koskinen, Tommi T; Lavvas, Panayotis; Harris, Matthew J; Yelle, Roger V

    2014-04-28

    The detection of hot atomic hydrogen and heavy atoms and ions at high altitudes around close-in extrasolar giant planets (EGPs) such as HD209458b implies that these planets have hot and rapidly escaping atmospheres that extend to several planetary radii. These characteristics, however, cannot be generalized to all close-in EGPs. The thermal escape mechanism and mass loss rate from EGPs depend on a complex interplay between photochemistry and radiative transfer driven by the stellar UV radiation. In this study, we explore how these processes change under different levels of irradiation on giant planets with different characteristics. We confirm that there are two distinct regimes of thermal escape from EGPs, and that the transition between these regimes is relatively sharp. Our results have implications for thermal mass loss rates from different EGPs that we discuss in the context of currently known planets and the detectability of their upper atmospheres. PMID:24664923

  18. Thermal escape from extrasolar giant planets.

    PubMed

    Koskinen, Tommi T; Lavvas, Panayotis; Harris, Matthew J; Yelle, Roger V

    2014-04-28

    The detection of hot atomic hydrogen and heavy atoms and ions at high altitudes around close-in extrasolar giant planets (EGPs) such as HD209458b implies that these planets have hot and rapidly escaping atmospheres that extend to several planetary radii. These characteristics, however, cannot be generalized to all close-in EGPs. The thermal escape mechanism and mass loss rate from EGPs depend on a complex interplay between photochemistry and radiative transfer driven by the stellar UV radiation. In this study, we explore how these processes change under different levels of irradiation on giant planets with different characteristics. We confirm that there are two distinct regimes of thermal escape from EGPs, and that the transition between these regimes is relatively sharp. Our results have implications for thermal mass loss rates from different EGPs that we discuss in the context of currently known planets and the detectability of their upper atmospheres.

  19. Theory of planetary atmospheres: an introduction to their physics and chemistry /2nd revised and enlarged edition/

    SciTech Connect

    Chamberlain, J.W.; Hunten, D.M.

    1987-01-01

    Theoretical models of planetary atmospheres are characterized in an introductory text intended for graduate physics students and practicing scientists. Chapters are devoted to the vertical structure of an atmosphere; atmospheric hydrodynamics; the chemistry and dynamics of the earth stratosphere; planetary astronomy; ionospheres; airglows, auroras, and aeronomy; and the stability of planetary atmospheres. Extensive graphs, diagrams, and tables of numerical data are provided.

  20. An extended upper atmosphere around the extrasolar planet HD209458b.

    PubMed

    Vidal-Madjar, A; Des Etangs, A Lecavelier; Désert, J-M; Ballester, G E; Ferlet, R; Hébrard, G; Mayor, M

    2003-03-13

    The planet in the system HD209458 is the first one for which repeated transits across the stellar disk have been observed. Together with radial velocity measurements, this has led to a determination of the planet's radius and mass, confirming it to be a gas giant. But despite numerous searches for an atmospheric signature, only the dense lower atmosphere of HD209458b has been observed, through the detection of neutral sodium absorption. Here we report the detection of atomic hydrogen absorption in the stellar Lyman alpha line during three transits of HD209458b. An absorption of 15 +/- 4% (1sigma) is observed. Comparison with models shows that this absorption should take place beyond the Roche limit and therefore can be understood in terms of escaping hydrogen atoms.

  1. Crosslink Radio Occultation for the Remote Sensing of Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Mannucci, A. J.; Ao, C. O.; Asmar, S.; Edwards, C. D.; Kahan, D. S.; Paik, M.; Pi, X.; Williamson, W.

    2015-12-01

    Radio occultation utilizing deep space telecommunication signals has been used with great success in the profiling of planetary atmospheres and ionospheres since the 1960s. A shortcoming of this technique, however, is the limited temporal and spatial sampling that it provides. We consider a different approach where radio occultation measurements are taken between two spacecraft orbiting an extra-terrestrial body. Such "crosslink" radio occultations between the Global Positioning System satellites and low-earth orbiting spacecraft have been routinely acquired to provide global observations of the Earth's atmosphere and ionosphere that are used for weather forecast, climate analysis, and space weather applications. The feasibility of applying this concept to other planets has recently been demonstrated for the first time, where crosslink occultation measurements have been acquired between the Mars Odyssey and Mars Reconnaissance Orbiter spacecraft. These measurements leverage the proximity link telecommunication payloads on each orbiter, which are nominally used to provide relay communication and navigation services to Mars landers and rovers. In this presentation, we will describe the Mars crosslink experiments and the corresponding data analysis in detail. In addition, we will discuss how the crosslink occultation concepts can be effectively applied in future space exploration missions.

  2. Clouds and Chemistry in the Atmosphere of Extrasolar Planet HR8799b

    SciTech Connect

    Barman, T S; Macintosh, B A; Konopacky, Q M; Marois, C

    2011-03-21

    Using the integral field spectrograph OSIRIS, on the Keck II telescope, broad near-infrared H and K-band spectra of the young exoplanet HR8799b have been obtained. In addition, six new narrow-band photometric measurements have been taken across the H and K bands. These data are combined with previously published photometry for an analysis of the planet's atmospheric properties. Thick photospheric dust cloud opacity is invoked to explain the planet's red near-IR colors and relatively smooth near-IR spectrum. Strong water absorption is detected, indicating a Hydrogen-rich atmosphere. Only weak CH{sub 4} absorption is detected at K band, indicating efficient vertical mixing and a disequilibrium CO/CH{sub 4} ratio at photospheric depths. The H-band spectrum has a distinct triangular shape consistent with low surface gravity. New giant planet atmosphere models are compared to these data with best fitting bulk parameters, T{sub eff} = 1100K {+-} 100 and log(g) = 3.5 {+-} 0.5 (for solar composition). Given the observed luminosity (log L{sub obs}/L{sub {circle_dot}} {approx} -5.1), these values correspond to a radius of 0.75 R{sub Jup{sub 0.12}{sup +0.17}} and mass {approx} 0.72 M{sub Jup{sub -0.6}{sup +2.6}} - strikingly inconsistent with interior/evolution models. Enhanced metallicity (up to {approx} 10 x that of the Sun) along with thick clouds and non-equilibrium chemistry are likely required to reproduce the complete ensemble of spectroscopic and photometric data and the low effective temperatures (< 1000K) required by the evolution models.

  3. Plasma-induced Escape and Alterations of Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Johnson, R. E.; Tucker, O. J.; Ewrin, J.; Cassidy, T. A.; Leblanc, F.

    2009-12-01

    The atmospheres of planets and planetary satellites are typically imbedded in space plasmas. Depending on the interaction with the induced or intrinsic fields energetic ions can have access to the thermosphere and the corona affecting their composition and thermal structure and causing loss to space. These processes are often lumped together as ‘atmospheric sputtering’ (Johnson 1994). In this talk I will review the results of simulations of the plasma bombardment at a number of solar system bodies and use those data to describe the effect on the upper atmosphere and on escape. Of considerable recent interest is the modeling of escape from Titan. Prior to Cassini’s tour of the Saturnian system, plasma-induced escape was suggested to be the dominant loss process, but recent models of enhanced thermal escape, often referred to as ‘slow hydrodynamic’ escape, have been suggested to lead to much larger Titan atmospheric loss rates (Strobel 2008; Cui et al. 2008). Such a process has been suggested to be active at some point in time on a number of solar system bodies. I will present hybrid fluid/ kinetic models of the upper atmosphere of certain bodies in order to test both the plasma-induced and thermal escape processes. Preliminary results suggest that the loss rates estimated using the ‘slow hydrodynamic’ escape process can be orders of magnitude too large. The implications for Mars, Titan and Pluto will be discussed. Background for this talk is contained in the following papers (Johnson 2004; 2009; Chaufray et al. 2007; Johnson et al. 2008; 2009; Tucker and Johnson 2009). References: Chaufray, J.Y., R. Modolo, F. Leblanc, G. Chanteur, R.E. Johnson, and J.G. Luhmann, Mars Solar Wind interaction: formation of the Martian corona and atmosphric loss to space, JGR 112, E09009, doi:10.1029/2007JE002915 (2007) Cui, J., Yelle, R. V., Volk, K. Distribution and escape of molecular hydrogen in Titan's thermosphere and exosphere. J. Geophys. Res. 113, doi:10

  4. The applications of chemical thermodynamics and chemical kinetics to planetary atmospheres research

    NASA Technical Reports Server (NTRS)

    Fegley, Bruce, Jr.

    1990-01-01

    A review of the applications of chemical thermodynamics and chemical kinetics to planetary atmospheres research during the past four decades is presented with an emphasis on chemical equilibrium models and thermochemical kinetics. Several current problems in planetary atmospheres research such as the origin of the atmospheres of the terrestrial planets, atmosphere-surface interactions on Venus and Mars, deep mixing in the atmospheres of the gas giant planets, and the origin of the atmospheres of outer planet satellites all require laboratory data on the kinetics of thermochemical reactions for their solution.

  5. Extrasolar Planets & The Power of the Dark Side

    SciTech Connect

    Charbonneau, David

    2009-04-24

    It is only in the last decade that we have direct evidence for planets orbiting nearby Sun-like stars. If such planets happen to pass in front of their stars, we are presented with a golden opportunity to learn about the nature of these objects. Measurements of the dimming of starlight and gravitational wobble allow us to derive the planetary radius and mass, and, by inference, its composition. Recently, we used the Hubble Telescope to detect and study the atmosphere of an extrasolar planet for the first time. I will describe what we have learned about these planets 

  6. Atom Resonance Lines for Modeling Atmosphere: Studies of Pressure-Broadening of Alkali Atom Resonance Lines for Modeling Atmospheres of Extrasolar Giant Planets and Brown Dwarfs

    NASA Technical Reports Server (NTRS)

    Hasan, Hashima (Technical Monitor); Kirby, K.; Babb, J.; Yoshino, K.

    2005-01-01

    We report on progress made in a joint program of theoretical and experimental research to study the line-broadening of alkali atom resonance lines due to collisions with species such as helium and molecular hydrogen. Accurate knowledge of the line profiles of Na and K as a function of temperature and pressure will allow such lines to serve as valuable diagnostics of the atmospheres of brown dwarfs and extra-solar giant planets. A new experimental apparatus has been designed, built and tested over the past year, and we are poised to begin collecting data on the first system of interest, the potassium resonance lines perturbed by collisions with helium. On the theoretical front, calculations of line-broadening due to sodium collisions with helium are nearly complete, using accurate molecular potential energy curves and transition moments just recently computed for this system. In addition we have completed calculations of the three relevant potential energy curves and associated transition moments for K - He, using the MOLPRO quantum chemistry codes. Currently, calculations of the potential surfaces describing K-H2 are in progress.

  7. Planetary Magnetic Fields and Solar Forcing: Implications for Atmospheric Evolution

    NASA Astrophysics Data System (ADS)

    Lundin, Rickard; Lammer, Helmut; Ribas, Ignasi

    2007-03-01

    reason that Mars and Venus, planets lacking strong intrinsic magnetic fields, have so much less water than the Earth? Climatologic and atmospheric loss process over evolutionary timescales of planetary atmospheres can only be understood if one considers the fact that the radiation and plasma environment of the Sun has changed substantially with time. Standard stellar evolutionary models indicate that the Sun after its arrival at the Zero-Age Main Sequence (ZAMS) 4.5 Gyr ago had a total luminosity of ≈70% of the present Sun. This should have led to a much cooler Earth in the past, while geological and fossil evidence indicate otherwise. In addition, observations by various satellites and studies of solar proxies (Sun-like stars with different age) indicate that the young Sun was rotating more than 10 times its present rate and had correspondingly strong dynamo-driven high-energy emissions which resulted in strong X-ray and extreme ultraviolet (XUV) emissions, up to several 100 times stronger than the present Sun. Further, evidence of a much denser early solar wind and the mass loss rate of the young Sun can be determined from collision of ionized stellar winds of the solar proxies, with the partially ionized gas in the interstellar medium. Empirical correlations of stellar mass loss rates with X-ray surface flux values allows one to estimate the solar wind mass flux at earlier times, when the solar wind may have been more than 1000 times more massive. The main conclusions drawn on basis of the Sun-in-time-, and a time-dependent model of plasma energization/escape is that: 1. Solar forcing is effective in removing volatiles, primarily water, from planets,

  8. Compact remote multisensing instrument for planetary surfaces and atmospheres characterization.

    PubMed

    Nurul Abedin, M; Bradley, Arthur T; Ismail, Syed; Sharma, Shiv K; Sandford, Stephen P

    2013-05-10

    This paper describes a prototype feasibility demonstration system of a multipurpose Raman-fluorescence spectrograph and compact lidar system suitable for planetary sciences missions. The key measurement features of this instrument are its abilities to: i) detect minerals and organics at low levels in the dust constituents of surface, subsurface material and rocks on Mars, ii) determine the distribution of trace fluorescent ions with time-resolved fluorescence spectroscopy to learn about the geological conditions under which these minerals formed, iii) inspect material toxicity from a mobile robotic platform during local site characterization, iv) measure dust aerosol and cloud distributions, v) measure near-field atmospheric carbon dioxide, and vi) identify surface CO(2)-ice, surface water ice, and surface or subsurface methane hydrate. This prototype instrument and an improved follow-on design are described and have the capability for scientific investigations discussed above, to remotely investigate geological processes from a robotic platform at more than a 20-m radial distance with potential to go beyond 100 m. It also provides single wavelength (532 nm) aerosol/cloud profiling over very long ranges (>10 km with potential to 20 km). Measurement results obtained with this prototype unit from a robotic platform and calculated potential performance are presented in this paper. PMID:23669823

  9. Compact remote multisensing instrument for planetary surfaces and atmospheres characterization.

    PubMed

    Nurul Abedin, M; Bradley, Arthur T; Ismail, Syed; Sharma, Shiv K; Sandford, Stephen P

    2013-05-10

    This paper describes a prototype feasibility demonstration system of a multipurpose Raman-fluorescence spectrograph and compact lidar system suitable for planetary sciences missions. The key measurement features of this instrument are its abilities to: i) detect minerals and organics at low levels in the dust constituents of surface, subsurface material and rocks on Mars, ii) determine the distribution of trace fluorescent ions with time-resolved fluorescence spectroscopy to learn about the geological conditions under which these minerals formed, iii) inspect material toxicity from a mobile robotic platform during local site characterization, iv) measure dust aerosol and cloud distributions, v) measure near-field atmospheric carbon dioxide, and vi) identify surface CO(2)-ice, surface water ice, and surface or subsurface methane hydrate. This prototype instrument and an improved follow-on design are described and have the capability for scientific investigations discussed above, to remotely investigate geological processes from a robotic platform at more than a 20-m radial distance with potential to go beyond 100 m. It also provides single wavelength (532 nm) aerosol/cloud profiling over very long ranges (>10 km with potential to 20 km). Measurement results obtained with this prototype unit from a robotic platform and calculated potential performance are presented in this paper.

  10. An automated method for tracking clouds in planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Luz, D.; Berry, D. L.; Roos-Serote, M.

    2008-05-01

    We present an automated method for cloud tracking which can be applied to planetary images. The method is based on a digital correlator which compares two or more consecutive images and identifies patterns by maximizing correlations between image blocks. This approach bypasses the problem of feature detection. Four variations of the algorithm are tested on real cloud images of Jupiter's white ovals from the Galileo mission, previously analyzed in Vasavada et al. [Vasavada, A.R., Ingersoll, A.P., Banfield, D., Bell, M., Gierasch, P.J., Belton, M.J.S., Orton, G.S., Klaasen, K.P., Dejong, E., Breneman, H.H., Jones, T.J., Kaufman, J.M., Magee, K.P., Senske, D.A. 1998. Galileo imaging of Jupiter's atmosphere: the great red spot, equatorial region, and white ovals. Icarus, 135, 265, doi:10.1006/icar.1998.5984]. Direct correlation, using the sum of squared differences between image radiances as a distance estimator (baseline case), yields displacement vectors very similar to this previous analysis. Combining this distance estimator with the method of order ranks results in a technique which is more robust in the presence of outliers and noise and of better quality. Finally, we introduce a distance metric which, combined with order ranks, provides results of similar quality to the baseline case and is faster. The new approach can be applied to data from a number of space-based imaging instruments with a non-negligible gain in computing time.

  11. Analytical theories for spacecraft entry into planetary atmospheres and design of planetary probes

    NASA Astrophysics Data System (ADS)

    Saikia, Sarag J.

    This dissertation deals with the development of analytical theories for spacecraft entry into planetary atmospheres and the design of entry spacecraft or probes for planetary science and human exploration missions. Poincare's method of small parameters is used to develop an improved approximate analytical solution for Yaroshevskii's classical planetary entry equation for the ballistic entry of a spacecraft into planetary atmospheres. From this solution, other important expressions are developed including deceleration, stagnation-point heat rate, and stagnation-point integrated heat load. The accuracy of the solution is assessed via numerical integration of the exact equations of motion. The solution is also compared to the classical solutions of Yaroshevskii and Allen and Eggers. The new second-order analytical solution is more accurate than Yaroshevskii's fifth-order solution for a range of shallow (-3 deg) to steep (up to -90 deg) entry flight path angles, thereby extending the range of applicability of the solution as compared to the classical Yaroshevskii solution, which is restricted to an entry flight path of approximately -40 deg. Universal planetary entry equations are used to develop a new analytical theory for ballistic entry of spacecraft for moderate to large initial flight path angles. Chapman's altitude variable is used as the independent variable. Poincare's method of small parameters is used to develop an analytical solution for the velocity and the flight path angle. The new solution is used to formulate key expressions for range, time-of-flight, deceleration, and aerodynamic heating parameters (e.g., stagnation-point heat rate, total stagnation-point heat load, and average heat input). The classical approximate solution of Chapman's entry equation appears as the zero-order term in the new solution. The new solution represents an order of magnitude enhancement in the accuracy compared to existing analytical solutions for moderate to large entry

  12. Incorporation of the planetary boundary layer in atmospheric models

    NASA Technical Reports Server (NTRS)

    Moeng, Chin-Hoh; Wyngaard, John; Pielke, Roger; Krueger, Steve

    1993-01-01

    The topics discussed include the following: perspectives on planetary boundary layer (PBL) measurements; current problems of PBL parameterization in mesoscale models; and convective cloud-PBL interactions.

  13. Intermediate Models of Planetary Circulations in the Atmosphere and Ocean.

    NASA Astrophysics Data System (ADS)

    McWilliams, James C.; Gent, Peter R.

    1980-08-01

    Large-scale extratropical motions (with dimensions comparable to, or somewhat smaller than, the planetary radius) in the atmosphere and ocean exhibit a more restricted range of phenomena than are admissible in the primitive equations for fluid motions, and there have been many previous proposals for simpler, more phenomenologically limited models of these motions. The oldest and most successful of these is the quasi-geostrophic model. An extensive discussion is made of models intermediate between the quasi-geostrophic and primitive ones, some of which have been previously proposed [e.g., the balance equations (BE), where tendencies in the equation for the divergent component of velocity are neglected, or the geostrophic momentum approximation (GM), where ageostrophic accelerations are neglected relative to geostrophic ones] and some of which are derived here. Virtues of these models are assessed in the dual measure of nearly geostrophic momentum balance (i.e., small Rossby number) and approximate frontal structure (i.e., larger along-axis velocities and length scales than their cross-axis counterparts), since one or both of these circumstances is usually characteristic of planetary motions. Consideration is also given to various coordinate transformations, since they can yield simpler expressions for the governing differential equations of the intermediate models. In particular, a new set of coordinates is proposed, isentropic geostrophic coordinates,(IGC), which has the advantage of making implicit the advections due to ageostrophic horizontal and vertical velocities under various approximations. A generalization of quasi-geostrophy is made. named hypo-geostrophy (HG), which is an asymptotic approximation of one higher order accuracy in Rossby number. The governing equations are simplest in IGC for both HG and GM; we name the latter in these coordinates isentropic semi-geostrophy (ISG), in analogy to Hoskins' (1975) semi-geostrophy (SG). HG, GM and BE are, in our

  14. Effects of the seasonal cycle on superrotation in planetary atmospheres

    SciTech Connect

    Mitchell, Jonathan L.; Vallis, Geoffrey K.; Potter, Samuel F.

    2014-05-20

    The dynamics of dry atmospheric general circulation model simulations forced by seasonally varying Newtonian relaxation are explored over a wide range of two control parameters and are compared with the large-scale circulation of Earth, Mars, and Titan in their relevant parameter regimes. Of the parameters that govern the behavior of the system, the thermal Rossby number (Ro) has previously been found to be important in governing the spontaneous transition from an Earth-like climatology of winds to a superrotating one with prograde equatorial winds, in the absence of a seasonal cycle. This case is somewhat unrealistic as it applies only if the planet has zero obliquity or if surface thermal inertia is very large. While Venus has nearly vanishing obliquity, Earth, Mars, and Titan (Saturn) all have obliquities of ∼25° and varying degrees of seasonality due to their differing thermal inertias and orbital periods. Motivated by this, we introduce a time-dependent Newtonian cooling to drive a seasonal cycle using idealized model forcing, and we define a second control parameter that mimics non-dimensional thermal inertia of planetary surfaces. We then perform and analyze simulations across the parameter range bracketed by Earth-like and Titan-like regimes, assess the impact on the spontaneous transition to superrotation, and compare Earth, Mars, and Titan to the model simulations in the relevant parameter regime. We find that a large seasonal cycle (small thermal inertia) prevents model atmospheres with large thermal Rossby numbers from developing superrotation by the influences of (1) cross-equatorial momentum advection by the Hadley circulation and (2) hemispherically asymmetric zonal-mean zonal winds that suppress instabilities leading to equatorial momentum convergence. We also demonstrate that baroclinic instabilities must be sufficiently weak to allow superrotation to develop. In the relevant parameter regimes, our seasonal model simulations compare favorably to

  15. Effects of the Seasonal Cycle on Superrotation in Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Mitchell, Jonathan L.; Vallis, Geoffrey K.; Potter, Samuel F.

    2014-05-01

    The dynamics of dry atmospheric general circulation model simulations forced by seasonally varying Newtonian relaxation are explored over a wide range of two control parameters and are compared with the large-scale circulation of Earth, Mars, and Titan in their relevant parameter regimes. Of the parameters that govern the behavior of the system, the thermal Rossby number (Ro) has previously been found to be important in governing the spontaneous transition from an Earth-like climatology of winds to a superrotating one with prograde equatorial winds, in the absence of a seasonal cycle. This case is somewhat unrealistic as it applies only if the planet has zero obliquity or if surface thermal inertia is very large. While Venus has nearly vanishing obliquity, Earth, Mars, and Titan (Saturn) all have obliquities of ~25° and varying degrees of seasonality due to their differing thermal inertias and orbital periods. Motivated by this, we introduce a time-dependent Newtonian cooling to drive a seasonal cycle using idealized model forcing, and we define a second control parameter that mimics non-dimensional thermal inertia of planetary surfaces. We then perform and analyze simulations across the parameter range bracketed by Earth-like and Titan-like regimes, assess the impact on the spontaneous transition to superrotation, and compare Earth, Mars, and Titan to the model simulations in the relevant parameter regime. We find that a large seasonal cycle (small thermal inertia) prevents model atmospheres with large thermal Rossby numbers from developing superrotation by the influences of (1) cross-equatorial momentum advection by the Hadley circulation and (2) hemispherically asymmetric zonal-mean zonal winds that suppress instabilities leading to equatorial momentum convergence. We also demonstrate that baroclinic instabilities must be sufficiently weak to allow superrotation to develop. In the relevant parameter regimes, our seasonal model simulations compare favorably to

  16. 3.6 AND 4.5 {mu}m PHASE CURVES AND EVIDENCE FOR NON-EQUILIBRIUM CHEMISTRY IN THE ATMOSPHERE OF EXTRASOLAR PLANET HD 189733b

    SciTech Connect

    Knutson, Heather A.; Lewis, Nikole; Showman, Adam P.; Fortney, Jonathan J.; Laughlin, Gregory; Burrows, Adam; Cowan, Nicolas B.; Agol, Eric; Aigrain, Suzanne; Charbonneau, David; Desert, Jean-Michel; Deming, Drake; Henry, Gregory W.; Langton, Jonathan

    2012-07-20

    We present new, full-orbit observations of the infrared phase variations of the canonical hot Jupiter HD 189733b obtained in the 3.6 and 4.5 {mu}m bands using the Spitzer Space Telescope. When combined with previous phase curve observations at 8.0 and 24 {mu}m, these data allow us to characterize the exoplanet's emission spectrum as a function of planetary longitude and to search for local variations in its vertical thermal profile and atmospheric composition. We utilize an improved method for removing the effects of intrapixel sensitivity variations and robustly extracting phase curve signals from these data, and we calculate our best-fit parameters and uncertainties using a wavelet-based Markov Chain Monte Carlo analysis that accounts for the presence of time-correlated noise in our data. We measure a phase curve amplitude of 0.1242% {+-} 0.0061% in the 3.6 {mu}m band and 0.0982% {+-} 0.0089% in the 4.5 {mu}m band, corresponding to brightness temperature contrasts of 503 {+-} 21 K and 264 {+-} 24 K, respectively. We find that the times of minimum and maximum flux occur several hours earlier than predicted for an atmosphere in radiative equilibrium, consistent with the eastward advection of gas by an equatorial super-rotating jet. The locations of the flux minima in our new data differ from our previous observations at 8 {mu}m, and we present new evidence indicating that the flux minimum observed in the 8 {mu}m is likely caused by an overshooting effect in the 8 {mu}m array. We obtain improved estimates for HD 189733b's dayside planet-star flux ratio of 0.1466% {+-} 0.0040% in the 3.6 {mu}m band and 0.1787% {+-} 0.0038% in the 4.5 {mu}m band, corresponding to brightness temperatures of 1328 {+-} 11 K and 1192 {+-} 9 K, respectively; these are the most accurate secondary eclipse depths obtained to date for an extrasolar planet. We compare our new dayside and nightside spectra for HD 189733b to the predictions of one-dimensional radiative transfer models from

  17. 3.6 and 4.5 μm Phase Curves and Evidence for Non-equilibrium Chemistry in the Atmosphere of Extrasolar Planet HD 189733b

    NASA Astrophysics Data System (ADS)

    Knutson, Heather A.; Lewis, Nikole; Fortney, Jonathan J.; Burrows, Adam; Showman, Adam P.; Cowan, Nicolas B.; Agol, Eric; Aigrain, Suzanne; Charbonneau, David; Deming, Drake; Désert, Jean-Michel; Henry, Gregory W.; Langton, Jonathan; Laughlin, Gregory

    2012-07-01

    We present new, full-orbit observations of the infrared phase variations of the canonical hot Jupiter HD 189733b obtained in the 3.6 and 4.5 μm bands using the Spitzer Space Telescope. When combined with previous phase curve observations at 8.0 and 24 μm, these data allow us to characterize the exoplanet's emission spectrum as a function of planetary longitude and to search for local variations in its vertical thermal profile and atmospheric composition. We utilize an improved method for removing the effects of intrapixel sensitivity variations and robustly extracting phase curve signals from these data, and we calculate our best-fit parameters and uncertainties using a wavelet-based Markov Chain Monte Carlo analysis that accounts for the presence of time-correlated noise in our data. We measure a phase curve amplitude of 0.1242% ± 0.0061% in the 3.6 μm band and 0.0982% ± 0.0089% in the 4.5 μm band, corresponding to brightness temperature contrasts of 503 ± 21 K and 264 ± 24 K, respectively. We find that the times of minimum and maximum flux occur several hours earlier than predicted for an atmosphere in radiative equilibrium, consistent with the eastward advection of gas by an equatorial super-rotating jet. The locations of the flux minima in our new data differ from our previous observations at 8 μm, and we present new evidence indicating that the flux minimum observed in the 8 μm is likely caused by an overshooting effect in the 8 μm array. We obtain improved estimates for HD 189733b's dayside planet-star flux ratio of 0.1466% ± 0.0040% in the 3.6 μm band and 0.1787% ± 0.0038% in the 4.5 μm band, corresponding to brightness temperatures of 1328 ± 11 K and 1192 ± 9 K, respectively; these are the most accurate secondary eclipse depths obtained to date for an extrasolar planet. We compare our new dayside and nightside spectra for HD 189733b to the predictions of one-dimensional radiative transfer models from Burrows et al. and conclude that fits to

  18. Observations of Extrasolar Planet Transits: What's next?

    NASA Astrophysics Data System (ADS)

    Rauer, H.

    2014-03-01

    Transits of extrasolar planets are a goldmine for our understanding of the physical nature of planets beyond the Solar System. Measurements of radii from transit observations combined with mass determinations from radial velocity spectroscopy, or transit timing variations, have provided the first indications to the planetary composition and interior structure. It turns out that planets show a much richer diversity than found in our own planetary system, considering e.g. the so-called 'super-Earths', 'mini-Neptunes', and inflated giant planets. Transiting exoplanets also allow for spectroscopic observations of their atmospheres, either during transit or near secondary eclipse. Exoplanets showing transits have therefore been identified as key observables, not only for planet detection, but in particular for investigating further planetary nature. As a result, a new generation of instruments (space- and groundbased) for exoplanet transit observations is already in the construction phase and is planned for the near future. Most of these target specifically stars bright enough for spectroscopic follow-up observations, a èlesson learned' from past transit surveys. A clear goal for future investigations of habitable planets is the detection and characterization of terrestrial planets which potentially could harbor life. This talk will review the status and in particular the future of transit observations, with a focus on rocky planets in the habitable zone of their host stars.

  19. Red clouds in reducing atmospheres. [polymer production by UV irradiation in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Khare, B. N.; Sagan, C.

    1973-01-01

    A dark reddish-brown high-molecular weight polymer is produced by long wavelength ultraviolet irradiation of abundant gases in reducing planetary atmospheres. The polymer is examined by paper chromatography, mass spectrometry, and infrared, visible, and ultraviolet spectroscopy. High carbon-number straight-chain alkanes with NH2 and, probably, OH and C = O groups are identified, along with amino acids. There are chemical similarities between this polymer and organic compounds recovered from carbonaceous chondrites and precambrian sediments. The visible and near-ultraviolet transmission spectrum of the polymer shows its absorption optical depth to be redder than lambda(-2) and perhaps similar in coloration to the clouds of Jupiter, Saturn, and Titan. The nitrile content is small, and the polymer should be semitransparent in the 5 micrometer atmospheric window. Such polymers may be a common constituent of clouds in the outer solar system and on the early earth.

  20. Nonthermal atoms in planetary, satellite, and cometary atmospheres

    NASA Astrophysics Data System (ADS)

    Kupperman, David Gerson

    1999-08-01

    The effect of nonthermal atoms is investigated in planetary, satellite, and cometary atmospheres. In the Earth's lower thermosphere, it is demonstrated that nonthermal N(4S) and O(3P) atoms increase the peak NO density, bringing closer model and observational (108 cm-3) densities. However, they are insufficient to remove the total NO deficit and only result in a peak NO density of approximately 3 × 107 cm-3 at 105 km. The loss of nonthermal N(4S) atoms from Titan and Triton are found to be 9 × 1024 and 1.5 × 1024 N atoms s-1, respectively. We find that the observational estimates of Strobel et al. [1992] are consistent with our modeling of escape from Titan. The loss of O atoms from Mars by nonthermal processes is a vital part of understanding the H2O and CO2 budgets in respect to how the Martian atmosphere has evolved. Anderson and Hord [1971] inferred the H escape flux to be approximately 1.8 × 108 cm -2 s-1 from Mariner 6 and 7 ultraviolet data. McElroy et al. [1977] initially calculated an 0 atom escape rate that was approximately half the H escape rate. However, with more sophisticated modeling this result was shown to be an order of magnitude too large [Lammer and Bauer, 1991; Fox, 1993; Luhmann, 1997]. In this work, we demonstrate that the O escape rate due to dissociative recombination of O2 + can be in stoichiometric balance with H escape over a solar cycle. Observations of comet Hale-Bopp reveal a third type of tail consisting of neutral sodium atoms. Using a point source of atomic sodium to model the observed tail, the sodium production is found to be 3.5 × 10 25 atoms s-1. This result suggests that the source of the sodium is either from the nucleus or inner coma. The production rates of water and carbon monoxide near perihelion are found to be 1031 s-1 and 2.7 × 1030 s-1 , respectively. The abundance of observed Na in the tail is inconsistent with cosmic abundances, suggesting that the majority of the sodium is trapped in the comet nucleus or

  1. Problem of photochemical equilibrium of ozone in planetary atmospheres: Ozone distribution in the lower atmosphere of Mars

    NASA Technical Reports Server (NTRS)

    Grams, G. W.; SHARDANAND

    1972-01-01

    The inherent errors of applying terrestrial atmospheric ozone distribution studies to the atmosphere of other planets are discussed. Limitations associated with some of the earlier treatments of photochemical equilibrium distributions of ozone in planetary atmospheres are described. A technique having more universal application is presented. Ozone concentration profiles for the Martian atmosphere based on the results of the Mariner 4 radio occultation experiment and the more recent results with Mariner 6 and Mariner 7 have been calculated using this approach.

  2. Extrasolar planets: constraints for planet formation models.

    PubMed

    Santos, Nuno C; Benz, Willy; Mayor, Michel

    2005-10-14

    Since 1995, more than 150 extrasolar planets have been discovered, most of them in orbits quite different from those of the giant planets in our own solar system. The number of discovered extrasolar planets demonstrates that planetary systems are common but also that they may possess a large variety of properties. As the number of detections grows, statistical studies of the properties of exoplanets and their host stars can be conducted to unravel some of the key physical and chemical processes leading to the formation of planetary systems.

  3. Validation of Atmospheric Dynamics (VADY) - connections between planetary waves and atmospheric circulation types

    NASA Astrophysics Data System (ADS)

    Lang, Benjamin; Jacobeit, Jucundus; Beck, Christoph; Philipp, Andreas

    2015-04-01

    The climate research program "Medium-range Climate Predictions" (MiKlip), funded by the Federal Ministry of Education and Research in Germany (BMBF), has the aim to develop a climate model system (MPI-ESM) that can provide reliable decadal predictions of climate, including extreme weather events. A substantial part of the development process is a comprehensive model validation. Within MiKlip, it includes comparisons of model simulations and observations in order to allow statements about the performance of the model and to give particular recommendations for the further development of the model. The research project "Validation of Atmospheric Dynamics" (VADY), conducted by the cooperation partners "Institute of Geography at the University of Augsburg" (IGUA) and the "German Aerospace Centre" (DLR), contributes to model validation within MiKlip with a special focus on atmospheric waves and circulation dynamics. Within the framework of VADY, DLR validates the representation of atmospheric waves on different levels and scales based on suitable activity indices (e.g. the so-called large-scale dynamical activity index (LDAI), which is a measure for the activity of planetary waves). The focus of IGUA is on the model validation with respect to the representation of atmospheric circulation types, dynamical modes and the teleconnectivity of the atmospheric circulation. Currently, the connection between LDAI and atmospheric circulation types on different levels and for different seasons in the North Atlantic-European region is analysed by considering, in particular, the North Atlantic Oscillation. Results will be shown for the connection between LDAI and atmospheric circulation types and subsequently for the representation of the identified connections in the decadal-prediction model system of MPI-ESM.

  4. Analytic theory of orbit contraction and ballistic entry into planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Longuski, J. M.; Vinh, N. X.

    1980-01-01

    A space object traveling through an atmosphere is governed by two forces: aerodynamic and gravitational. On this premise, equations of motion are derived to provide a set of universal entry equations applicable to all regimes of atmospheric flight from orbital motion under the dissipate force of drag through the dynamic phase of reentry, and finally to the point of contact with the planetary surface. Rigorous mathematical techniques such as averaging, Poincare's method of small parameters, and Lagrange's expansion, applied to obtain a highly accurate, purely analytic theory for orbit contraction and ballistic entry into planetary atmospheres. The theory has a wide range of applications to modern problems including orbit decay of artificial satellites, atmospheric capture of planetary probes, atmospheric grazing, and ballistic reentry of manned and unmanned space vehicles.

  5. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1992-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically derived microwave absorption properties for such atmospheric constituents, or using laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. The goal of this investigation was to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.

  6. Laboratory Evaluation and Application of Microwave Absorption Properties Under Simulated Conditions for Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1997-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or using laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. Laboratory measurements completed under this grant (NAGW-533), have shown that the opacity from, SO2 under simulated Venus conditions is best described by a different lineshape than was previously used in theoretical predictions. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.

  7. The Potential Feasibility of Chlorinic Photosynthesis on Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Haas, Johnson

    2009-09-01

    It is highly likely that the first convincing evidence of extrasolar life will arrive in the form of atmospheric absorption spectra. The modern search for life-bearing extrasolar planets emphasizes the potential detection of O2 and O3 absorption spectra in exoplanetary atmospheres as archetypal signatures of biology. However, oxygenic photosynthesis apparently failed to evolve independently more than once on Earth, and is thus unlikely to be reliably ubiquitous throughout the universe. Alternative evolutionary paths may yield planetary atmospheres tinted with the waste products of other dominant metabolisms, including potentially exotic biochemistries. This study examines the potential feasibility of one such exotic metabolism: chlorinic photosynthesis (CPS), defined as biologically-mediated halogenation of aqueous chloride to HClO, Cl2 or partially-oxidized intermediates (e.g. haloalkanes, haloacids, haloaromatics), coupled with photosynthetic CO2 fixation. This metabolic couple is feasible thermodynamically and appears to be geochemically plausible under approximately terrestrial conditions. This study hypothesizes that planetary biospheres dominated by CPS would develop atmospheres enriched with dihalogens and other halogenated compounds, evolve a highly oxidizing surface geochemical environment, and foster biological selection pressures favoring halogen resistance and eventual metazoan heterotrophy based on dihalogen and halocarbon respiration. Planets favoring the evolution of CPS would probably receive equivalent or greater surface UV flux than Earth did in the Paleoarchean (promoting abiotic photo-oxidation of aqueous halides, and establishing a strong biological selective pressure toward their accommodation), and would orbit stars having equivalent or greater bulk metallicities (promoting greater planetary halide abundances) relative to the Sun. Directed searches for such worlds should probably focus on A, F and G0 spectral class stars having bulk

  8. Detecting tree-like multicellular life on extrasolar planets.

    PubMed

    Doughty, Christopher E; Wolf, Adam

    2010-11-01

    Over the next two decades, NASA and ESA are planning a series of space-based observatories to find Earth-like planets and determine whether life exists on these planets. Previous studies have assessed the likelihood of detecting life through signs of biogenic gases in the atmosphere or a red edge. Biogenic gases and the red edge could be signs of either single-celled or multicellular life. In this study, we propose a technique with which to determine whether tree-like multicellular life exists on extrasolar planets. For multicellular photosynthetic organisms on Earth, competition for light and the need to transport water and nutrients has led to a tree-like body plan characterized by hierarchical branching networks. This design results in a distinct bidirectional reflectance distribution function (BRDF) that causes differing reflectance at different sun/view geometries. BRDF arises from the changing visibility of the shadows cast by objects, and the presence of tree-like structures is clearly distinguishable from flat ground with the same reflectance spectrum. We examined whether the BRDF could detect the existence of tree-like structures on an extrasolar planet by using changes in planetary albedo as a planet orbits its star. We used a semi-empirical BRDF model to simulate vegetation reflectance at different planetary phase angles and both simulated and real cloud cover to calculate disk and rotation-averaged planetary albedo for a vegetated and non-vegetated planet with abundant liquid water. We found that even if the entire planetary albedo were rendered to a single pixel, the rate of increase of albedo as a planet approaches full illumination would be comparatively greater on a vegetated planet than on a non-vegetated planet. Depending on how accurately planetary cloud cover can be resolved and the capabilities of the coronagraph to resolve exoplanets, this technique could theoretically detect tree-like multicellular life on exoplanets in 50 stellar systems

  9. Detecting tree-like multicellular life on extrasolar planets.

    PubMed

    Doughty, Christopher E; Wolf, Adam

    2010-11-01

    Over the next two decades, NASA and ESA are planning a series of space-based observatories to find Earth-like planets and determine whether life exists on these planets. Previous studies have assessed the likelihood of detecting life through signs of biogenic gases in the atmosphere or a red edge. Biogenic gases and the red edge could be signs of either single-celled or multicellular life. In this study, we propose a technique with which to determine whether tree-like multicellular life exists on extrasolar planets. For multicellular photosynthetic organisms on Earth, competition for light and the need to transport water and nutrients has led to a tree-like body plan characterized by hierarchical branching networks. This design results in a distinct bidirectional reflectance distribution function (BRDF) that causes differing reflectance at different sun/view geometries. BRDF arises from the changing visibility of the shadows cast by objects, and the presence of tree-like structures is clearly distinguishable from flat ground with the same reflectance spectrum. We examined whether the BRDF could detect the existence of tree-like structures on an extrasolar planet by using changes in planetary albedo as a planet orbits its star. We used a semi-empirical BRDF model to simulate vegetation reflectance at different planetary phase angles and both simulated and real cloud cover to calculate disk and rotation-averaged planetary albedo for a vegetated and non-vegetated planet with abundant liquid water. We found that even if the entire planetary albedo were rendered to a single pixel, the rate of increase of albedo as a planet approaches full illumination would be comparatively greater on a vegetated planet than on a non-vegetated planet. Depending on how accurately planetary cloud cover can be resolved and the capabilities of the coronagraph to resolve exoplanets, this technique could theoretically detect tree-like multicellular life on exoplanets in 50 stellar systems.

  10. Cosmic ray impact on extrasolar earth-like planets in close-in habitable zones.

    PubMed

    Griessmeier, J-M; Stadelmann, A; Motschmann, U; Belisheva, N K; Lammer, H; Biernat, H K

    2005-10-01

    Because of their different origins, cosmic rays can be subdivided into galactic cosmic rays and solar/stellar cosmic rays. The flux of cosmic rays to planetary surfaces is mainly determined by two planetary parameters: the atmospheric density and the strength of the internal magnetic moment. If a planet exhibits an extended magnetosphere, its surface will be protected from high-energy cosmic ray particles. We show that close-in extrasolar planets in the habitable zone of M stars are synchronously rotating with their host star because of the tidal interaction. For gravitationally locked planets the rotation period is equal to the orbital period, which is much longer than the rotation period expected for planets not subject to tidal locking. This results in a relatively small magnetic moment. We found that an Earth-like extrasolar planet, tidally locked in an orbit of 0.2 AU around an M star of 0.5 solar masses, has a rotation rate of 2% of that of the Earth. This results in a magnetic moment of less than 15% of the Earth's current magnetic moment. Therefore, close-in extrasolar planets seem not to be protected by extended Earth-like magnetospheres, and cosmic rays can reach almost the whole surface area of the upper atmosphere. Primary cosmic ray particles that interact with the atmosphere generate secondary energetic particles, a so-called cosmic ray shower. Some of the secondary particles can reach the surface of terrestrial planets when the surface pressure of the atmosphere is on the order of 1 bar or less. We propose that, depending on atmospheric pressure, biological systems on the surface of Earth-like extrasolar planets at close-in orbital distances can be strongly influenced by secondary cosmic rays.

  11. PLANETARY CORE FORMATION WITH COLLISIONAL FRAGMENTATION AND ATMOSPHERE TO FORM GAS GIANT PLANETS

    SciTech Connect

    Kobayashi, Hiroshi; Krivov, Alexander V.; Tanaka, Hidekazu

    2011-09-01

    Massive planetary cores ({approx}10 Earth masses) trigger rapid gas accretion to form gas giant planets such as Jupiter and Saturn. We investigate the core growth and the possibilities for cores to reach such a critical core mass. At the late stage, planetary cores grow through collisions with small planetesimals. Collisional fragmentation of planetesimals, which is induced by gravitational interaction with planetary cores, reduces the amount of planetesimals surrounding them, and thus the final core masses. Starting from small planetesimals that the fragmentation rapidly removes, less massive cores are formed. However, planetary cores acquire atmospheres that enlarge their collisional cross section before rapid gas accretion. Once planetary cores exceed about Mars mass, atmospheres significantly accelerate the growth of cores. We show that, taking into account the effects of fragmentation and atmosphere, initially large planetesimals enable formation of sufficiently massive cores. On the other hand, because the growth of cores is slow for large planetesimals, a massive disk is necessary for cores to grow enough within a disk lifetime. If the disk with 100 km sized initial planetesimals is 10 times as massive as the minimum mass solar nebula, planetary cores can exceed 10 Earth masses in the Jovian planet region (>5 AU).

  12. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1987-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and Earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorping properties of potential constituents is available. The use of theoretically derived microwave absorption properties for such atmospheric constituents, or laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. Laboratory measurement of the microwave properties of atmospheric gases under simulated conditions for the outer planets were conducted. Results of these measurements are discussed.

  13. On the averaging of ratios of specific heats in a multicomponent planetary atmosphere

    NASA Technical Reports Server (NTRS)

    Dubisch, R.

    1974-01-01

    The use of adiabatic relations in the calculation of planetary atmospheres requires knowledge of the ratio of specific heats of a mixture of gases under various pressure and temperature conditions. It is shown that errors introduced by simple averaging of the ratio of specific heats in a multicomponent atmosphere can be roughly 0.4%. Therefore, the gamma-averaging error can become important when integrating through the atmosphere to a large depth.

  14. Noble gases in planetary atmospheres - Implications for the origin and evolution of atmospheres

    NASA Technical Reports Server (NTRS)

    Pollack, J. B.; Black, D. C.

    1982-01-01

    The radiogenic and primordial noble gas contents of the Venus, earth, and Mars atmospheres are compared with one another and with the noble gas content of other extraterrestrial samples, particularly meteorites. Key trends in the primordial noble gas content of terrestrial planetary atmospheres are shown to include: (1) a several-orders-of-magnitude decrease in Ne-20 and Ar-36 from Venus to earth to Mars; (2) a nearly constant Ne-20/Ar-36 ratio, which is comparable to that found in the more primitive carbonaceous chondrites and which is two orders of magnitude smaller than the solar ratio; (3) a sizable fractionation of Ar, Kr, and Xe from their solar ratios, though the degree of fractionation (especially for Ar-36/Xe-132) appears to decrease systematically from carbonaceous chondrites to Mars to earth to Venus; and (4) large differences in Ne and Xe isotopic ratios among earth, meteorites, and the sun. It is suggested that the grain-accretion hypothesis can explain all four trends, though the assumptions needed to achieve this agreement are far from proven.

  15. Outer satellite atmospheres: Their nature and planetary interactions

    NASA Technical Reports Server (NTRS)

    Smyth, W. H.; Combi, M. R.

    1984-01-01

    Significant insights regarding the nature and interactions of Io and the planetary magnetosphere were gained through modeling studies of the spatial morphology and brightness of the Io sodium cloud. East-west intensity asymmetries in Region A are consistent with an east-west electric field and the offset of the magnetic and planetary-spin axes. East-west orbital asymmetries and the absolute brightness of Region B suggest a low-velocity (3 km/sec) satellite source of 1 to 2 x 10(26) sodium atoms/sec. The time-varying spatial structure of the sodium directional features in near Region C provides direct evidence for a magnetospheric-wind-driven escape mechanism with a high-velocity (20 km/sec) source of 1 x 10(26) atoms/sec and a flux distribution enhanced at the equator relative to the poles. A model for the Io potassium cloud is presented and analysis of data suggests a low velocity source rate of 5 x 10(24) atoms/sec. To understand the role of Titan and non-Titan sources for H atoms in the Saturn system, the lifetime of hydrogen in the planetary magnetosphere was incorporated into the earlier Titan torus model of Smyth (1981) and its expected impact discussed. A particle trajectory model for cometary hydrogen is presented and applied to the Lyman-alpha distribution of Comet Kohoutek (1973XII).

  16. On Detecting Biospheres from Chemical Thermodynamic Disequilibrium in Planetary Atmospheres.

    PubMed

    Krissansen-Totton, Joshua; Bergsman, David S; Catling, David C

    2016-01-01

    Atmospheric chemical disequilibrium has been proposed as a method for detecting extraterrestrial biospheres from exoplanet observations. Chemical disequilibrium is potentially a generalized biosignature since it makes no assumptions about particular biogenic gases or metabolisms. Here, we present the first rigorous calculations of the thermodynamic chemical disequilibrium in Solar System atmospheres, in which we quantify the available Gibbs energy: the Gibbs free energy of an observed atmosphere minus that of atmospheric gases reacted to equilibrium. The purely gas phase disequilibrium in Earth's atmosphere is mostly attributable to O2 and CH4. The available Gibbs energy is not unusual compared to other Solar System atmospheres and smaller than that of Mars. However, Earth's fluid envelope contains an ocean, allowing gases to react with water and requiring a multiphase calculation with aqueous species. The disequilibrium in Earth's atmosphere-ocean system (in joules per mole of atmosphere) ranges from ∼20 to 2 × 10(6) times larger than the disequilibria of other atmospheres in the Solar System, where Mars is second to Earth. Only on Earth is the chemical disequilibrium energy comparable to the thermal energy per mole of atmosphere (excluding comparison to Titan with lakes, where quantification is precluded because the mean lake composition is unknown). Earth's disequilibrium is biogenic, mainly caused by the coexistence of N2, O2, and liquid water instead of more stable nitrate. In comparison, the O2-CH4 disequilibrium is minor, although kinetics requires a large CH4 flux into the atmosphere. We identify abiotic processes that cause disequilibrium in the other atmospheres. Our metric requires minimal assumptions and could potentially be calculated from observations of exoplanet atmospheres. However, further work is needed to establish whether thermodynamic disequilibrium is a practical exoplanet biosignature, requiring an assessment of false positives, noisy

  17. On Detecting Biospheres from Chemical Thermodynamic Disequilibrium in Planetary Atmospheres.

    PubMed

    Krissansen-Totton, Joshua; Bergsman, David S; Catling, David C

    2016-01-01

    Atmospheric chemical disequilibrium has been proposed as a method for detecting extraterrestrial biospheres from exoplanet observations. Chemical disequilibrium is potentially a generalized biosignature since it makes no assumptions about particular biogenic gases or metabolisms. Here, we present the first rigorous calculations of the thermodynamic chemical disequilibrium in Solar System atmospheres, in which we quantify the available Gibbs energy: the Gibbs free energy of an observed atmosphere minus that of atmospheric gases reacted to equilibrium. The purely gas phase disequilibrium in Earth's atmosphere is mostly attributable to O2 and CH4. The available Gibbs energy is not unusual compared to other Solar System atmospheres and smaller than that of Mars. However, Earth's fluid envelope contains an ocean, allowing gases to react with water and requiring a multiphase calculation with aqueous species. The disequilibrium in Earth's atmosphere-ocean system (in joules per mole of atmosphere) ranges from ∼20 to 2 × 10(6) times larger than the disequilibria of other atmospheres in the Solar System, where Mars is second to Earth. Only on Earth is the chemical disequilibrium energy comparable to the thermal energy per mole of atmosphere (excluding comparison to Titan with lakes, where quantification is precluded because the mean lake composition is unknown). Earth's disequilibrium is biogenic, mainly caused by the coexistence of N2, O2, and liquid water instead of more stable nitrate. In comparison, the O2-CH4 disequilibrium is minor, although kinetics requires a large CH4 flux into the atmosphere. We identify abiotic processes that cause disequilibrium in the other atmospheres. Our metric requires minimal assumptions and could potentially be calculated from observations of exoplanet atmospheres. However, further work is needed to establish whether thermodynamic disequilibrium is a practical exoplanet biosignature, requiring an assessment of false positives, noisy

  18. On the polarity of cyclostrophic flow in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Conrath, B. J.; Harris, I.

    1981-01-01

    Fluids which are completely inviscid in the mathematical sense do not exist. Thus, the concepts of gradient flow and cyclostrophic balance are interpreted as approximate solutions of a boundary value problem for small but finite viscosity. Large scale phenomena such as the superrotation of Venus and cyclones are effectively bounded by the rigidly rotating planetary surface. This polarizes the circulation and excludes so-called anomalous motions from the flow regime. With scale phenomena such as dust devils, both directions are observed which is attributed to the stochastic nature of wind systems surrounding the disturbance.

  19. The effect of carbon monoxide on planetary haze formation

    SciTech Connect

    Hörst, S. M.; Tolbert, M. A

    2014-01-20

    Organic haze plays a key role in many planetary processes ranging from influencing the radiation budget of an atmosphere to serving as a source of prebiotic molecules on the surface. Numerous experiments have investigated the aerosols produced by exposing mixtures of N{sub 2}/CH{sub 4} to a variety of energy sources. However, many N{sub 2}/CH{sub 4} atmospheres in both our solar system and extrasolar planetary systems also contain carbon monoxide (CO). We have conducted a series of atmosphere simulation experiments to investigate the effect of CO on the formation and particle size of planetary haze analogues for a range of CO mixing ratios using two different energy sources, spark discharge and UV. We find that CO strongly affects both number density and particle size of the aerosols produced in our experiments and indicates that CO may play an important, previously unexplored, role in aerosol chemistry in planetary atmospheres.

  20. Possibility of growth of airborne microbes in outer planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Dimmick, R. L.; Chatigny, M. A.

    1975-01-01

    It is shown that airborne bacteria can maintain metabolic functions in a suitable atmosphere. It is theorized that particles in the Jovian atmosphere would have physical half-lives of 10 to 1500 years, depending upon which of two turbulent models is chosen.

  1. VUV photochemistry simulation of planetary upper atmosphere using synchrotron radiation.

    PubMed

    Carrasco, Nathalie; Giuliani, Alexandre; Correia, Jean Jacques; Cernogora, Guy

    2013-07-01

    The coupling of a gas reactor, named APSIS, with a vacuum-ultraviolet (VUV) beamline at the SOLEIL synchrotron radiation facility, for a photochemistry study of gas mixtures, is reported. The reactor may be irradiated windowless with gas pressures up to hundreds of millibar, and thus allows the effect of energetic photons below 100 nm wavelength to be studied on possibly dense media. This set-up is perfectly suited to atmospheric photochemistry investigations, as illustrated by a preliminary report of a simulation of the upper atmospheric photochemistry of Titan, the largest satellite of Saturn. Titan's atmosphere is mainly composed of molecular nitrogen and methane. Solar VUV irradiation with wavelengths no longer than 100 nm on the top of the atmosphere enables the dissociation and ionization of nitrogen, involving a nitrogen chemistry specific to nitrogen-rich upper atmospheres.

  2. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1989-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. Work performed has shown that laboratory measurements of the millimeter-wave opacity of ammonia between 7.5 mm and 9.3 mm and also at the 3.2 mm wavelength require a different lineshape to be used in the theoretical prediction for millimeter-wave ammonia opacity than was previously used. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.

  3. Laboratory measurements of microwave and millimeter-wave properties of planetary atmospheric constituents

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1989-01-01

    Accurate data on microwave and millimeter-wave properties of potential planetary atmospheric constituents is critical for the proper interpretation of radio occultation measurements, and of radio astronomical observations of both continuum and spectral line emissions. Such data is also needed to correct for atmospheric effects on radar studies of surface reflectivity. Since the refractive and absorptive properties of atmospheric constituents often vary drastically from theoretically-predicted profiles, especially under the extreme conditions characteristic of the planetary atmosphere, laboratory measurements under simulated planetary conditions are required. This paper reviews the instrumentation and techniques used for laboratory measurement of the refractivity and absorptivity of atmospheric constituents at wavelengths longward of 1 mm, under simulated planetary conditions (temperature, pressure, and broadening gases). Techniques for measuring both gases and condensates are considered. Also reviewed are the relative accuracies of the various techniques. Laboratory measurements are reviewed which have already been made, and additional measurements which are needed for interpretation of data from Venus and the outer planets, are highlighted.

  4. Laboratory Evaluation and Application of Microwave Absorption Properties under Simulated Conditions for Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    2005-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments, entry probe radio signal absorption measurements, and earth- based or spacecraft-based radio astronomical (emission) observations can be used to infer abundances of microwave absorbing constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or the use of laboratory measurements of such properties taken under environmental conditions that are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. For example, new laboratory measurements completed recently by Mohammed and Steffes (2003 and 2004) under this grant (NAG5-12122,5/1/02-4/30/05), have shown that the millimeter-wavelength opacities from both gaseous phosphine (PH3) and gaseous ammonia ("3) under simulated conditions for the outer planets vary significantly from that predicted by theory over a wide range of temperatures and pressures. These results have directly impacted planning and scientific goals for study of Saturn's atmosphere with the Cassini Radio Science Experiment, as discussed below. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both spacecraft entry probe and orbiter (or flyby) radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the

  5. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1992-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or using laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. For example, laboratory measurements performed by Fahd and Steffes have shown that the opacity from gaseous SO2 under simulated Venus conditions can be well described by the Van Vleck-Weisskopf lineshape at wavelengths shortward of 2 cm, but that the opacity of wavelengths greater than 2 cm is best described by a different lineshape that was previously used in theoretical predictions. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.

  6. Laboratory Evaluation and Application of Microwave Absorption Properties under Simulated Conditions for Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    2002-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments, entry probe radio signal absorption measurements, and earth-based or spacecraft-based radio astronomical (emission) observations can be used to infer abundances of microwave absorbing constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or the use of laboratory measurements of such properties taken under environmental conditions that are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. Laboratory measurements have shown that the centimeter-wavelength opacity from gaseous phosphine (PH3) under simulated conditions for the outer planets far exceeds that predicted from theory over a wide range of temperatures and pressures. This fundamentally changed the resulting interpretation of Voyager radio occultation data at Saturn and Neptune. It also directly impacts planning and scientific goals for study of Saturn's atmosphere with the Cassini Radio Science Experiment and the Rossini RADAR instrument. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both radio occultation experiments and radio astronomical observations, and over a range of frequencies which correspond to those used in both spacecraft entry probe and orbiter (or flyby) radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations

  7. Research in planetary studies and operation of the Mauna Kea Observatory

    NASA Technical Reports Server (NTRS)

    Cruikshank, Dale P.

    1986-01-01

    The research programs are highlighted in the following areas: major planets; planetary satellites and rings; asteroids; comets; dark organic matter; theoretical and analytical structures; extrasolar planetary; and telescopes.

  8. Comparative Planetary Nitrogen Atmospheres: Titan, Triton and Pluto

    NASA Astrophysics Data System (ADS)

    Strobel, Darrell F.; Zhu, Xun

    2016-06-01

    Titan has a massive atmosphere in comparison to Triton and Pluto which are widely regarded as the largest endmembers of Kuiper-Belt objects and as 'twins' with thin buffered N2 atmospheres controlled by interactions with surface ices, primarily N2 and CH4 frost. But one can compare them with Titan's upper atmosphere by noting that 14 microbars on Titan is at an altitude of approximately 400 km. At this level Titan has haze layers as Pluto does and less so on Triton. The talk will emphasize the fundamental role that CH4 plays in controlling the thermal structure of these atmospheres and is one of the principal reasons for the differences in the thermal structure of Pluto's and Triton's atmospheres. Titan and Pluto have in common photochemical production of nitriles at detectable abundances, whereas Triton does not. The cold upper atmosphere of Pluto remains a mystery as the reported abundances of HCN are insufficient to cool the atmosphere in contrast to Titan's thermosphere.

  9. Diversity of Planetary Atmospheric Circulations and Climates in a Simplified General Circulation Model

    NASA Astrophysics Data System (ADS)

    Wang, Yixiong; Read, Peter

    2014-04-01

    The parametric dependence of terrestrial planetary atmospheric circulations and climates on characteristic parameters is studied. A simplified general circulation model-PUMA is employed to investigate the dynamic effects of planetary rotation rate and equator-to-pole temperature difference on the circulation and climate of terrestrial planetary atmospheres. Five different types of circulation regime are identified by mapping the experimental results in a 2-D parameter space defined by thermal Rossby number and frictional Taylor number. The effect of the transfer and redistribution of radiative energy is studied by building up a new two-band semi-gray radiative-convective scheme, which is capable of modelling greenhouse and anti-greenhouse effects while keeping the tunable parameters as few as possible. The results will provide insights into predicting the habitability of terrestrial exoplanets.

  10. Modification of planetary atmospheres by material from the rings

    NASA Technical Reports Server (NTRS)

    Atreya, S. K.

    1984-01-01

    The modification of the atmospheres and ionospheres of ringed planets by the injection of ionized and neutral material from the rings is discussed, on the basis of Pioneer and Voyager observations. It is shown that although no direct evidence exists for the injection of material from the rings into the atmosphere, such an interaction could account for the observed thermal structure and ionospheric properties of Jupiter, Saturn, Uranus, and the Jovian satellite Io.

  11. Possibility of growth of airborne microbes in outer planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Dimmick, R. L.; Chatigny, M. A.

    1976-01-01

    The state of the art of laboratory aerobiological research is briefly reviewed. Experiments are described in which the biological behavior of microbes in or on aerosol particles is investigated in a stirred settling chamber and a rotating drum. Experimental findings are summarized which indicate that airborne bacteria can maintain metabolic functions in a suitable atmosphere. These studies have been undertaken in consideration of the possibility that Jupiter's atmosphere might be contaminated if a space probe enters a biological stratum.

  12. Laboratory Evaluation and Application of Microwave Absorption Properties Under Simulated Conditions for Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1998-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments, entry probe radio signal absorption measurements, and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or using laboratory measurements of such properties taken under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often leads to significant misinterpretation of available opacity data. For example, laboratory measurements completed recently by Kolodner and Steffes (ICARUS 132, pp. 151-169, March 1998, attached as Appendix A) under this grant (NAGS-4190), have shown that the opacity from gaseous H2SO4 under simulated Venus conditions is best described by a different formalism than was previously used. The recognition of the need to make such laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressures which correspond to the altitudes probed by both spacecraft entry probe and orbiter radio occultation experiments and by radio astronomical observations, and over a range of frequencies which correspond to those used in such experiments, has led to the development of a facility at Georgia Tech which is capable of making such measurements. It has been the goal of this investigation to conduct such measurements and to apply the results to a wide range of planetary observations, both spacecraft and earth-based, in order to determine the identity and abundance profiles of constituents in those planetary atmospheres.

  13. GRAVITY WAVES ON HOT EXTRASOLAR PLANETS. I. PROPAGATION AND INTERACTION WITH THE BACKGROUND

    SciTech Connect

    Watkins, Chris; Cho, J. Y-K. E-mail: J.Cho@qmul.ac.u

    2010-05-01

    We study the effects of gravity waves, or g-modes, on hot extrasolar planets. These planets are expected to possess stably stratified atmospheres, which support gravity waves. In this paper, we review the derivation of the equation that governs the linear dynamics of gravity waves and describe its application to a hot extrasolar planet, using HD 209458 b as a generic example. We find that gravity waves can exhibit a wide range of behaviors, even for a single atmospheric profile. The waves can significantly accelerate or decelerate the background mean flow, depending on the difference between the wave phase and mean flow speeds. In addition, the waves can provide significant heating ({approx}10{sup 2} to {approx}10{sup 3} K per planetary rotation), especially to the region of the atmosphere above about 10 scale heights from the excitation region. Furthermore, by propagating horizontally, gravity waves provide a mechanism for transporting momentum and heat from the dayside of a tidally locked planet to its nightside. We discuss work that needs to be undertaken to incorporate these effects in current atmosphere models of extrasolar planets.

  14. Study of Some Planetary Atmospheres Features by Probe Entry and Descent Simulations

    NASA Technical Reports Server (NTRS)

    Gil, P. J. S.; Rosa, P. M. B.

    2005-01-01

    Characterization of planetary atmospheres is analyzed by its effects in the entry and descent trajectories of probes. Emphasis is on the most important variables that characterize atmospheres e.g. density profile with altitude. Probe trajectories are numerically determined with ENTRAP, a developing multi-purpose computational tool for entry and descent trajectory simulations capable of taking into account many features and perturbations. Real data from Mars Pathfinder mission is used. The goal is to be able to determine more accurately the atmosphere structure by observing real trajectories and what changes are to expect in probe descent trajectories if atmospheres have different properties than the ones assumed initially.

  15. Exploring extrasolar worlds: from gas giants to terrestrial habitable planets.

    PubMed

    Tinetti, Giovanna; Griffith, Caitlin A; Swain, Mark R; Deroo, Pieter; Beaulieu, Jean Philippe; Vasisht, Gautam; Kipping, David; Waldmann, Ingo; Tennyson, Jonathan; Barber, Robert J; Bouwman, Jeroen; Allard, Nicole; Brown, Linda R

    2010-01-01

    Almost 500 extrasolar planets have been found since the discovery of 51 Peg b by Mayor and Queloz in 1995. The traditional field of planetology has thus expanded its frontiers to include planetary environments not represented in our Solar System. We expect that in the next five years space missions (Corot, Kepler and GAIA) or ground-based detection techniques will both increase exponentially the number of new planets discovered and lower the present limit of a approximately 1.9 Earth-mass object [e.g. Mayor et al., Astron. Astrophys., 2009, 507, 487]. While the search for an Earth-twin orbiting a Sun-twin has been one of the major goals pursued by the exoplanet community in the past years, the possibility of sounding the atmospheric composition and structure of an increasing sample of exoplanets with current telescopes has opened new opportunities, unthinkable just a few years ago. As a result, it is possible now not only to determine the orbital characteristics of the new bodies, but moreover to study the exotic environments that lie tens of parsecs away from us. The analysis of the starlight not intercepted by the thin atmospheric limb of its planetary companion (transit spectroscopy), or of the light emitted/reflected by the exoplanet itself, will guide our understanding of the atmospheres and the surfaces of these extrasolar worlds in the next few years. Preliminary results obtained by interpreting current atmospheric observations of transiting gas giants and Neptunes are presented. While the full characterisation of an Earth-twin might requires a technological leap, our understanding of large terrestrial planets (so called super-Earths) orbiting bright, later-type stars is within reach by current space and ground telescopes.

  16. Exploring extrasolar worlds: from gas giants to terrestrial habitable planets.

    PubMed

    Tinetti, Giovanna; Griffith, Caitlin A; Swain, Mark R; Deroo, Pieter; Beaulieu, Jean Philippe; Vasisht, Gautam; Kipping, David; Waldmann, Ingo; Tennyson, Jonathan; Barber, Robert J; Bouwman, Jeroen; Allard, Nicole; Brown, Linda R

    2010-01-01

    Almost 500 extrasolar planets have been found since the discovery of 51 Peg b by Mayor and Queloz in 1995. The traditional field of planetology has thus expanded its frontiers to include planetary environments not represented in our Solar System. We expect that in the next five years space missions (Corot, Kepler and GAIA) or ground-based detection techniques will both increase exponentially the number of new planets discovered and lower the present limit of a approximately 1.9 Earth-mass object [e.g. Mayor et al., Astron. Astrophys., 2009, 507, 487]. While the search for an Earth-twin orbiting a Sun-twin has been one of the major goals pursued by the exoplanet community in the past years, the possibility of sounding the atmospheric composition and structure of an increasing sample of exoplanets with current telescopes has opened new opportunities, unthinkable just a few years ago. As a result, it is possible now not only to determine the orbital characteristics of the new bodies, but moreover to study the exotic environments that lie tens of parsecs away from us. The analysis of the starlight not intercepted by the thin atmospheric limb of its planetary companion (transit spectroscopy), or of the light emitted/reflected by the exoplanet itself, will guide our understanding of the atmospheres and the surfaces of these extrasolar worlds in the next few years. Preliminary results obtained by interpreting current atmospheric observations of transiting gas giants and Neptunes are presented. While the full characterisation of an Earth-twin might requires a technological leap, our understanding of large terrestrial planets (so called super-Earths) orbiting bright, later-type stars is within reach by current space and ground telescopes. PMID:21302557

  17. Transmission spectroscopy of HAT-P-32b with the LBT: confirmation of clouds/hazes in the planetary atmosphere

    NASA Astrophysics Data System (ADS)

    Mallonn, M.; Strassmeier, K. G.

    2016-05-01

    Aims: Spectroscopic observations of a transit event of an extrasolar planet offer the opportunity to study the composition of the planetary atmosphere. This can be done with comparably little telescope time using a low-resolution multi-object spectrograph at a large aperture telescope. We observed a transit of the inflated hot Jupiter HAT-P-32b with the Multi-Object Double Spectrograph at the Large Binocular Telescope to characterize its atmosphere from 3300 to 10 000 Å. Methods: A time series of target and reference star spectra was binned in two broad-band wavelength channels, from which differential transit light curves were constructed. These broad-band light curves were used to confirm previous transit parameter determinations. To derive the planetary transmission spectrum with a resolution of R ~ 60, we created a chromatic set of 62 narrow-band light curves. The spectrum was corrected for the third light of a nearby M star. Additionally, we undertook a photometric monitoring campaign of the host star to correct for the influence of starspots. Results: The transmission spectrum of HAT-P-32b shows no pressure-broadened absorption features from Na and K, which is interpreted by the presence of clouds or hazes in the planetary atmosphere. This result is in agreement with previous studies on the same planet. The presence of TiO in gas phase could be ruled out. We find a 2.8σ indication of increased absorption in the line core of potassium (K I 7699 Å). No narrow absorption features of Na and Hα were detected. Furthermore, tentative indications were found for a slope of increasing opacity toward blue wavelengths from the near-IR to the near-UV with an amplitude of two scale heights. If confirmed by follow-up observations, it can be explained by aerosols either causing Mie scattering or causing Rayleigh scattering with an aerosol - gas scale height ratio below unity. The host star was found to be photometrically stable within the measurement precision. Based on

  18. Impact Erosion of Planetary Atmospheres: Some Surprising Results

    NASA Astrophysics Data System (ADS)

    Newman, William I.; Symbalisty, Eugene M. D.; Ahrens, Thomas J.; Jones, Eric M.

    1999-04-01

    We have investigated by analytical and computational means the effect of Cretaceous-Tertiary (K/T) size impacts (5×1030erg, 9-km-radius bolide of 1019g) on terrestrial atmospheres. We have extended analytically the approximate solution due to A. S. Kompaneets (1960,Sov. Phys. Dokl. Engl. Transl.5, 46-48) for the blast wave obtained for atmospheric nuclear explosions (idealized to isothermal atmospheres) to ideal adiabatic atmospheres and to data-based models of the Earth's atmosphere. For the first time, we have been able to obtainanalyticallythe particle trajectories in an isothermal atmosphere. The outcome of this nonlinear analysis is that a massive impact (without the subsequent ejection of substantial mass) would only influence a column of ≈30-km radius in the Earth's atmosphere and that the shocked gas would be propelled up and against the column “wall,” but would not escape from the planet. We examined the validity of “hemispheric blowoff,” the hypothesis that all material in a hemisphere lying above a plane tangent to the point of impact radially accelerated outward and, if sufficiently energetic, would also be ejected. We adapted and used a state-of-the-art code (CAVEAT), a hybrid Los Alamos-Sandia Lagrangian-Eulerian finite difference scheme for multimaterial flow problems with large distortion and internal slip. In our CAVEAT calculations, the vapor cloud produced by the impact produces a shock that is orders of magnitude stronger than any previous use of such codes. We developed new methods to test the accuracy and convergence of CAVEAT for K/T size impact events, and it proved to be a robust tool. We explored a K/T size impact where the 9-km-radius bolide was vaporized and injected into the atmosphere and found no radial outflow in agreement with the analytic model but, instead, a 50-km-radius vertical column formed with only a small fraction of material reaching escape velocity-no more than about 7% of the vaporized bolide plus atmospheric

  19. Atmospheric tides on Venus. III - The planetary boundary layer

    NASA Astrophysics Data System (ADS)

    Dobrovolskis, A. R.

    1983-10-01

    Diurnal solar heating of Venus' surface produces variable temperatures, winds, and pressure gradients within a shallow layer at the bottom of the atmosphere. The corresponding asymmetric mass distribution experiences a tidal torque tending to maintain Venus' slow retrograde rotation. It is shown that including viscosity in the boundary layer does not materially affect the balance of torques. On the other hand, friction between the air and ground can reduce the predicted wind speeds from about 5 to about 1 m/sec in the lower atmosphere, more consistent with the observations from Venus landers and descent probes. Implications for aeolian activity on Venus' surface and for future missions are discussed.

  20. Evidence for water in the rocky debris of a disrupted extrasolar minor planet.

    PubMed

    Farihi, J; Gänsicke, B T; Koester, D

    2013-10-11

    The existence of water in extrasolar planetary systems is of great interest because it constrains the potential for habitable planets and life. We have identified a circumstellar disk that resulted from the destruction of a water-rich and rocky extrasolar minor planet. The parent body formed and evolved around a star somewhat more massive than the Sun, and the debris now closely orbits the white dwarf remnant of the star. The stellar atmosphere is polluted with metals accreted from the disk, including oxygen in excess of that expected for oxide minerals, indicating that the parent body was originally composed of 26% water by mass. This finding demonstrates that water-bearing planetesimals exist around A- and F-type stars that end their lives as white dwarfs.

  1. On Stellar Activity Enhancement Due to Interactions with Extrasolar Giant Planets.

    PubMed

    Cuntz; Saar; Musielak

    2000-04-20

    We present a first attempt to identify and quantify possible interactions between recently discovered extrasolar giant planets (and brown dwarfs) and their host stars, resulting in activity enhancement in the stellar outer atmospheres. Many extrasolar planets have masses comparable to or larger than Jupiter and are within a distance of 0.5 AU, suggesting the possibility of their significant influence on stellar winds, coronae, and even chromospheres. Beyond the well-known rotational synchronization, the interactions include tidal effects (in which enhanced flows and turbulence in the tidal bulge lead to increased magnetoacoustic heating and dynamo action) and direct magnetic interaction between the stellar and planetary magnetic fields. We discuss relevant parameters for selected systems and give preliminary estimates of the relative interaction strengths.

  2. Evidence for water in the rocky debris of a disrupted extrasolar minor planet.

    PubMed

    Farihi, J; Gänsicke, B T; Koester, D

    2013-10-11

    The existence of water in extrasolar planetary systems is of great interest because it constrains the potential for habitable planets and life. We have identified a circumstellar disk that resulted from the destruction of a water-rich and rocky extrasolar minor planet. The parent body formed and evolved around a star somewhat more massive than the Sun, and the debris now closely orbits the white dwarf remnant of the star. The stellar atmosphere is polluted with metals accreted from the disk, including oxygen in excess of that expected for oxide minerals, indicating that the parent body was originally composed of 26% water by mass. This finding demonstrates that water-bearing planetesimals exist around A- and F-type stars that end their lives as white dwarfs. PMID:24115434

  3. Outer satellite atmospheres: Their nature and planetary interactions

    NASA Technical Reports Server (NTRS)

    Smyth, W. H.

    1981-01-01

    Modeling capabilities and initial model calculations are reported for the peculiar directional features of the Io sodium cloud discovered by Pilcher and the extended atomic oxygen atmosphere of Io discovered by Brown. Model results explaining the directional feature by a localized emission from the satellite are encouraging, but as yet, inconclusive; whereas for the oxygen cloud, an escape rate of 1 to 2 x 10 to the 27th power atoms/sec or higher from Io is suggested. Preliminary modeling efforts were also initiated for the extended hydrogen ring-atmosphere of Saturn detected by the Voyager spacecraft and for possible extended atmospheres of some of the smaller satellites located in the E-ring. Continuing research efforts reported for the Io sodium cloud include further refinement in the modeling of the east-west asymmetry data, the asymmetric line profile shape, and the intersection of the cloud with the Io plasma torus. In addition, the completed pre-Voyager modeling of Titan's hydrogen torus is included and the near completed model development for the extended atmosphere of comets is discussed.

  4. Aerobots and Hydrobots for Planetary Exploration

    NASA Technical Reports Server (NTRS)

    Barrett, Chris

    2000-01-01

    In this new Millennium, NASA will expand its presence in space. Many new planetary bodies have been discovered, and some previously known bodies are now believed to have oceans. We now know of 66 moons in our own Solar System, one with an atmosphere, 16 with water ice or oceans, and 5 with both. In addition, we now know of 20 extra-solar planets. In order to expand our presence in space and explore in a cost effective manner, we need a repertoire of new types of planetary exploration vehicles to explore both atmospheres and oceans. To address this need a spectrum of new classes of vehicles are being developed. These include aerobots and hydrobots, and incorporate Department of Defense miniaturization developments and smart materials. This paper outlines: the remarkable miniaturization developments applicable to robotic vehicles for the exploration of planetary atmospheres and oceans; Aerobots, the vehicles designed for planetary atmospheric exploration; Hydrobots, those designed for planetary ocean exploration; planetary atmospheric data; and Europa ocean exploration missions.

  5. Some remarks on coherent structures out of chaos in planetary atmospheres and oceans.

    PubMed

    Nezlin, Mikhail V.

    1994-06-01

    In the context of planetary atmospheres and oceans, it is natural to define "coherent structures" as "long-lived," or "solitary," Rossby vortices. These can be described by the generalized Charney-Obukhov equation (in fluid dynamics) or the analogous generalized Hasegawa-Mima equation (in plasma physics). These two equations contain KdV-type nonlinearities which (together with the compensating dispersive spreading) determine the formation of the coherent structures and explain the clear-cut cyclonic/anticyclonic asymmetry observed experimentally in long-lived planetary Rossby vortices. Examples are given of natural vortices which are (and which are not) coherent structures. PMID:12780093

  6. Parameterized rotating convection for core and planetary atmosphere dynamics

    NASA Astrophysics Data System (ADS)

    Zhang, K.

    1991-04-01

    New types of convective instability and associated nonlinear phenomena in rapidly rotating spherical systems have been discovered through numerical simulations. The Prandtl number, defined as the ratio of the viscous and thermal diffusivities of a fluid, Pr = nu/kappa, plays a crucial role in determining the fundamental features of both the instabilities and the corresponding nonlinear convection. The results shed new light on regimes of convection in the earth's core and the atmospheres of the major planets.

  7. Photochemical Formation of Aerosol in Planetary Atmospheres: Photon and Water Mediated Chemistry of SO_2

    NASA Astrophysics Data System (ADS)

    Kroll, Jay A.; Donaldson, D. J.; Vaida, Veronica

    2016-06-01

    Sulfur compounds have been observed in a number of planetary atmospheres throughout our solar system. Our current understanding of sulfur chemistry explains much of what we observe in Earth's atmosphere. However, several discrepancies between modeling and observations of the Venusian atmosphere show there are still problems in our fundamental understanding of sulfur chemistry. This is of particular concern due to the important role sulfur compounds play in the formation of aerosols, which have a direct impact on planetary climates, including Earth's. We investigate the role of water complexes in the hydration of sulfur oxides and dehydration of sulfur acids and will present spectroscopic studies to document such effects. I will present recent work investigating mixtures of SO_2 and water that generate large quantities of aerosol when irradiated with solar UV light, even in the absence of traditional OH chemistry. I will discuss a proposed mechanism for the formation of sulfurous acid (H_2SO_3) and present recent experimental work that supports this proposed mechanism. Additionally, the implications that photon-induced hydration of SO_2 has for aerosol formation in the atmosphere of earth as well as other planetary atmospheres will be discussed.

  8. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1985-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and Earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The use of theoretically-derived microwave absorption properties for such atmospheric constituents, or laboratory measurements of such properties under environmental conditions which are significantly different than those of the planetary atmosphere being studied, often lead to significant misinterpretation of available opacity data. Steffes and Eshleman showed that under environmental conditions corresponding to the middle atmosphere of Venus, the microwave absorption due to atmospheric SO2 was 50 percent greater than that calculated from Van Vleck-Weiskopff theory. Similarly, the opacity from gaseous H2SO4 was found to be a factor of 7 greater than theoretically predicted for conditions of the Venus middle atmosphere. The recognition of the need to make such measurements over a range of temperatures and pressures which correspond to the periapsis altitudes of radio occultation experiments, and over a range of frequencies which correspond to both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements.

  9. The Role of Remote Sensing Displays in Earth Climate and Planetary Atmospheric Research

    NASA Technical Reports Server (NTRS)

    DelGenio, Anthony D.; Hansen, James E. (Technical Monitor)

    2001-01-01

    The communities of scientists who study the Earth's climate and the atmospheres of the other planets barely overlap, but the types of questions they pose and the resulting implications for the use and interpretation of remote sensing data sets have much in common. Both seek to determine the characteristic behavior of three-dimensional fluids that also evolve in time. Climate researchers want to know how and why the general patterns that define our climate today might be different in the next century. Planetary scientists try to understand why circulation patterns and clouds on Mars, Venus, or Jupiter are different from those on Earth. Both disciplines must aggregate large amounts of data covering long time periods and several altitudes to have a representative picture of the rapidly changing atmosphere they are studying. This emphasis separates climate scientists from weather forecasters, who focus at any one time on a limited number of images. Likewise, it separates planetary atmosphere researchers from planetary geologists, who rely primarily on single images (or mosaics of images covering the globe) to study two-dimensional planetary surfaces that are mostly static over the duration of a spacecraft mission yet reveal dynamic processes acting over thousands to millions of years. Remote sensing displays are usually two-dimensional projections that capture an atmosphere at an instant in time. How scientists manipulate and display such data, how they interpret what they see, and how they thereby understand the physical processes that cause what they see, are the challenges I discuss in this chapter. I begin by discussing differences in how novices and experts in the field relate displays of data to the real world. This leads to a discussion of the use and abuse of image enhancement and color in remote sensing displays. I then show some examples of techniques used by scientists in climate and planetary research to both convey information and design research

  10. Research in planetary studies and operation of the Mauna Kea Observatory. Semiannual progress report, January-December 1986

    SciTech Connect

    Cruikshank, D.P.

    1986-12-01

    The research programs are highlighted in the following areas: major planets; planetary satellites and rings; asteroids; comets; dark organic matter; theoretical and analytical structures; extrasolar planetary; and telescopes.

  11. Outer satellite atmospheres: Their extended nature and planetary interactions

    NASA Technical Reports Server (NTRS)

    Smyth, W. H.; Combi, M. R.

    1984-01-01

    Model calculations for the brightness of the sodium cloud in Region A were performed to clarify the role played by the plasma torus sink in producing the east-west intensity asymmetry observed in the sodium D-lines. It was determined that the east-west electric field, proposed by Barbosa and Kievelson (1983) and Ip and Goertz (1983) to explain the dawn-dusk asymmetry in the torus ion emissions measured by the Voyager UVS instrument, could also produce the east-west sodium intensity asymmetry discovered earlier by Bergstralh et al. (1975, 1977). Model results for the directional features of the sodium cloud are also reported. The completion of the development of the Io potassium cloud model, progress in improving the Titan hydrogen torus model, and efforts in developing our model for hydrogen cometary atmospheres are also discussed.

  12. Other satellite atmospheres: Their nature and planetary interactions

    NASA Technical Reports Server (NTRS)

    Smyth, W. H.

    1982-01-01

    The Io sodium cloud model was successfully generated to include the time and spatial dependent lifetime sink produced by electron impact ionization as the plasma torus oscillates about the satellite plane, while simultaneously including the additional time dependence introduced by the action of solar radiation pressure on the cloud. Very preliminary model results are discussed and continuing progress in analysis of the peculiar directional features of the sodium cloud is also reported. Significant progress was made in developing a model for the Io potassium cloud and differences anticipated between the potassium and sodium cloud are described. An effort to understand the hydrogen atmosphere associated with Saturn's rings was initiated and preliminary results of a very and study are summarized.

  13. Formation, Habitability, and Detection of Extrasolar Moons

    PubMed Central

    Williams, Darren; Kipping, David; Limbach, Mary Anne; Turner, Edwin; Greenberg, Richard; Sasaki, Takanori; Bolmont, Émeline; Grasset, Olivier; Lewis, Karen; Barnes, Rory; Zuluaga, Jorge I.

    2014-01-01

    Abstract The diversity and quantity of moons in the Solar System suggest a manifold population of natural satellites exist around extrasolar planets. Of peculiar interest from an astrobiological perspective, the number of sizable moons in the stellar habitable zones may outnumber planets in these circumstellar regions. With technological and theoretical methods now allowing for the detection of sub-Earth-sized extrasolar planets, the first detection of an extrasolar moon appears feasible. In this review, we summarize formation channels of massive exomoons that are potentially detectable with current or near-future instruments. We discuss the orbital effects that govern exomoon evolution, we present a framework to characterize an exomoon's stellar plus planetary illumination as well as its tidal heating, and we address the techniques that have been proposed to search for exomoons. Most notably, we show that natural satellites in the range of 0.1–0.5 Earth mass (i) are potentially habitable, (ii) can form within the circumplanetary debris and gas disk or via capture from a binary, and (iii) are detectable with current technology. Key Words: Astrobiology—Extrasolar planets—Habitability—Planetary science—Tides. Astrobiology 14, 798–835. PMID:25147963

  14. Remote sensing of the turbulence characteristics of a planetary atmosphere by radio occultation of a space probe.

    NASA Technical Reports Server (NTRS)

    Woo, R.; Ishimaru, A.

    1973-01-01

    The purpose of this paper is to analyze the effects of small-scale turbulence on radio waves propagating through a planetary atmosphere. The analysis provides a technique for inferring the turbulence characteristics of a planetary atmosphere from the radio signals received from a spacecraft as it is occulted by the planet. The planetary turbulence is assumed to be localized and smoothly varying, with the structure constant varying exponentially with altitude. Rytov's method is used to derive the variance of log-amplitude and phase fluctuations of a wave propagating through the atmosphere.

  15. Planetary atmospheres minor species sensor balloon flight test to near space

    NASA Astrophysics Data System (ADS)

    Peale, Robert E.; Fredricksen, Christopher J.; Muraviev, Andrei V.; Maukonen, Douglas; Quddusi, Hajrah M.; Calhoun, Seth; Colwell, Joshua E.; Lachenmeier, Timothy A.; Dewey, Russell G.; Stern, Alan; Padilla, Sebastian; Bode, Rolfe

    2015-05-01

    The Planetary Atmospheres Minor Species Sensor (PAMSS) is an intracavity laser absorption spectrometer that uses a mid-infrared quantum cascade laser in an open external cavity for sensing ultra-trace gases with parts-per-billion sensitivity. PAMSS was flown on a balloon by Near Space Corporation from Madras OR to 30 km on 17 July 2014. Based on lessons learned, it was modified and was flown a second time to 32 km by World View Enterprises from Pinal AirPark AZ on 8 March 2015. Successes included continuous operation and survival of software, electronics, optics, and optical alignment during extreme conditions and a rough landing. Operation of PAMSS in the relevant environment of near space has significantly elevated its Technical Readiness Level for trace-gas sensing with potential for planetary and atmospheric science in harsh environments.

  16. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1986-01-01

    The recognition of the need to make laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressure which correspond to the altitudes probed by radio occultation experiments, and over a range of frequencies which correspond to both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. Construction was completed of the outer planets simulator and measurements were conducted of the microwave absorption and refraction from nitrogen under simulated Titan conditions. The results of these and previous laboratory measurements were applied to a wide range of microwave opacity measurements, in order to derive constituent densities and distributions in planetary atmospheres such as Venus.

  17. Middle Atmosphere Dynamics with Gravity Wave Interactions in the Numerical Spectral Model: Tides and Planetary Waves

    NASA Technical Reports Server (NTRS)

    Mayr, Hans G.; Mengel, J. G.; Chan, K. L.; Huang, F. T.

    2010-01-01

    As Lindzen (1981) had shown, small-scale gravity waves (GW) produce the observed reversals of the zonal-mean circulation and temperature variations in the upper mesosphere. The waves also play a major role in modulating and amplifying the diurnal tides (DT) (e.g., Waltersheid, 1981; Fritts and Vincent, 1987; Fritts, 1995a). We summarize here the modeling studies with the mechanistic numerical spectral model (NSM) with Doppler spread parameterization for GW (Hines, 1997a, b), which describes in the middle atmosphere: (a) migrating and non-migrating DT, (b) planetary waves (PW), and (c) global-scale inertio gravity waves. Numerical experiments are discussed that illuminate the influence of GW filtering and nonlinear interactions between DT, PW, and zonal mean variations. Keywords: Theoretical modeling, Middle atmosphere dynamics, Gravity wave interactions, Migrating and non-migrating tides, Planetary waves, Global-scale inertio gravity waves.

  18. Analytical design of sensors for measuring during terminal phase of atmospheric temperature planetary entry

    NASA Technical Reports Server (NTRS)

    Millard, J. P.; Green, M. J.; Sommer, S. C.

    1972-01-01

    An analytical study was conducted to develop a sensor for measuring the temperature of a planetary atmosphere from an entry vehicle traveling at supersonic speeds and having a detached shock. Such a sensor has been used in the Planetary Atmosphere Experiments Test Probe (PAET) mission and is planned for the Viking-Mars mission. The study specifically considered butt-welded thermocouple sensors stretched between two support posts; however, the factors considered are sufficiently general to apply to other sensors as well. This study included: (1) an investigation of the relation between sensor-measured temperature and free-stream conditions; (2) an evaluation of the effects of extraneous sources of heat; (3) the development of a computer program for evaluating sensor response during entry; and (4) a parametric study of sensor design characteristics.

  19. Rugged, no-moving-parts windspeed and static pressure probe designs for measurements in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Bedard, A. J., Jr.; Nishiyama, R. T.

    1993-01-01

    Instruments developed for making meteorological observations under adverse conditions on Earth can be applied to systems designed for other planetary atmospheres. Specifically, a wind sensor developed for making measurements within tornados is capable of detecting induced pressure differences proportional to wind speed. Adding strain gauges to the sensor would provide wind direction. The device can be constructed in a rugged form for measuring high wind speeds in the presence of blowing dust that would clog bearings and plug passages of conventional wind speed sensors. Sensing static pressure in the lower boundary layer required development of an omnidirectional, tilt-insensitive static pressure probe. The probe provides pressure inputs to a sensor with minimum error and is inherently weather-protected. The wind sensor and static pressure probes have been used in a variety of field programs and can be adapted for use in different planetary atmospheres.

  20. Optical and Hygroscopic Studies of Aerosols In Simulated Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Hasenkopf, Christa A.

    2011-08-01

    Basic characteristics of the early Earth climate, the only known environment in the Universe in which life has been known to emerge and thrive, remain a mystery. In particular, little is understood about the Earth's atmosphere 2.8 billion years ago. From climate models and laboratory studies, it is postulated that an organic haze, much like that found on Saturn's largest moon Titan, covered the early Earth. This haze, generated from photolysis of carbon dioxide (CO2) and methane (CH4), may have had profound climatic consequences. Climate models of the early Earth that include this haze have had to rely upon optical properties of a Titan laboratory analog. Titan haze, though thought to be similar, is formed from a different combination of precursor gases and by different energy sources than early Earth haze. This thesis examines the direct and indirect radiative effects of aerosol on early Earth climate by studying the optical and hygroscopic properties of a laboratory analog. A Titan analog is studied for comparison and to better understand spacecraft-retrieved haze chemical and optical properties from Titan. The properties of the laboratory analogs, generated in a flowing reactor cell with a continuum ultraviolet (UV) light source, were primarily measured using cavity ringdown aerosol extinction spectroscopy and UV-visible (UV-Vis) transmission spectroscopy. We find that the optical properties of our early Earth analog are significantly different than those of the Titan analog from Khare et al. (1984). In both the UV and visible, when modeled as fractals, particles with the optical properties of the early Earth analog have approximately 30% larger extinction efficiencies than particles with Khare et al. (1984) values. This result implies our early Earth haze analog would provide a more efficient UV shield and have a stronger antigreenhouse effect than the Khare et al. (1984) Titan analog. Our Titan analog has significantly smaller imaginary refractive index values

  1. Decadal regime shift linkage between global marine fish landings and atmospheric planetary wave forcing

    NASA Astrophysics Data System (ADS)

    Powell, A. M., Jr.; Xu, J.

    2015-04-01

    This investigation focuses on a global forcing mechanism for decadal regime shifts and their subsequent impacts. The proposed global forcing mechanism is that the global atmospheric planetary waves can lead to changes in the global surface air-sea conditions and subsequently fishery changes. In this study, the five decadal regime shifts (1956-1957, 1964-1965, 1977-1978, 1988-1989, and 1998-1999) in the most recent 59-year period (1950-2008) have been identified based on Student t tests and their association with global marine ecosystem change has been discussed. Changes in the three major oceanic (Pacific, Atlantic, and Indian) ecosystems will be explored with the goal of demonstrating the linkage between stratospheric planetary waves and the ocean surface forcing that leads to fisheries impacts. The global forcing mechanism is described with a top-down approach to help the multidisciplinary audience follow the analysis. Following previous work, this analysis addresses how changes in the atmospheric planetary waves may influence the vertical wind structure, surface wind stress, and their connection with the global ocean ecosystems based on a coupling of the atmospheric regime shifts with the decadal regime shifts determined from marine life changes. The multiple decadal regime shifts related to changes in marine life are discussed using the United Nations Food and Agriculture Organization's (FAO) global fish capture data (catch/stock). Analyses are performed to demonstrate that examining the interactions between the atmosphere, ocean, and fisheries is a plausible approach to explaining decadal climate change in the global marine ecosystems and its impacts. The results show a consistent mechanism, ocean wind stress, responsible for marine shifts in the three major ocean basins. Changes in the planetary wave pattern affect the ocean wind stress patterns. A change in the ocean surface wind pattern from longwave (relatively smooth and less complex) to shorter

  2. Decadal regime shift linkage between global marine fish landings and atmospheric planetary wave forcing

    NASA Astrophysics Data System (ADS)

    Powell, A. M., Jr.; Xu, J.

    2014-08-01

    This investigation focuses on a global forcing mechanism for decadal regime shifts and their subsequent impacts. The proposed global forcing mechanism is the global atmospheric planetary waves that can lead to changes in the global surface air-sea conditions and subsequently fishery changes. In this study, the five decadal regime shifts (1956-1957, 1964-1965, 1977-1978, 1988-1989, and 1998-1999) in the recent 59 years (1950-2008) have been identified based on student t tests and their association with global marine ecosystem change has been discussed. Changes in the three major oceanic (Pacific, Atlantic and Indian) ecosystems will be explored with the goal of demonstrating the linkage between stratospheric planetary waves and the ocean surface forcing that leads to fisheries impacts. Due to the multidisciplinary audience, the global forcing mechanism is described from a top-down approach to help the multidisciplinary audience follow the analysis. Following previous work, this analysis addresses how changes in the atmospheric planetary waves may influence the vertical wind structure, surface wind stress, and their connection with the global ocean ecosystems based on a coupling of the atmospheric regime shifts with the decadal regime shifts determined from marine life changes. The multiple decadal regime shifts related to changes in marine life are discussed using the United Nations Food and Agriculture Organization's (FAO) global fish capture data (catch/stock). Analyses are performed to demonstrate the interactions between the atmosphere, ocean, and fisheries are a plausible approach to explaining decadal climate change in the global marine ecosystems and its impacts. The results show a consistent mechanism, ocean wind stress, responsible for marine shifts in the three major ocean basins. Changes in the planetary wave pattern affect the ocean wind stress patterns. A change in the ocean surface wind pattern from long wave (relatively smooth and less complex) to

  3. Observations of Exoplanet Atmospheres

    NASA Astrophysics Data System (ADS)

    Crossfield, Ian J. M.

    2015-10-01

    Detailed characterization of an extrasolar planet's atmosphere provides the best hope for distinguishing the makeup of its outer layers, and the only hope for understanding the interplay between initial composition, chemistry, dynamics and circulation, and disequilibrium processes. In recent years, some areas have seen rapid progress, while developments in others have come more slowly and/or have been hotly contested. This article gives an observer's perspective on the current understanding of extrasolar planet atmospheres prior to the considerable advances expected from the next generation of observing facilities. Atmospheric processes of both transiting and directly imaged planets are discussed, including molecular and atomic abundances, cloud properties, thermal structure, and planetary energy budgets. In the future we can expect a continuing and accelerating stream of new discoveries, which will fuel the ongoing exoplanet revolution for many years to come.

  4. Evaporation and accretion of extrasolar comets following white dwarf kicks

    NASA Astrophysics Data System (ADS)

    Stone, Nicholas; Metzger, Brian D.; Loeb, Abraham

    2015-03-01

    Several lines of observational evidence suggest that white dwarfs receive small birth kicks due to anisotropic mass-loss. If other stars possess extrasolar analogues to the Solar Oort cloud, the orbits of comets in such clouds will be scrambled by white dwarf natal kicks. Although most comets will be unbound, some will be placed on low angular momentum orbits vulnerable to sublimation or tidal disruption. The dusty debris from these comets will manifest itself as an IR excess temporarily visible around newborn white dwarfs; examples of such discs may already have been seen in the Helix Nebula, and around several other young white dwarfs. Future observations with the James Webb Space Telescope may distinguish this hypothesis from alternatives such as a dynamically excited Kuiper Belt analogue. Although competing hypotheses exist, the observation that ≳15 per cent of young white dwarfs possess such discs, if interpreted as indeed being cometary in origin, provides indirect evidence that low-mass gas giants (thought necessary to produce an Oort cloud) are common in the outer regions of extrasolar planetary systems. Hydrogen abundances in the atmospheres of older white dwarfs can, if sufficiently low, also be used to place constraints on the joint parameter space of natal kicks and exo-Oort cloud models.

  5. Spectra of van der Waals complexes (dimers) with applications to planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Fox, Kenneth; Kim, Sang J.

    1988-01-01

    Spectral features observed in the atmosphere of Titan by the Voyager IR experiment have been attributed to weakly bound complexes of N2 and H2, dominant and minor constituents, respectively. The abundance of H2-N2 dimers there was computed. Current calculations include quantitative spectral line positions and intensities for N2-Ar and CO2-CO2 relating to Titan and Earth, and to Mars and Venus, respectively. This work suggests applications to spectra of planetary atmospheres obtained in spacecraft missions.

  6. Extrasolar planets and Their Parent Stars

    NASA Astrophysics Data System (ADS)

    Israelian, Garik

    2010-11-01

    Extrasolar planetas (exoplanets), or planets orbiting stars other than our own Sun, are a relatively new field of the astronomical and planetary sciences. After the discovery of Pluto in 1930, planet-finding activities appeared to have reached an end for the foreseeable future. Several brown dwarfs have been discovered between 1930 and 1993 orbiting other solar-type star. Brown dwarfs (or "failed stars") are low-mass celestial objects (M?10MJUP) that formed by stellar processes but did not obtain the critical mass required to sustain hydrogen burning within their core. Other claims for planetary detections were also made during the period 1944 - 1970 but were never verified or were later shown to be false, produced by timing artifacts or instrumentation errors. The first confirmed detection of an extrasolar planet occurred in 1992 when two bodies were found to be orbiting the millisecond pulsar PSR 1257+12 (Wolszczan and Frail, 1992). The first detection of an extrasolar planet orbiting a solar-type star occurred in 1994 with the claim of a Jupiter-type planet orbiting 51 Pegasi (Mayor and Queloz, 1995). As of January 2010, we currently know of 429 planets orbiting solar-type stars The vast majority of these detections have occurred via the radial velocity method (Udry & Santos 2007), although other methods such as that of transiting photometry and microlensing may become increasingly important in future planet searches as we seek to detect terrestrial-sized planetary bodies and utilize space- based observing programs.

  7. Superrotation planetary atmospheres: Mechanical analogy, angular momentum budget and simulation of the spin up process

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Harris, I.; Conrath, B. J.

    1981-01-01

    Superrotation rates observed in planetary atmospheres are analyzed based on the concept of a thermally driven zonally symmetric circulation. Specifically, how this superrotation is produced and maintained against the tendency for friction to oppose differential motions between the atmosphere and the underlying planet is addressed. The time evolution of a fluid leading from corotation under uniform heating to superrotation under globally nonuniform heating is simulated using a three dimensional zonally symmetric spectral model and Laplace transformation. The increased tendency toward geostrophy combined with the increase of surface pressure toward the poles (due to meridional mass transport), induces the atmosphere to subrotate temporarily at lower altitudes. The resulting viscous shear near the surface thus permits angular momentum to flow from the planet into the atmosphere where it propagates upwards and, combined with the change in moment of inertia, produces large superrotation rates at higher viscosities.

  8. A Mechanism for Land-Atmosphere Feedback Involving Planetary Wave Structures

    NASA Technical Reports Server (NTRS)

    Koster, Randal D.; Chang, Yehui; Schubert, Siegfried D.

    2014-01-01

    While the ability of land surface conditions to influence the atmosphere has been demonstrated in various modeling and observational studies, the precise mechanisms by which land-atmosphere feedback occurs are still largely unknown particularly the mechanisms that allow land moisture state in one region to affect atmospheric conditions in another. Such remote impacts are examined here in the context of atmospheric general circulation model (AGCM) simulations, leading to the identification of one potential mechanism: the phase-locking and amplification of a planetary wave through the imposition of a spatial pattern of soil moisture at the land surface. This mechanism, shown here to be relevant in the AGCM, apparently also operates in nature, as suggested by supporting evidence found in reanalysis data.

  9. The spectroscopic search for the trace aerosols in the planetary atmospheres - the results of numerical simulations

    NASA Astrophysics Data System (ADS)

    Blecka, Maria I.

    2010-05-01

    The passive remote spectrometric methods are important in examinations the atmospheres of planets. The radiance spectra inform us about values of thermodynamical parameters and composition of the atmospheres and surfaces. The spectral technology can be useful in detection of the trace aerosols like biological substances (if present) in the environments of the planets. We discuss here some of the aspects related to the spectroscopic search for the aerosols and dust in planetary atmospheres. Possibility of detection and identifications of biological aerosols with a passive InfraRed spectrometer in an open-air environment is discussed. We present numerically simulated, based on radiative transfer theory, spectroscopic observations of the Earth atmosphere. Laboratory measurements of transmittance of various kinds of aerosols, pollens and bacterias were used in modeling.

  10. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1988-01-01

    Radio absorptivity data for planetary atmospheres obtained from spacecraft radio occultation experiments and earth-based radio astronomical observations can be used to infer abundances of microwave absorbing atmospheric constituents in those atmospheres, as long as reliable information regarding the microwave absorbing properties of potential constituents is available. The key activity for this grant year has continued to be laboratory measurements of the microwave and millimeter-wave properties of the simulated atmospheres of the outer planets and their satellites. A Fabry-Perot spectrometer system capable of operation from 32 to 41 GHz was developed. Initially this spectrometer was used to complete laboratory measurements of the 7.5 to 9.3 mm absorption spectrum of ammonia. Laboratory measurements were begun at wavelengths near 3.2 mm, where a large number of observations of the emission from the outer planets were made. A description of this system is presented.

  11. DETECTING PLANETARY GEOCHEMICAL CYCLES ON EXOPLANETS: ATMOSPHERIC SIGNATURES AND THE CASE OF SO{sub 2}

    SciTech Connect

    Kaltenegger, L.; Sasselov, D.

    2010-01-10

    We study the spectrum of a planetary atmosphere to derive detectable features in low resolution of different global geochemical cycles on exoplanets-using the sulfur cycle as our example. We derive low-resolution detectable features for first generation space- and ground-based telescopes as a first step in comparative planetology. We assume that the surfaces and atmospheres of terrestrial exoplanets (Earth-like and super-Earths) will most often be dominated by a specific geochemical cycle. Here we concentrate on the sulfur cycle driven by outgassing of SO{sub 2} and H{sub 2}S followed by their transformation to other sulfur-bearing species, which is clearly distinguishable from the carbon cycle, which is driven by outgassing of CO{sub 2}. Due to increased volcanism, the sulfur cycle is potentially the dominant global geochemical cycle on dry super-Earths with active tectonics. We calculate planetary emission, reflection, and transmission spectrum from 0.4 mum to 40 mum with high and low resolution to assess detectable features using current and Archean Earth models with varying SO{sub 2} and H{sub 2}S concentrations to explore reducing and oxidizing habitable environments on rocky planets. We find specific spectral signatures that are observable with low resolution in a planetary atmosphere with high SO{sub 2} and H{sub 2}S concentration. Therefore, first generation space- and ground-based telescopes can test our understanding of geochemical cycles on rocky planets and potentially distinguish planetary environments dominated by the carbon and sulfur cycles.

  12. The role of nonlinear self-interaction in the dynamics of planetary-scale atmospheric fluctuations

    NASA Astrophysics Data System (ADS)

    Saffioti, C.; Malguzzi, P.; Speranza, A.

    2016-09-01

    A central role in the general circulation of the atmosphere is played by planetary-scale inertial fluctuations with zonal wavenumber in the range k = 1-4. Geopotential variance in this range is markedly non-gaussian and a great fraction of it is non-propagating, in contrast with the normal distribution of amplitudes and the basically propagating character of fluctuations in the baroclinic range (3 > k > 15). While a wave dispersion relationship can be identified in the baroclinic range, no clear relationship between time and space scales emerges in the ultra-long regime (k < 5, period >10 days). We investigate the hypothesis that nonlinear self-interaction of planetary waves influences the mobility (and, therefore, the dispersion) of ultra-long planetary fluctuations. By means of a perturbation expansion of the barotropic vorticity equation we derive a minimal analytic description of the impact of self-nonlinearity on mobility and we show that this is responsible for a correction term to phase speed, with the prevalent effect of slowing down the propagation of waves. The intensity of nonlinear self-interaction is shown to increase with the complexity of the flow, depending on both its zonal and meridional modulations. Reanalysis data of geopotential height and zonal wind are analysed in order to test the effect of self-nonlinearity on observed planetary flows.

  13. The role of nonlinear self-interaction in the dynamics of planetary-scale atmospheric fluctuations

    NASA Astrophysics Data System (ADS)

    Saffioti, C.; Malguzzi, P.; Speranza, A.

    2016-09-01

    A central role in the general circulation of the atmosphere is played by planetary-scale inertial fluctuations with zonal wavenumber in the range k = 1–4. Geopotential variance in this range is markedly non-gaussian and a great fraction of it is non-propagating, in contrast with the normal distribution of amplitudes and the basically propagating character of fluctuations in the baroclinic range (3 > k > 15). While a wave dispersion relationship can be identified in the baroclinic range, no clear relationship between time and space scales emerges in the ultra-long regime (k < 5, period >10 days). We investigate the hypothesis that nonlinear self-interaction of planetary waves influences the mobility (and, therefore, the dispersion) of ultra-long planetary fluctuations. By means of a perturbation expansion of the barotropic vorticity equation we derive a minimal analytic description of the impact of self-nonlinearity on mobility and we show that this is responsible for a correction term to phase speed, with the prevalent effect of slowing down the propagation of waves. The intensity of nonlinear self-interaction is shown to increase with the complexity of the flow, depending on both its zonal and meridional modulations. Reanalysis data of geopotential height and zonal wind are analysed in order to test the effect of self-nonlinearity on observed planetary flows.

  14. Detection of Extrasolar Planets by Transit Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William; Koch, David; Webster, Larry; Dunham, Edward; Witteborn, Fred; Jenkins, Jon; Caldwell, Douglas; Showen, Robert; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    A knowledge of other planetary systems that includes information on the number, size, mass, and spacing of the planets around a variety of star types is needed to deepen our understanding of planetary system formation and processes that give rise to their final configurations. Recent discoveries show that many planetary systems are quite different from the solar system in that they often possess giant planets in short period orbits. The inferred evolution of these planets and their orbital characteristics imply the absence of Earth-like planets near the habitable zone. Information on the properties of the giant-inner planets is now being obtained by both the Doppler velocity and the transit photometry techniques. The combination of the two techniques provides the mass, size, and density of the planets. For the planet orbiting star HD209458, transit photometry provided the first independent confirmation and measurement of the diameter of an extrasolar planet. The observations indicate a planet 1.27 the diameter of Jupiter with 0.63 of its mass (Charbonneau et al. 1999). The results are in excellent agreement with the theory of planetary atmospheres for a planet of the indicated mass and distance from a solar-like star. The observation of the November 23, 1999 transit of that planet made by the Ames Vulcan photometer at Lick Observatory is presented. In the future, the combination of the two techniques will greatly increase the number of discoveries and the richness of the science yield. Small rocky planets at orbital distances from 0.9 to 1.2 AU are more likely to harbor life than the gas giant planets that are now being discovered. However, new technology is needed to find smaller, Earth-like planets, which are about three hundred times less massive than Jupiter-like planets. The Kepler project is a space craft mission designed to discover hundreds of Earth-size planets in and near the habitable zone around a wide variety of stars. To demonstrate that the

  15. Transit of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Doyle, Laurance R.

    1998-01-01

    During the past five years we have pursued the detection of extrasolar planets by the photometric transit method, i.e. the detection of a planet by watching for a drop in the brightness of the light as it crosses in front of a star. The planetary orbit must cross the line-of-sight and so most systems will not be lined up for such a transit to ever occur. However, we have looked at eclipsing binary systems which are already edge-on. Such systems must be very small in size as this makes the differential light change due to a transit much greater for a given planet size (the brightness difference will be proportional to the area of the transiting planet to the disc area of the star). Also, the planet forming region should be closer to the star as small stars are generally less luminous (that is, if the same thermal regime for planet formation applies as in the solar system). This led to studies of the habitable zone around other stars, as well. Finally, we discovered that our data could be used to detect giant planets without transits as we had been carefully timing the eclipses of the stars (using a GPS antenna for time) and this will drift by being offset by any giant planets orbiting around the system, as well. The best summary of our work may be to just summarize the 21 refereed papers produced during the time of this grant. This will be done is chronological order and in each section separately.

  16. Habitable Planetary Systems (un)like our own: Which of the Known Extra-Solar Systems Could Harbor Earth-like Planets?

    NASA Astrophysics Data System (ADS)

    Raymond, Sean; Mandell, A.; Sigurdsson, S.

    2006-12-01

    Gas giant planets are far easier than terrestrial planets to detect around other stars, and are thought to form much more quickly than terrestrial planets. Thus, in systems with giant planets, the final stages of terrestrial planet formation are strongly affected by the giant planets' dynamical presence. Observations of giant planet orbits may therefore constrain the systems that can harbor potentially habitable, Earth-like planets. We combine two recent studies (1,2) and establish rough inner and outer limits for the giant planet orbits that allow terrestrial planets of at least 0.3 Earth masses to form in the habitable zone (HZ). For a star like the Sun, potentially habitable planets can form in systems with relatively low-eccentricity giant planets inside 0.5 Astronomical Units (AU) or outside 2.5 AU. More than one third of the currently known giant planet systems could have formed and now harbor a habitable planet. We thank NASA Astrobiology Institute for funding, through the Penn State, NASA Goddard, Virtual Planetary Laboratory, and University of Colorado lead teams. (1. Raymond, S.N., 2006, ApJ, 643, L131.; 2. Raymond, S.N., Mandell, A.M., Sigurdsson, S. 2006, Science, 313, 1413).

  17. NASA's Planetary Data System: Support for the Delivery of Derived Data Sets at the Atmospheres Node

    NASA Astrophysics Data System (ADS)

    Chanover, Nancy J.; Beebe, Reta; Neakrase, Lynn; Huber, Lyle; Rees, Shannon; Hornung, Danae

    2015-11-01

    NASA’s Planetary Data System is charged with archiving electronic data products from NASA planetary missions that are sponsored by NASA’s Science Mission Directorate. This archive, currently organized by science disciplines, uses standards for describing and storing data that are designed to enable future scientists who are unfamiliar with the original experiments to analyze the data, and to do this using a variety of computer platforms, with no additional support. These standards address the data structure, description contents, and media design. The new requirement in the NASA ROSES-2015 Research Announcement to include a Data Management Plan will result in an increase in the number of derived data sets that are being delivered to the PDS. These data sets may come from the Planetary Data Archiving, Restoration and Tools (PDART) program, other Data Analysis Programs (DAPs) or be volunteered by individuals who are publishing the results of their analysis. In response to this increase, the PDS Atmospheres Node is developing a set of guidelines and user tools to make the process of archiving these derived data products more efficient. Here we provide a description of Atmospheres Node resources, including a letter of support for the proposal stage, a communication schedule for the planned archive effort, product label samples and templates in extensible markup language (XML), documentation templates, and validation tools necessary for producing a PDS4-compliant derived data bundle(s) efficiently and accurately.

  18. An IRAS search for extra-solar Oort clouds

    NASA Technical Reports Server (NTRS)

    Stern, S. Alan; Stocke, John; Weissman, Paul R.

    1991-01-01

    The presumptively close connection between Oort cloud formation and planetary formation is that the detection of comet clouds around other stars would imply the presence of extrasolar planetary systems. Low-resolution IRAS data and an S/N-enhancement method are presently used to search 17 nearby stars for comet cloud-indicating IR emission. While no such detections were obtained, upper limits have been set for extrasolar Oort clouds (ESOCs) around the candidate stars; the nondetections may be a results either of the absence of the ESOCs around these stars or, with greater probability, of the sensitivity and background confusion limitations of IRAS data.

  19. Kinetics of Suprathermal Atoms and Molecules in the Rarefied Planetary Atmospheres

    SciTech Connect

    Shematovich, Valery I.

    2008-12-31

    Ground-based and space observations have revealed that the upper layers of planetary atmospheres contain both a thermal fraction of neutral atoms and molecules with the mean particle kinetic energy corresponding to the local gas temperature and a suprathermal (hot) fraction of neutral particles with the mean kinetic energy much higher than the local atmospheric temperature. Atmospheric photochemistry and solar wind/magnetospheric plasma inflow play an important role in the formation of suprathermal atoms and molecules in the rarefied atmospheric gas. The current physical and mathematical models of suprathermal atom formation are presented. These models are used to investigate the formation and kinetics of suprathermal carbon, nitrogen, and oxygen atoms in the upper atmospheres of Venus, Earth, and Mars where they are formed in significant amounts due to the atmospheric photochemistry. The role and input of such photochemical reactions as photo- and electron impact dissociation of the main atmospheric constituents as well as in the exothermic ion-molecular reactions including the dissociative recombination of the ionospheric ions into the formation of hot O populations in the upper atmospheres of the terrestrial planets are estimated.

  20. The HARPS search for southern extra-solar planets. XXX. Planetary systems around stars with solar-like magnetic cycles and short-term activity variation

    NASA Astrophysics Data System (ADS)

    Dumusque, X.; Lovis, C.; Ségransan, D.; Mayor, M.; Udry, S.; Benz, W.; Bouchy, F.; Lo Curto, G.; Mordasini, C.; Pepe, F.; Queloz, D.; Santos, N. C.; Naef, D.

    2011-11-01

    We present the discovery of four new long-period planets within the HARPS high-precision sample: HD 137388b (Msini = 0.22 MJ), HD 204941b (Msini = 0.27 MJ), HD 7199b (Msini = 0.29 MJ), HD 7449b (Msini = 1.04 MJ). A long-period companion, probably a second planet, is also found orbiting HD 7449. Planets around HD 137388, HD 204941, and HD 7199 have rather low eccentricities (less than 0.4) relative to the 0.82 eccentricity of HD 7449b. All these planets were discovered even though their hosting stars have clear signs of activity. Solar-like magnetic cycles, characterized by long-term activity variations, can be seen for HD 137388, HD 204941 and HD 7199, whereas the measurements of HD 7449 reveal a short-term activity variation, most probably induced by magnetic features on the stellar surface. We confirm that magnetic cycles induce a long-term radial velocity variation and propose a method to reduce considerably the associated noise. The procedure consists of fitting the activity index and applying the same solution to the radial velocities because a linear correlation between the activity index and the radial velocity is found. Tested on HD 137388, HD 204941, and HD 7199, this correction reduces considerably the stellar noise induced by magnetic cycles and allows us to derive precisely the orbital parameters of planetary companions. Based on observations made with the HARPS instrument on the ESO 3.6-m telescope at La Silla Observatory (Chile), under programme IDs 072.C-0488 and 183.C-0972.Radial velocities (Tables 4-7) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/535/A55

  1. Observed properties of extrasolar planets.

    PubMed

    Howard, Andrew W

    2013-05-01

    Observational surveys for extrasolar planets probe the diverse outcomes of planet formation and evolution. These surveys measure the frequency of planets with different masses, sizes, orbital characteristics, and host star properties. Small planets between the sizes of Earth and Neptune substantially outnumber Jupiter-sized planets. The survey measurements support the core accretion model, in which planets form by the accumulation of solids and then gas in protoplanetary disks. The diversity of exoplanetary characteristics demonstrates that most of the gross features of the solar system are one outcome in a continuum of possibilities. The most common class of planetary system detectable today consists of one or more planets approximately one to three times Earth's size orbiting within a fraction of the Earth-Sun distance. PMID:23641110

  2. Observed properties of extrasolar planets.

    PubMed

    Howard, Andrew W

    2013-05-01

    Observational surveys for extrasolar planets probe the diverse outcomes of planet formation and evolution. These surveys measure the frequency of planets with different masses, sizes, orbital characteristics, and host star properties. Small planets between the sizes of Earth and Neptune substantially outnumber Jupiter-sized planets. The survey measurements support the core accretion model, in which planets form by the accumulation of solids and then gas in protoplanetary disks. The diversity of exoplanetary characteristics demonstrates that most of the gross features of the solar system are one outcome in a continuum of possibilities. The most common class of planetary system detectable today consists of one or more planets approximately one to three times Earth's size orbiting within a fraction of the Earth-Sun distance.

  3. Studies of satellite and planetary surfaces and atmospheres. [Jupiter, Saturn, and Mars and their satellites

    NASA Technical Reports Server (NTRS)

    Sagan, C.

    1978-01-01

    Completed or published research supported by NASA is summarized. Topics cover limb darkening and the structure of the Jovian atmosphere; the application of generalized inverse theory to the recovery of temperature profiles; models for the reflection spectrum of Jupiter's North Equatorial Belt; isotropic scattering layer models for the red chromosphore on Titan; radiative-convective equilibrium models of the Titan atmosphere; temperature structure and emergent flux of the Jovian planets; occultation of epsilon Geminorum by Mars and the structure and extinction of the Martian upper atmosphere; lunar occultation of Saturn; astrometric results and the normal reflectances of Rhea, Titan, and Iapetus; near limb darkening of solids of planetary interest; scattering light scattering from particulate surfaces; comparing the surface of 10 to laboratory samples; and matching the spectrum of 10: variations in the photometric properties of sulfur-containing mixtures.

  4. Planetary atmosphere models: A research and instructional web-based resource

    NASA Astrophysics Data System (ADS)

    Gray, Samuel Augustine

    The effects of altitude change on the temperature, pressure, density, and speed of sound were investigated. These effects have been documented in Global Reference Atmospheric Models (GRAMs) to be used in calculating the conditions in various parts of the atmosphere for several planets. Besides GRAMs, there are several websites that provide online calculators for the 1976 US Standard Atmosphere. This thesis presents the creation of an online calculator of the atmospheres of Earth, Mars, Venus, Titan, and Neptune. The websites consist of input forms for altitude and temperature adjustment followed by a results table for the calculated data. The first phase involved creating a spreadsheet reference based on the 1976 US Standard Atmosphere and other planetary GRAMs available. Microsoft Excel was used to input the equations and make a graphical representation of the temperature, pressure, density, and speed of sound change as altitude changed using equations obtained from the GRAMs. These spreadsheets were used later as a reference for the JavaScript code in both the design and comparison of the data output of the calculators. The websites were created using HTML, CSS, and JavaScript coding languages. The calculators could accurately display the temperature, pressure, density, and speed of sound of these planets from surface values to various stages within the atmosphere. These websites provide a resource for students involved in projects and classes that require knowledge of these changes in these atmospheres. This project also created a chance for new project topics to arise for future students involved in aeronautics and astronautics.

  5. THE EFFECTS OF SNOWLINES ON C/O IN PLANETARY ATMOSPHERES

    SciTech Connect

    Oeberg, Karin I.; Murray-Clay, Ruth; Bergin, Edwin A.

    2011-12-10

    The C/O ratio is predicted to regulate the atmospheric chemistry in hot Jupiters. Recent observations suggest that some exoplanets, e.g., Wasp 12-b, have atmospheric C/O ratios substantially different from the solar value of 0.54. In this Letter, we present a mechanism that can produce such atmospheric deviations from the stellar C/O ratio. In protoplanetary disks, different snowlines of oxygen- and carbon-rich ices, especially water and carbon monoxide, will result in systematic variations in the C/O ratio both in the gas and in the condensed phases. In particular, between the H{sub 2}O and CO snowlines most oxygen is present in icy grains-the building blocks of planetary cores in the core accretion model-while most carbon remains in the gas phase. This region is coincidental with the giant-planet-forming zone for a range of observed protoplanetary disks. Based on standard core accretion models of planet formation, gas giants that sweep up most of their atmospheres from disk gas outside of the water snowline will have a C/O {approx} 1, while atmospheres significantly contaminated by evaporating planetesimals will have a stellar or substellar C/O when formed at the same disk radius. The overall metallicity will also depend on the atmosphere formation mechanism, and exoplanetary atmospheric compositions may therefore provide constraints on where and how a specific planet formed.

  6. On the role of electron-driven processes in planetary and cometary atmospheres

    NASA Astrophysics Data System (ADS)

    Campbell, Laurence

    2013-05-01

    Electrons in the solar wind and photoelectrons produced by sunlight, sometimes accelerated in the magnetosphere, produce ionisation, dissociation and excitation of atoms and molecules in planetary and cometary atmospheres. These primary electrons, and secondary electrons from ionisation, interact further, progressively losing energy until reaching thermal equilibrium. The product ions and excited species take part in chemical reactions, producing new species. Thus electron-driven processes are significant in determining the populations of minor species and the rates of energy transfer in upper-planetary and cometary atmospheres. The radiation emitted by excited species is valuable in remote sensing. Thus modelling of electron-driven processes is necessary in both observing and understanding these atmospheres. This requires detailed simulation of a large number of electron-impact processes and subsequent radiative and collisional processes, including chemical reactions, which have a vast range of time scales from nanoseconds to days. In most cases thermal equilibrium is not attained, so a statistical-equilibrium calculation is employed. Some vibrational excitations and the products of many slower reactions do not reach statistical equilibrium, hence non-equilibrium calculations are also required. In all such calculations the availability of accurate atomic and molecular data, such as electron-impact cross sections, is critical. Here we show the parallel application of new electron-impact excitation cross sections and enhanced computational techniques in a number of examples, including the determination of the abundance of carbon monoxide in comet Hale-Bopp, electron heating rates in the atmosphere of Titan, predictions of infrared emissions from the upper atmospheres of Mars and Venus and non-equilibrium processes in the atmosphere of Jupiter.

  7. Ultra-High Resolution Spectroscopic Remote Sensing: A Microscope on Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Kostiuk, Theodor

    2010-01-01

    Remote sensing of planetary atmospheres is not complete without studies of all levels of the atmosphere, including the dense cloudy- and haze filled troposphere, relatively clear and important stratosphere and the upper atmosphere, which are the first levels to experience the effects of solar radiation. High-resolution spectroscopy can provide valuable information on these regions of the atmosphere. Ultra-high spectral resolution studies can directly measure atmospheric winds, composition, temperature and non-thermal phenomena, which describe the physics and chemistry of the atmosphere. Spectroscopy in the middle to long infrared wavelengths can also probe levels where dust of haze limit measurements at shorter wavelength or can provide ambiguous results on atmospheric species abundances or winds. A spectroscopic technique in the middle infrared wavelengths analogous to a radio receiver. infrared heterodyne spectroscopy [1], will be describe and used to illustrate the detailed study of atmospheric phenomena not readily possible with other methods. The heterodyne spectral resolution with resolving power greater than 1,000.000 measures the true line shapes of emission and absorption lines in planetary atmospheres. The information on the region of line formation is contained in the line shapes. The absolute frequency of the lines can be measured to I part in 100 ,000,000 and can be used to accurately measure the Doppler frequency shift of the lines, directly measuring the line-of-sight velocity of the gas to --Im/s precision (winds). The technical and analytical methods developed and used to measure and analyze infrared heterodyne measurements will be described. Examples of studies on Titan, Venus, Mars, Earth, and Jupiter will be presented. 'These include atmospheric dynamics on slowly rotating bodies (Titan [2] and Venus [3] and temperature, composition and chemistry on Mars 141, Venus and Earth. The discovery and studies of unique atmospheric phenomena will also be

  8. Characterization of Extrasolar Planets Using SOFIA

    NASA Technical Reports Server (NTRS)

    Deming, Drake

    2010-01-01

    Topics include: the landscape of extrasolar planets, why focus on transiting planets, some history and Spitzer results, problems in atmospheric structure or hot Jupiters and hot super Earths, what observations are needed to make progress, and what SOFIA can currently do and comments on optimized instruments.

  9. Studying Venus' atmosphere and ionosphere with Planetary Radio Interferometry and Doppler Experiment (PRIDE)

    NASA Astrophysics Data System (ADS)

    Bocanegra-Bahamon, T. M.; Cimo, G.; Duev, D. A.; Gurvits, L. I.; Marty, J. Ch.; Pogrebenko, S. V.; Rosenblatt, P.

    2014-04-01

    The Planetary Radio Interferometry and Doppler Experiment (PRIDE) is a technique that can provide a multi-disciplinary enhancement of the science return of planetary missions. By performing precise Doppler tracking of a spacecraft carrier radio signal, at Earth-based radio telescopes, and VLBI-style processing of these signals in phase-referencing mode, the technique allows the determination of the radial velocity and lateral coordinates of the spacecraft with very high accuracy[1]. Because of the accurate examination of the changes in phase and amplitude of the radio signal propagating from the spacecraft to the multiple stations on Earth, the PRIDE technique can be used for several fields of planetary research. The application of this technique for atmospheric studies has been assessed by observing ESA's Venus Express (VEX) during Venus occultation events in 2012 and 2014, and by participating in one of the Venus Express Atmospheric Drag Experiment (VExADE) campaigns in 2012. Both studies are contributing to the characterization efforts of the atmosphere and ionosphere of Venus. During the Venus Express Atmospheric Drag Experiment (VExADE) campaigns VEX's orbit pericenter was lowered into an altitude range of approximately 165 to 175 km in order to probe Venus upper atmosphere above its north pole. The first VExADE campaigns were carried out between 2009-2010 using Doppler tracking data acquired by the VEX radio science experiment (VeRa), which provided the first in situ measurements of the density of Venus' polar thermosphere at solar minimum conditions [2]. In the December 2012 campaign the PRIDE-team participated by tracking VEX with several radio telescopes from the European VLBI Network (EVN) during pericenter passage. A Doppler frequency drop of ∼40 mHz was detected as VEX reached the lowest altitudes at around 170 km. The tracking data for each pericenter pass is fitted for precise orbit determination, from which drag acceleration estimates and the

  10. Witnessing Extrasolar Asteroid Destruction?

    NASA Astrophysics Data System (ADS)

    Xu, Siyi; Jura, Michael; Su, Kate; Meng, Huan

    2014-11-01

    40 white dwarfs with excess infrared radiation due to a circumstellar dust disk from tidally disrupted asteroids have been identified. Recently, we identified one dusty white dwarf whose infrared fluxes have been increasing since May 2014. Very likely, it is caused by a recent tidal disruption event of extrasolar asteroid. We propose DDT to follow it up in a timely manner because the flare could dissipate very soon. This proposal provides a unique opportunity to study the destruction of an extrasolar asteroid.

  11. Bok Prize Lecture (shared) Towards a Physical Characterization of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Seager, Sara

    2004-03-01

    We have entered a new era in planetary astrophysics with well over 100 giant planets now known to orbit nearby sun-like stars. Recent theoretical and observational advances have given us new constraints on the physical characteristics of extrasolar planets, while ongoing and proposed observing programs and space missions hold great promise for the future of extrasolar planet science. I will discuss the emerging understanding of the extrasolar transiting planet HD209458b, tying together several recent observational constraints as well as key upcoming measurements.I will also briefly review scientific highlights and prospects for the future detection and study of Earth-like extrasolar planets.

  12. Planetary atmosphere evolution: do other habitable planets exist and can we detect them?

    PubMed

    Kasting, J F

    1996-01-01

    The goal of this conference is to consider whether it is possible within the next few decades to detect Earth-like planets around other stars using telescopes or interferometers on the ground or in space. Implicit in the term "Earth-like" is the idea that such planets might be habitable by Earth-like organisms, or that they might actually be inhabited. Here, I shall address two questions from the standpoint of planetary atmosphere evolution. First, what are the chances that habitable planets exist around other stars? And, second, if inhabited planets exist, what would be the best way to detect them?

  13. Application of the Stogryn-Hirschfelder treatment of weak dimers to planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Slanina, Zdenek; Fox, Kenneth; Kim, Sang J.

    1992-01-01

    The thermodynamics of carbon dioxide dimerization is treated as an example of the evaluation of weak dimer populations in planetary atmospheres (e.g., Mars and Venus). Two approaches considered are the Stogryn-Hirschfelder (1960) treatment using the Lennard-Jones interaction and calculations based on recent quantum chemical data. Several improvements of these treatments are developed. It is indicated that carbon dioxide dimers may be less or more abundant at the surfaces of Mars or Venus, respectively, than is suggested by previous calculations.

  14. Laboratory studies on N(2D) reactions of relevance to the chemistry of planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Balucani, N.; Casavecchia, P.

    Molecular nitrogen is a very stable molecule, practically inert from a chemical point of view. For a nitrogen chemistry to occur in the planetary atmospheres which contain N2 , it is necessary to transform it into an active form, such as atoms or ions. As far as the production of atomic nitrogen in the upper atmospheres of planets (like Mars) or moons (like Titan) is concerned, several processes - as N2 dissociation induced by electron impact, EUV photolysis (λ <80 nm) and dissociative photoionization, or galactic cosmic ray absorption and N+ dissociative recombination all 2 lead to atomic nitrogen, notably in the ground, 4 S3/2 , and first electronically excited, 2 D3/2,5/2 , states with comparable yields. The radiative lifetimes of the metastable states 2 D3/2 and 2 D5/2 are quite long (12.3 and 48 hours, respectively), because the transition from a doublet to a quartet state is strongly forbidden. In addition, the physical quenching of N(2 D) is often a slow process and in some important cases the main fate of N(2 D) is chemical reaction with other constituents of the planetary atmospheres. The production of N atoms in the 2 D state is an important fact, because N(4 S) atoms exhibit very low reactivity with closed-shell molecules and the probability of collision with an open-shell radical is small. Unfortunately laboratory experiments on the gas-phase reactions of N(2 D) have been lacking until recently, because of serious experimental difficulties in studying these reactive systems. Accurate kinetic data on the reactions of N(2 D) with the some molecules of relevance to the chemistry of planetary atmospheres have finally become available in the late 90's, but a better knowledge of the reactive behavior requires a dynamical investigation of N(2 D) reactions. The capability of generating intense continuous beams of N(2 D) achieved in our laboratory some years ago has opened up the possibility of studying the reactive scattering of this species under single

  15. Laboratory studies at high resolution of the infrared absorption spectra of a number of gases found in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hunt, R. H.

    1983-01-01

    The infrared absorption spectra of a number of gases found in planetary atmospheres were studied at high resolution. Absorption line measurements which can be of value for the interpretation of planetary spectra in terms of molecular abundances and conditions in the planetary atmospheres were provided. The high resolution spectra have yielded measurements of individual vibration rotation line parameters including positions, strengths, pressure broadened widths and, where assignments were unknown, the temperature sensitivity of the strengths. Such information allows the determinations of the absorption of a given molecular gas under planetary conditions of temperature and pressure and at the same time it provides the data necessary if the spectra are to be understood in terms of basic molecular theory. Thus this work has included spectral analysis in the form of line assignments as well as fitting of the data to Hamiltonian models. Such fitting is very useful in that it helps to confirm and extend the assignments.

  16. Extrasolar planets detections and statistics through gravitational microlensing

    NASA Astrophysics Data System (ADS)

    Cassan, A.

    2014-10-01

    Gravitational microlensing was proposed thirty years ago as a promising method to probe the existence and properties of compact objects in the Galaxy and its surroundings. The particularity and strength of the technique is based on the fact that the detection does not rely on the detection of the photon emission of the object itself, but on the way its mass affects the path of light of a background, almost aligned source. Detections thus include not only bright, but also dark objects. Today, the many successes of gravitational microlensing have largely exceeded the original promises. Microlensing contributed important results and breakthroughs in several astrophysical fields as it was used as a powerful tool to probe the Galactic structure (proper motions, extinction maps), to search for dark and compact massive objects in the halo and disk of the Milky Way, to probe the atmospheres of bulge red giant stars, to search for low-mass stars and brown dwarfs and to hunt for extrasolar planets. As an extrasolar planet detection method, microlensing nowadays stands in the top five of the successful observational techniques. Compared to other (complementary) detection methods, microlensing provides unique information on the population of exoplanets, because it allows the detection of very low-mass planets (down to the mass of the Earth) at large orbital distances from their star (0.5 to 10 AU). It is also the only technique that allows the discovery of planets at distances from Earth greater than a few kiloparsecs, up to the bulge of the Galaxy. Microlensing discoveries include the first ever detection of a cool super-Earth around an M-dwarf star, the detection of several cool Neptunes, Jupiters and super-Jupiters, as well as multi-planetary systems and brown dwarfs. So far, the least massive planet detected by microlensing has only three times the mass of the Earth and orbits a very low mass star at the edge of the brown dwarf regime. Several free-floating planetary

  17. Light scattering by randomly oriented cubes and parallelepipeds. [for interpretation of observed data from planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Liou, K. N.; Cai, Q.; Pollack, J. B.; Cuzzi, J. N.

    1983-01-01

    In this paper, the geometric ray tracing theory for the scattering of light by hexagonal cylinders to cubes and parallelepipeds has been modified. Effects of the real and imaginary parts of the refractive index and aspect ratio of the particle on the scattering phase function and the degree of linear polarization are investigated. Causes of the physical features in the scattering polarization patterns are identified in terms of the scattering contribution due to geometric reflections and refractions. The single-scattering phase function and polarization data presented in this paper should be of some use for the interpretation of observed scattering and polarization data from planetary atmospheres and for the physical understanding of the transfer of radiation in an atmosphere containing nonspherical particles.

  18. Polarization radiation in the planetary atmosphere delimited by a heterogeneous diffusely reflecting surface

    NASA Technical Reports Server (NTRS)

    Strelkov, S. A.; Sushkevich, T. A.

    1983-01-01

    Spatial frequency characteristics (SFC) and the scattering functions were studied in the two cases of a uniform horizontal layer with absolutely black bottom, and an isolated layer. The mathematical model for these examples describes the horizontal heterogeneities in a light field with regard to radiation polarization in a three dimensional planar atmosphere, delimited by a heterogeneous surface with diffuse reflection. The perturbation method was used to obtain vector transfer equations which correspond to the linear and nonlinear systems of polarization radiation transfer. The boundary value tasks for the vector transfer equation that is a parametric set and one dimensional are satisfied by the SFC of the nonlinear system, and are expressed through the SFC of linear approximation. As a consequence of the developed theory, formulas were obtained for analytical calculation of albedo in solving the task of dissemination of polarization radiation in the planetary atmosphere with uniform Lambert bottom.

  19. Stellar occultations by turbulent planetary atmospheres. I - A heuristic scattering model. II - The Beta Scorpii events

    NASA Technical Reports Server (NTRS)

    Hubbard, W. B.; Jokipii, J. R.

    1977-01-01

    Effects of atmospheric turbulence on stellar-occultation inversion procedures are investigated using a heuristic scattering model that is believed to reproduce the essential features of turbulence. A quantitative estimate is made of the size of the error in deducing the mean refractivity profile of a planetary atmosphere, taking into account constant as well as exponential scattering. It is shown that ordinary turbulence has no important effect on the average intensity profile in a stellar occultation but could have an important instantaneous effect. A critical examination of possible manifestations of turbulent scattering during occultations of Beta Sco by Jupiter indicates that all observed phenomena during these events can be understood in terms of scintillations produced by turbulence.

  20. Large laser sparks for laboratory simulation of high-energy-density events in planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Babankova, Dagmar; Juha, Libor; Civias, Svatopluk; Bittner, Michal; Cihelka, Jaroslav; Bartnik, Andrzej; Fiedorowicz, Henryk; Mikolajczyk, Janusz; Ryc, Leszek; Pfeifer, Miroslav; Skala, Jiri; Ullschmied, Jiri

    2005-09-01

    Single ≤1 kJ pulses from a high-power laser are focused into molecular gases to create large laser sparks. This provides a unique way to mimic the chemical effects of high-energy-density events in planetary atmospheres (cometary impact, lightning) matching the natural energy-density, its spatio-temporal evolution and plasma-volume scaling of such events in a fully-controlled laboratory environment. Some chemical reactions initiated by laser-induced dielectric breakdown (LIDB) in both pure molecular gases and mixtures related to the chemical evolution of the Earth's early atmosphere were studied. Most of the experiments were carried out in a static gas cell. However, an initial series of experiments was also performed with a gas-puff target placed within a vacuum interaction chamber. Under these dynamic conditions the hot core of a laser spark can be directly investigated.

  1. Views from EPOXI. Colors in Our Solar System as an Analog for Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Crow, Carolyn A.; McFadden, L. A.; Robinson, T.; Livengood, T. A.; Hewagama, T.; Barry, R. K.; Deming, L. D.; Meadows, V.; Lisse, C. M.

    2010-01-01

    With extrasolar planet detection becoming more common place, the frontiers of extrasolar planet science have moved beyond detection to the observations required to determine planetary properties. Once the existing observational challenges have been overcome, the first visible-light studies of extrasolar Earth-sized planets will likely employ filter photometry or low-resolution. spectroscopy to observe disk-integrated radiation from the unresolved planet. While spectroscopy of these targets is highly desirable, and provides the most robust form of characterization. S/N considerations presently limit spectroscopic measurements of extrasolar worlds. Broadband filter photometry will thus serve as a first line of characterization. In this paper we use Extrasolar Observation and Characterization (EPOCh) filter photometry of the Earth. Moon and Mars model spectra. and previous photometric and spectroscopic observations of a range the solar system planets. Titan, and Moon to explore the limitations of using color as a baseline for understanding extrasolar planets

  2. Infrared spectra of van de Waals complexes of importance in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Fraser, G. T.; Pine, A. S.; Lafferty, W. J.

    1990-01-01

    It has been suggested that (CO2)2 and Ar-CO2 are important constituents of the planetary atmospheres of Venus and Mars. Recent results on the laboratory spectroscopy of CO2 containing van der Waals complexes which may be of use in the modeling of the spectra of planetary atmospheres are presented. Sub-Doppler infrared spectra were obtained for (CO2)2, (CO2)3, and rare-gas-CO2 complexes in the vicinity of the CO2 Fermi diad at 2.7 micrometers using a color-center-laser optothermal spectrometer. From the spectroscopic constants the geometries of the complexes have been determined and van der Waals vibrational frequencies have been estimated. The equilibrium configurations are C2h, C3h, and C2v, for (CO2)2, (CO2)3, and the rare-gas-CO2 complexes, respectively. Most of the homogeneous linewidths for the revibrational transitions range from 0.5 to 22 MHz, indicating that predissociation is as much as four orders of magnitude faster than radiative processes for vibrational relaxation in these complexes.

  3. Mars Atmosphere and Thermal-Vacuum Testing for Future Planetary Exploration Missions

    NASA Astrophysics Data System (ADS)

    Hein, Peter; Doring, Daniel

    2012-07-01

    Satellites, space probes, and their subsystems are usually thoroughly tested under vacuum and varied thermal environments before launch. IABG’s Space Test Centre in Ottobrunn, Germany, is specialized on providing these conditions for manufactures of commercial and scientific spacecraft. For planetary missions (like ESA’s ExoMars) testing also has to be performed at planetary-ambient conditions as the available atmosphere will change the heat transfer conditions within the instruments. In the case of mars missions, this atmosphere consists mostly of carbon dioxide (CO2) at a pressure of 7 mbar and temperatures as low as -120°C. The challenges under these conditions are to prevent the carbon dioxide from icing on the cold surfaces in the chamber and therefore causing pressure instabilities and safety issues if the current conditions inside the chamber are unknown. Therefore it is necessary to understand the effects taking place inside the chamber and to know, for example, the amount of CO2 currently inside the facility. Two types of thermal-vacuum test facilities are presented: A balanced electrical heating / LN2 cooling (BHC) type and a GN2-blower type with an external thermal conditioning unit (TCU) that moves the process of heat- ing/cooling outside the vacuum vessel. Their specific technology does (or does not) enable them for mars atmosphere testing. Some considerations about safety measures necessary for handling the potentially suffocating carbon dioxide are given. Results of a successful subsystem test with data on temperature and pressure stability are presented and improvements for simulating mars atmosphere in a thermal- vacuum test facility are discussed such as simulating mars weather and improved simulation of mars day-night cycle.

  4. Strong scintillations during atmospheric occultations Theoretical intensity spectra. [radio scattering during spacecraft occultations by planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hinson, D. P.

    1986-01-01

    Each of the two Voyager spacecraft launched in 1977 has completed a reconnaissance of the Jovian and Saturnian systems. In connection with occultation experiments, strong scintillations were observed. Further theoretical work is required before these scintillations can be interpreted. The present study is, therefore, concerned with the derivation of a theory for strong scattering during atmospheric occultation experiments, taking into account as fundamental quantity of interest the spatial spectrum (or spectral density) of intensity fluctuations. Attention is given to a theory for intensity spectra, and numerical calculations. The new formula derived for Phi-i accounts for strong scattering of electromagnetic waves during atmospheric occultations.

  5. Ash Dispersal in Planetary Atmospheres: Continuum vs. Non-continuum Effects

    NASA Astrophysics Data System (ADS)

    Fagents, S. A.; Baloga, S. M.; Glaze, L. S.

    2013-12-01

    The dispersal of ash from a volcanic vent on any given planet is dictated by particle properties (density, shape, and size distribution), the intensity of the eruptive source, and the characteristics of the planetary environment (atmospheric structure, wind field, and gravity) into which the ash is erupted. Relating observations of potential pyroclastic deposits to source locations and eruption conditions requires a detailed quantitative understanding of the settling rates of individual particles under changing ambient conditions. For atmospheres that are well described by continuum mechanics, the conventional Newtonian description of particle motion allows particle settling velocities to be related to particle characteristics via a drag coefficient. However, under rarefied atmospheric conditions (i.e., on Mars and at high altitude on Earth), non-continuum effects become important for ash-sized particles, and an equation of motion based on statistical mechanics is required for calculating particle motion. We have developed a rigorous new treatment of particle settling under variable atmospheric conditions and applied it to Earth and Mars. When non-continuum effects are important (as dictated by the mean free path of atmospheric gas relative to the particle size), fall velocities are greater than those calculated by continuum mechanics. When continuum conditions (i.e., higher atmospheric densities) are reached during descent, our model switches to a conventional formulation that determines the appropriate drag coefficient as the particle transits varying atmospheric properties. The variation of settling velocity with altitude allows computation of particle trajectories, fall durations and downwind dispersal. Our theoretical and numerical analyses show that several key, competing factors strongly influence the downwind trajectories of ash particles and the extents of the resulting deposits. These factors include: the shape of the particles (non-spherical particles

  6. Scientific Value of a Saturn Atmospheric Probe Mission

    NASA Technical Reports Server (NTRS)

    Simon-Miller, A. A.; Lunine, J. I.; Atreya, S. K.; Spilker, T. R.; Coustenis, A.; Atkinson, D. H.

    2012-01-01

    Atmospheric entry probe mISSions to the giant planets can uniquely discriminate between competing theories of solar system formation and the origin and evolution of the giant planets and their atmospheres. This provides for important comparative studies of the gas and ice giants, and to provide a laboratory for studying the atmospheric chemistries, dynamics, and interiors of all the planets including Earth. The giant planets also represent a valuable link to extrasolar planetary systems. As outlined in the recent Planetary Decadal Survey, a Saturn Probe mission - with a shallow probe - ranks as a high priority for a New Frontiers class mission [1].

  7. Characterization of potentially habitable planets: Retrieval of atmospheric and planetary properties from emission spectra

    NASA Astrophysics Data System (ADS)

    von Paris, P.; Hedelt, P.; Selsis, F.; Schreier, F.; Trautmann, T.

    2013-03-01

    Context. An increasing number of potentially habitable terrestrial planets and planet candidates are found by ongoing planet search programs. The search for atmospheric signatures to establish planetary habitability and the presence of life might be possible in the future. Aims: We want to quantify the accuracy of retrieved atmospheric parameters (composition, temperature, pressure) that might be obtained from infrared emission spectroscopy. Methods: We use synthetic observations of the atmospheres of hypothetical potentially habitable planets. These were constructed with a parametrized atmosphere model, a high-resolution radiative transfer model and a simplified noise model. The simulated observations were used to fit the model parameters. Furthermore, classic statistical tools such as χ2 statistics and least-square fits were used to analyze the simulated observations. Results: When adopting the design of currently planned or proposed exoplanet characterization missions, we find that emission spectroscopy could provide weak limits on the surface conditions of terrestrial planets, hence their potential habitability. However, these mission designs are unlikely to allow the composition of the atmosphere of a habitable planet to be characterized, even though CO2 is detected. Upon increasing the signal-to-noise ratios by about a factor of 2-5 (depending on spectral resolution) compared to current mission designs, the CO2 content could be characterized to within two orders of magnitude. The detection of the O3 biosignature remains marginal. The atmospheric temperature structure could not be constrained. Therefore, a full atmospheric characterization seems to be beyond the capabilities of such missions when using only emission spectroscopy during secondary eclipse or target visits. Other methods such as transmission spectroscopy or orbital photometry are probably needed in order to give additional constraints and break degeneracies.

  8. Intercomparison of Martian Lower Atmosphere Simulated Using Different Planetary Boundary Layer Parameterization Schemes

    NASA Technical Reports Server (NTRS)

    Natarajan, Murali; Fairlie, T. Duncan; Dwyer Cianciolo, Alicia; Smith, Michael D.

    2015-01-01

    We use the mesoscale modeling capability of Mars Weather Research and Forecasting (MarsWRF) model to study the sensitivity of the simulated Martian lower atmosphere to differences in the parameterization of the planetary boundary layer (PBL). Characterization of the Martian atmosphere and realistic representation of processes such as mixing of tracers like dust depend on how well the model reproduces the evolution of the PBL structure. MarsWRF is based on the NCAR WRF model and it retains some of the PBL schemes available in the earth version. Published studies have examined the performance of different PBL schemes in NCAR WRF with the help of observations. Currently such assessments are not feasible for Martian atmospheric models due to lack of observations. It is of interest though to study the sensitivity of the model to PBL parameterization. Typically, for standard Martian atmospheric simulations, we have used the Medium Range Forecast (MRF) PBL scheme, which considers a correction term to the vertical gradients to incorporate nonlocal effects. For this study, we have also used two other parameterizations, a non-local closure scheme called Yonsei University (YSU) PBL scheme and a turbulent kinetic energy closure scheme called Mellor- Yamada-Janjic (MYJ) PBL scheme. We will present intercomparisons of the near surface temperature profiles, boundary layer heights, and wind obtained from the different simulations. We plan to use available temperature observations from Mini TES instrument onboard the rovers Spirit and Opportunity in evaluating the model results.

  9. Scintillations during occultations by planets. I - An approximate theory. [for planetary atmosphere structure

    NASA Technical Reports Server (NTRS)

    Young, A. T.

    1976-01-01

    Fluctuations are observed during occultations of both stars and spacecraft by planetary atmospheres. Existing treatments of spacecraft scintillations ignore a major effect unique to occultations: the severe flattening of the Fresnel zone or source image by defocusing. Other large effects, due to 'saturation' of the scintillation, have also been ignored. The deeper portions of atmospheric temperature and density profiles inferred from occultation data are seriously in error if other planets' atmospheres are as turbulent as our own. Thus, profiles obtained from entry probes (e.g., the Soviet Venera series) are probably more accurate than those from radio occultation (Mariner 5 and 10) data. Scintillation greatly reduces the information obtainable from occultation observations; much of the detail attributed to layering in published profiles is probably due to aliasing of turbulence. This paper gives an approximately correct theoretical treatment that is a substantial improvement over published theories, and shows how a more accurate theory could be constructed. Some methods for a more accurate determination of atmospheric structure are proposed.

  10. THE COMPOSITIONAL DIVERSITY OF EXTRASOLAR TERRESTRIAL PLANETS. I. IN SITU SIMULATIONS

    SciTech Connect

    Bond, Jade C.; Lauretta, Dante S.; O'Brien, David P.

    2010-06-01

    Extrasolar planet host stars have been found to be enriched in key planet-building elements. These enrichments have the potential to drastically alter the composition of material available for terrestrial planet formation. Here, we report on the combination of dynamical models of late-stage terrestrial planet formation within known extrasolar planetary systems with chemical equilibrium models of the composition of solid material within the disk. This allows us to determine the bulk elemental composition of simulated extrasolar terrestrial planets. A wide variety of resulting planetary compositions are found, ranging from those that are essentially 'Earth like', containing metallic Fe and Mg silicates, to those that are dominated by graphite and SiC. This shows that a diverse range of terrestrial planets may exist within extrasolar planetary systems.

  11. Comparative Study on Hot Atom Coronae of Solar and Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Shematovich, Valery

    Solar/stellar forcing on the upper atmospheres of the solar and extrasolar planets via both absorption of the XUV (soft X-rays and extreme ultraviolet) radiation and atmospheric sputtering results in the formation of an extended neutral corona populated by the suprathermal (hot) H, C, N, and O atoms (see, e.g., Johnson et al., 2008). The hot corona, in turn, is altered by an inflow of the solar wind/magnetospheric plasma and local pick-up ions onto the planetary exosphere. Such inflow results in the formation of the superthermal atoms (energetic neutral atoms - ENAs) due to the charge exchange with the high-energy precipitating ions and can affect the long-term evolution of the atmosphere due to the atmospheric escape. The origin, kinetics and transport of the suprathermal H, C, N, and O atoms in the transition regions (from thermosphere to exosphere) of the planetary atmospheres are discussed. Reactions of dissociative recombination of the ionospheric ions CO _{2} (+) , CO (+) , O _{2} (+) , and N _{2} (+) with thermal electrons are the main photochemical sources of hot atoms. The dissociation of atmospheric molecules by the solar/stellar XUV radiation and accompanying photoelectron fluxes and the induced exothermic photochemistry are also the important sources of the suprathermal atoms. Such kinetic systems with the non-thermal processes are usually investigated with the different (test particles, DSMC, and hybrid) versions of the kinetic Monte Carlo method. In our studies the kinetic energy distribution functions of suprathermal and superthermal atoms were calculated using the stochastic model of the hot planetary corona (Shematovich, 2004, 2010; Groeller et al., 2014), and the Monte Carlo model (Shematovich et al., 2011, 2013) of the high-energy proton and hydrogen atom precipitation into the atmosphere respectively. These functions allowed us to estimate the space distribution of suprathermals in the planetary transition regions. An application of these

  12. Detecting Extrasolar Planets With Millimeter-Wave Observatories

    NASA Astrophysics Data System (ADS)

    1996-01-01

    Do nearby stars have planetary systems like our own? How do such systems evolve? How common are such systems? Proposed radio observatories operating at millimeter wavelengths could start answering these questions within the next 6-10 years, according to scientists at the National Radio Astronomy Observatory (NRAO). Bryan Butler, Robert Brown, Richard Simon, Al Wootten and Darrel Emerson, all of NRAO, presented their findings today to the American Astronomical Society meeting in San Antonio, TX. Detecting planets circling other stars is a particularly difficult task, and only a few such planets have been discovered so far. In order to answer fundamental questions about planetary systems and their origin, scientists need to find and study many more extrasolar planets. According to the NRAO scientists, millimeter-wavelength observatories could provide valuable information about extrasolar planetary systems at all stages of their evolution. "With instruments planned by 2005, we could detect planets the size of Jupiter around a solar-type star out to a distance of 100 light-years," said Robert Brown, Associate Director of NRAO. "That means," he added, "that we could survey approximately 2,000 stars of different types to learn if they have planets this size." Millimeter waves occupy the portion of the electromagnetic spectrum between radio microwaves and infrared waves. Telescopes for observing at millimeter wavelengths utilize advanced electronic equipment similar to that used in radio telescopes observing at longer wavelengths. Millimeter-wave observatories offer a number of advantages in the search for extrasolar planets. Planned multi-antenna millimeter-wave telescopes can provide much higher resolving power, or ability to see fine detail, than current optical or infrared telescopes. Millimeter-wave observations would not be degraded by interference from the "zodiacal light" reflected by interplanetary dust, either in the extrasolar system or our own solar system

  13. Carbon to oxygen ratios in extrasolar planetesimals

    NASA Astrophysics Data System (ADS)

    Wilson, David J.; Gänsicke, Boris T.; Farihi, Jay; Koester, Detlev

    2016-07-01

    Observations of small extrasolar planets with a wide range of densities imply a variety of planetary compositions and structures. Currently, the only technique to measure the bulk composition of extrasolar planetary systems is the analysis of planetary debris accreting on to white dwarfs, analogous to abundance studies of meteorites. We present measurements of the carbon and oxygen abundances in the debris of planetesimals at ten white dwarfs observed with the Hubble Space Telescope, along with C/O ratios of debris in six systems with previously reported abundances. We find no evidence for carbon-rich planetesimals, with C/O < 0.8 by number in all 16 systems. Our results place an upper limit on the occurrence of carbon-rich systems at <17 per cent with a 2σ confidence level. The range of C/O of the planetesimals is consistent with that found in the Solar system, and appears to follow a bimodal distribution: a group similar to the CI chondrites, with log (< C/O >) = -0.92, and oxygen-rich objects with C/O less than or equal to that of the bulk Earth. The latter group may have a higher mass fraction of water than the Earth, increasing their relative oxygen abundance.

  14. Attitude and angular rates of planetary probes during atmospheric descent: Implications for imaging

    NASA Astrophysics Data System (ADS)

    Lorenz, Ralph D.

    2010-04-01

    Attitude dynamics data from planetary missions are reviewed to obtain a zeroth-order expectation on the tilts and angular rates to be expected on atmospheric probes during descent: these rates are a strong driver on descent imager design. While recent Mars missions have been equipped with capable inertial measurements, attitude measurements for missions to other planetary bodies are rather limited but some angular motion estimates can be derived from accelerometer, Doppler or other data. It is found that robust camera designs should tolerate motions of the order of 20-40°/s, encountered by Mars Pathfinder, Pioneer Venus, Venera and the high speed part of the Huygens descent on Titan. Under good conditions, parachute-stabilized probes can experience rates of 1-5°/s, seen by the Mars Exploration Rovers and Viking, Galileo at Jupiter, and the slow speed parts of the Huygens descent. In the lowest 20 km of the descent on Titan, the Huygens probe was within 2° of vertical over 95% of the time. Some factors influencing these motions are discussed.

  15. Gamma-ray and neutron spectroscopy of planetary surfaces and atmospheres

    SciTech Connect

    Reedy, R.C.

    1987-01-01

    The neutrons and gamma rays escaping from a planet can be used to map the concentrations of various elements in its surface. In a planet, the high-energy particles in the galactic cosmic rays induce a cascade of particles that includes many neutrons. The ..gamma.. rays are made by the decay of the naturally-occurring radioelements and by nuclear excitations induced by cosmic-ray particles and their secondaries (especially neutron capture or inelastic scattering reactions). After a short history of planetary ..gamma..-ray and neutron spectroscopy, the ..gamma..-ray spectrometer and active neutron detection system planned for the Mars Observer Mission are presented. The results of laboratory experiments that simulate the cosmic-ray bombardments of planetary surfaces and the status of the theoretical calculations for the processes that make and transport neutrons and ..gamma.. rays will be reviewed. Studies of Mars, including its atmosphere, are emphasized, as are new ideas, concepts, and problems that have arisen over the last decade, such as Doppler broadening and peaks from neutron scattering with germanium nuclei in a ..gamma..-ray spectrometer. 23 refs., 1 fig.

  16. DETECTING AND CONSTRAINING N{sub 2} ABUNDANCES IN PLANETARY ATMOSPHERES USING COLLISIONAL PAIRS

    SciTech Connect

    Schwieterman, Edward W.; Meadows, Victoria S.; Misra, Amit; Robinson, Tyler D.; Domagal-Goldman, Shawn

    2015-09-01

    Characterizing the bulk atmosphere of a terrestrial planet is important for determining surface pressure and potential habitability. Molecular nitrogen (N{sub 2}) constitutes the largest fraction of Earth's atmosphere and is likely to be a major constituent of many terrestrial exoplanet atmospheres. Due to its lack of significant absorption features, N{sub 2} is extremely difficult to remotely detect. However, N{sub 2} produces an N{sub 2}–N{sub 2} collisional pair, (N{sub 2}){sub 2}, which is spectrally active. Here we report the detection of (N{sub 2}){sub 2} in Earth's disk-integrated spectrum. By comparing spectra from NASA's EPOXI mission to synthetic spectra from the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional spectral Earth model, we find that (N{sub 2}){sub 2} absorption produces a ∼35% decrease in flux at 4.15 μm. Quantifying N{sub 2} could provide a means of determining bulk atmospheric composition for terrestrial exoplanets and could rule out abiotic O{sub 2} generation, which is possible in rarefied atmospheres. To explore the potential effects of (N{sub 2}){sub 2} in exoplanet spectra, we used radiative transfer models to generate synthetic emission and transit transmission spectra of self-consistent N{sub 2}–CO{sub 2}–H{sub 2}O atmospheres, and analytic N{sub 2}–H{sub 2} and N{sub 2}–H{sub 2}–CO{sub 2} atmospheres. We show that (N{sub 2}){sub 2} absorption in the wings of the 4.3 μm CO{sub 2} band is strongly dependent on N{sub 2} partial pressures above 0.5 bar and can significantly widen this band in thick N{sub 2} atmospheres. The (N{sub 2}){sub 2} transit transmission signal is up to 10 ppm for an Earth-size planet with an N{sub 2}-dominated atmosphere orbiting within the habitable zone of an M5V star and could be substantially larger for planets with significant H{sub 2} mixing ratios.

  17. Simulating super earth atmospheres in the laboratory

    NASA Astrophysics Data System (ADS)

    Claudi, R.; Erculiani, M. S.; Galletta, G.; Billi, D.; Pace, E.; Schierano, D.; Giro, E.; D'Alessandro, M.

    2016-01-01

    Several space missions, such as JWST, TESS and the very recently proposed ARIEL, or ground-based experiments, as SPHERE and GPI, have been proposed to measure the atmospheric transmission, reflection and emission spectra of extrasolar planets. The planet atmosphere characteristics and possible biosignatures will be inferred by studying planetary spectra in order to identify the emission/absorption lines/bands from atmospheric molecules such as water (H2O), carbon monoxide (CO), methane (CH4), ammonia (NH3), etc. In particular, it is important to know in detail the optical characteristics of gases in the typical physical conditions of the planetary atmospheres and how these characteristics could be affected by radiation driven photochemical and biochemical reaction. The main aim of the project `Atmosphere in a Test Tube' is to provide insights on exoplanet atmosphere modification due to biological intervention. This can be achieved simulating planetary atmosphere at different pressure and temperature conditions under the effects of radiation sources, used as proxies of different bands of the stellar emission. We are tackling the characterization of extrasolar planet atmospheres by mean of innovative laboratory experiments described in this paper. The experiments are intended to reproduce the conditions on warm earths and super earths hosted by low-mass M dwarfs primaries with the aim to understand if a cyanobacteria population hosted on a Earth-like planet orbiting an M0 star is able to maintain its photosynthetic activity and produce traceable signatures.

  18. Using the transit of Venus to probe the upper planetary atmosphere.

    PubMed

    Reale, Fabio; Gambino, Angelo F; Micela, Giuseppina; Maggio, Antonio; Widemann, Thomas; Piccioni, Giuseppe

    2015-01-01

    During a planetary transit, atoms with high atomic number absorb short-wavelength radiation in the upper atmosphere, and the planet should appear larger during a primary transit observed in high-energy bands than in the optical band. Here we measure the radius of Venus with subpixel accuracy during the transit in 2012 observed in the optical, ultraviolet and soft X-rays with Hinode and Solar Dynamics Observatory missions. We find that, while Venus's optical radius is about 80 km larger than the solid body radius (the top of clouds and haze), the radius increases further by >70 km in the extreme ultraviolet and soft X-rays. This measures the altitude of the densest ion layers of Venus's ionosphere (CO2 and CO), useful for planning missions in situ, and a benchmark case for detecting transits of exoplanets in high-energy bands with future missions, such as the ESA Athena. PMID:26102562

  19. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1986-01-01

    After long arduous work with the simulator, measurements of the refractivity and absorptivity of nitrogen under conditions similar to those for Titan were completed. The most significant measurements, however, were those of the microwave absorption from gaseous ammonia under simulated conditions for the Jovian atmospheres over wavelengths from 1.3 to 22 cm. The results of these measurements are critical in that they confirm the theoretical calculation of the ammonia opacity using the Ben-Reuven lineshape. The application of both these results, and results obtained previously, to planetary observations at microwave frequencies were especially rewarding. Applications of the results for ammonia to radio astronomical observations of Jupiter in the 1.3 to 20 cm wavelength range and the application of results for gaseous H2SO4 under simulated Venus conditions are discussed.

  20. Noble gas isotopic composition as a key reference parameter in a planetary atmospheric evolution model

    NASA Astrophysics Data System (ADS)

    Ozima, M.

    2010-12-01

    The isotopic composition of noble gases is a key reference parameter in discussing the evolution of planetary atmospheres. Currently, two widely occurring noble gas components are identified in the early solar system, one is the Solar Wind noble gas (SW-noble gas, hereafter) and another is the Q-noble gas in unaltered meteorites: both noble gases are characterized by their ubiquitous occurrence and high isotopic homogeneity. Since the SW-noble gas is directly ejected from the Sun, it has been assumed to be a good proxy of the average noble gas isotopic composition in the Sun, namely the solar noble gas. The systematic enrichment of the heavier isotopes in the Q-noble gas relative to the SW-noble gas is then commonly attributed to its isotopic fractionation from the SW-noble gas. However, the isotopic compositions of the SW-noble gas either implanted on lunar soils or trapped by artificial targets show considerable isotopic variation depending on the velocity of the Solar Wind. Therefore, it is important to examine how closely the SW-noble gas represents the indigenous solar noble gas component or the mean isotopic composition of noble gases of the Sun. Here we show that the isotopic composition of the SW-noble gas is substantially fractionated relative to the solar value, and therefore should not be used as a reference parameter. We further suggest that the post D-burning Q-noble gas (see below) is the better proxy of the solar noble gas, and this should be used as a reference of the Solar noble gas isotopic composition in discussing the planetary atmospheric evolution. The most distinct difference between the Q- and the SW-noble gas is apparent in a 3He/4He isotopic ratio: 4.64e-4 in Q-He [1], but 1.23e-4 in SW-He[2]. The difference is attributed to the conversion of deuteron (D) to 3He in the Sun, namely the D-burning [3], due to high temperature during the pre-main sequence stage of the Sun. With the use of recent data on D/H ratios from helio-seismology [4] and

  1. Fast ion-molecule reactions in planetary atmospheres: a semiempirical capture approach.

    PubMed

    Faure, Alexandre; Vuitton, Véronique; Thissen, Roland; Wiesenfeld, Laurent; Dutuit, Odile

    2010-01-01

    The description of planetary and interstellar chemistry relies strongly on ion-molecule reaction rate data collected at room temperature or above. However, the temperature in the ionospheres of planets and in the interstellar medium can decrease down to 100 K and 10 K, respectively. We present here a simple semiempirical method to extend available measurements towards those temperatures. Our approach is based on the long-range capture theory combined with room temperature data. Results are presented for cation-molecule and anion-molecule reactions. An overall good agreement is observed between our model and various experimental data in the temperature range 20-295 K. Deviations larger than a factor of 2 are found, however, with ion trap measurements below approximately 50 K. Predictions are also made for reactions of carbon chain and hydrocarbon ions with atomic hydrogen, of particular importance in Titan's atmosphere and in interstellar clouds.

  2. Using the transit of Venus to probe the upper planetary atmosphere

    PubMed Central

    Reale, Fabio; Gambino, Angelo F.; Micela, Giuseppina; Maggio, Antonio; Widemann, Thomas; Piccioni, Giuseppe

    2015-01-01

    During a planetary transit, atoms with high atomic number absorb short-wavelength radiation in the upper atmosphere, and the planet should appear larger during a primary transit observed in high-energy bands than in the optical band. Here we measure the radius of Venus with subpixel accuracy during the transit in 2012 observed in the optical, ultraviolet and soft X-rays with Hinode and Solar Dynamics Observatory missions. We find that, while Venus's optical radius is about 80 km larger than the solid body radius (the top of clouds and haze), the radius increases further by >70 km in the extreme ultraviolet and soft X-rays. This measures the altitude of the densest ion layers of Venus's ionosphere (CO2 and CO), useful for planning missions in situ, and a benchmark case for detecting transits of exoplanets in high-energy bands with future missions, such as the ESA Athena. PMID:26102562

  3. Proposal for constructing an advanced software tool for planetary atmospheric modeling

    NASA Technical Reports Server (NTRS)

    Keller, Richard M.; Sims, Michael H.; Podolak, Esther; Mckay, Christopher P.; Thompson, David E.

    1990-01-01

    Scientific model building can be a time intensive and painstaking process, often involving the development of large and complex computer programs. Despite the effort involved, scientific models cannot easily be distributed and shared with other scientists. In general, implemented scientific models are complex, idiosyncratic, and difficult for anyone but the original scientist/programmer to understand. We believe that advanced software techniques can facilitate both the model building and model sharing process. We propose to construct a scientific modeling software tool that serves as an aid to the scientist in developing and using models. The proposed tool will include an interactive intelligent graphical interface and a high level, domain specific, modeling language. As a testbed for this research, we propose development of a software prototype in the domain of planetary atmospheric modeling.

  4. Microwave spectra of van der Waals complexes of importance in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Suenram, R. D.; Lovas, F. J.

    1990-01-01

    The Fourier-transform Fabry-Perot pulsed-molecular-beam microwave spectrometer at NIST was used to study the microwave spectra of a number of molecular dimers and trimers that may be present in planetary atmospheres. The weak van der Waals bonds associated with these species usually give rise to rotational-tunneling splittings in the microwave spectra. The microwave spectrum of the water dimer species was used to illustrate the complications that can arise in the study of the rotational spectra of these loosely bound species. In addition to the water dimer species, the microwave spectra of the following hydrogen-bonded and van der Waals complexes were studied: (CO2)2-H2O, CO2-(H2O)2, CO2-H2S, N2-H2O, CO-H2O, SO2-H2O, and O3-H2O.

  5. Using the transit of Venus to probe the upper planetary atmosphere.

    PubMed

    Reale, Fabio; Gambino, Angelo F; Micela, Giuseppina; Maggio, Antonio; Widemann, Thomas; Piccioni, Giuseppe

    2015-06-23

    During a planetary transit, atoms with high atomic number absorb short-wavelength radiation in the upper atmosphere, and the planet should appear larger during a primary transit observed in high-energy bands than in the optical band. Here we measure the radius of Venus with subpixel accuracy during the transit in 2012 observed in the optical, ultraviolet and soft X-rays with Hinode and Solar Dynamics Observatory missions. We find that, while Venus's optical radius is about 80 km larger than the solid body radius (the top of clouds and haze), the radius increases further by >70 km in the extreme ultraviolet and soft X-rays. This measures the altitude of the densest ion layers of Venus's ionosphere (CO2 and CO), useful for planning missions in situ, and a benchmark case for detecting transits of exoplanets in high-energy bands with future missions, such as the ESA Athena.

  6. Water Planetary and Cometary Atmospheres: H2O/HDO Transmittance and Fluorescence Models

    NASA Technical Reports Server (NTRS)

    Villanueva, G. L.; Mumma, M. J.; Bonev, B. P.; Novak, R. E.; Barber, R. J.; DiSanti, M. A.

    2012-01-01

    We developed a modern methodology to retrieve water (H2O) and deuterated water (HDO) in planetary and cometary atmospheres, and constructed an accurate spectral database that combines theoretical and empirical results. Based on a greatly expanded set of spectroscopic parameters, we built a full non-resonance cascade fluorescence model and computed fluorescence efficiencies for H2O (500 million lines) and HDO (700 million lines). The new line list was also integrated into an advanced terrestrial radiative transfer code (LBLRTM) and adapted to the CO2 rich atmosphere of Mars, for which we adopted the complex Robert-Bonamy formalism for line shapes. We then retrieved water and D/H in the atmospheres of Mars, comet C/2007 WI, and Earth by applying the new formalism to spectra obtained with the high-resolution spectrograph NIRSPEC/Keck II atop Mauna Kea (Hawaii). The new model accurately describes the complex morphology of the water bands and greatly increases the accuracy of the retrieved abundances (and the D/H ratio in water) with respect to previously available models. The new model provides improved agreement of predicted and measured intensities for many H2O lines already identified in comets, and it identifies several unassigned cometary emission lines as new emission lines of H2O. The improved spectral accuracy permits retrieval of more accurate rotational temperatures and production rates for cometary water.

  7. The theorems of planetary atmosphere and the application to the prediction of the disaster

    NASA Astrophysics Data System (ADS)

    Zhang, Shi-Jie; Han, Yan-Ben; Hu, Hui

    In this article, first we recall the cultural circles in the ancient China, the method of the calamity forecasting was beginning from the combine of the numeric art and astronomical culture. From that time to now the combine has been undergo three times. In the first time the rule of season completely determined by combining the temperature of atmosphere surface layer with the apparent motion of the Sun and the Moon, in the second time, the mystical astrology with the method of man-made calamities and celestial phenomena was generated, in the last time, the rule of climatic change by research on the combination of math-physical theorems and high upper-air general circulation was unveiled. At present, the three theorems of planetary atmospheric movement within the stratosphere and mesosphere are mentioned. Study on the incomplete ionospheric magnetic fluid from the main geomagnetic field, the cooling effect within adiabatic-compressed-restoring geomagnetic force lines, has been gained. The physcial mechanics, the bool pool phenomena in high layer atmospheric circulation, are given.

  8. 12 years of atmospheric monitoring by the Planetary Fourier Spectrometer onboard Mars Express

    NASA Astrophysics Data System (ADS)

    Giuranna, Marco; Grassi, Davide; Aronica, Alessandro; Scaccabarozzi, Diego; Saggin, Bortolino; Aoki, Shohei; Wolkenberg, Paulina; Formisano, Vittorio

    2016-04-01

    We use thermal-infrared spectra returned by the Mars Express Planetary Fourier Spectrometer (PFS-MEx) to retrieve atmospheric and surface temperature, and dust and water ice aerosol optical depth. More than 2,500,000 spectra have been used to build this new dataset, covering the full range of season, latitude, longitude, and local time. The data presented here span more than six Martian years (from MY26, Ls = 331°, 10 January 2004 to MY 33, Ls = 78°, 6 December 2015). We successfully retrieved atmospheric temperatures and aerosols opacity in the polar regions, including the polar nights. By exploiting PFS/MEx capability to perform observations at different local times (LT), this dataset allows investigation of the daily cycles of suspended dust and ice. We present an overview of the seasonal and latitudinal dependence of atmospheric quantities during the relevant period, as well as an assessment of the interannual variability in the current Martian climate, including spatial, daily (LT), seasonal, and interannual variations of the aphelion equatorial cloud belt. With unprecedented spatial and temporal coverage and details revealed, this dataset offers new challenges to the GCMs and, at the same time, a new reference for the MYs complementary to those observed by MGS-TES.

  9. Probing the Dynamics of a Planetary Atmosphere by Analyzing Small Scale Temperature Variations

    NASA Astrophysics Data System (ADS)

    Matcheva, K.; Drossart, P.; Raynaud, E.; Sicardy, B.

    2002-09-01

    The vertical temperature profile of a planetary atmosphere obtained via in situ or remote sensing techniques typically exhibits small scale fluctuations, which are usually interpreted as signatures of propagating atmospheric waves. By studying the observed wave amplitude and phase behavior, and the altitude variations of the vertical wavelength of individual wave modes one can acquire valuable information about the dominant dissipative processes in the atmosphere as well as detect the presence of vertical gradients in the background horizontal wind. The method is based on the use of the Continuous Wavelet Transform of the temperature profile for identifying and subsequently reconstructing the dominant wave modes present in the atmosphere. Model generated waves are then used to fit the observations by varying the strength of the background wind shear and the eddy diffusion coefficient. Molecular and eddy dissipative processes can only limit the wave amplitude growth, whereas presence of vertical wind shear can result both in increase and decrease of the wave temperature amplitude, which is also accompanied by corresponding variations in the vertical wavenumber. This effect could be very large for waves with a horizontal phase speed comparable to the background horizontal wind. We demonstrate the developed technique in a study of Jupiter's stratosphere and lower thermosphere using the temperature profiles retrieved from the 1999 HIP 9396 stellar occultation by the northern polar region of the Jovian atmosphere (Raynaud et al. submitted to Icarus). The quality of the data allows us to successfully identify and reconstruct three dominant wave modes, which peak at different altitudes and compare them to model results. This work is supported by the Marie Curie Fellowship Program of the European Community under contract HPMF-CT-2000-01005.

  10. XUV-driven mass loss from extrasolar giant planets orbiting active stars

    NASA Astrophysics Data System (ADS)

    Chadney, J. M.; Galand, M.; Unruh, Y. C.; Koskinen, T. T.; Sanz-Forcada, J.

    2015-04-01

    Upper atmospheres of Hot Jupiters are subject to extreme radiation conditions that can result in rapid atmospheric escape. The composition and structure of the upper atmospheres of these planets are affected by the high-energy spectrum of the host star. This emission depends on stellar type and age, which are thus important factors in understanding the behaviour of exoplanetary atmospheres. In this study, we focus on Extrasolar Giant Planets (EPGs) orbiting K and M dwarf stars. XUV spectra for three different stars - ɛ Eridani, AD Leonis and AU Microscopii - are constructed using a coronal model. Neutral density and temperature profiles in the upper atmosphere of hypothetical EGPs orbiting these stars are then obtained from a fluid model, incorporating atmospheric chemistry and taking atmospheric escape into account. We find that a simple scaling based solely on the host star's X-ray emission gives large errors in mass loss rates from planetary atmospheres and so we have derived a new method to scale the EUV regions of the solar spectrum based upon stellar X-ray emission. This new method produces an outcome in terms of the planet's neutral upper atmosphere very similar to that obtained using a detailed coronal model of the host star. Our results indicate that in planets subjected to radiation from active stars, the transition from Jeans escape to a regime of hydrodynamic escape at the top of the atmosphere occurs at larger orbital distances than for planets around low activity stars (such as the Sun).

  11. Homes for extraterrestrial life: extrasolar planets.

    PubMed

    Latham, D W

    2001-12-01

    Astronomers are now discovering giant planets orbiting other stars like the sun by the dozens. But none of these appears to be a small rocky planet like the earth, and thus these planets are unlikely to be capable of supporting life as we know it. The recent discovery of a system of three planets is especially significant because it supports the speculation that planetary systems, as opposed to single orbiting planets, may be common. Our ability to detect extrasolar planets will continue to improve, and space missions now in development should be able to detect earth-like planets.

  12. Direct Imaging of Warm Extrasolar Planets

    SciTech Connect

    Macintosh, B

    2005-04-11

    One of the most exciting scientific discoveries in the last decade of the twentieth century was the first detection of planets orbiting a star other than our own. By now more than 130 extrasolar planets have been discovered indirectly, by observing the gravitational effects of the planet on the radial velocity of its parent star. This technique has fundamental limitations: it is most sensitive to planets close to their star, and it determines only a planet's orbital period and a lower limit on the planet's mass. As a result, all the planetary systems found so far are very different from our own--they have giant Jupiter-sized planets orbiting close to their star, where the terrestrial planets are found in our solar system. Such systems have overturned the conventional paradigm of planet formation, but have no room in them for habitable Earth-like planets. A powerful complement to radial velocity detections of extrasolar planets will be direct imaging--seeing photons from the planet itself. Such a detection would allow photometric measurements to determine the temperature and radius of a planet. Also, direct detection is most sensitive to planets in wide orbits, and hence more capable of seeing solar systems resembling our own, since a giant planet in a wide orbit does not preclude the presence of an Earth-like planet closer to the star. Direct detection, however, is extremely challenging. Jupiter is roughly a billion times fainter than our sun. Two techniques allowed us to overcome this formidable contrast and attempt to see giant planets directly. The first is adaptive optics (AO) which allows giant earth-based telescopes, such as the 10 meter W.M. Keck telescope, to partially overcome the blurring effects of atmospheric turbulence. The second is looking for young planets: by searching in the infrared for companions to young stars, we can see thermal emission from planets that are still warm with the heat of their formation. Together with a UCLA team that leads the

  13. Usefulness and Limitations of Energy Limited Escape: Titan and Other Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Johnson, Robert E.; Volkov, Alexey N.; Tucker, Orenthal J.

    2015-11-01

    Because thermal conduction and IR cooling are inefficient heat transfer processes, adiabatic expansion leading to molecular escape is often the dominant cooling process for energy deposited in the upper atmosphere of planetary bodies. This led to the use of the energy-limited escape (EL) approximation in which the loss rate is roughly proportional to the heating rate, Q. In applying the EL approximation, it was also frequently assumed that the adiabatic expansion resulted in the gas outflow going sonic. Johnson et al. (2013) used molecular kinetic simulations of an atmosphere with a heated layer to show this was not necessarily the case and estimated a critical heating rate, Qc. For Q greater than ~Qc a sonic point formed below the exobase where the gas properties were collision dominated. As Q increased above ~Qc sonic escape was eventually limited by the energy and number fluxes from the below the heated layer. In that case, adiabatic cooling did dominate upper atmosphere cooling, but the escape rate did not increase with increasing Q as predicted by the EL model. Instead, the escape rate remained nearly constant and the energy per molecule carried off increased nearly monotonically with Q. For heating rates from about twice Qc to more than an order of magnitude lower, the molecular escape rate was well approximated by the energy limited rate, but the upper atmospheric structure could not be described by a fluid model with a sonic point and escape was Jeans-like although the Jeans expressions was often a poor approximation. That is, molecules escape from well below the nominal exobase and collisions remained important well above it (Tucker et al. 2009; 2013) resulting in enhanced-Jeans-like escape (Volkov et al. 2011a,b; Erwin et al. 2013). Here we give a new expression for the escape rate produced by adiabatic cooling and expansion of the upper atmosphere and apply it to atmospheric loss from an early Titan atmosphere and related atmospheres.Ref.: Erwin,J.T., et

  14. Formation, habitability, and detection of extrasolar moons.

    PubMed

    Heller, René; Williams, Darren; Kipping, David; Limbach, Mary Anne; Turner, Edwin; Greenberg, Richard; Sasaki, Takanori; Bolmont, Emeline; Grasset, Olivier; Lewis, Karen; Barnes, Rory; Zuluaga, Jorge I

    2014-09-01

    The diversity and quantity of moons in the Solar System suggest a manifold population of natural satellites exist around extrasolar planets. Of peculiar interest from an astrobiological perspective, the number of sizable moons in the stellar habitable zones may outnumber planets in these circumstellar regions. With technological and theoretical methods now allowing for the detection of sub-Earth-sized extrasolar planets, the first detection of an extrasolar moon appears feasible. In this review, we summarize formation channels of massive exomoons that are potentially detectable with current or near-future instruments. We discuss the orbital effects that govern exomoon evolution, we present a framework to characterize an exomoon's stellar plus planetary illumination as well as its tidal heating, and we address the techniques that have been proposed to search for exomoons. Most notably, we show that natural satellites in the range of 0.1-0.5 Earth mass (i) are potentially habitable, (ii) can form within the circumplanetary debris and gas disk or via capture from a binary, and (iii) are detectable with current technology.

  15. Formation, habitability, and detection of extrasolar moons.

    PubMed

    Heller, René; Williams, Darren; Kipping, David; Limbach, Mary Anne; Turner, Edwin; Greenberg, Richard; Sasaki, Takanori; Bolmont, Emeline; Grasset, Olivier; Lewis, Karen; Barnes, Rory; Zuluaga, Jorge I

    2014-09-01

    The diversity and quantity of moons in the Solar System suggest a manifold population of natural satellites exist around extrasolar planets. Of peculiar interest from an astrobiological perspective, the number of sizable moons in the stellar habitable zones may outnumber planets in these circumstellar regions. With technological and theoretical methods now allowing for the detection of sub-Earth-sized extrasolar planets, the first detection of an extrasolar moon appears feasible. In this review, we summarize formation channels of massive exomoons that are potentially detectable with current or near-future instruments. We discuss the orbital effects that govern exomoon evolution, we present a framework to characterize an exomoon's stellar plus planetary illumination as well as its tidal heating, and we address the techniques that have been proposed to search for exomoons. Most notably, we show that natural satellites in the range of 0.1-0.5 Earth mass (i) are potentially habitable, (ii) can form within the circumplanetary debris and gas disk or via capture from a binary, and (iii) are detectable with current technology. PMID:25147963

  16. Title: Characterizing a Frozen Extrasolar World

    NASA Technical Reports Server (NTRS)

    Skemer, Andrew J.; Morley, Caroline V.; Allers, Katelyn N.; Geballe, Thomas R.; Marley, Mark S.; Fortney, Jonathan J.; Faherty, Jacqueline K.; Bjoraker, Gordon L.

    2016-01-01

    The recently discovered brown dwarf WISE 0855 presents our first opportunity to study an object outside the Solar System that is nearly as cold as our own gas giant planets. However the traditional methodology for characterizing brown dwarfs-near infrared spectroscopy-is not currently feasible as WISE 0855 is too cold and faint. To characterize this frozen extrasolar world we obtained a 4.5-5.2 micrometers spectrum, the same bandpass long used to study Jupiter's deep thermal emission. Our spectrum reveals the presence of atmospheric water vapor and clouds, with an absorption profile that is strikingly similar to Jupiter. The spectrum is high enough quality to allow the investigation of dynamical and chemical processes that have long been studied in Jupiter's atmosphere, but this time on an extrasolar world.

  17. DETECTING OCEANS ON EXTRASOLAR PLANETS USING THE GLINT EFFECT

    SciTech Connect

    Robinson, Tyler D.; Meadows, Victoria S.; Crisp, David

    2010-09-20

    Glint, the specular reflection of sunlight off Earth's oceans, may reveal the presence of oceans on an extrasolar planet. As an Earth-like planet nears crescent phases, the size of the ocean glint spot increases relative to the fraction of the illuminated disk, while the reflectivity of this spot increases. Both effects change the planet's visible reflectivity as a function of phase. However, strong forward scattering of radiation by clouds can also produce increases in a planet's reflectivity as it approaches crescent phases, and surface glint can be obscured by Rayleigh scattering and atmospheric absorption. Here, we explore the detectability of glint in the presence of an atmosphere and realistic phase-dependent scattering from oceans and clouds. We use the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model to simulate Earth's broadband visible brightness and reflectivity over an orbit. Our validated simulations successfully reproduce phase-dependent Earthshine observations. We find that the glinting Earth can be as much as 100% brighter at crescent phases than simulations that do not include glint, and that the effect is dependent on both orbital inclination and wavelength, where the latter dependence is caused by Rayleigh scattering limiting sensitivity to the surface. We show that this phenomenon may be observable using the James Webb Space Telescope paired with an external occulter.

  18. Role of desorption processes in the formation of K in tenuous planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Madey, T. E.; Yakshinskiy, B. V.

    2001-11-01

    We will discuss recent laboratory data indicating that DIET processes (desorption induced by electronic transitions) may affect planetary atmospheres. We focus on the origins of neutral potassium vapor in the atmospheres of the planet Mercury, the Moon, and the icy satellites of Jupiter. We are conducting ultrahigh-vacuum studies of adsorption and desorption of atomic potassium on model mineral systems (SiO2 thin films), as well as on models of icy satellite surfaces (condensed water ice films). We found evidence previously that non-thermal processes - mainly photon-stimulated desorption (PSD) by UV photons - may play a dominant role in desorption of Na atoms from the lunar surface[1], and the present results indicate that K can be desorbed by PSD. The desorption mechanism involves a photon-excited charge-exchange process, in which adsorbed ionic K is converted to neutral K, which desorbs. Recent data on desorption from a lunar sample will be discussed. [1] B. V. Yakshinskiy and T. E. Madey, Nature 400(1999) 642; Surface Science 451 (2000) 160. This work has been supported in part by NASA

  19. The Astrometric Imaging Telescope - A space-based observatory for extra-solar planet detection

    NASA Technical Reports Server (NTRS)

    Pravdo, Steven H.

    1991-01-01

    The paper describes the objectives, techniques, instrumentation, and mission of the planned Astrometric Imaging Telescope. This space-based observatory is designed to detect and characterize extra-solar planetary systems. Results will contribute to the understanding of the astrophysics of stellar and planetary formation and provide an impetus for the study of exobiology.

  20. Stratospheric Observatory for Infrared Astornomy and Planetary Science

    NASA Astrophysics Data System (ADS)

    Reach, William T.; SOFIA Sciece Mission Operations

    2016-10-01

    The Stratospheric Observatory for Infrared Astronomy enables observations at far-infrared wavelengths, including the range 30-300 microns that is nearly completely obscured from the ground. By flying in the stratosphere above 95% of atmospheric water vapor, access is opened to photometric, spectroscopic, and polarimetric observations of Solar System targets spanning small bodies through major planets. Extrasolar planetary systems can be observed through their debris disks or transits, and forming planetary systems through protoplanetary disks, protostellar envelopes, and molecular cloud cores. SOFIA operates out of Southern California most of the year. For the summer of 2016, we deployed to New Zealand with 3 scientific instruments. The HAWC+ far-infrared photopolarimeter was recently flown and is in commissioning, and two projects are in Phase A study to downselect to one new facility instrument. The Cycle 5 observing proposal results are anticipated to be be released by the time of this DPS meeting, and successful planetary proposals will be advertised.

  1. How common are aeolian processes on planetary bodies with very thin atmospheres?

    NASA Astrophysics Data System (ADS)

    Pähtz, Thomas; Duran, Orencio

    2016-04-01

    Observations from the Voyager 2, New Horizons, and Rosetta missions indicate that aeolian surface features, such as ripples and dunes, do not only occur on the surfaces of Earth, Mars, and Titan, but seemingly also on the surfaces of planetary bodies with extremely thin atmospheres, such as Triton, Pluto, and the comet 67P/Churyumov-Gerasimenko. This is highly intriguing since the saltation-threshold wind shear velocities predicted for these bodies from standard saltation-threshold models are so large that wind erosion actually should not occur. Here, guided by coupled DEM/RANS numerical simulations of sediment transport in Newtonian fluid using the numerical model by Duran et al. (POF 24, 103306, 2012), we propose an analytical model based entirely on physical princinples that predicts the minimal fluid speeds required to sustain sediment transport in Newtonian fluid. The analytical model is consistent with measurements of the transport threshold in water and Earth's air and with a recent observational estimate of the threshold on Mars. When applied to Triton and Pluto, it predicts threshold wind shear velocities (ut) of about 1-3m/s, which is comparable to wind shear occurring during storms on Earth and Mars, for particles with diameters (d) within the range d ∈ [200,3000]μm. The minimal values (≈ 1m/s) are thereby predicted for surprisingly large particles with d ≈ 2000μm. When applied to 67P/Churyumov-Gerasimenko, the analytical model predicts threshold wind shear velocities that are fairly extreme (e.g., ut = 45m/s for d = 1cm), but nonetheless consistent with wind shear velocities estimated to occur on this comet. From our results, we conclude that surface-shaping wind erosion and thus the occurrence of aeolian surface features might be much more common on low-air-density planetary bodies than previously thought.

  2. Aerial Vehicle Surveys of other Planetary Atmospheres and Surfaces: Imaging, Remote-sensing, and Autonomy Technology Requirements

    NASA Technical Reports Server (NTRS)

    Young, Larry A.; Pisanich, Gregory; Ippolito, Corey; Alena, Rick

    2005-01-01

    The objective of this paper is to review the anticipated imaging and remote-sensing technology requirements for aerial vehicle survey missions to other planetary bodies in our Solar system that can support in-atmosphere flight. In the not too distant future such planetary aerial vehicle (a.k.a. aerial explorers) exploration missions will become feasible. Imaging and remote-sensing observations will be a key objective for these missions. Accordingly, it is imperative that optimal solutions in terms of imaging acquisition and real-time autonomous analysis of image data sets be developed for such vehicles.

  3. Possibilities for the detection of microbial life on extrasolar planets.

    PubMed

    Knacke, Roger F

    2003-01-01

    We consider possibilities for the remote detection of microbial life on extrasolar planets. The Darwin/Terrestrial Planet Finder (TPF) telescope concepts for observations of terrestrial planets focus on indirect searches for life through the detection of atmospheric gases related to life processes. Direct detection of extraterrestrial life may also be possible through well-designed searches for microbial life forms. Satellites in Earth orbit routinely monitor colonies of terrestrial algae in oceans and lakes by analysis of reflected ocean light in the visible region of the spectrum. These remote sensing techniques suggest strategies for extrasolar searches for signatures of chlorophylls and related photosynthetic compounds associated with life. However, identification of such life-related compounds on extrasolar planets would require observations through strong, interfering absorptions and scattering radiances from the remote atmospheres and landmasses. Techniques for removal of interfering radiances have been extensively developed for remote sensing from Earth orbit. Comparable techniques would have to be developed for extrasolar planet observations also, but doing so would be challenging for a remote planet. Darwin/TPF coronagraph concepts operating in the visible seem to be best suited for searches for extrasolar microbial life forms with instruments that can be projected for the 2010-2020 decades, although resolution and signal-to-noise ratio constraints severely limit detection possibilities on terrestrial-type planets. The generation of telescopes with large apertures and extremely high spatial resolutions that will follow Darwin/TPF could offer striking possibilities for the direct detection of extrasolar microbial life.

  4. Possibilities for the detection of microbial life on extrasolar planets.

    PubMed

    Knacke, Roger F

    2003-01-01

    We consider possibilities for the remote detection of microbial life on extrasolar planets. The Darwin/Terrestrial Planet Finder (TPF) telescope concepts for observations of terrestrial planets focus on indirect searches for life through the detection of atmospheric gases related to life processes. Direct detection of extraterrestrial life may also be possible through well-designed searches for microbial life forms. Satellites in Earth orbit routinely monitor colonies of terrestrial algae in oceans and lakes by analysis of reflected ocean light in the visible region of the spectrum. These remote sensing techniques suggest strategies for extrasolar searches for signatures of chlorophylls and related photosynthetic compounds associated with life. However, identification of such life-related compounds on extrasolar planets would require observations through strong, interfering absorptions and scattering radiances from the remote atmospheres and landmasses. Techniques for removal of interfering radiances have been extensively developed for remote sensing from Earth orbit. Comparable techniques would have to be developed for extrasolar planet observations also, but doing so would be challenging for a remote planet. Darwin/TPF coronagraph concepts operating in the visible seem to be best suited for searches for extrasolar microbial life forms with instruments that can be projected for the 2010-2020 decades, although resolution and signal-to-noise ratio constraints severely limit detection possibilities on terrestrial-type planets. The generation of telescopes with large apertures and extremely high spatial resolutions that will follow Darwin/TPF could offer striking possibilities for the direct detection of extrasolar microbial life. PMID:14678662

  5. Polarimetry of hot-Jupiter systems and radiative transfer models of planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Bott, Kimberly; Bailey, Jeremy; Kedziora-Chudczer, Lucyna; Cotton, Daniel; Marshall, Jonathan

    2016-01-01

    Thousands of exoplanets and planet candidates have been detected. The next important step in the contexts of astrobiology, planetary classification and planet formation is to characterise them. My dissertation aims to provide further characterisation to four hot Jupiter exoplanets: the relatively well-characterised HD 189733b, WASP-18b which is nearly large enough to be a brown dwarf, and two minimally characterised non-transiting hot Jupiters: HD 179949b and tau Bootis b.For the transiting planets, this is done through two means. First, published data from previous observations of the secondary eclipse (and transit for HD 189733b) are compared to models created with the Versatile Software for the Transfer of Atmospheric Radiation (VSTAR). Second, new polarimetric observations from the HIgh Precision Polarimetric Instrument are compared to Lambert-Rayleigh polarised light phase curves. For the non-transiting planets, only the polarimetric measurements are compared to models, but toy radiative transfer models are produced for concept. As an introduction to radiative transfer models, VSTAR is applied to the planet Uranus to measure its D/H isotope ratio. A preliminary value is derived for D/H in one part of the atmosphere.Fitting a single atmospheric model to the transmitted, reflected, and emitted light, I confirm the presence of water on HD 189733b, and present a new temperature profile and cloud profile for the planet. For WASP-18b, I confirm the general shape of the temperature profile. No conclusions can be drawn from the polarimetric measurements for the non-transiting planets. I detect a possible variation with phase for transiting planet WASP-18b but cannot confirm it at this time. Alternative sources to the planet are discussed. For HD 189733b, I detect possible variability in the polarised light at the scale expected for the planet. However, the data are also statistically consistent with no variability and are not matched to the phase of the planet.

  6. Commission 53: Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Boss, Alan; Lecavelier des Etangs, Alain; Mayor, Michel; Bodenheimer, Peter; Collier-Cameron, Andrew; Kokubo, Eiichiro; Mardling, Rosemary; Minniti, Dante; Queloz, Didier

    2012-04-01

    Commission 53 was created at the 2006 Prague General Assembly (GA) of the IAU, in recognition of the outburst of astronomical progress in the field of extrasolar planet discovery, characterization, and theoretical work that has occurred since the discovery of the first planet in orbit around a solar-type star in 1995. Commission 53 is the logical successor to the IAU Working Group on Extrasolar Planets (WGESP), which ended its six years of existence in August 2006. The founding President of Commission 53 was Michael Mayor, in honor of his seminal contributions to this new field of astronomy. The current President is Alan Boss, the former chair of the WGESP. The current members of the Commission 53 (C53) Organizing Committee (OC) began their service in August 2009 at the conclusion of the Rio de Janeiro IAU GA.

  7. Planetary Systems and the Origins of Life

    NASA Astrophysics Data System (ADS)

    Pudritz, Ralph; Higgs, Paul; Stone, Jonathon

    2013-01-01

    Preface; Part I. Planetary Systems and the Origins of Life: 1. Observations of extrasolar planetary systems Shay Zucker; 2. The atmospheres of extrasolar planets L. Jeremy Richardson and Sara Seager; 3. Terrestrial planet formation Edward Thommes; 4. Protoplanetary disks, amino acids and the genetic code Paul Higgs and Ralph Pudritz; 5. Emergent phenomena in biology: the origin of cellular life David Deamer; Part II. Life on Earth: 6. Extremophiles: defining the envelope for the search for life in the Universe Lynn Rothschild; 7. Hyperthermophilic life on Earth - and on Mars? Karl Stetter; 8. Phylogenomics: how far back in the past can we go? Henner Brinkmann, Denis Baurain and Hervé Philippe; 9. Horizontal gene transfer, gene histories and the root of the tree of life Olga Zhaxybayeva and J. Peter Gogarten; 10. Evolutionary innovation versus ecological incumbency Adolf Seilacher; 11. Gradual origins for the Metazoans Alexandra Pontefract and Jonathan Stone; Part III. Life in the Solar System?: 12. The search for life on Mars Chris McKay; 13. Life in the dark dune spots of Mars: a testable hypothesis Eörs Szathmary, Tibor Ganti, Tamas Pocs, Andras Horvath, Akos Kereszturi, Szaniszlo Berzci and Andras Sik; 14. Titan: a new astrobiological vision from the Cassini-Huygens data François Raulin; 15. Europa, the Ocean Moon: tides, permeable ice, and life Richard Greenberg; Index.

  8. VISTA: a micro-thermogravimeter to analyze condensable species in planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Palomba, Ernesto; Zampetti, Emiliano; Longobardo, Andrea; Biondi, David; Saggin, Bortolino; Boccaccini, Angelo; Dirri, Fabrizio

    Thermogravimetry is a technique largely used in order to study absorption/desorption and sublimation/evaporation processes in several environments. Micro-thermogravimetry (mu-TGA) is particularly suitable for space applications, due to the very small mass, volume and power required by mu-TGA sensors. VISTA (Volatile In Situ Thermogravimetry Analyser) is a micro-thermogravimeter developed at IAPS-INAF (Rome) which aims to measure the amount of volatiles of scientific interest (e.g. water, organics) in planetary environments. It is based on Piezoelectric Crystal Microbalances (PCM), whose resonant frequency is linearly related to the deposited mass. The PCM heating/cooling allows the release/deposition of volatile materials, allowing to measure their abundance and to infer their composition. The instrument has been selected in the payload of the ESA MarcoPolo-R proposed mission, aiming to analyze in situ and bring to Earth samples of asteroidal regolith. In this framework, VISTA would measure the water and organic content in the asteroid regolith, detect the possible cometary-like activity of the asteroid and assess the contamination issue. VISTA could be used also to assess relevant scientific issue concerning planetary atmospheres. It has been studied for the ESA Cosmic Vision proposed missions EVE (European Venus Explorer) and TAE (Titan Aerial Explorer), which planned an in-situ analysis of the Venus and Titan atmosphere, respectively. In the framework of a Venus in-situ mission, VISTA would have the following goals: - Measurement of dew points of condensable species, and hence of humidity (by cooling the PCM down to condensation temperatures) - Measurement of amount of refractory species in the Venus cloud aerosols (by heating the PCM) - Measurement of electric charge of cloud particles (by coupling the thermogravimeter and an electric field generator) In the framework of a Titan in-situ mission, the heating of the VISTA PCM would: - determine the presence of

  9. THE COMPOSITIONAL DIVERSITY OF EXTRASOLAR TERRESTRIAL PLANETS. II. MIGRATION SIMULATIONS

    SciTech Connect

    Carter-Bond, Jade C.; O'Brien, David P.; Raymond, Sean N.

    2012-11-20

    Prior work has found that a variety of terrestrial planetary compositions are expected to occur within known extrasolar planetary systems. However, such studies ignored the effects of giant planet migration, which is thought to be very common in extrasolar systems. Here we present calculations of the compositions of terrestrial planets that formed in dynamical simulations incorporating varying degrees of giant planet migration. We used chemical equilibrium models of the solid material present in the disks of five known planetary host stars: the Sun, GJ 777, HD4203, HD19994, and HD213240. Giant planet migration has a strong effect on the compositions of simulated terrestrial planets as the migration results in large-scale mixing between terrestrial planet building blocks that condensed at a range of temperatures. This mixing acts to (1) increase the typical abundance of Mg-rich silicates in the terrestrial planets' feeding zones and thus increase the frequency of planets with Earth-like compositions compared with simulations with static giant planet orbits, and (2) drastically increase the efficiency of the delivery of hydrous phases (water and serpentine) to terrestrial planets and thus produce waterworlds and/or wet Earths. Our results demonstrate that although a wide variety of terrestrial planet compositions can still be produced, planets with Earth-like compositions should be common within extrasolar planetary systems.

  10. Helium 584 Å and H Lyman-α Airglow in Giant Planetary Atmospheres: Modeling, Observations, and Implications

    NASA Astrophysics Data System (ADS)

    Parkinson, Christopher; Esposito, Larry W.

    2016-07-01

    The atmosphere of the outer planets is mainly composed of H2 and neutral atomic helium. The study of He 584 Å and H Lyman-α brightnesses is interesting as the EUV and FUV (Extreme and Far Ultraviolet) planetary airglow have the potential to yield useful information about mixing and other important parameters in their thermospheres. Time variation, asymmetries, and polar enhancement of the airglow are also possible and analysis of the public archived NASA mission data sets (i.e. Voyager and Cassini) can help solve some of the outstanding problems associated with these phenomena. The comparison of observations with results from sophisticated photochemical and radiative transfer models can also help ameliorate unexplained differences in the dynamical processes operating within planetary upper atmospheres. Powerful analysis techniques allow us to extract information on atmospheric mixing, temperatures, and temporal changes due to the solar and seasonal cycles from the variations in distribution and intensity of airglow emissions that result. The presentation will discuss the implications of interpretations from comparison of modeling and observations in giant planetary atmospheres.

  11. Satellite radio occultation investigations of internal gravity waves in the planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Kirillovich, Ivan; Gubenko, Vladimir; Pavelyev, Alexander

    Internal gravity waves (IGWs) modulate the structure and circulation of the Earth’s atmosphere, producing quasi-periodic variations in the wind velocity, temperature and density. Similar effects are anticipated for the Venus and Mars since IGWs are a characteristic of stably stratified atmosphere. In this context, an original method for the determination of IGW parameters from a vertical temperature profile measurement in a planetary atmosphere has been developed [Gubenko et al., 2008, 2011, 2012]. This method does not require any additional information not contained in the profile and may be used for the analysis of profiles measured by various techniques. The criterion for the IGW identification has been formulated and argued. In the case when this criterion is satisfied, the analyzed temperature fluctuations can be considered as wave-induced. The method is based on the analysis of relative amplitudes of the wave field and on the linear IGW saturation theory in which these amplitudes are restricted by dynamical (shear) instability processes in the atmosphere. When the amplitude of an internal wave reaches the shear instability threshold, energy is assumed to be dissipated in such a way that the IGW amplitude is maintained at the instability threshold level as the wave propagates upwards. We have extended the developed technique [Gubenko et al., 2008] in order to reconstruct the complete set of wave characteristics including such important parameters as the wave kinetic and potential energy per unit mass and IGW fluxes of the energy and horizontal momentum [Gubenko et al., 2011]. We propose also an alternative method to estimate the relative amplitudes and to extract IGW parameters from an analysis of perturbations of the Brunt-Vaislala frequency squared [Gubenko et al., 2011]. An application of the developed method to the radio occultation (RO) temperature data has given the possibility to identify the IGWs in the Earth's, Martian and Venusian atmospheres and

  12. Toward a coherent set of radiative transfer tools for the analysis of planetary atmospheres .

    NASA Astrophysics Data System (ADS)

    Grassi, D.; Ignatiev, N. I.; Zasova, L. V.; Piccioni, G.; Adriani, A.; Moriconi, M. L.; Sindoni, G.; D'Aversa, E.; Snels, M.; Altieri, F.; Migliorini, A.; Stefani, S.; Politi, R.; Dinelli, B. M.; Geminale, A.; Rinaldi, G.

    The IAPS experience in the field of analysis of planetary atmospheres from visual and infrared measurements dates back to the early '90 in the frame of the IFSI participation to the Mars96 program. Since then, the forward models as well as retrieval schemes have been constantly updated and have seen a large usage in the analysis of data from Mars Express, Venus Express and Cassini missions. At the eve of a new series of missions (Juno, ExoMars, JUICE), we review the tools currently available to the Italian community, the latest developments and future perspectives. Notably, recent reanalysis of PFS-MEX and VIRTIS-VEX data \\citep{Grassi2014} leaded to a full convergence of complete Bayesian retrieval schemes and approximate forward models, achieving a degree of maturity and flexibility quite close to the state-of-the-art NEMESIS package \\citep{Irwin2007}. As a test case, the retrieval code for the JIRAM observations of hot-spots will be discussed, with extensive validation against simulated observations.

  13. A Chemical Kinetics Network for Lightning and Life in Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Rimmer, P. B.; Helling, Ch

    2016-05-01

    There are many open questions about prebiotic chemistry in both planetary and exoplanetary environments. The increasing number of known exoplanets and other ultra-cool, substellar objects has propelled the desire to detect life and prebiotic chemistry outside the solar system. We present an ion-neutral chemical network constructed from scratch, Stand2015, that treats hydrogen, nitrogen, carbon, and oxygen chemistry accurately within a temperature range between 100 and 30,000 K. Formation pathways for glycine and other organic molecules are included. The network is complete up to H6C2N2O3. Stand2015 is successfully tested against atmospheric chemistry models for HD 209458b, Jupiter, and the present-day Earth using a simple one-dimensional photochemistry/diffusion code. Our results for the early Earth agree with those of Kasting for CO2, H2, CO, and O2, but do not agree for water and atomic oxygen. We use the network to simulate an experiment where varied chemical initial conditions are irradiated by UV light. The result from our simulation is that more glycine is produced when more ammonia and methane is present. Very little glycine is produced in the absence of any molecular nitrogen and oxygen. This suggests that the production of glycine is inhibited if a gas is too strongly reducing. Possible applications and limitations of the chemical kinetics network are also discussed.

  14. Arctic Sea Ice Export Through Fram Strait and Atmospheric Planetary Waves

    NASA Technical Reports Server (NTRS)

    Cavalieri, Donald J.; Koblinsky, Chester (Technical Monitor)

    2001-01-01

    A link is found between the variability of Arctic sea ice export through Ram Strait and the phase of the longest atmospheric planetary wave (zonal wave 1) in SLP for the period 1958-1997. Previous studies have identified a link between From Strait ice export and the North Atlantic Oscillation (NAO), but this link has been described as unstable because of a lack of consistency over time scales longer than the last two decades. Inconsistent and low correlations are also found between From Strait ice export and the Arctic Oscillation (AD) index. This paper shows that the phase of zonal wave 1 explains 60% - 70% of the simulated From Strait ice export variance over the Goodyear period 1958 - 1997. Unlike the NAB and AD links, these high variances are consistent for both the first and second halves of the Goodyear period. This consistency is attributed to the sensitivity of the wave I phase at high latitudes to the presence of secondary low pressure systems in the Barents Sea that serve to drive sea ice southward through From Strait. These results provide further evidence that the phase of zonal wave 1 in SLP at high latitudes drives regional as well as hemispheric low frequency Arctic Ocean and sea ice variability.

  15. Atmosphere in a Test Tube

    NASA Astrophysics Data System (ADS)

    Claudi, R.; Pace, E.; Ciaravella, A.; Micela, G.; Piccioni, G.; Billi, D.; Cestelli Guidi, M.; Coccola, L.; Erculiani, M. S.; Fedel, M.; Galletta, G.; Giro, E.; La Rocca, N.; Morosinotto, T.; Poletto, L.; Schierano, D.; Stefani, S.

    The ancestor philosophers' dream of thousand of new world is finally realised: more than 1800 extrasolar planets have been discovered in the neighborhood of our Sun. Most of them are very different from those we used to know in our Solar System. Others orbit the Habitable Zone (HZ) of their parent stars. Space missions, as JWST and the very recently proposed ARIEL, or ground based instruments, like SPHERE@VLT, GPI@GEMINI and EPICS@ELT, have been proposed and built to measure the atmospheric transmission, reflection and emission spectra over a wide wavelength range of these new worlds. In order to interpret the spectra coming out by this new instrumentation, it is important to know in detail the optical characteristics of gases in the typical physical conditions of the planetary atmospheres and how those characteristics could be affected by radiation driven photochemical and bio-chemical reaction. Insights in this direction can be achieved from laboratory studies of simulated planetary atmosphere of different pressure and temperature conditions under the effects of radiation sources, used as proxies of different bands of the stellar emission. ''Atmosphere in a Test Tube'' is a collaboration among several Italian astronomical, biological and engineering institutes in order to share their experiencece in performing laboratory experiments on several items concerning extrasolar planet atmospheres.

  16. Pervasive orbital eccentricities dictate the habitability of extrasolar earths.

    PubMed

    Kita, Ryosuke; Rasio, Frederic; Takeda, Genya

    2010-09-01

    The long-term habitability of Earth-like planets requires low orbital eccentricities. A secular perturbation from a distant stellar companion is a very important mechanism in exciting planetary eccentricities, as many of the extrasolar planetary systems are associated with stellar companions. Although the orbital evolution of an Earth-like planet in a stellar binary system is well understood, the effect of a binary perturbation on a more realistic system containing additional gas-giant planets has been very little studied. Here, we provide analytic criteria confirmed by a large ensemble of numerical integrations that identify the initial orbital parameters leading to eccentric orbits. We show that an extrasolar earth is likely to experience a broad range of orbital evolution dictated by the location of a gas-giant planet, which necessitates more focused studies on the effect of eccentricity on the potential for life. PMID:20879864

  17. Pervasive orbital eccentricities dictate the habitability of extrasolar earths.

    PubMed

    Kita, Ryosuke; Rasio, Frederic; Takeda, Genya

    2010-09-01

    The long-term habitability of Earth-like planets requires low orbital eccentricities. A secular perturbation from a distant stellar companion is a very important mechanism in exciting planetary eccentricities, as many of the extrasolar planetary systems are associated with stellar companions. Although the orbital evolution of an Earth-like planet in a stellar binary system is well understood, the effect of a binary perturbation on a more realistic system containing additional gas-giant planets has been very little studied. Here, we provide analytic criteria confirmed by a large ensemble of numerical integrations that identify the initial orbital parameters leading to eccentric orbits. We show that an extrasolar earth is likely to experience a broad range of orbital evolution dictated by the location of a gas-giant planet, which necessitates more focused studies on the effect of eccentricity on the potential for life.

  18. A laboratory investigation of the production and properties of molecular and radical species pertinent to planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Fahr, Askar; Herron, John; Laufer, Allan H.

    1990-01-01

    Vinylidene (H2C=C) is shown to be the largest photodecomposition channel in the direct photolysis of both C2H2 and C2H4. The chemistry of H2C=C as it relates to planetary atmospheres is discussed. The vinyl radical (C2H3), important in the acetylene chemistry cycle, has been directly observed spectroscopically and the kinetics of several key reactions of this species measured.

  19. Extrasolar Planet Inferometric Survey (EPIcS)

    NASA Technical Reports Server (NTRS)

    Shao, Michael; Baliunas, Sallie; Boden, Andrew; Kulkarni, Shrinivas; Lin, Douglas N. C.; Loredo, Tom; Queloz, Didier; Shaklan, Stuart; Tremaine, Scott; Wolszczan, Alexander

    2004-01-01

    The discovery of the nature of the solar system was a crowning achievement of Renaissance science. The quest to evaluate the properties of extrasolar planetary systems is central to both the intellectual understanding of our origins and the cultural understanding of humanity's place in the Universe; thus it is appropriate that the goals and objectives of NASA's breakthrough Origins program emphasize the study of planetary systems, with a focus on the search for habitable planets. We propose an ambitious research program that will use SIM - the first major mission of the Origins program - to explore planetary systems in our Galactic neighborhood. Our program is a novel two-tiered SIM survey of nearby stars that exploits the capabilities of SIM to achieve two scientific objectives: (i) to identify Earth-like planets in habitable regions around nearby Sunlike stars: and (ii) to explore the nature and evolution of planetary systems in their full variety. The first of these objectives was recently recommended by the Astronomy and Astrophysics Survey Committee (the McKee-Taylor Committee) as a prerequisite for the development of the Terrestrial Planet Finder mission later in the decade. Our program combines this two-part survey with preparatory and contemporaneous research designed to maximize the scientific return from the limited and thus precious observing resources of SIM.

  20. Characterization of extrasolar terrestrial planets from diurnal photometric variability.

    PubMed

    Ford, E B; Seager, S; Turner, E L

    2001-08-30

    The detection of massive planets orbiting nearby stars has become almost routine, but current techniques are as yet unable to detect terrestrial planets with masses comparable to the Earth's. Future space-based observatories to detect Earth-like planets are being planned. Terrestrial planets orbiting in the habitable zones of stars-where planetary surface conditions are compatible with the presence of liquid water-are of enormous interest because they might have global environments similar to Earth's and even harbour life. The light scattered by such a planet will vary in intensity and colour as the planet rotates; the resulting light curve will contain information about the planet's surface and atmospheric properties. Here we report a model that predicts features that should be discernible in the light curve obtained by low-precision photometry. For extrasolar planets similar to Earth, we expect daily flux variations of up to hundreds of per cent, depending sensitively on ice and cloud cover as well as seasonal variations. This suggests that the meteorological variability, composition of the surface (for example, ocean versus land fraction) and rotation period of an Earth-like planet could be derived from photometric observations. Even signatures of Earth-like plant life could be constrained or possibly, with further study, even uniquely determined.

  1. Extrasolar Planets in the Classroom

    ERIC Educational Resources Information Center

    George, Samuel J.

    2011-01-01

    The field of extrasolar planets is still, in comparison with other astrophysical topics, in its infancy. There have been about 300 or so extrasolar planets detected and their detection has been accomplished by various different techniques. Here we present a simple laboratory experiment to show how planets are detected using the transit technique.…

  2. A Balloon-Borne Telescope System for Planetary Atmosphere and Plasma Studies

    NASA Astrophysics Data System (ADS)

    Taguchi, M.; Yoshida, K.; Sakamoto, Y.; Kanazawa, T.; Shoji, Y.; Sawakami, T.; Takahashi, Y.; Hoshino, N.; Sato, T.; Sakanoi, T.

    2007-12-01

    A telescope floating in the polar stratosphere can continuously monitor planets for more than 24 hours. Thin, clear and stable air of the stratosphere makes it possible to observe planets in a condition free from cloud with fine seeing and high atmospheric transmittance. Moreover, a balloon-borne telescope system is less expensive compared with a huge terrestrial telescope or a direct planetary probe mission. Targets of a balloon-borne telescope system will extend over various atmospheric and plasma phenomena on almost all the planets, i.e., a sodium tail of Mercury, lightning, airglow and aurora in the atmospheres of Venus, Jupiter and Saturn, escaping atmospheres of the Earth-type planets, satellite-induced luminous events in the Jovian atmosphere, etc. The first target is global dynamics of the Venusian atmosphere by detecting cloud motion in UV and NIR imagery. A decoupling mechanism and a pair of control moment gyros (CMGs) are mounted at the top of the gondola. The decoupling mechanism isolates the gondola from a balloon and also transfers an excess angular momentum of the CMGs to the balloon. The attitude of the gondola is stabilized at a constant sun azimuthal angle so that a solar cell panel faces to the sun. A 300 mm F30 Schmidt-Cassegrain telescope is installed at the bottom of the gondola. DC/DC converters, a PC, a high voltage power supply for a piezo-electrically moving mirror and digital video recorders are contained in a sealed cell. The azimuthal angle is detected by a sun-sensor. A PC processes sensor output to control DC motors used in the decoupling mechanism and CMGs with an accuracy in azimuthal attitude of about 0.5 deg. The two-axis gimbal mount of the telescope is controlled by the same PC, guiding an object within a field-of-view of a guide telescope. Residual tracking error is detected by a position sensitive photomultiplier tube and corrected by the two-axis moving mirror installed in the optical system. The optical path is divided into

  3. HAT-P-15b: A 10.9 DAY EXTRASOLAR PLANET TRANSITING A SOLAR-TYPE STAR

    SciTech Connect

    Kovacs, G.; Bakos, G. A.; Hartman, J. D.; Torres, G.; Noyes, R. W.; Latham, D. W.; Sasselov, D. D.; Stefanik, R. P.; Esquerdo, G. A.; Fernandez, J. M.; Howard, A. W.; Marcy, G. W.; Isaacson, H.; Fischer, D. A.; Johnson, J. A.; Lazar, B. Beky J.; Papp, I.; Sari, P.

    2010-12-01

    We report the discovery of HAT-P-15b, a transiting extrasolar planet in the 'period valley', a relatively sparsely populated period regime of the known extrasolar planets. The host star, GSC 2883-01687, is a G5 dwarf with V= 12.16. It has a mass of 1.01 {+-} 0.04 M{sub sun}, radius of 1.08 {+-} 0.04 R{sub sun}, effective temperature 5568 {+-} 90 K, and metallicity [Fe/H] = +0.22 {+-} 0.08. The planetary companion orbits the star with a period P = 10.863502 {+-} 0.000027 days, transit epoch T{sub c} = 2454638.56019 {+-} 0.00048 (BJD), and transit duration 0.2285 {+-} 0.0015 days. It has a mass of 1.946 {+-} 0.066 M{sub J} and radius of 1.072 {+-} 0.043 R{sub J} yielding a mean density of 1.96 {+-} 0.22 g cm{sup -3}. At an age of 6.8{sup +2.5}{sub -1.6} Gyr, the planet is H/He-dominated and theoretical models require about 2% (10 M{sub +}) worth of heavy elements to reproduce its measured radius. With an estimated equilibrium temperature of {approx}820 K during transit, and {approx}1000 K at occultation, HAT-P-15b is a potential candidate to study moderately cool planetary atmospheres by transmission and occultation spectroscopy.

  4. Modelling of N2 Vegard-Kaplan and LBH emissions in the planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Jain, Sonal Kumar; Bhardwaj, Anil

    The N_{2} triplet band emissions are common features in the dayglow of Earth. Recent discoveries of N _{2} Vegard-Kaplan (VK) band emissions on Mars by SPICAM/Mars-Express and N _{2} VK and LBH band emissions on Titan by Cassini's UVIS have led planetary scientists to look for the processes governing the N _{2} triplet and singlet band emissions in different planetary atmospheres. We have developed a model to calculate N _{2} triplet and Lyman-Birge-Hopefield (LBH) band emissions in the dayglow of Venus, Mars, Titan, and Pluto. The Steady state photoelectron fluxes and volume excitation rates have been calculated using the Analytical Yield Spectra (AYS) technique. Since interstate cascading is important for triplet and singlet states of N _{2}, the population of any given level of N _{2} triplet and singlet states is calculated under statistical equilibrium considering direct excitation, cascading, and quenching effects. Relative population of all vibrational levels of each triplet and singlet states is calculated in the model. Line of sight intensities and height-integrated overhead intensities have been calculated for VK ( A(3Sigma_u^+) - X(1Sigma^+_g) ), first positive ( B(3Pi_g) - A(3Sigma^+_u) ), second positive ( C(3Pi_u) - B(3Pi_g) ), Wu-Benesch (W(3Delta_u) - B(3Pi_g) ), B '-> B, E -> B, E-> C, E-> A, and LBH (a(1Pi_g) - X(1Sigma^+_g) ) bands of N _{2}. The N _{2} VK band span wavelength range from far ultraviolet to visible, and some transitions even originate at wavelength more than 1000 nm. Our calculations show that the overhead intensity of VK bands in the wavelength range 400-800, 300-190, 200-300, and 150-200 nm are 22%, 39%, 35%, and 4% of the total VK band emission. On Titan, the calculated intensities of N _{2} VK and LBH bands in 150-190 and 120-190 nm wavelength range, respectively, are in good agreement with the Cassini-UVIS observation. On Mars, calculated intensities of N _{2} VK bands are in agreement with the SPICAM observed limb profile of

  5. HITRAN2016 : new and improved data and tools towards studies of planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Gordon, Iouli; Rothman, Laurence S.; Wilzewski, Jonas S.; Kochanov, Roman V.; Hill, Christian; Tan, Yan; Wcislo, Piotr

    2016-10-01

    The HITRAN2016 molecular spectroscopic database is scheduled to be released this year. It will replace the current edition, HITRAN2012 [1], which has been in use, along with some intermediate updates, since 2012.We have added, revised, and improved many transitions and bands of molecular species and their isotopologues. Also, the amount of parameters has also been significantly increased, now incorporating, for instance, broadening by He, H2 and CO2 which are dominant in different planetary atmospheres [2]; non-Voigt line profiles [3]; and other phenomena. This poster will provide a summary of the updates, emphasizing details of some of the most important or drastic improvements or additions.To allow flexible incorporation of the new parameters and improve the efficiency of the database usage, the whole database has been reorganized into a relational database structure and presented to the user by means of a very powerful, easy-to-use internet program called HITRANonline [4] accessible at . This interface allows the user many queries in standard and user-defined formats. In addition, a powerful application called HAPI (HITRAN Application Programing Interface) [5] was developed. HAPI is a set of Python libraries that allows much more functionality for the user. Demonstration of the power of the new tools will also be offered.This work is supported by the NASA PATM (NNX13AI59G), PDART (NNX16AG51G) and AURA (NNX14AI55G) programs.References[1] L.S. Rothman et al, JQSRT 130, 4 (2013)[2] J. S. Wilzewski et al., JQSRT 168, 193 (2016)[3] P. Wcislo et al., JQSRT 177, 75 (2016)[4] C. Hill et al, JQSRT 177, 4 (2016)[5] R.V. Kochanov et al, JQSRT 177, 15 (2016)

  6. Planetary-scale wave structures of the earth's atmosphere revealed from the COSMIC observations

    NASA Astrophysics Data System (ADS)

    Anisetty, S. K. A. V. Prasad Rao; Brahmanandam, P. S.; Uma, G.; Babu, A. Narendra; Huang, Ching-Yuang; Kumar, G. Anil; Ram, S. Tulasi; Wang, Hsiao-Lan; Chu, Yen-Hsyang

    2014-02-01

    GPS radio occultation (GPS RO) method, an active satellite-to-satellite remote sensing technique, is capable of producing accurate, all-weather, round the clock, global refractive index, density, pressure, and temperature profiles of the troposphere and stratosphere. This study presents planetary-scale equatorially trapped Kelvin waves in temperature profiles retrieved using COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) satellites during 2006-2009 and their interactions with background atmospheric conditions. It is found that the Kelvin waves are not only associated with wave periods of higher than 10 days (slow Kelvin waves) with higher zonal wave numbers (either 1 or 2), but also possessing downward phase progression, giving evidence that the source regions of them are located at lower altitudes. A thorough verification of outgoing longwave radiation (OLR) reveals that deep convection activity has developed regularly over the Indonesian region, suggesting that the Kelvin waves are driven by the convective activity. The derived Kelvin waves show enhanced (diminished) tendencies during westward (eastward) phase of the quasi-biennial oscillation (QBO) in zonal winds, implying a mutual relation between both of them. The El Niño and Southern Oscillation (ENSO) below 18 km and the QBO features between 18 and 27 km in temperature profiles are observed during May 2006-May 2010 with the help of an adaptive data analysis technique known as Hilbert Huang Transform (HHT). Further, temperature anomalies computed using COSMIC retrieved temperatures are critically evaluated during different phases of ENSO, which has revealed interesting results and are discussed in light of available literature.

  7. Elemental compositions of two extrasolar rocky planetesimals

    SciTech Connect

    Xu, S.; Jura, M.; Klein, B.; Zuckerman, B.; Koester, D. E-mail: jura@astro.ucla.edu E-mail: ben@astro.ucla.edu

    2014-03-10

    We report Keck/HIRES and Hubble Space Telescope/COS spectroscopic studies of extrasolar rocky planetesimals accreted onto two hydrogen atmosphere white dwarfs, G29-38 and GD 133. In G29-38, eight elements are detected, including C, O, Mg, Si, Ca, Ti, Cr, and Fe while in GD 133, O, Si, Ca, and marginally Mg are seen. These two extrasolar planetesimals show a pattern of refractory enhancement and volatile depletion. For G29-38, the observed composition can be best interpreted as a blend of a chondritic object with some refractory-rich material, a result from post-nebular processing. Water is very depleted in the parent body accreted onto G29-38, based on the derived oxygen abundance. The inferred total mass accretion rate in GD 133 is the lowest of all known dusty white dwarfs, possibly due to non-steady state accretion. We continue to find that a variety of extrasolar planetesimals all resemble to zeroth order the elemental composition of bulk Earth.

  8. Turbulence in planetary occultations. II - Effects on atmospheric profiles derived from Doppler measurements. III - Effects on atmospheric profiles derived from intensity measurements

    NASA Technical Reports Server (NTRS)

    Haugstad, B. S.

    1978-01-01

    The nature and magnitude of turbulence-induced errors in atmospheric profiles derived from Doppler measurements made during radio occultations are investigated. It is found that turbulence in planetary atmospheres induces both fluctuating and systematic errors in derived profiles, but the errors of both types are very small. Consideration of the occultation of Mariner 10 by Venus and of the Pioneer occultations by Jupiter shows that the rms fractional errors in the atmospheric profiles derived from these observations were less than 0.01 in both temperature and pressure, while the fractional systematic errors were typically of the order of 1 millionth. The extent to which atmospheric profiles derived from radio and optical intensity measurements are affected by turbulence is also examined. The results indicate that turbulence in planetary atmospheres has only a marginal effect on derived profiles in the weak-scattering limit and that the turbulence-induced errors in this case are always much larger than the corresponding errors in profiles derived from radio Doppler measurements.

  9. Detecting Extrasolar Planets With Millimeter-Wave Observatories

    NASA Astrophysics Data System (ADS)

    1996-01-01

    Do nearby stars have planetary systems like our own? How do such systems evolve? How common are such systems? Proposed radio observatories operating at millimeter wavelengths could start answering these questions within the next 6-10 years, according to scientists at the National Radio Astronomy Observatory (NRAO). Bryan Butler, Robert Brown, Richard Simon, Al Wootten and Darrel Emerson, all of NRAO, presented their findings today to the American Astronomical Society meeting in San Antonio, TX. Detecting planets circling other stars is a particularly difficult task, and only a few such planets have been discovered so far. In order to answer fundamental questions about planetary systems and their origin, scientists need to find and study many more extrasolar planets. According to the NRAO scientists, millimeter-wavelength observatories could provide valuable information about extrasolar planetary systems at all stages of their evolution. "With instruments planned by 2005, we could detect planets the size of Jupiter around a solar-type star out to a distance of 100 light-years," said Robert Brown, Associate Director of NRAO. "That means," he added, "that we could survey approximately 2,000 stars of different types to learn if they have planets this size." Millimeter waves occupy the portion of the electromagnetic spectrum between radio microwaves and infrared waves. Telescopes for observing at millimeter wavelengths utilize advanced electronic equipment similar to that used in radio telescopes observing at longer wavelengths. Millimeter-wave observatories offer a number of advantages in the search for extrasolar planets. Planned multi-antenna millimeter-wave telescopes can provide much higher resolving power, or ability to see fine detail, than current optical or infrared telescopes. Millimeter-wave observations would not be degraded by interference from the "zodiacal light" reflected by interplanetary dust, either in the extrasolar system or our own solar system

  10. Photochemical abiotic synthesis of amino-acid precursors from simulated planetary atmospheres by vacuum ultraviolet light

    NASA Astrophysics Data System (ADS)

    Takahashi, Jun-Ichi; Masuda, Hitomi; Kaneko, Takeo; Kobayashi, Kensei; Saito, Takeshi; Hosokawa, Teruo

    2005-07-01

    For the purpose of investigating the photon energy dependence of the photoinduced abiotic synthesis of organic molecules, gas mixtures that simulate typical planetary atmospheres, including a carbon source (CO or CH4), a nitrogen source (N2 or NH3), and H2O, were irradiated with synchrotron radiation through a vacuum-ultraviolet transmitting window. Three kinds of window material, fused silica, synthetic quartz, and MgF2, were used as a high-energy-cutting filter, whose absorption-edge energies are 6.4, 8.1, and 10.5 eV, respectively. Three types of gas mixture, Titan-type (CH4-N2-H2O), comet-type (CO-NH3-H2O), and primitive-Earth-type (CO-N2-H2O), were irradiated with vacuum-ultraviolet photons in the three energy ranges. After the irradiation, amino-acid formation yields in the acid-hydrolyzed solution of the product were measured with a high-performance liquid chromatograph method. From the Titan- and comet-type mixtures, amino acids were detected by irradiation with photons lower than 8.1 eV. For both mixtures, the averaged quantum yields of glycine generation in the photon energy region of 7-10.5 eV were of the order of 10-5, which was larger by about one order than that in the region 5-8 eV. On the other hand, from the primitive-Earth-type mixture, amino-acid formation was difficult to detect even with irradiation as high as 10.5 eV, even though amino acids were generated in comparable yields from the Titan- and comet-type mixtures by irradiation with soft x rays or proton beam, whose energies are much higher. These results suggest that the vacuum ultraviolet light is a more effective energy source for the generation of the precursors of bioorganic compounds in extraterrestrial environments than in primitive-Earth atmosphere.

  11. Laboratory and theoretical work in the service of planetary atmospheric research

    NASA Astrophysics Data System (ADS)

    Coustenis, Athena

    2015-08-01

    A large quantity of observations is obtained by instruments onboard space missions exploring our solar system and by large ground-based telescopes observing the planets and also the exoplanets. Spectroscopy plays a major role in this type of investigation. To analyze and exploit these observations, planetary scientists need spectroscopic data covering wide ranges in wavelength but also in temperature, pressure, distance, etc.The outer regions of our solar system in particular, including the giant gaseous planets Jupiter and Saturn and their satellites, have recently been the target of space missions such as Cassini-Huygens and several investigations from the ground. Titan, the largest moon of Saturn, in particular, offers many similarities with our own planet, among which a dense atmosphere whose major component is dinitrogen at about 95%. Combining with methane (at a few percent) and hydrogen, gives rise to a complex organic chemistry with hydrocarbons and nitriles. Oxygen compounds also exist in Titan’s atmosphere. By studying Titan, we learn about our own planet and our Solar system Solar as a whole [1,2,3]. To properly interpret the Cassini-Huygens data and in anticipation of future missions like ESA’s JUICE to the Jupiter system, spectroscopic data are crucially needed. In the field of exoplanets (over 1000 discovered to date), it also becomes urgent to have adequate data of several molecules in order to analyze the observations returned to us every day by major observatories on Earth and in the space [4,5]. I will discuss recent applications from theoretical and experimental studies on the investigation of Titan and exoplanets, with emphasis on methane. I will also present some needs for future analyses.References: [1] Campargue, A., et al. 2012. Icarus 219, 110-128. [2] Coustenis, A., et al. 2013. Astrophys. J. 799, 177, 9p. [3] Hirtzig, et al., 2013. Icarus 226, 470-486 and corrigendum 1182-1182. [4] Tinetti, G., Encrenaz, Th., Coustenis, A., 2013

  12. Photochemical abiotic synthesis of amino-acid precursors from simulated planetary atmospheres by vacuum ultraviolet light

    SciTech Connect

    Takahashi, Jun-ichi; Masuda, Hitomi; Kaneko, Takeo; Kobayashi, Kensei; Saito, Takeshi; Hosokawa, Teruo

    2005-07-15

    For the purpose of investigating the photon energy dependence of the photoinduced abiotic synthesis of organic molecules, gas mixtures that simulate typical planetary atmospheres, including a carbon source (CO or CH{sub 4}), a nitrogen source (N{sub 2} or NH{sub 3}), and H{sub 2}O, were irradiated with synchrotron radiation through a vacuum-ultraviolet transmitting window. Three kinds of window material, fused silica, synthetic quartz, and MgF{sub 2}, were used as a high-energy-cutting filter, whose absorption-edge energies are 6.4, 8.1, and 10.5 eV, respectively. Three types of gas mixture, Titan-type (CH{sub 4}-N{sub 2}-H{sub 2}O), comet-type (CO-NH{sub 3}-H{sub 2}O), and primitive-Earth-type (CO-N{sub 2}-H{sub 2}O), were irradiated with vacuum-ultraviolet photons in the three energy ranges. After the irradiation, amino-acid formation yields in the acid-hydrolyzed solution of the product were measured with a high-performance liquid chromatograph method. From the Titan- and comet-type mixtures, amino acids were detected by irradiation with photons lower than 8.1 eV. For both mixtures, the averaged quantum yields of glycine generation in the photon energy region of 7-10.5 eV were of the order of 10{sup -5}, which was larger by about one order than that in the region 5-8 eV. On the other hand, from the primitive-Earth-type mixture, amino-acid formation was difficult to detect even with irradiation as high as 10.5 eV, even though amino acids were generated in comparable yields from the Titan- and comet-type mixtures by irradiation with soft x rays or proton beam, whose energies are much higher. These results suggest that the vacuum ultraviolet light is a more effective energy source for the generation of the precursors of bioorganic compounds in extraterrestrial environments than in primitive-Earth atmosphere.

  13. Imaging Extrasolar Giant Planets

    NASA Astrophysics Data System (ADS)

    Bowler, Brendan P.

    2016-10-01

    High-contrast adaptive optics (AO) imaging is a powerful technique to probe the architectures of planetary systems from the outside-in and survey the atmospheres of self-luminous giant planets. Direct imaging has rapidly matured over the past decade and especially the last few years with the advent of high-order AO systems, dedicated planet-finding instruments with specialized coronagraphs, and innovative observing and post-processing strategies to suppress speckle noise. This review summarizes recent progress in high-contrast imaging with particular emphasis on observational results, discoveries near and below the deuterium-burning limit, and a practical overview of large-scale surveys and dedicated instruments. I conclude with a statistical meta-analysis of deep imaging surveys in the literature. Based on observations of 384 unique and single young (≈5-300 Myr) stars spanning stellar masses between 0.1 and 3.0 M ⊙, the overall occurrence rate of 5-13 M Jup companions at orbital distances of 30-300 au is {0.6}-0.5+0.7 % assuming hot-start evolutionary models. The most massive giant planets regularly accessible to direct imaging are about as rare as hot Jupiters are around Sun-like stars. Dividing this sample into individual stellar mass bins does not reveal any statistically significant trend in planet frequency with host mass: giant planets are found around {2.8}-2.3+3.7 % of BA stars, <4.1% of FGK stars, and <3.9% of M dwarfs. Looking forward, extreme AO systems and the next generation of ground- and space-based telescopes with smaller inner working angles and deeper detection limits will increase the pace of discovery to ultimately map the demographics, composition, evolution, and origin of planets spanning a broad range of masses and ages.

  14. Planet Formation and the Characteristics of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    An overview of current theories of planetary growth, emphasizing the formation of extrasolar planets, is presented. Models of planet formation are based upon observations of the Solar System, extrasolar planets, and young stars and their environments. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth like terrestrial planets, but if they become massive enough before the protoplanetary disk dissipates, then they are able to accumulate substantial amounts of gas. These models predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. A potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path. The implications of the giant planets found in recent radial velocity searches for the abundances of habitable planets are discussed.

  15. PHOTOMETRIC ORBITS OF EXTRASOLAR PLANETS

    SciTech Connect

    Brown, Robert A.

    2009-09-10

    We define and analyze the photometric orbit (PhO) of an extrasolar planet observed in reflected light. In our definition, the PhO is a Keplerian entity with six parameters: semimajor axis, eccentricity, mean anomaly at some particular time, argument of periastron, inclination angle, and effective radius, which is the square root of the geometric albedo times the planetary radius. Preliminarily, we assume a Lambertian phase function. We study in detail the case of short-period giant planets (SPGPs) and observational parameters relevant to the Kepler mission: 20 ppm photometry with normal errors, 6.5 hr cadence, and three-year duration. We define a relevant 'planetary population of interest' in terms of probability distributions of the PhO parameters. We perform Monte Carlo experiments to estimate the ability to detect planets and to recover PhO parameters from light curves. We calibrate the completeness of a periodogram search technique, and find structure caused by degeneracy. We recover full orbital solutions from synthetic Kepler data sets and estimate the median errors in recovered PhO parameters. We treat in depth a case of a Jupiter body-double. For the stated assumptions, we find that Kepler should obtain orbital solutions for many of the 100-760 SPGP that Jenkins and Doyle estimate Kepler will discover. Because most or all of these discoveries will be followed up by ground-based radial velocity observations, the estimates of inclination angle from the PhO may enable the calculation of true companion masses: Kepler photometry may break the 'msin i' degeneracy. PhO observations may be difficult. There is uncertainty about how low the albedos of SPGPs actually are, about their phase functions, and about a possible noise floor due to systematic errors from instrumental and stellar sources. Nevertheless, simple detection of SPGPs in reflected light should be robust in the regime of Kepler photometry, and estimates of all six orbital parameters may be feasible in

  16. Planetary Surface Instruments Workshop

    NASA Technical Reports Server (NTRS)

    Meyer, Charles (Editor); Treiman, Allan H. (Editor); Kostiuk, Theodor (Editor)

    1996-01-01

    This report on planetary surface investigations and planetary landers covers: (1) the precise chemical analysis of solids; (2) isotopes and evolved gas analyses; (3) planetary interiors; planetary atmospheres from within as measured by landers; (4) mineralogical examination of extraterrestrial bodies; (5) regoliths; and (6) field geology/processes.

  17. Laboratory studies, analysis, and interpretation of the spectra of hydrocarbons present in planetary atmospheres including cyanoacetylene, acetylene, propane, and ethane

    NASA Technical Reports Server (NTRS)

    Blass, William E.; Daunt, Stephen J.; Peters, Antoni V.; Weber, Mark C.

    1990-01-01

    Combining broadband Fourier transform spectrometers (FTS) from the McMath facility at NSO and from NRC in Ottawa and narrow band TDL data from the laboratories with computational physics techniques has produced a broad range of results for the study of planetary atmospheres. Motivation for the effort flows from the Voyager/IRIS observations and the needs of Voyager analysis for laboratory results. In addition, anticipation of the Cassini mission adds incentive to pursue studies of observed and potentially observable constituents of planetary atmospheres. Current studies include cyanoacetylene, acetylene, propane, and ethane. Particular attention is devoted to cyanoacetylen (H3CN) which is observed in the atmosphere of Titan. The results of a high resolution infrared laboratory study of the line positions of the 663, 449, and 22.5/cm fundamental bands are presented. Line position, reproducible to better than 5 MHz for the first two bands, are available for infrared astrophysical searches. Intensity and broadening studies are in progress. Acetylene is a nearly ubiquitous atmospheric constituent of the outer planets and Titan due to the nature of methane photochemistry. Results of ambient temperature absolute intensity measurements are presented for the fundamental and two two-quantum hotband in the 730/cm region. Low temperature hotband intensity and linewidth measurements are planned.

  18. ATMOSPHERIC CIRCULATION OF ECCENTRIC HOT NEPTUNE GJ436b

    SciTech Connect

    Lewis, Nikole K.; Showman, Adam P.; Fortney, Jonathan J.; Marley, Mark S.; Freedman, Richard S.; Lodders, Katharina

    2010-09-01

    GJ436b is a unique member of the transiting extrasolar planet population being one of the smallest and least irradiated and possessing an eccentric orbit. Because of its size, mass, and density, GJ436b could plausibly have an atmospheric metallicity similar to Neptune (20-60 times solar abundances), which makes it an ideal target to study the effects of atmospheric metallicity on dynamics and radiative transfer in an extrasolar planetary atmosphere. We present three-dimensional atmospheric circulation models that include realistic non-gray radiative transfer for 1, 3, 10, 30, and 50 times solar atmospheric metallicity cases of GJ436b. Low metallicity models (1 and 3 times solar) show little day/night temperature variation and strong high-latitude jets. In contrast, higher metallicity models (30 and 50 times solar) exhibit day/night temperature variations and a strong equatorial jet. Spectra and light curves produced from these simulations show strong orbital phase dependencies in the 50 times solar case and negligible variations with orbital phase in the 1 times solar case. Comparisons between the predicted planet/star flux ratio from these models and current secondary eclipse measurements support a high metallicity atmosphere (30-50 times solar abundances) with disequilibrium carbon chemistry at play for GJ436b. Regardless of the actual atmospheric composition of GJ436b, our models serve to illuminate how metallicity influences the atmospheric circulation for a broad range of warm extrasolar planets.

  19. On the origin of jets and vortices in turbulent planetary atmospheres.

    NASA Astrophysics Data System (ADS)

    Jougla, Thibault; Dritschel, David G.

    2016-04-01

    Stratified rotating fluids tend to form large scale coherent structures. These structures are present in many different geophysical fluids, for example jet streams in the Earth's atmosphere, the famous and conspicuous jets in the Jovian atmosphere, and oceanic jets like the latent jets and the well-known main currents including the Gulf stream and Kuroshio. Observations, numerical models, and laboratory experiments have sought to explain their origins and their evolutions. To investigate the coexistence, evolution and vertical structure of jets and vortices in turbulent planetary atmospheres, we make use of the widely studied two-layer quasi-geostrophic shallow water model on the β-plane. Numerical simulations at ultra-high resolution are carried out with the Combined Lagrangian Advection Method [1]. Following Panetta 1988 [2], to characterise the pole to equator heating variation on a planet, a vertical shear is imposed and maintained by thermal damping. To crudely represent convection from the bottom layer to the top layer, hetons are constantly added to the flow. Many numerical simulations covering a large range of parameters have been run. The thermal damping and vertical shear dependence has been widely studied and analysed. The baroclinicity of the flow is clearly evident in all cases studied. Moreover, the flow is strongly dependent on thermal damping. There is a competition between baroclinic instabilities trying to reduce the imposed vertical shear and thermal damping trying to maintain the vertical shear. Without any thermal damping, the imposed vertical shear quickly erodes. On the other hand if the thermal damping is very high, the flow is mainly dominated by incoherent, small-scale turbulence. For weaker thermal damping, the competition between baroclinic instability and thermal damping may lead to oscillations between stable and turbulent phases. However, thermal damping does not have a significant impact on the number of homogeneous regions and jets

  20. Comparative Planetology and the Search for Habitable Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Meadows, V. S.

    2008-12-01

    In the last decade, comparative planetology has grown to encompass not just the planets in our own Solar System, but also the more than 300 planets that are now known to orbit other stars in our Galaxy. The vast majority of the planets discovered so far are gas or ice giants, but a growing fraction have masses less than 10 Earth masses, and so may be terrestrial. Over the next two decades, NASA and ESA are planning to build large space-borne telescopes that will enable statistical studies and the first direct detection and characterization of terrestrial planets beyond our Solar System. These missions will allow the study of planets formed under diverse initial conditions, and at stages of evolution that are billions of years younger or older than the Earth. Ultimately though, these missions will finally provide the technical capability to search for habitable environments and life on planets beyond our Solar System. The scientific foundation that will guide this search is built on comparative climate studies of the planets in our own Solar System. From the perspective of extrasolar planet studies, the evolution of the climates of Venus, Earth and Mars inform the definition and characteristics of planetary habitability. Climate and chemistry models, developed initially to be flexible enough for Venus, Earth and Mars studies, and validated against measurements and observations of these planets, are now being modified to model a diversity of plausible extrasolar planetary environments. Specifically, these models have been used to better understand the interaction between the parent star, and the global environment and biosphere of a terrestrial planet for planetary systems unlike our Solar System. Additionally, planetary radiative transfer models developed for Venus, Earth and Mars studies can be used to predict the spectroscopic appearance of distant planetary environments and to simulate a telescopic view of the Earth as an extrasolar planet. This presentation will

  1. Optical Spectra of Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.; Hubeny, Ivan; Sudarsky, David; Burrows, Adam

    2004-01-01

    The flux distribution of a planet relative to its host star is a critical quantity for planning space observatories to detect and characterize extrasolar giant planets (EGP's). In this paper, we present optical planet-star contrasts of Jupiter-mass planets as a function of stellar type, orbital distance, and planetary cloud characteristics. As originally shown by Sudarsky et al. (2000, 2003), the phaseaveraged brightness of an EGP does not necessarily decrease monotonically with greater orbital distance because of changes in its albedo and absorption spectrum at lower temperatures. We apply our results to Eclipse, a 1.8-m optical telescope + coronograph to be proposed as a NASA Discovery mission later this year.

  2. Analytic evaluation of the weighting functions for remote sensing of blackbody planetary atmospheres : the case of limb viewing geometry

    NASA Technical Reports Server (NTRS)

    Ustinov, Eugene A.

    2006-01-01

    In a recent publication (Ustinov, 2002), we proposed an analytic approach to evaluation of radiative and geophysical weighting functions for remote sensing of a blackbody planetary atmosphere, based on general linearization approach applied to the case of nadir viewing geometry. In this presentation, the general linearization approach is applied to the limb viewing geometry. The expressions, similar to those obtained in (Ustinov, 2002), are obtained for weighting functions with respect to the distance along the line of sight. Further on, these expressions are converted to the expressions for weighting functions with respect to the vertical coordinate in the atmosphere. Finally, the numerical representation of weighting functions in the form of matrices of partial derivatives of grid limb radiances with respect to the grid values of atmospheric parameters is used for a convolution with the finite field of view of the instrument.

  3. Direct imaging of extra-solar planets

    SciTech Connect

    Olivier, S.S.; Max, V.E.; Brase, J.M.; Caffano, C.J.; Gavel, D.T.; Macintosh, B.A.

    1997-03-01

    Direct imaging of extra-solar planets may be possible with the new generation of large ground-based telescopes equipped with state- of- the-art adaptive optics (AO) systems to compensate for the blurring effect of the Earth`s atmosphere. The first of these systems is scheduled to begin operation in 1998 on the 10 in Keck II telescope. In this paper, general formulas for high-contrast imaging with AO systems are presented and used to calculate the sensitivity of the Keck AO system. The results of these calculations show that the Keck AO system should achieve the sensitivity necessary to detect giant planets around several nearby bright stars.

  4. A TEOM (tm) particulate monitor for comet dust, near Earth space, and planetary atmospheres

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Scientific missions to comets, near earth space, and planetary atmospheres require particulate and mass accumulation instrumentation for both scientific and navigation purposes. The Rupprecht & Patashnick tapered element oscillating microbalance can accurately measure both mass flux and mass distribution of particulates over a wide range of particle sizes and loadings. Individual particles of milligram size down to a few picograms can be resolved and counted, and the accumulation of smaller particles or molecular deposition can be accurately measured using the sensors perfected and toughened under this contract. No other sensor has the dynamic range or sensitivity attained by these picogram direct mass measurement sensors. The purpose of this contract was to develop and implement reliable and repeatable manufacturing methods; build and test prototype sensors; and outline a quality control program. A dust 'thrower' was to be designed and built, and used to verify performance. Characterization and improvement of the optical motion detection system and drive feedback circuitry was to be undertaken, with emphasis on reliability, low noise, and low power consumption. All the goals of the contract were met or exceeded. An automated glass puller was built and used to make repeatable tapered elements. Materials and assembly methods were standardized, and controllers and calibrated fixtures were developed and used in all phases of preparing, coating and assembling the sensors. Quality control and reliability resulted from the use of calibrated manufacturing equipment with measurable working parameters. Thermal and vibration testing of completed prototypes showed low temperature sensitivity and high vibration tolerance. An electrostatic dust thrower was used in vacuum to throw particles from 2 x 10(exp 6) g to 7 x 10(exp -12) g in size. Using long averaging times, particles as small as 0.7 to 4 x 10(exp 11) g were weighted to resolutions in the 5 to 9 x 10(exp -13) g range

  5. Developments with the planetWRF and planetMPAS Planetary Atmospheric Models

    NASA Astrophysics Data System (ADS)

    Richardson, Mark I.; Lee, Christopher; Lian, Yuan; Mischna, Michael A.; Newman, Claire E.; Toigo, Anthony

    2016-10-01

    planetWRF is based upon the NCAR Weather Research and Forecasting (WRF) model and has been applied to Mars, Titan and Pluto. planetWRF offers global-scale, two-way interactive nested mesoscale, and microscale LES simulation of planetary atmospheres using a rectangular grid.Recently, a fully-coupled dust and water cycle aerosol scheme has been introduced based on Morrison and Gettelman [Lee et al., this conference]. The scheme treats both dust and water ice as two-moment distributions. Significantly, the scheme treats all processes (nucleation, growth, advection, sedimentation, radiation) using the two-moment distributions, with no lossy conversion between spectral and radius-bin representation.The LES modeing capability has been augmented with the ability to import HiRISE DTMs to allow simulation of small-scale flow over topography including the first order effects of local slope and shadowing. Simulations of Victoria crater (visited by Opportunity) show dramatic variations of surface temperature on scales of a few meters during the morning and distinct changes in the patterns of wind stress as the crater interior is coupled and decoupled from boundary layer convection at different times. The LES has also been augmented to run with dynamically and radiatively interactive dust.planetMPAS is based upon the NCAR Model for Prediction Across Scales (MPAS), an unstructured mesh model that allows for far more uniform resolution of the whole globe, uses a fully compressible nonhydrostatic dynamical core, and an advanced terrain-following coordinate system. The MPAS model been designed to use WRF physics routines. As such, planetMPAS and planetWRF are alternate dynamical cores within the same modeling system. planetMPAS has major advantages over WRF for certain kinds of global simulations: high-precision tracer problems, e.g. Argon transport on Mars; uniform resolution of polar regions, e.g. water ice cap interactions with the martian global water cycle; and convection

  6. Working model of the atmosphere and near planetary space of Jupiter

    NASA Technical Reports Server (NTRS)

    Moroz, V. I. (Editor)

    1978-01-01

    Basic physical characteristics of Jupiter, its gravitational field, atmosphere, electromagnetic radiation, magnetosphere, meteorite situation and satellites are presented in tables, graphs and figures. Means of observation of the atmosphere and three models of the atmosphere are presented and analyzed.

  7. On the thermal loss of a planetary atmosphere due to irradiation by the solar EUV during earlier and present epochs

    NASA Astrophysics Data System (ADS)

    Kulikov, Yuri N.; Lammer, Helmut

    2008-09-01

    Abstract. Since early 1980's a number of idealized hydrodynamic models have been developed to study thermal atmospheric escape from terrestrial planets due to extreme solar EUV-heating which was expected during the fist billion years after the Sun arrived to the Zero- Age-Main-Sequence. Later on such a type of "hydro-escape" models have been extrapolated to include also low mass outer solar system planets like Titan and Pluto irradiated by the present time solar EUV flux. From all these models Parker-type supersonic solutions have been obtained with a transonic point typically located at a distance of about 10 planetary radii or more from the planets. We have examined critically these idealized hydrodynamic models and found that the assumptions on which they are based are incompatible with the obtained supersonic solutions. As a result the thermal loss rates in the "hydro-escape" models seem to be grossly overestimated, temperature and density altitude profiles substantially deformed. An approximate method to solve this hydrodynamic modelling problem which is based on a combination of the hydrodynamic and kinetic approaches for estimating atmospheric loss from a planetary atmosphere exposed to high solar EUV radiation is suggested and analysed and its application to a specific planet is discussed.

  8. Taxonomy of the extrasolar planet.

    PubMed

    Plávalová, Eva

    2012-04-01

    When a star is described as a spectral class G2V, we know that the star is similar to our Sun. We know its approximate mass, temperature, age, and size. When working with an extrasolar planet database, it is very useful to have a taxonomy scale (classification) such as, for example, the Harvard classification for stars. The taxonomy has to be easily interpreted and present the most relevant information about extrasolar planets. I propose an extrasolar planet taxonomy scale with four parameters. The first parameter concerns the mass of an extrasolar planet in the form of units of the mass of other known planets, where M represents the mass of Mercury, E that of Earth, N Neptune, and J Jupiter. The second parameter is the planet's distance from its parent star (semimajor axis) described in a logarithm with base 10. The third parameter is the mean Dyson temperature of the extrasolar planet, for which I established four main temperature classes: F represents the Freezing class, W the Water class, G the Gaseous class, and R the Roasters class. I devised one additional class, however: P, the Pulsar class, which concerns extrasolar planets orbiting pulsar stars. The fourth parameter is eccentricity. If the attributes of the surface of the extrasolar planet are known, we are able to establish this additional parameter where t represents a terrestrial planet, g a gaseous planet, and i an ice planet. According to this taxonomy scale, for example, Earth is 1E0W0t, Neptune is 1N1.5F0i, and extrasolar planet 55 Cnc e is 9E-1.8R1.

  9. Taxonomy of the extrasolar planet.

    PubMed

    Plávalová, Eva

    2012-04-01

    When a star is described as a spectral class G2V, we know that the star is similar to our Sun. We know its approximate mass, temperature, age, and size. When working with an extrasolar planet database, it is very useful to have a taxonomy scale (classification) such as, for example, the Harvard classification for stars. The taxonomy has to be easily interpreted and present the most relevant information about extrasolar planets. I propose an extrasolar planet taxonomy scale with four parameters. The first parameter concerns the mass of an extrasolar planet in the form of units of the mass of other known planets, where M represents the mass of Mercury, E that of Earth, N Neptune, and J Jupiter. The second parameter is the planet's distance from its parent star (semimajor axis) described in a logarithm with base 10. The third parameter is the mean Dyson temperature of the extrasolar planet, for which I established four main temperature classes: F represents the Freezing class, W the Water class, G the Gaseous class, and R the Roasters class. I devised one additional class, however: P, the Pulsar class, which concerns extrasolar planets orbiting pulsar stars. The fourth parameter is eccentricity. If the attributes of the surface of the extrasolar planet are known, we are able to establish this additional parameter where t represents a terrestrial planet, g a gaseous planet, and i an ice planet. According to this taxonomy scale, for example, Earth is 1E0W0t, Neptune is 1N1.5F0i, and extrasolar planet 55 Cnc e is 9E-1.8R1. PMID:22506608

  10. High-Contrast Imaging using Adaptive Optics for Extrasolar Planet Detection

    SciTech Connect

    Evans, Julia Wilhelmsen

    2006-01-01

    Direct imaging of extrasolar planets is an important, but challenging, next step in planetary science. Most planets identified to date have been detected indirectly--not by emitted or reflected light but through the effect of the planet on the parent star. For example, radial velocity techniques measure the doppler shift in the spectrum of the star produced by the presence of a planet. Indirect techniques only probe about 15% of the orbital parameter space of our solar system. Direct methods would probe new parameter space, and the detected light can be analyzed spectroscopically, providing new information about detected planets. High contrast adaptive optics systems, also known as Extreme Adaptive Optics (ExAO), will require contrasts of between 10-6 and 10-7 at angles of 4-24 λ/D on an 8-m class telescope to image young Jupiter-like planets still warm with the heat of formation. Contrast is defined as the intensity ratio of the dark wings of the image, where a planet might be, to the bright core of the star. Such instruments will be technically challenging, requiring high order adaptive optics with > 2000 actuators and improved diffraction suppression. Contrast is ultimately limited by residual static wavefront errors, so an extrasolar planet imager will require wavefront control with an accuracy of better than 1 nm rms within the low- to mid-spatial frequency range. Laboratory demonstrations are critical to instrument development. The ExAO testbed at the Laboratory for Adaptive Optics was designed with low wavefront error and precision optical metrology, which is used to explore contrast limits and develop the technology needed for an extrasolar planet imager. A state-of-the-art, 1024-actuator micro-electrical-mechanical-systems (MEMS) deformable mirror was installed and characterized to provide active wavefront control and test this novel technology. I present 6.5 x 10-8 contrast measurements with a prolate shaped pupil and

  11. UV photoabsorption cross sections of CO, N2, and SO2 for studies of the ISM and planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Smith, Peter L.; Rufus, J.; Yoshino, K.; Parkinson, W. H.; Stark, Glenn; Pickering, Juliet C.; Thorne, A. P.

    2002-01-01

    We report high-resolution laboratory measurements of photoabsorption cross sections of CO, N2, and SO2 in the wavelength range 80 to 320 nm. The motivation is to provide the quantitative data that are needed to analyze observations of absorption by, and to model photochemical processes in, the interstellar medium and a number of planetary atmospheres. Because of the high resolution of the spectrometers used, we can minimize distortion of the spectrum that occurs when instrument widths are greater than the widths of spectral features being measured. In many cases, we can determine oscillator strengths of individual rotational lines - a unique feature of our work.

  12. Connection between the spherical albedo and the observable characteristics of a planetary atmosphere

    SciTech Connect

    Fomin, N.N.; Yanovitskii, E.G.

    1986-07-01

    Semiempirical dependences of the geometrical albedo and the reflection coefficient at the center of a planetary disk on the spherical albedo are found. The nonsteady analogs of these quantities are studied on the basis of the approximate equations obtained. These analogs can be used in the analysis of radiation transfer in forbidden molecular absorption bands.

  13. The correlation of VLF propagation variations with atmospheric planetary-scale waves

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Deland, R. J.; Potemra, T. A.; Gavin, R. F.

    1973-01-01

    Variations in the received daytime phase of long distance, cesium-controlled, VLF transmission were compared to the height variations of the 10-mb isobaric surface during the first three months of 1965 and 1969. The VLF phase values are also compared to height variations of constant electron densities in the E-region and to variations of f-min which have been shown to be well correlated with planetary-scale variations in the stratosphere by Deland and Cavalieri (1973). The VLF phase variations show good correlation with these previous ionospheric measurements and with the 10-mb surfaces. The planetary scale waves in the stratosphere are shown to be travelling on the average eastward in 1965 and westward in 1969. These correlations are interpreted as due to the propagation of travelling planetary scale waves with westward tilted wave fronts. Upward energy transport due to the vertical structure of those waves is also discussed. These correlations provide further evidence for the coupling between the lower ionosphere at about 70 km altitude (the daytime VLF reflection height and the stratosphere, and they demonstrate the importance of planetary wave phenomena to VLF propagation.

  14. Planetary population synthesis coupled with atmospheric escape: a statistical view of evaporation

    SciTech Connect

    Jin, Sheng; Ji, Jianghui; Mordasini, Christoph; Van Boekel, Roy; Henning, Thomas; Parmentier, Vivien E-mail: mordasini@mpia.de

    2014-11-01

    We apply hydrodynamic evaporation models to different synthetic planet populations that were obtained from a planet formation code based on the core-accretion paradigm. We investigated the evolution of the planet populations using several evaporation models, which are distinguished by the driving force of the escape flow (X-ray or EUV), the heating efficiency in energy-limited evaporation regimes, or both. Although the mass distribution of the planet populations is barely affected by evaporation, the radius distribution clearly shows a break at approximately 2 R {sub ⊕}. We find that evaporation can lead to a bimodal distribution of planetary sizes and to an 'evaporation valley' running diagonally downward in the orbital distance—planetary radius plane, separating bare cores from low-mass planets that have kept some primordial H/He. Furthermore, this bimodal distribution is related to the initial characteristics of the planetary populations because low-mass planetary cores can only accrete small primordial H/He envelopes and their envelope masses are proportional to their core masses. We also find that the population-wide effect of evaporation is not sensitive to the heating efficiency of energy-limited description. However, in two extreme cases, namely without evaporation or with a 100% heating efficiency in an evaporation model, the final size distributions show significant differences; these two scenarios can be ruled out from the size distribution of Kepler candidates.

  15. New Planetary Energy Balance, Ocean-Atmosphere Interaction and their Effects on Extreme Events in North Atlantic

    NASA Astrophysics Data System (ADS)

    Karrouk, Mohammed-Said

    2016-04-01

    Global warming has now reached the energetic phase of H2O's return to the ground after the saturation of the atmosphere in evaporation since the 80s and 90s of the last century, which were characterized by severe droughts, mainly in Africa. This phase is the result of the accumulation of thermal energy exchanges in the Earth-Ocean-Atmosphere system that resulted in the thrust reversal of the energy balance toward the poles. This situation is characterized by a new thermal distribution: above the ocean, the situation is more in surplus compared to the mainland, or even opposite when the balance is negative on the land, and in the atmosphere, warm thermal advection easily reach the North Pole (planetary crests), as well as cold advection push deep into North Africa and the Gulf of Mexico (planetary valleys). This "New Ground Energy Balance" establishes a "New Meridian Atmospheric Circulation (MAC)" with an undulating character throughout the year, including the winter characterized by intense latitudinal very active energy exchanges between the surplus areas (tropical) and the deficit (polar) on the one hand, and the atmosphere, the ocean and the continent on the other. The excess radiation balance increases the potential evaporation of the atmosphere and provides a new geographical distribution of H2O worldwide: the excess water vapor is easily converted by cold advection (polar vortex) to heavy rains that cause floods or snow storms that paralyze the normal functioning of human activities, which creates many difficulties for users and leaves damage and casualties, but ensures water availability missing since a long time in many parts of the world, in Africa, Europe and America. The new thermal distribution reorganizes the geography of atmospheric pressure: the ocean energy concentration is transmitted directly to the atmosphere, and the excess torque is pushed northward. The Azores anticyclone is strengthened and is a global lock by the Atlantic ridge at Greenland

  16. Detection of extrasolar planets via microlensing and occultation

    NASA Astrophysics Data System (ADS)

    Safizadeh, Neda

    2001-07-01

    As recently as five years ago, no extrasolar planetary companions of main sequence stars had been identified. The discovery 51 Peg b by Mayor & Queloz [49], was the first of many planetary detections. Since then, over fifty other planets have been found, all with the radial velocity technique. Here, we give an overview of various detection strategies for planets. We discuss studies in three separate areas of searching for extrasolar planets; high magnification and astrometric deviations during a microlensing event given a lens with a planetary companion, and the observational progress of a planet transit survey. We study the effects of a planetary companion to the lens during a microlensing event with numerical methods. By studying the photometric light curve of a microlensing event during its peak amplification, we find that a planetary signature can be definitively detected in the lensing zone (0.6-1.6 Einstein Ring Radii or RE) for masses greater than Jupiter's. The probability remains substantial for Saturn and even 10 Earth masses. The peak of the event can be predicted in advance, allowing for extrasolar planet detection with a relatively small use of resources over a short period of time. We introduce a new method of searching for extrasolar planets by monitoring the astrometric deviations of the source star during a microlensing event. We show that astrometric deviation curves can give information about the presence of a planet and allow for parameter extraction. By monitoring the center-of-light motion of microlensing alerts using high precision astrometric instruments, the probability of detecting a planet orbiting the lens is high. The addition of astrometric information to the photometric microlensing light curve greatly helps in determining the planetary mass and projected separation. We introduce a new numerical method for calculating astrometric motion and detecting probabilities. Lastly, we search for planet transits in old, relatively metal rich

  17. Formation of spectral lines in a planetary atmosphere. II - Spectroscopic evidence for the structure of the visible Venus clouds.

    NASA Technical Reports Server (NTRS)

    Hunt, G. E.

    1972-01-01

    We demonstrate in this article that there is spectroscopic evidence for the structure of the visible Venus cloud layers. From physically realistic models of the lower Venus atmosphere, we have shown that only observations of the phase variations of the CO2 bands in the Venus spectrum can provide the information for a unique identification of the structure of the cloud layers. It is proved that Venus cannot have a single dense cloud layer, but must have two scattering layers; a thin aerosol layer situated in the lower stratosphere, overlying a dense cloud deck. The aerosol plays an important role in the scattering of radiation, so that its identification provides an explanation of the reflecting layer-scattering model controversy for the interpretation of spectra formed in a cloudy planetary atmosphere.

  18. A Massively Parallel Particle Code for Rarefied Ionized and Neutral Gas Flows in Earth and Planetary Atmospheres, Ionospheres and Magnetospheres

    NASA Technical Reports Server (NTRS)

    Combi, Michael R.

    2004-01-01

    In order to understand the global structure, dynamics, and physical and chemical processes occurring in the upper atmospheres, exospheres, and ionospheres of the Earth, the other planets, comets and planetary satellites and their interactions with their outer particles and fields environs, it is often necessary to address the fundamentally non-equilibrium aspects of the physical environment. These are regions where complex chemistry, energetics, and electromagnetic field influences are important. Traditional approaches are based largely on hydrodynamic or magnetohydrodynamic MHD) formulations and are very important and highly useful. However, these methods often have limitations in rarefied physical regimes where the molecular collision rates and ion gyrofrequencies are small and where interactions with ionospheres and upper neutral atmospheres are important.

  19. Atmospheres in a Test Tube

    NASA Astrophysics Data System (ADS)

    Claudi, R.; Erculiani, M. S.; Giro, E.; D'Alessandro, M.; Galletta, G.

    2013-09-01

    The "Atmosphere in a Test Tube" project is a laboratory experiment that will be able to reproduce condition of extreme environments by means of a simulator. These conditions span from those existing inside some parts of the human body to combinations of temperatures, pressures, irradiation and atmospheric gases present on other planets. In this latter case the experiments to be performed will be useful as preliminary tests for both simulation of atmosphere of exoplanets and Solar System planets and Astrobiology experiments that should be performed by planetary landers or by instruments to be launched in the next years. In particular at INAF Astronomical Observatory of Padova Laboratory we are approaching the characterization of extrasolar planet atmospheres taking advantage by innovative laboratory experiments with a particular focus on low mass Neptunes and Super earths and low mass M dwarfs primaries.

  20. Pressure Effects on Product Channels of Hydrocarbon Radical-Radical Reactions; Implications for Modelling of Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Fahr, A.; Halpern, J.; N'doumi, M.

    2011-10-01

    Previously we had studied the kinetics and product channels of small unsaturated hydrocarbon radical (C2 and C3s) reactions relevant to planetary atmospheric modelling. Reactions of C2 radicals (such as vinyl, H2CCH and ethynyl C2H) and C3 radicals (such as propargyl, HCCCH2 and allyl, H2CCCH3) can affect the abundances of a large number of stable observable C3, C4, C5, C6 and larger molecules, including linear, aromatic and even poly aromatic molecules. We have experimentally determined pressuredependent product yields for self- and cross-radical reactions performed at 298 K and at selected pressures between ~4 Torr (0.5 kPa) and 760 Torr (101 kPa). Final products were determined by gas chromatograph with mass spectrometry/flame ionization detection (GC/MS/FID). In some cases complementary computational studies extended the pressure and temperature range of the observations and provided valuable information on complex reaction mechanisms. These studies provide a systematic framework so that important energetic and structural parameters for radical-radical reactions can be assessed. Here we report a compilation of our earlier results relevant to planetary atmospheres in addition to recent ones for allyl radical (H2CCCH3) reactions.

  1. Extrasolar planet detection

    NASA Technical Reports Server (NTRS)

    Korechoff, R. P.; Diner, D. J.; Tubbs, E. F.; Gaiser, S. L.

    1994-01-01

    This paper discusses the concept of extrasolar planet detection using a large-aperture infared imaging telescope. Coronagraphic stellar apodization techniques are less efficient at infrared wavelengths compared to the visible, as a result of practical limitations on aperture dimensions, thus necessitating additional starlight suppression to make planet detection feasible in this spectral domain. We have been investigating the use of rotational shearing interferometry to provide up to three orders of magnitude of starlight suppression over broad spectral bandwidths. We present a theoretical analysis of the system performance requirements needed to make this a viable instrument for planet detection, including specifications on the interferometer design and telescope aperture characteristics. The concept of using rotational shearing interferometry as a wavefront error detector, thus providing a signal that can be used to adaptively correct the wavefront, will be discussed. We also present the status of laboratory studies of on-axis source suppression using a recently constructed rotational shearing interferometer that currently operates in the visible.

  2. Planetary astronomy

    NASA Technical Reports Server (NTRS)

    Morrison, David; Hunten, Donald; Ahearn, Michael F.; Belton, Michael J. S.; Black, David; Brown, Robert A.; Brown, Robert Hamilton; Cochran, Anita L.; Cruikshank, Dale P.; Depater, Imke

    1991-01-01

    The authors profile the field of astronomy, identify some of the key scientific questions that can be addressed during the decade of the 1990's, and recommend several facilities that are critically important for answering these questions. Scientific opportunities for the 1990' are discussed. Areas discussed include protoplanetary disks, an inventory of the solar system, primitive material in the solar system, the dynamics of planetary atmospheres, planetary rings and ring dynamics, the composition and structure of the atmospheres of giant planets, the volcanoes of IO, and the mineralogy of the Martian surface. Critical technology developments, proposed projects and facilities, and recommendations for research and facilities are discussed.

  3. On the wavelength dependence of the effects of turbulence on average refraction angles in occultations by planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Haugstad, B. S.; Eshleman, V. R.

    1979-01-01

    The dependence of the effects of planetary atmospheric turbulence on radio or optical wavelength in occultation experiments is discussed, and the analysis of Hubbard and Jokipii (1977) is criticized. It is argued that in deriving a necessary condition for the applicability of their method, Hubbard and Jokipii neglect a factor proportional to the square of the ratio of atmospheric or local Fresnel zone radius and the inner scale of turbulence, and fail to establish sufficient conditions, thereby omitting the square of the ratio of atmospheric scale height and the local Fresnel zone radius. The total discrepancy is said to mean that the results correspond to geometrical optics instead of wave optics, as claimed, thus being inapplicable in a dicussion of wavelength dependence. Calculations based on geometrical optics show that the bias in the average bending angle depends on the wavelength in the same way as does the bias in phase path caused by turbulence in a homogeneous atmosphere. Hubbard and Jokipii comment that the criterion of Haugstad and Eshleman is incorrect and show that there is a large wave optical domain where the results are independent of wavelength.

  4. Earth-like habitats in planetary systems

    NASA Astrophysics Data System (ADS)

    Fritz, J.; Bitsch, B.; Kührt, E.; Morbidelli, A.; Tornow, C.; Wünnemann, K.; Fernandes, V. A.; Grenfell, J. L.; Rauer, H.; Wagner, R.; Werner, S. C.

    2014-08-01

    Understanding the concept of habitability is clearly related to an evolutionary knowledge of the particular planet-in-question. However, additional indications so-called "systemic aspects" of the planetary system as a whole governs a particular planet's claim on habitability. In this paper we focus on such systemic aspects and discuss their relevance to the formation of an "Earth-like" habitable planet. This contribution summarizes our results obtained by lunar sample work and numerical models within the framework of the Research Alliance "Planetary Evolution and Life". We consider various scenarios which simulate the dynamical evolution of the Solar System and discuss the consequences for the likelihood of forming an Earth-like world orbiting another star. Our model approach is constrained by observations of the modern Solar System and the knowledge of its history. Results suggest that on the one hand the long-term presence of terrestrial planets is jeopardized due to gravitational interactions if giant planets are present. On the other hand the habitability of inner rocky planets may be supported in those planetary systems hosting giant planets. Gravitational interactions within a complex multiple-body structure including giant planets may supply terrestrial planets with materials which formed in the colder region of the proto-planetary disk. During these processes, water, the prime requisite for habitability, is delivered to the inner system. This may occur either during the main accretion phase of terrestrial planets or via impacts during a post-accretion bombardment. Results for both processes are summarized and discussed with reference to the lunar crater record. Starting from a scenario involving migration of the giant planets this contribution discusses the delivery of water to Earth, the modification of atmospheres by impacts in a planetary system context and the likelihood of the existence of extrasolar Earth-like habitable worlds.

  5. Laboratory evaluation of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1984-01-01

    The microwave absorbing properties of gaseous sulfuric acid (H2SO4) under Venus atmospheric conditions are investigated. The results are applied to measurements from Mariner 5, Mariner 10, and Pioneer/Venus Radio Occultation experiments, to determine abundancies of gaseous sulfuric acid in the Venus atmosphere. The microwave properties of the vapors accompanying liquid H2SO4 are studied to estimate the vapor pressure in an atmospheric model.

  6. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1985-01-01

    Radio absorptivity data for the Venus middle atmosphere (1 to 6 atm, temperatures from 500 to 575K) obtained from spacecraft radio occultation experiments (at 3.6 to 13.4 cm wavelengths) and earth-based radio astronomical observations (1 to 3 cm wavelength range) are compared to laboratory observations at the latter wavelength range under simulated Venus conditions to infer abundances of microwave-absorbing atmospheric constituents, i.e. H2SO4 in a CO2 atmosphere.

  7. The final fate of planetary systems

    NASA Astrophysics Data System (ADS)

    Gaensicke, Boris

    2015-12-01

    The discovery of the first extra-solar planet around a main-sequence star in 1995 has changed the way we think about the Universe: our solar system is not unique. Twenty years later, we know that planetary systems are ubiquitous, orbit stars spanning a wide range in mass, and form in an astonishing variety of architectures. Yet, one fascinating aspect of planetary systems has received relatively little attention so far: their ultimate fate.Most planet hosts will eventually evolve into white dwarfs, Earth-sized stellar embers, and the outer parts of their planetary systems (in the solar system, Mars and beyond) can survive largely intact for billions of years. While scattered and tidally disrupted planetesimals are directly detected at a small number of white dwarfs in the form infrared excess, the most powerful probe for detecting evolved planetary systems is metal pollution of the otherwise pristine H/He atmospheres.I will present the results of a multi-cycle HST survey that has obtained COS observations of 136 white dwarfs. These ultraviolet spectra are exquisitely sensitive to the presence of metals contaminating the white atmosphere. Our sophisticated model atmosphere analysis demonstrates that at least 27% of all targets are currently accreting planetary debris, and an additional 29% have very likely done so in the past. These numbers suggest that planet formation around A-stars (the dominant progenitors of today's white dwarf population) is similarly efficient as around FGK stars.In addition to post-main sequence planetary system demographics, spectroscopy of the debris-polluted white dwarf atmospheres provides a direct window into the bulk composition of exo-planetesimals, analogous to the way we use of meteorites to determine solar-system abundances. Our ultraviolet spectroscopy is particularly sensitive to the detection of Si, a dominant rock-forming species, and we identify up to ten additional volatile and refractory elements in the most strongly

  8. Jupiter-like planets as dynamical barriers to inward-migrating super-Earths: a new understanding of the origin of Uranus and Neptune and predictions for extrasolar planetary systems

    NASA Astrophysics Data System (ADS)

    Morbidelli, Alessandro; Izidoro Da Costa, Andre'; Raymond, Sean

    2014-11-01

    Planets of 1-4 times Earth's size on orbits shorter than 100 days exist around 30-50% of all Sun-like stars. These ``hot super-Earths'' (or ``mini-Neptunes''), or their building blocks, might have formed on wider orbits and migrated inward due to interactions with the gaseous protoplanetary disk. The Solar System is statistically unusual in its lack of hot super-Earths. Here, we use a suite of dynamical simulations to show that gas-giant planets act as barriers to the inward migration of super-Earths initially placed on more distant orbits. Jupiter's early formation may have prevented Uranus and Neptune (and perhaps Saturn's core) from becoming hot super-Earths. It may actually have been crucial to the very formation of Uranus and Neptune. In fact, the large spin obliquities of these two planets argue that they experienced a stage of giant impacts from multi-Earth mass planetary embryos. We show that the dynamical barrier offered by Jupiter favors the mutual accretion of multiple migrating planetary embryos, favoring the formation of a few massive objects like Uranus and Neptune. Our model predicts that the populations of hot super-Earth systems and Jupiter-like planets should be anti-correlated: gas giants (especially if they form early) should be rare in systems with many hot super-Earths. Testing this prediction will constitute a crucial assessment of the validity of the migration hypothesis for the origin of close-in super-Earths.

  9. Earth as an Exoplanet: Lessons in Recognizing Planetary Habitability

    NASA Astrophysics Data System (ADS)

    Meadows, Victoria; Robinson, Tyler; Misra, Amit; Ennico, Kimberly; Sparks, William B.; Claire, Mark; Crisp, David; Schwieterman, Edward; Bussey, D. Ben J.; Breiner, Jonathan

    2015-01-01

    Earth will always be our best-studied example of a habitable world. While extrasolar planets are unlikely to look exactly like Earth, they may share key characteristics, such as oceans, clouds and surface inhomogeneity. Earth's globally-averaged characteristics can therefore help us to recognize planetary habitability in data-limited exoplanet observations. One of the most straightforward ways to detect habitability will be via detection of 'glint', specular reflectance from an ocean (Robinson et al., 2010). Other methods include undertaking a census of atmospheric greenhouse gases, or attempting to measure planetary surface temperature and pressure, to determine if liquid water would be feasible on the planetary surface. Here we present recent research on detecting planetary habitability, led by the NASA Astrobiology Institute's Virtual Planetary Laboratory Team. This work includes a collaboration with the NASA Lunar Science Institute on the detection of ocean glint and ozone absorption using Lunar Crater Observation and Sensing Satellite (LCROSS) Earth observations (Robinson et al., 2014). This data/model comparison provides the first observational test of a technique that could be used to determine exoplanet habitability from disk-integrated observations at visible and near-infrared wavelengths. We find that the VPL spectral Earth model is in excellent agreement with the LCROSS Earth data, and can be used to reliably predict Earth's appearance at a range of phases relevant to exoplanet observations. Determining atmospheric surface pressure and temperature directly for a potentially habitable planet will be challenging due to the lack of spatial-resolution, presence of clouds, and difficulty in spectrally detecting many bulk constituents of terrestrial atmospheres. Additionally, Rayleigh scattering can be masked by absorbing gases and absorption from the underlying surface. However, new techniques using molecular dimers of oxygen (Misra et al., 2014) and nitrogen

  10. Photochemical aerosol formation in planetary atmospheres: A comparison between Pluto and Titan

    NASA Astrophysics Data System (ADS)

    Lavvas, Panayotis; Strobel, Darrell F.; Lellouch, Emmanuel; Gurwell, Mark A.; Cheng, Andrew F.; Summers, Michael; Gladstone, Randy

    2016-10-01

    The New Horizons mission observations have revealed us that Pluto's atmosphere is rich in photochemical hazes that extend to high altitudes above its surface [1], apparently similar to those observed in Titan's atmosphere [2].We use detailed models combining photochemistry and microphysics in order to simulate the aerosol formation and growth in Pluto's atmosphere, as performed for Titan's atmosphere [3]. Here we discuss the possible mechanisms leading to the formation of haze particles in Pluto's atmosphere, and we evaluate the contribution of different growth processes (e.g. coagulation vs. condensation) to the resulting particle properties.Moreover we investigate the role of these particles in the radiative balance of Pluto's atmosphere and we compare the resulting particle properties, with those retrieved for Titan's upper atmosphere based on Cassini observations [4]. We discuss the similarities and difference between Pluto's and Titan's aerosols.[1] Gladstone et al., 2016, Science, 351, 6271[2] West et al., 2015, Titan's Haze, in Titan, Interior, Surface, Atmosphere and Space environment, Cambridge University Press[3] Lavvas et al., 2013, PNAS, pnas.1217059110[4] Lavvas et al., 2015, DPS47, id.205.08

  11. Extrasolar planet interactions

    NASA Astrophysics Data System (ADS)

    Barnes, Rory; Greenberg, Richard

    2008-05-01

    The dynamical interactions of planetary systems may be a clue to their formation histories. Therefore, the distribution of these interactions provides important constraints on models of planet formation. We focus on each system's apsidal motion and proximity to dynamical instability. Although only 25 multiple planet systems have been discovered to date, our analyses in these terms have revealed several important features of planetary interactions. 1) Many systems interact such that they are near the boundary between stability and instability. 2) Planets tend to form such that at least one planet's eccentricity periodically drops to near zero. 3) Mean-motion resonant pairs would be unstable if not for the resonance. 4) Scattering of approximately equal mass planets is unlikely to produce the observed distribution of apsidal behavior. 5) Resonant interactions may be identified through calculating a system's proximity to instability, regardless of knowledge of angles such as mean longitude and longitude of periastron (e.g. GJ 317 b and c are probably in a 4:1 resonance). These properties of planetary systems have been identified through calculation of two parameters that describe the interaction. The apsidal interaction can be quantified by determining how close a planet is to an apsidal separatrix (a boundary between qualitatively different types of apsidal oscillations, e.g. libration or circulation of the major axes). This value can be calculated through short numerical integrations. The proximity to instability can be measured by comparing the observed orbital elements to an analytic boundary that describes a type of stability known as Hill stability. We have set up a website dedicated to presenting the most up-to-date information on dynamical interactions: http://www.lpl.arizona.edu/~rory/research/xsp/dynamics.

  12. Absorption profile of a planetary atmosphere: a proposal for a scattering independent determination.

    PubMed

    Fymat, A L; Lenoble, J

    1972-10-01

    The use of scattering theory to infer atmospheric optical parameters requires the separation of absorption and scattering. It is demonstrated that a gradient flux relation exists that would provide the absorption (altitude) profile independently of scattering and irrespective of the state of polarization of the light field. The relation is derived for an atmosphere of plane-parallel or spherical geometry and for broad (continuum) and narrow (spectral line) frequency bands. The results are shown to hold, in particular, for the polarizations induced by both Rayleigh and Mie scattering in the field. Experimental setups are proposed for each of the cases considered of atmospheric geometry and frequency bandwidth. A final discussion considers the relevance of the present determination of the atmospheric absorption profile to the related problems of aerosol relative concentration, interpretation of radiometric and spectrometric data formed in the presence of scattering, clouds morphology, and radiative heat budget of the atmosphere.

  13. Earth as an Extrasolar Planet: Earth Model Validation Using EPOXI Earth Observations

    PubMed Central

    Meadows, Victoria S.; Crisp, David; Deming, Drake; A'Hearn, Michael F.; Charbonneau, David; Livengood, Timothy A.; Seager, Sara; Barry, Richard K.; Hearty, Thomas; Hewagama, Tilak; Lisse, Carey M.; McFadden, Lucy A.; Wellnitz, Dennis D.

    2011-01-01

    Abstract The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole-disk Earth model simulations used to better understand remotely detectable extrasolar planet characteristics. We have used these data to upgrade, correct, and validate the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model. This comprehensive model now includes specular reflectance from the ocean and explicitly includes atmospheric effects such as Rayleigh scattering, gas absorption, and temperature structure. We have used this model to generate spatially and temporally resolved synthetic spectra and images of Earth for the dates of EPOXI observation. Model parameters were varied to yield an optimum fit to the data. We found that a minimum spatial resolution of ∼100 pixels on the visible disk, and four categories of water clouds, which were defined by using observed cloud positions and optical thicknesses, were needed to yield acceptable fits. The validated model provides a simultaneous fit to Earth's lightcurve, absolute brightness, and spectral data, with a root-mean-square (RMS) error of typically less than 3% for the multiwavelength lightcurves and residuals of ∼10% for the absolute brightness throughout the visible and NIR spectral range. We have extended our validation into the mid-infrared by comparing the model to high spectral resolution observations of Earth from the Atmospheric Infrared Sounder, obtaining a fit with residuals of ∼7% and brightness temperature errors of less than 1 K in the atmospheric window. For the purpose of understanding the observable characteristics of the distant Earth at arbitrary viewing geometry and observing cadence, our validated forward

  14. 3D climate modeling of Earth-like extrasolar planets orbiting different types of host stars

    NASA Astrophysics Data System (ADS)

    Godolt, M.; Grenfell, J. L.; Hamann-Reinus, A.; Kitzmann, D.; Kunze, M.; Langematz, U.; von Paris, P.; Patzer, A. B. C.; Rauer, H.; Stracke, B.

    2015-06-01

    The potential habitability of a terrestrial planet is usually defined by the possible existence of liquid water on its surface, since life as we know it needs liquid water at least during a part of its life cycle. The potential presence of liquid water on a planetary surface depends on many factors such as, most importantly, surface temperatures. The properties of the planetary atmosphere and its interaction with the radiative energy provided by the planet's host star are thereby of decisive importance. In this study we investigate the influence of different main-sequence stars (F, G, and K-type stars) upon the climate of Earth-like extrasolar planets and their potential habitability by applying a state-of-the-art three-dimensional (3D) Earth climate model accounting for local and dynamical processes. The calculations have been performed for planets with Earth-like atmospheres at orbital distances (and corresponding orbital periods) where the total amount of energy received from the various host stars equals the solar constant. In contrast to previous 3D modeling studies, we include the effect of ozone radiative heating upon the vertical temperature structure of the atmospheres. The global orbital mean results obtained have been compared to those of a one-dimensional (1D) radiative convective climate model to investigate the approximation of global mean 3D results by those of 1D models. The different stellar spectral energy distributions lead to different surface temperatures and due to ozone heating to very different vertical temperature structures. As previous 1D studies we find higher surface temperatures for the Earth-like planet around the K-type star, and lower temperatures for the planet around the F-type star compared to an Earth-like planet around the Sun. However, this effect is more pronounced in the 3D model results than in the 1D model because the 3D model accounts for feedback processes such as the ice-albedo and the water vapor feedback. Whether the

  15. Earth as an extrasolar planet: Earth model validation using EPOXI earth observations.

    PubMed

    Robinson, Tyler D; Meadows, Victoria S; Crisp, David; Deming, Drake; A'hearn, Michael F; Charbonneau, David; Livengood, Timothy A; Seager, Sara; Barry, Richard K; Hearty, Thomas; Hewagama, Tilak; Lisse, Carey M; McFadden, Lucy A; Wellnitz, Dennis D

    2011-06-01

    The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole-disk Earth model simulations used to better understand remotely detectable extrasolar planet characteristics. We have used these data to upgrade, correct, and validate the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model. This comprehensive model now includes specular reflectance from the ocean and explicitly includes atmospheric effects such as Rayleigh scattering, gas absorption, and temperature structure. We have used this model to generate spatially and temporally resolved synthetic spectra and images of Earth for the dates of EPOXI observation. Model parameters were varied to yield an optimum fit to the data. We found that a minimum spatial resolution of ∼100 pixels on the visible disk, and four categories of water clouds, which were defined by using observed cloud positions and optical thicknesses, were needed to yield acceptable fits. The validated model provides a simultaneous fit to Earth's lightcurve, absolute brightness, and spectral data, with a root-mean-square (RMS) error of typically less than 3% for the multiwavelength lightcurves and residuals of ∼10% for the absolute brightness throughout the visible and NIR spectral range. We have extended our validation into the mid-infrared by comparing the model to high spectral resolution observations of Earth from the Atmospheric Infrared Sounder, obtaining a fit with residuals of ∼7% and brightness temperature errors of less than 1 K in the atmospheric window. For the purpose of understanding the observable characteristics of the distant Earth at arbitrary viewing geometry and observing cadence, our validated forward model can be

  16. Earth as an extrasolar planet: Earth model validation using EPOXI earth observations.

    PubMed

    Robinson, Tyler D; Meadows, Victoria S; Crisp, David; Deming, Drake; A'hearn, Michael F; Charbonneau, David; Livengood, Timothy A; Seager, Sara; Barry, Richard K; Hearty, Thomas; Hewagama, Tilak; Lisse, Carey M; McFadden, Lucy A; Wellnitz, Dennis D

    2011-06-01

    The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole-disk Earth model simulations used to better understand remotely detectable extrasolar planet characteristics. We have used these data to upgrade, correct, and validate the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model. This comprehensive model now includes specular reflectance from the ocean and explicitly includes atmospheric effects such as Rayleigh scattering, gas absorption, and temperature structure. We have used this model to generate spatially and temporally resolved synthetic spectra and images of Earth for the dates of EPOXI observation. Model parameters were varied to yield an optimum fit to the data. We found that a minimum spatial resolution of ∼100 pixels on the visible disk, and four categories of water clouds, which were defined by using observed cloud positions and optical thicknesses, were needed to yield acceptable fits. The validated model provides a simultaneous fit to Earth's lightcurve, absolute brightness, and spectral data, with a root-mean-square (RMS) error of typically less than 3% for the multiwavelength lightcurves and residuals of ∼10% for the absolute brightness throughout the visible and NIR spectral range. We have extended our validation into the mid-infrared by comparing the model to high spectral resolution observations of Earth from the Atmospheric Infrared Sounder, obtaining a fit with residuals of ∼7% and brightness temperature errors of less than 1 K in the atmospheric window. For the purpose of understanding the observable characteristics of the distant Earth at arbitrary viewing geometry and observing cadence, our validated forward model can be

  17. CARBON-RICH MOLECULAR CHAINS IN PROTOPLANETARY AND PLANETARY ATMOSPHERES: QUANTUM MECHANISMS AND ELECTRON ATTACHMENT RATES FOR ANION FORMATION

    SciTech Connect

    Carelli, F.; Grassi, T.; Gianturco, F. A.; Satta, M.

    2013-09-10

    The elementary mechanisms through which molecular polyynes could form stable negative ions after interacting with free electrons in planetary atmospheres (e.g., Titan's) are analyzed using quantum scattering calculations and quantum structure methods. The case of radical species and of nonpolar partners are analyzed via specific examples for both the C{sub n}H and HC{sub n}H series, with n values from 4 to 12. We show that attachment processes to polar radicals are dominating the anionic production and that the mediating role of dipolar scattering states is crucial to their formation. The corresponding attachment rates are presented as calculated upper limits to their likely values and are obtained down to the low temperatures of interest. The effects of the computed rates, when used in simple evolutionary models, are also investigated and presented in detail.

  18. The role of forced planetary waves in the annual cycle of the zonal mean circulation of the middle atmosphere

    NASA Technical Reports Server (NTRS)

    Holton, J. R.; Wehrbein, W. M.

    1980-01-01

    A severely truncated semispectral numerical model is used to simulate the annual cycle of the zonally averaged circulation in the middle atmosphere (16-96 km). The model includes only a single zonal harmonic wave component which interacts with the mean flow; the circulation is driven by diabatic heating and by a specified perturbation in the topography of the lower boundary, which is taken to be the 100 mb surface. A comparison of the annual cycle simulated by this model with the results of an analogous two-dimensional model indicates that planetary waves have relatively little influence on the zonal mean temperature profiles and on the solstice mean zonal winds at high latitudes. The primary effects of the forced waves are in decelerating the mean winds at low latitudes in the winter hemisphere to produce a region of weak westerlies, and in generating final warmings at the spring equinoxes.

  19. Tm:germanate Fiber Laser for Planetary Water Vapor Atmospheric Profiling

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; De Young, Russell

    2009-01-01

    The atmospheric profiling of water vapor is necessary for finding life on Mars and weather on Earth. The design and performance of a water vapor lidar based on a Tm:germanate fiber laser is presented.

  20. Microwave studies of planetary atmospheres. [by Mariner 2 Space Probe for Jupiter and Venus

    NASA Technical Reports Server (NTRS)

    Jones, D. E.

    1975-01-01

    Data from microwave observations of the atmospheres of Jupiter and Venus are examined. Radar features with corresponding coordinates of longitude and lattitude are given, along with scans of Mariner 2 radiometer beams.

  1. Minor constituents in planetary atmospheres: Ultraviolet spectroscopy from the orbiting astronomical observatory

    NASA Technical Reports Server (NTRS)

    Owen, T.; Sagan, C.

    1972-01-01

    OAO data between 2000 A and 3600 A, obtained by the Wisconsin experimental package objective grating scanning spectrometer, are used to set upper limits to the abundances of many minor constituents in the atmospheres of Mars, Jupiter, Saturn, and Venus.

  2. A Grant from NASA's Office of Space Station Science, Planetary Atmosphere's Program to Boston University

    NASA Technical Reports Server (NTRS)

    Yelle, Roger V.

    2000-01-01

    In the past three years of this program we have made contributions to a variety of subjects in research on Jupiter's Atmosphere, the Ultraviolet Spectroscopy of Jupiter, the abundance of CH4 in Pluto's atmosphere, and the emissivity of Pluto's Surface. We also performed work on two projects related to Titan, and an analysis of the visible spectrum of a brown dwarf. The highpoints are briefly summarized and a list of papers supported partly or wholly by this program is also provided.

  3. Planetary atmosphere representation for Monte-Carlo simulation of aerospace vehicle trajectories

    NASA Technical Reports Server (NTRS)

    Dutton, K.; Moerder, D.; Queen, E.; Suit, W.

    1990-01-01

    Methods of simulating large scale random atmospheric variations are examined for use in Monte Carlo simulations of hypervelocity vehicles. Random density, temperature, and pressure variations have a significant impact on the performance of such vehicles. Methods for generating random atmosphere profiles are described and compared in the context of a Monte Carlo simulation of the Aeroassist Flight Experiment (AFE). It is seen that these techniques result in statistically significant differences in key simulation point statistics.

  4. On the role of electron-driven processes in planetary and cometary atmospheres

    NASA Astrophysics Data System (ADS)

    Campbell, Laurence; Ingólfsson, Oddur; Brunger, Michael J.

    2012-11-01

    Electron impact excitation plays an important role in the upper atmospheres of planets and their satellites and also in the comae of comets, in both energy transfer and chemistry. Emissions produced by electron impact excitation are vital in remote sensing of these atmospheres. Modeling of the processes and emissions requires knowledge of both the plasma parameters and accurate cross sections or rates for the electron impact processes. This modeling is illustrated by four examples: electron cooling by CO2 in the atmosphere of Mars, infrared emissions from CO in the atmosphere of Venus, fourth positive emissions from CO in the coma of comet Hale-Bopp and emissions due to excitation of the higher-energy states of molecular oxygen in the atmosphere of Europa. In each case the assembly of the plasma parameters and accurate electron impact cross sections is described, together with the modeling techniques applied and the significant results. These include a possible explanation for low temperatures in part of the upper atmosphere of Mars, evidence that the abundance of CO in comet Hale Bopp has been overestimated and identification of a useful parameter for remote sensing of Europa.

  5. A method for computing visible and infrared polarized monochromatic radiation in planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Wauben, W. M. F.; de Haan, J. F.; Hovenier, J. W.

    1994-02-01

    In this paper we present a computational method, based on the so-called adding principle, for calculating the polarized monochromatic radiation in plane-parallel vertically inhomogeneous atmospheres. Our computer code is verified by comparing numerical results with those obtained by other investigators using different methods. We consider not only the well-known case of illumination by a unidirectional beam of light at the top of the atmosphere, but also illumination by isotropically radiating internal sources and illumination by an isotropically radiating ground surface below the atmosphere. Numerical results for all relevant Stokes parameters are tabulated for a two-layer atmosphere containing molecules and haze particles. These results pertain to the three types of illumination mentioned above. Furthermore, we describe some general features of polarized radiation in an optically thick homogeneous atmosphere containing cloud C1 water droplets. It is shown that multiple scattering of radiation in such a cloudy atmosphere may not be ignored at infrared wavelengths if molecular absorption is negligible.

  6. Radiative transfer in planetary atmospheres: Submillimeter-wave spectroscopy of comets

    NASA Technical Reports Server (NTRS)

    Schloerb, F. Peter

    1991-01-01

    During 1990, a significant step was made in asertaining the molecular composition of comets by our Planetary Astronomy group at the University of Massachusetts. We obtained several exciting new detections of submillimeter wave spectral lines from molecules in the coma of Comet Levy (1990c) using the 10m telescope of the Caltech Submillimeter Observatory, located on Mauna Kea. The molecules HCN, formaldahyde, and methanol were all detected in abundances that make them important minor constituents of the nucleus. Moreover, the emission was so strong that, for the first time, it was possible to map the distribution of these species in the coma and study their behavior as they flow outwards from the nucleus.

  7. Spectral properties of condensed phases of disulfur monoxide, polysulfur oxide, and irradiated sulfur. [in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hapke, Bruce; Graham, Francis

    1989-01-01

    The spectral reflectances of S2O, as well as the polysulfur oxide (PSO) condensate dissociation products of SO2 and condensates of elemental sulfur irradiated with UV light and X-rays, have been ascertained in the 200-1700 nm range with a view to the relevance of these compounds to the interpretation of planetary data. While S2O is a dark red solid, PSO is a pale yellow one that absorbs strongly in the UV but exhibits no bands in either the visible or near IR. Elemental S produces strong bands in the UV, and while it is normally white at room temperature, UV irradiation causes it to turn yellow. X-ray irradiation of S turns it orange.

  8. Radiative transfer in planetary atmospheres: Submillimeter-wave spectroscopy of comets

    NASA Astrophysics Data System (ADS)

    Schloerb, F. Peter

    1991-10-01

    During 1990, a significant step was made in asertaining the molecular composition of comets by our Planetary Astronomy group at the University of Massachusetts. We obtained several exciting new detections of submillimeter wave spectral lines from molecules in the coma of Comet Levy (1990c) using the 10m telescope of the Caltech Submillimeter Observatory, located on Mauna Kea. The molecules HCN, formaldahyde, and methanol were all detected in abundances that make them important minor constituents of the nucleus. Moreover, the emission was so strong that, for the first time, it was possible to map the distribution of these species in the coma and study their behavior as they flow outwards from the nucleus.

  9. Outer satellite atmospheres: Their extended nature and planetary interactions. [sodium cloud of Io, hydrogen torus of Titan, and comet atmospheres

    NASA Technical Reports Server (NTRS)

    Smyth, W. H.

    1980-01-01

    Highly developed numerical models are applied to interpret extended-atmosphere data for the sodium cloud of Io and the hydrogen torus of Titan. Solar radiation pressure was identified and verified by model calculations as the mechanism to explain two different east-west asymmetries observed in the sodium cloud. Analysis of sodium line profile data, suggesting that a Jupiter magnetospheric wind may be responsible for high speed sodium atoms emitted from Io, and preliminary modeling of the interaction of the Io plasma torus and Io's sodium cloud are also reported. Models presented for Titan's hydrogen torus are consistent both with the recent Pioneer 11 measurements and earlier Earth-orbiting observations by the Copernicus satellite. Progress is reported on developing models for extended gas and dust atmospheres of comets.

  10. Outer satellite atmospheres: Their nature and planetary interactions. [atmospheric models for Amalthea, Ganymede, Callisto, and Titan are presented

    NASA Technical Reports Server (NTRS)

    Smyth, W. H.

    1978-01-01

    Results show that Amalthea is likely to form a tightly-bound partial toroidal-shaped hydrogen cloud about its planet, while Ganymede, Callisto and Titan may have rather large, complete and nearly symmetric toroidal-shaped clouds. The toroidal cloud for Amalthea compares favorably with spacecraft data of Pioneer 10 for a satellite escape flux of order 10 to the 11th power atoms/sq cm/sec. Model results for Ganymede, Callisto and Titan suggest that these extended hydrogen atmospheres are likely to be detected by the Voyager spacecrafts and that Titan's cloud might also be detected by the Pioneer 11 spacecraft. Ions created because of atoms lost through ionization processes from these four extended hydrogen atmospheres and from the sodium cloud of Io are discussed.

  11. Constraining planetary atmospheric density: application of heuristic search algorithms to aerodynamic modeling of impact ejecta trajectories

    NASA Astrophysics Data System (ADS)

    Liu, Z. Y. C.; Shirzaei, M.

    2015-12-01

    Impact craters on the terrestrial planets are typically surrounded by a continuous ejecta blanket that the initial emplacement is via ballistic sedimentation. Following an impact event, a significant volume of material is ejected and falling debris surrounds the crater. Aerodynamics rule governs the flight path and determines the spatial distribution of these ejecta. Thus, for the planets with atmosphere, the preserved ejecta deposit directly recorded the interaction of ejecta and atmosphere at the time of impact. In this study, we develop a new framework to establish links between distribution of the ejecta, age of the impact and the properties of local atmosphere. Given the radial distance of the continuous ejecta extent from crater, an inverse aerodynamic modeling approach is employed to estimate the local atmospheric drags and density as well as the lift forces at the time of impact. Based on earlier studies, we incorporate reasonable value ranges for ejection angle, initial velocity, aerodynamic drag, and lift in the model. In order to solve the trajectory differential equations, obtain the best estimate of atmospheric density, and the associated uncertainties, genetic algorithm is applied. The method is validated using synthetic data sets as well as detailed maps of impact ejecta associated with five fresh martian and two lunar impact craters, with diameter of 20-50 m, 10-20 m, respectively. The estimated air density for martian carters range 0.014-0.028 kg/m3, consistent with the recent surface atmospheric density measurement of 0.015-0.020 kg/m3. This constancy indicates the robustness of the presented methodology. In the following, the inversion results for the lunar craters yield air density of 0.003-0.008 kg/m3, which suggest the inversion results are accurate to the second decimal place. This framework will be applied to older martian craters with preserved ejecta blankets, which expect to constrain the long-term evolution of martian atmosphere.

  12. Height of convective layer in planetary atmospheres with condensable and non-condensable greenhouse substances

    NASA Astrophysics Data System (ADS)

    Makarieva, A. M.; Gorshkov, V. G.; Pujol, T.

    2003-12-01

    Convection reduces greenhouse effect by transporting a certain amount of non-radiative dynamic energy to the upper atmosphere, where this energy dissipates and radiates into space without interaction with greenhouse substances in the lower atmosphere. In this paper we show that the height of the convective layer zc is finite and independent of atmospheric optical thickness τs at large values of the latter. We derive an analytical formula for zc at large values of τs for condensable and non-condensable greenhouse substances. The formula obtained yields reasonable quantitative estimates of the observed height of convective layer on Venus and at low latitudes on Earth, where atmospheric thickness of water vapor is maximum. The dissipative power of dynamic convective processes is limited by the incoming flux of solar radiation. Height of convective layer being finite, values of optical depth at the top of the convective layer and at the mean height of convective energy dissipation increase proportionally to the atmospheric optical thickness, while the contribution of convective energy fluxes to formation of the outgoing flux of thermal radiation proportionally diminishes. As far as optical thickness of condensable greenhouse substances grows exponentially with increasing surface temperature, the obtained results lead to the conclusion that the outgoing thermal radiation into space in the presence of convection tends exponentially to zero with increasing surface temperature, instead of reaching a finite plateau as suggested by earlier radiative-convective studies.

  13. Mass-independent isotope effects in planetary atmospheres and the early solar system.

    PubMed

    Thiemens, M H

    1999-01-15

    A class of isotope effects that alters isotope ratios on a mass-independent basis provides a tool for studying a wide range of processes in atmospheres of Earth and other planets as well as early processes in the solar nebula. The mechanism for the effect remains uncertain. Mass-independent isotopic compositions have been observed in O3, CO2, N2O, and CO in Earth's atmosphere and in carbonate from a martian meteorite, which suggests a role for mass-independent processes in the atmosphere of Mars. Observed mass-independent meteoritic oxygen and sulfur isotopic compositions may derive from chemical processes in the presolar nebula, and their distributions could provide insight into early solar system evolution.

  14. Studies of the chemistry of vibrationally and electronically excited species in planetary upper atmospheres

    NASA Technical Reports Server (NTRS)

    Fox, J. L.

    1984-01-01

    The vibrational distribution of O2(+) in the atmospheres of Venus and Mars was investigated to compare with analogous values in the Earth's atmosphere. The dipole moment of the Z(2) Pi sub u - X(2) Pi sub g transition of O2(+) is calculated as a function of internuclear distance. The band absorption oscillator strengths and band transition probabilities of the second negative system are derived. The vibrational distribution of O2(+) in the ionosphere of Venus is calculated for a model based on data from the Pioneer Venus neutral mass spectrometer.

  15. A map of the day-night contrast of the extrasolar planet HD 189733b.

    PubMed

    Knutson, Heather A; Charbonneau, David; Allen, Lori E; Fortney, Jonathan J; Agol, Eric; Cowan, Nicolas B; Showman, Adam P; Cooper, Curtis S; Megeath, S Thomas

    2007-05-10

    'Hot Jupiter' extrasolar planets are expected to be tidally locked because they are close (<0.05 astronomical units, where 1 au is the average Sun-Earth distance) to their parent stars, resulting in permanent daysides and nightsides. By observing systems where the planet and star periodically eclipse each other, several groups have been able to estimate the temperatures of the daysides of these planets. A key question is whether the atmosphere is able to transport the energy incident upon the dayside to the nightside, which will determine the temperature at different points on the planet's surface. Here we report observations of HD 189733, the closest of these eclipsing planetary systems, over half an orbital period, from which we can construct a 'map' of the distribution of temperatures. We detected the increase in brightness as the dayside of the planet rotated into view. We estimate a minimum brightness temperature of 973 +/- 33 K and a maximum brightness temperature of 1,212 +/- 11 K at a wavelength of 8 mum, indicating that energy from the irradiated dayside is efficiently redistributed throughout the atmosphere, in contrast to a recent claim for another hot Jupiter. Our data indicate that the peak hemisphere-integrated brightness occurs 16 +/- 6 degrees before opposition, corresponding to a hotspot shifted east of the substellar point. The secondary eclipse (when the planet moves behind the star) occurs 120 +/- 24 s later than predicted, which may indicate a slightly eccentric orbit.

  16. Zeppelin NT - Measurement Platform for the Exploration of Atmospheric Chemistry and Dynamics in the Planetary Boundary Layer

    NASA Astrophysics Data System (ADS)

    Hofzumahaus, Andreas; Holland, Frank; Oebel, Andreas; Rohrer, Franz; Mentel, Thomas; Kiendler-Scharr, Astrid; Wahner, Andreas; Brauchle, Artur; Steinlein, Klaus; Gritzbach, Robert

    2014-05-01

    The planetary boundary layer (PBL) is the chemically most active and complex part of the atmosphere where freshly emitted reactive trace gases, tropospheric radicals, atmospheric oxidation products and aerosols exhibit a large variability and spatial gradients. In order to investigate the chemical degradation of trace gases and the formation of secondary pollutants in the PBL, a commercial Zeppelin NT was modified to be used as an airborne measurement platform for chemical and physical observations with high spatial resolution. The Zeppelin NT was developed by Zeppelin Luftschifftechnik (ZLT) and is operated by Deutsche Zeppelin Reederei (DZR) in Friedrichshafen, Germany. The modification was performed in cooperation between Forschungszentrum Jülich and ZLT. The airship has a length of 75 m, can lift about 1 ton of scientific payload and can be manoeuvered with high precision by propeller engines. The modified Zeppelin can carry measurement instruments mounted on a platform on top of the Zeppelin, or inside the gondola beneath the airship. Three different instrument packages were developed to investigate a. gas-phase oxidation processes involving free radicals (OH, HO2) b. formation of secondary organic aerosols (SOA) c. new particle formation (nucleation) The presentation will describe the modified airship and provide an overview of its technical performance. Examples of its application during the recent PEGASOS flight campaigns in Europe will be given.

  17. Low-temperature Kinetic Studies of OH Radical Reactions Relevant to Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Townsend, T. M.; Antiñolo, M.; Ballesteros, B.; Jimenez, E.; Canosa, A.

    2011-05-01

    In the solar system, the temperature (T) of the atmosphere of giant planets or their satellites is only several tens of Kelvin (K). The temperature of the tropopause of Titan (satellite of Saturn) and the surface of Mars is 70 K and 210 K, respectively. In the Earth's atmosphere, T decreases from 298 K (surface) to 210 K close to the T-inversion region (tropopause). The principal oxidants in the Earth's lower atmosphere are ozone, the hydroxyl (OH) radical and hydrogen peroxide. A number of critical atmospheric chemical problems depend on the Earth's oxidising capacity, which is essentially the global burden of these oxidants. In the interstellar clouds and circumstellar envelopes, OH radicals have also been detected. As the chemistry of atmospheres is highly influenced by temperature, the knowledge of the T-dependence of the rate coefficients for OH-reactions (k) is the key to understanding the underlying molecular mechanisms. In general, these reactions take place on a short temporal scale. Therefore, a detection technique with high temporal resolution is required. Measurements of k at low temperatures can be achieved by maintaining a thermalised environment using either cryogenic cooling (T>200 K) or supersonic gas expansion with a Laval nozzle (several tens of K). The pulsed laser photolysis technique coupled with laser induced fluorescence detection has been widely used in our laboratory to determine the rate coefficients of OH-reactions with different volatile organic compounds, such as alcohols (1), saturated and unsaturated aliphatic aldehydes (2), linear ketones (3), as a function of temperature (260 350 K). An experimental system based on the CRESU (Cinetique de Reaction en Ecoulement Supersonique Uniforme or Reaction Kinetics in a Uniform Supersonic Flow) technique is currently under construction. This technique will allow the performance of kinetic studies of OH-reactions of astrophysical interest at temperatures lower than 200 K.

  18. Simulating Super Earth Atmospheres in the Laboratory

    NASA Astrophysics Data System (ADS)

    Claudi, R.; Erculiani, S. M.

    2014-03-01

    The "Atmosphere in a Test Tube" project is a laboratory experiment that will be able to reproduce condition of extreme environments by means of a simulator. These conditions span from those existing inside some parts of the human body to combinations of temperatures, pressures, irradiation and atmospheric gases present on other planets. In this latter case the experiments to be performed will be useful as preliminary tests for both simulation of atmosphere of exoplanets and Solar System planets and Astrobiology experiments that should be performed by planetary landers or by instruments to be launched in the next years. In particular at INAF Astronomical Observatory of Padova Laboratory we are approaching the characterization of extrasolar planet atmospheres taking advantage by innovative laboratory experiments with a particular focus on low mass Neptunes and Super earths and low mass M dwarfs primaries.

  19. Detonation propulsion experiments and theory. [for spacecraft in high pressure planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Back, L. H.; Dowler, W. L.; Varsi, G.

    1982-01-01

    Test data are presented for the use of a single detonation of explosives in long-cone, short-cone, straight, and firing-plug nozzles to provide propulsion in a simulated Jupiter atmosphere, as well as the ambient gases N, CO2 and He. The long-cone nozzle yielded a progressive increase with ambient pressure for the higher molecular weight gases CO2 and N, while the lower molecular weight He and simulated Jupiter atmosphere showed a specific pulse decrease with increasing ambient pressure. The short-plug nozzle yielded a small specific impulse reduction with increasing ambient pressure, and its results were found to be nearly independent of ambient gas molecular weight. All data gathered are analyzed by using first principles, approximate blast wave theory predictions, and two-dimensional numerical calculations. Rarefaction and oscillatory wave phenomena are found to significantly influence specific impulse.

  20. Electronic excitation and isentropic coefficients of high temperature planetary atmosphere plasmas

    SciTech Connect

    Colonna, Gianpiero; Capitelli, Mario

    2012-07-15

    In this paper, we have discussed the effects of electronically excited states of atomic species in affecting the isentropic coefficients of plasmas, focusing on mixtures representing the atmospheres of Jupiter, Mars, and Earth. General behaviors have been rationalized on the basis of simplified approaches. The contribution of the electronically excited states has been evidenced by comparing results obtained considering only the ground state and those obtained using either Fermi or Griem cutoff criteria.

  1. Calculation of polarization and anisotropy of resonant and fluorescent scattering. [in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Chamberlain, Joseph W.

    1990-01-01

    Formulas are derived for the swift calculation of the angular intensity distribution and the degree of polarization associated with the resonant and fluorescent scattering of radiation by atoms which occurs in the rarefied upper atmospheres of planets during sunlit airglow phenomena. Attention is given to spectral lines with hyperfine structure, which are indicative of nuclear spin processes. The method employed involves summations over Zeeman components, allowing an evaluation of polarization through the addition of underlying simple resonant and fluorescent scattering channels.

  2. A Comprehensive Study of Planetary-Scale Atmospheric Waves in the Mesosphere and Lower Thermosphere As Observed By Timed/Saber

    NASA Astrophysics Data System (ADS)

    Liu, G.; England, S.; Immel, T. J.; Frey, H. U.

    2014-12-01

    A comprehensive study of planetary-scale atmospheric waves in the mesosphere and lower thermosphere (MLT) is conducted by analyzing the multiple years of temperature observations from TIMED/SABER covering 2002-2011. Occurrences and properties of these waves are studied for various cases, with 62% of them are the zonal wavenumber-1 component, 20 % are the wavenumber-2 and 18% are the wavenumber-3. The mean wave amplitudes and vertical wavelengths are calculated to be 8 K and 30 km for the wavenumber-1, 5.5 K and 25 km for the wavenumber-2, and 5 K and 20 km for the wavenumber-3. These exhibit the signatures of planetary-scale atmospheric waves, which are believed to be important in the vertical coupling of the lower atmosphere with the ionosphere/thermosphere/mesosphere (ITM) system.

  3. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1991-01-01

    Laboratory measurements of microwave and millimeter wave properties of the simulated atmosphere of the outer planets and their satellites has continued. One of the focuses is on the development of a radiative transfer model of the Jovian atmosphere at wavelengths from 1 mm to 10 cm. This modeling effort led to laboratory measurements of the millimeter wave opacity of hydrogen sulfide (H2S) under simulated Jovian conditions. Descriptions of the modeling effort, the Laboratory experiment, and the observations are presented. Correlative studies of measurements with Pioneer-Venus radio occultation measurements with longer wavelength emission measurements have provided new ways for characterizing temporal and spatial variations in the abundance of both gases H2SO4 and SO2, and for modeling their roles in the subcloud atmosphere. Laboratory measurements were conducted on 1.35 cm (and 13 cm) opacity of gaseous SO2 and absorptivity of gaseous SO2 at the 3.2 mm wavelength under simulated Venus conditions. Laboratory measurements were completed on millimeter wave dielectric properties of liquid H2SO4, in order to model the effects of the opacity of the clouds of Venus onto millimeter wave emission spectrum.

  4. Evaporation of ice in planetary atmospheres: Ice-covered rivers on Mars

    NASA Technical Reports Server (NTRS)

    Wallace, D.; Sagan, C.

    1978-01-01

    The evaporation rate of water ice on the surface of a planet with an atmosphere involves an equilibrium between solar heating and radiative and evaporative cooling of the ice layer. The thickness of the ice is governed principally by the solar flux which penetrates the ice layer and then is conducted back to the surface. Evaporation from the surface is governed by wind and free convection. In the absence of wind, eddy diffusion is caused by the lower density of water vapor in comparison to the density of the Martian atmosphere. For mean martian insolations, the evaporation rate above the ice is approximately 10 to the minus 8th power gm/sq cm/s. Evaporation rates are calculated for a wide range of frictional velocities, atmospheric pressures, and insolations and it seems clear that at least some subset of observed Martian channels may have formed as ice-chocked rivers. Typical equilibrium thicknesses of such ice covers are approximately 10m to 30 m; typical surface temperatures are 210 to 235 K.

  5. On the hydrodynamic model of thermal escape from planetary atmospheres and its comparison with kinetic simulations

    NASA Astrophysics Data System (ADS)

    Volkov, A. N.

    2016-06-01

    Parkers' model of thermal escape implies the search of solutions of one-dimensional hydrodynamic equations for an inviscid but thermally conducting gas with a critical point and vanishing temperature far from the source. The properties of solutions of this model are studied for neutral mon- and diatomic gases with the viscosity index varying from 1/2 to 1. The domains of existence and uniqueness of solutions in terms of the source Jeans escape parameter and Knudsen number are established. The solutions are found to exist only in a narrow range of the critical point Jeans parameter. The lower and upper limits of this range correspond to solutions that are dominated by either heat conduction or adiabatic expansion. Thermal escape described by Parker's model occurs in two asymptotic regimes: the low-density (LD) regime, when escape is dominated by heat conduction, and the high-density (HD) regime, when escape is dominated by adiabatic expansion. Expressions for the mass and energy escape rates in these regimes are found theoretically. The comparison of results of hydrodynamic and kinetic simulations performed in identical conditions shows that Parker's model is capable of describing thermal escape only in the HD regime, providing decent agreement with the kinetic model in terms of the atmospheric structure below the exobase and the mass and energy escape rates. In the LD regime, Parker's model predicts a much faster drop in atmospheric temperature and less extended atmospheres, and can both over- and underestimate the escape rates in orders of magnitude.

  6. THIS -- next-generation mid-infrared remote sensing of planetary atmospheres using a tuneable heterodyne infrared spectrometer

    NASA Astrophysics Data System (ADS)

    Sonnabend, G.; Wirtz, D.; Vetterle, V.; Schieder, R.

    2003-12-01

    The Cologne spectrometer THIS (Tuneable Heterodyne Infrared Spectrometer) opens the mid-infrared wavelength region from 8 to 17 microns to ultra-high-resolution spectroscopy. The main scientific goal of THIS is to analyze highly resolved lineshape data of molecules (e.g. O3, NH3, CH4, N2O, HxCy etc.) to deduce physical parameters like wind velocities or height profiles of gases in either the Earth's or other planetary atmospheres. Also astronomical observations of non-solar-system IR-sources like IRC+10216 as well as the measurement of pure rotational transitions of H2 in the interstellar-medium from ground based telescopes are planned in the near future. THIS is a proposed second-generation instrument for the stratospheric observatory SOFIA. With a system noise temperature of less than three times the quantum limit THIS is the first widely tuneable and transportable infrared heterodyne receiver having a sensitivity equivalent to CO2-laser based heterodyne systems. A quantum-cascade-laser is used as local oscillator. Its radiation is superimposed to that from the signal by use of a Fabry-Perot ring-resonator to provide optimum efficiency. The frequency mixing is done by a Mercury-Cadmium-Telluride photomixer and spectral analysis with a resolution of up to 3x107 is performed by means of an Acousto-Optical spectrometer. We report on THIS' successful first observing run performed at the west auxiliary telescope at McMath-Pierce solar observatory on Kitt Peak/Arizona in 11/2002. Very weak non-LTE CO2 emission from the atmosphere of Venus have been observed as well as trace gases in Earth's atmosphere and molecular features in sunspots.

  7. Simulating influence of QBO phase on planetary waves during a stratospheric warming in a general circulation model of the middle atmosphere

    NASA Astrophysics Data System (ADS)

    Koval, Andrey; Gavrilov, Nikolai; Pogoreltsev, Alexander; Savenkova, Elena

    2016-04-01

    One of the important factors of dynamical interactions between the lower and upper atmosphere is energy and momentum transfer by atmospheric internal gravity waves. For numerical modeling of the general circulation and thermal regime of the middle and upper atmosphere, it is important to take into account accelerations of the mean flow and heating rates produced by dissipating internal waves. The quasi-biennial oscillations (QBOs) of the zonal mean flow at lower latitudes at stratospheric heights can affect the propagation conditions of planetary waves. We perform numerical simulation of global atmospheric circulation for the initial conditions corresponding to the years with westerly and easterly QBO phases. We focus on the changes in amplitudes of stationary planetary waves (SPWs) and traveling normal atmospheric modes (NAMs) in the atmosphere during SSW events for the different QBO phases. For these experiments, we use the global circulation of the middle and upper atmosphere model (MUAM). There is theory of PW waveguide describing atmospheric regions where the background wind and temperature allow the wave propagation. There were introduced the refractive index for PWs and found that strongest planetary wave propagation is in areas of large positive values of this index. Another important PW characteristic is the Eliassen-Palm flux (EP-flux). These characteristics are considered as useful tools for visualizing the PW propagation conditions. Sudden stratospheric warming (SSW) event has significant influence on the formation of the weather anomalous and climate changes in the troposphere. Also, SSW event may affect the dynamical and energy processes in the upper atmosphere. The major SSW events imply significant temperature rises (up to 30 - 40 K) at altitudes 30 - 50 km accompanying with corresponding decreases, or reversals, of climatological eastward zonal winds in the stratosphere.

  8. Earth, Jupiter and Saturn as guides for extrasolar planets and brown dwarfs: a lightning climatology study

    NASA Astrophysics Data System (ADS)

    Hodosán, Gabriella; Asensio Torres, Rubén; Helling, Christiane; Vorgul, Irena

    2015-04-01

    Large-scale electrostatic discharges (i.e. lightning) have been observed in the Solar System. Apart from Earth there are direct detections from Jupiter and Saturn and indirect (only radio) detection from Uranus and Neptune. Recent observations made by the Venus Explorer revealed radio signals that may be related to lightning. Observations indicate that clouds form on extrasolar planets and brown dwarfs. The conditions in these clouds may be good for lightning to occur, which can be a main ionization process in these atmospheres (lightning in mineral clouds e.g.: Bailey et al. 2014, ApJ, 784, 43; Helling at al. 2013, ApJ, 767, 136; Helling et al. 2013, P&SS, 77, 152). In this study our aim is to compare lightning climatology from Earth, Jupiter and Saturn and use these statistics as a guide to study potential lightning on extrasolar planetary objects. Earth is a fair analogy for rocky or ocean planets while Jupiter and Saturn resemble giant planets and brown dwarfs. To give an estimate on the total lightning energy (or power) that can reach us from a particular extrasolar body, we need to know how much lightning can occur on the object globally. We will show the possibilities in the number and quality of the giant planet data sets, which may give a fine comparison of future observations of extrasolar giant gas planets and even brown dwarfs. Data were obtained from Lightning Imaging Sensor (LIS)/Optical Transient Detector (OTD) (e.g.: Cecil et al. 2014, Atmospheric Research, 135, 404), Sferics Timing and Ranging Network (STARNET) (e.g.: Morales Rodrigues et al. 2011, 2014, XIV and XV International Conference on Atmospheric Electricity) and World Wide Lightning Location Network (WWLLN) (e.g.: Hutchins et al. 2012, Radio Science, 47, RS6005), four major lightning detecting networks, which monitor lightning occurrence in the optical or radio range on Earth. We compare flash/stroke rates in space and time and use the data to refer to Earth as a transiting exoplanet. We

  9. CALIBRATION OF EQUILIBRIUM TIDE THEORY FOR EXTRASOLAR PLANET SYSTEMS

    SciTech Connect

    Hansen, Brad M. S.

    2010-11-01

    We provide an 'effective theory' of tidal dissipation in extrasolar planet systems by empirically calibrating a model for the equilibrium tide. The model is valid to high order in eccentricity and parameterized by two constants of bulk dissipation-one for dissipation in the planet and one for dissipation in the host star. We are able to consistently describe the distribution of extrasolar planetary systems in terms of period, eccentricity, and mass (with a lower limit of a Saturn mass) with this simple model. Our model is consistent with the survival of short-period exoplanet systems, but not with the circularization period of equal mass stellar binaries, suggesting that the latter systems experience a higher level of dissipation than exoplanet host stars. Our model is also not consistent with the explanation of inflated planetary radii as resulting from tidal dissipation. The paucity of short-period planets around evolved A stars is explained as the result of enhanced tidal inspiral resulting from the increase in stellar radius with evolution.

  10. The HARPS search for southern extra-solar planets. XXXIV. A planetary system around the nearby M dwarf GJ 163, with a super-Earth possibly in the habitable zone

    NASA Astrophysics Data System (ADS)

    Bonfils, X.; Lo Curto, G.; Correia, A. C. M.; Laskar, J.; Udry, S.; Delfosse, X.; Forveille, T.; Astudillo-Defru, N.; Benz, W.; Bouchy, F.; Gillon, M.; Hébrard, G.; Lovis, C.; Mayor, M.; Moutou, C.; Naef, D.; Neves, V.; Pepe, F.; Perrier, C.; Queloz, D.; Santos, N. C.; Ségransan, D.

    2013-08-01

    The meter-per-second precision achieved by today's velocimeters enables us to search for 1-10 M⊕ planets in the habitable zone of cool stars. This paper reports on the detection of three planets orbiting GJ 163 (HIP 19394), a M3 dwarf monitored by our ESO/HARPS search for planets. We made use of the HARPS spectrograph to collect 150 radial velocities of GJ 163 over a period of eight years. We searched the radial-velocity time series for coherent signals and found five distinct periodic variabilities. We investigated the stellar activity and called into question the planetary interpretation for two signals. Before more data can be acquired we concluded that at least three planets are orbiting GJ 163. They have orbital periods of Pb = 8.632 ± 0.002, Pc = 25.63 ± 0.03, and Pd = 604 ± 8 days and minimum masses msini = 10.6 ± 0.6, 6.8 ± 0.9, and 29 ± 3 M⊕, respectively. We hold our interpretations for the two additional signals with periods P(e) = 19.4 and P(f) = 108 days. The inner pair presents an orbital period ratio of 2.97, but a dynamical analysis of the system shows that it lays outside the 3:1 mean motion resonance. The planet GJ 163c, in particular, is a super-Earth with an equilibrium temperature of Teq = (302 ± 10)(1 - A)1/4 K and may lie in the so-called habitable zone for albedo values (A = 0.34 - 0.89) moderately higher than that of Earth (A⊕ = 0.2-0.3). Based on observations made with the HARPS instrument on the ESO 3.6 m telescope under the program IDs 072.C-0488, 082.C-0718, and 183.C-0437 at Cerro La Silla (Chile).Table 6 is available in electronic form at http://www.aanda.orgRadial-velocity time series (Table 6) are also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/556/A110

  11. Multiplex gas chromatography: an alternative concept for gas chromatographic analysis of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Valentin, J. R.

    1989-01-01

    Gas chromatography (GC) is a powerful technique for analyzing gaseous mixtures. Applied to the earth's atmosphere, GC can be used to determine the permanent gases--such as carbon dioxide, nitrogen, and oxygen--and to analyze organic pollutants in air. The U.S. National Aeronautics and Space Administration (NASA) has used GC in spacecraft missions to Mars (the Viking Biology Gas Exchange Experiment [GEX] and the Viking Gas Chromatograph-Mass Spectrometer [GC-MS]) and to Venus (the Pioneer Venus Gas Chromatograph [PVGC] on board the Pioneer Venus sounder probe) for determining the atmospheric constituents of these two planets. Even though conventional GC was very useful in the Viking and Pioneer missions, spacecraft constraints and limitations intrinsic to the technique prevented the collection of more samples. With the Venus probe, for instance, each measurement took a relatively long time to complete (10 min), and successive samples could not be introduced until the previous samples had left the column. Therefore, while the probe descended through the Venusian atmosphere, only three samples were acquired at widely separated altitudes. With the Viking mission, the sampling rate was not a serious problem because samples were acquired over a period of one year. However, the detection limit was a major disadvantage. The GC-MS could not detect simple hydrocarbons and simple alcohols below 0.1 ppm, and the GEX could not detect them below 1 ppm. For more complex molecules, the detection limits were at the parts-per-billion level for both instruments. Finally, in both the Viking and Pioneer missions, the relatively slow rate of data acquisition limited the number of analyses, and consequently, the amount of information returned. Similar constraints are expected in future NASA missions. For instance, gas chromatographic instrumentation is being developed to collect and analyze organic gases and aerosols in the atmosphere of Titan (one of Saturn's satellites). The Titan

  12. Multiplex gas chromatography: an alternative concept for gas chromatographic analysis of planetary atmospheres.

    PubMed

    Valentin, J R

    1989-03-01

    Gas chromatography (GC) is a powerful technique for analyzing gaseous mixtures. Applied to the earth's atmosphere, GC can be used to determine the permanent gases--such as carbon dioxide, nitrogen, and oxygen--and to analyze organic pollutants in air. The U.S. National Aeronautics and Space Administration (NASA) has used GC in spacecraft missions to Mars (the Viking Biology Gas Exchange Experiment [GEX] and the Viking Gas Chromatograph-Mass Spectrometer [GC-MS]) and to Venus (the Pioneer Venus Gas Chromatograph [PVGC] on board the Pioneer Venus sounder probe) for determining the atmospheric constituents of these two planets. Even though conventional GC was very useful in the Viking and Pioneer missions, spacecraft constraints and limitations intrinsic to the technique prevented the collection of more samples. With the Venus probe, for instance, each measurement took a relatively long time to complete (10 min), and successive samples could not be introduced until the previous samples had left the column. Therefore, while the probe descended through the Venusian atmosphere, only three samples were acquired at widely separated altitudes. With the Viking mission, the sampling rate was not a serious problem because samples were acquired over a period of one year. However, the detection limit was a major disadvantage. The GC-MS could not detect simple hydrocarbons and simple alcohols below 0.1 ppm, and the GEX could not detect them below 1 ppm. For more complex molecules, the detection limits were at the parts-per-billion level for both instruments. Finally, in both the Viking and Pioneer missions, the relatively slow rate of data acquisition limited the number of analyses, and consequently, the amount of information returned. Similar constraints are expected in future NASA missions. For instance, gas chromatographic instrumentation is being developed to collect and analyze organic gases and aerosols in the atmosphere of Titan (one of Saturn's satellites). The Titan

  13. Influence of planetary scale waves on the upper atmospheric optical dayglow emissions over equatorial-low-latitude

    NASA Astrophysics Data System (ADS)

    Laskar, F. I.; Duggirala, P. R.; Thatiparthi, V. L.; Chakrabarti, S.; Reddy, M.; Raghavarao, R.; Pathan, B. M.; Khekale, P. V.

    2012-12-01

    Systematic measurement of optical dayglow emissions at multiple wavelengths, namely, 557.7nm , 630.0nm, and 777.4nm have been carried out over a large field-of-view using a newly built Multiwavelength Imaging Spectograph using Echelle-grating (MISE) during January-February 2011 from a low latitude station, Hyderabad (Geographic: 17.5 deg. N, 78.5 deg. E; Mag.: 8.6 deg. N, 151.8 deg. E), India. Several large and small scale features are seen in all the wavelengths. In contrast to the earlier measurement of OI-630.0nm red-line emission during the high solar activity period (2001), current optical dayglow measurements during relatively low solar epoch (2011) show no similarity with that of the solar flux. However, it is noted that the variation in strength of the equatorial electrojet (EEJ) seems to be similar to that of optical measurements in 2011. This is also in contrast with the measurements in 2001, where no similarity was seen between EEJ and OI-630.0nm dayglow intensity. Periodogram analysis of these two data sets (optical and EEJ) show a marked difference in the occurrence of the quasi-16-day planetary wave periods before noon and in the afternoon hours. In order to investigate the coupling of atmospheric regions, periodogram analysis of total electron content (TEC) and SABER measured mesosphere and lower thermosphere (MLT) temperature data were carried out. Interestingly, the TEC data from Bangalore (Mag. Lat 4 deg. N) shows contrasting behaviour in terms of periodicities before noon and afternoon similar to those in optical dayglow intensities, SABER temperatures, and the strength of the EEJ while the TEC periodicities of another further away station (Ahmedabad, Mag. Lat 15 deg. N) does not show any such behaviour. It is suggested that planetary wave of periods of quasi-9-day and quasi-16-day, which are observed in MLT have their influence on the behaviour of the upper atmosphere as seen in optical, radio and magnetic measurements. These results point to

  14. Collaborative project. Ocean-atmosphere interaction from meso- to planetary-scale. Mechanics, parameterization, and variability

    SciTech Connect

    Saravanan, Ramalingam; Small, Justin

    2015-12-01

    Most climate models are currently run with grid spacings of around 100km, which, with today’s computing power, allows for long (up to 1000 year) simulations, or ensembles of simulations to explore climate change and variability. However this grid spacing does not resolve important components of the weather/climate system such as atmospheric fronts and mesoscale systems, and ocean boundary currents and eddies. The overall aim of this project has been to look at the effect of these small-scale features on the weather/climate system using a suite of high and low resolution climate models, idealized models and observations. High-resolution global coupled integrations using CAM/CESM were carried out at NCAR by the lead PI. At TAMU, we have complemented the work at NCAR by analyzing datasets from the high-resolution (28km) CESM integrations (Small et al., 2014) as well as very high resolution (9km, 3km) runs using a coupled regional climate (CRCM) carried out locally. The main tasks carried out were: 1. Analysis of surface wind in observations and high-resolution CAM/CCSM simulations 2. Development of a feature-tracking algorithm for studying midlatitude air-sea interaction by following oceanic mesoscale eddies and creating composites of the atmospheric response overlying the eddies. 3. Applying the Lagrangian analysis technique in the Gulf Stream region to compare data from observational reanalyses, global CESM coupled simulations, 9km regional coupled simulations and 3km convection-resolving regional coupled simulations. Our main findings are that oceanic mesoscale eddies influence not just the atmospheric boundary layer above them, but also the lower portions of the free troposphere above the boundary layer. Such a vertical response could have implications for a remote influence of Gulf Stream oceanic eddies on North Atlantic weather patterns through modulation of the storm track, similar to what has been noted in the North Pacific. The coarse resolution

  15. Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1987-01-01

    Laboratory measurements were conducted to evaluate properties of atmospheric gases under simulated conditions for the outer planets. A significant addition to this effort was the capability to make such measurements at millimeter wavelengths. Measurements should soon be completed on the millimeter wave absorption from ammonia under Jovian conditions. Also studied will be the feasibility of measuring the microwave and millimeter wave properties of phosphine (PH3) under simulated Jovian conditions. Further analysis and application of the laboratory results to microwave and millimeter wave absorption data for the outer planet, such as Voyager Radio Occultation experiments, will be pursued.

  16. Atomic carbon emission from photodissociation of CO2. [planetary atmospheric chemistry

    NASA Technical Reports Server (NTRS)

    Wu, C. Y. R.; Phillips, E.; Lee, L. C.; Judge, D. L.

    1978-01-01

    Atomic carbon fluorescence, C I 1561, 1657, and 1931 A, has been observed from photodissociation of CO2, and the production cross sections have been measured. A line emission source provided the primary photons at wavelengths from threshold to 420 A. The present results suggest that the excited carbon atoms are produced by total dissociation of CO2 into three atoms. The cross sections for producing the O I 1304-A fluorescence through photodissociation of CO2 are found to be less than 0.01 Mb in the wavelength region from 420 to 835 A. The present data have implications with respect to photochemical processes in the atmospheres of Mars and Venus.

  17. Mathematics of Radiation Propagation in Planetary Atmospheres: Absorption, Refraction, Time Delay, Occultation, and Abel Inversion

    NASA Astrophysics Data System (ADS)

    Huestis, D. L.

    Forward integration calculation of air mass, refraction, and time delay requires care even for very smooth model atmospheres. The literature abounds in examples of injudicious approximations, assumptions, transformations, variable substitutions, and failures to verify that the formulas work with unlimited accuracy for simple cases and also survive challenges from mathematically pathological but physically realizable cases. A few years ago we addressed the problem of evaluation of the Chapman function for attenuation along a straight line path in an exponential atmosphere. In this presentation we will describe issues and approaches for integration over light paths curved by refraction. The inverse problem, determining the altitude profile of mass density (index of refraction) or the concentration of an individual chemical species (absorption), from occultation data, also has its mathematically interesting (i.e., difficult) aspects. Now we automatically have noise and thus statistical analysis is just as important as calculus and numerical analysis. Here we will describe a new approach of least-squares fitting occultation data to an expansion over compact basis functions. This approach, which avoids numerical differentiation and singular integrals, was originally developed to analyze laboratory imaging data.Forward integration calculation of air mass, refraction, and time delay requires care even for very smooth model atmospheres. The literature abounds in examples of injudicious approximations, assumptions, transformations, variable substitutions, and failures to verify that the formulas work with unlimited accuracy for simple cases and also survive challenges from mathematically pathological but physically realizable cases. A few years ago we addressed the problem of evaluation of the Chapman function for attenuation along a straight line path in an exponential atmosphere. In this presentation we will describe issues and approaches for integration over light paths

  18. From Sub-Neptunes to Earth-like Exoplanets: Modeling Optically Thick and Thin Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Chen, Howard; Rogers, Leslie; Kasting, James

    2016-01-01

    Exoplanet surveys have revealed a wide diversity of planet properties in the Milky Way. Here, we present the results from two projects modeling planet atmospheres; one considering the hydrogen/helium envelopes of sub-Neptune-mass planets, and the other, the climate of Earth-like planets.First, we modify the state-of-the-art stellar evolution code Modules for Experimental Astrophysics (MESA) to model the thermal evolution of gaseous Sub-Neptune sized planets. Including photo-evaporation, we find a resulting convergent evolution trend that could potentially imprint itself on the close-in planet population as a preferred H/He mass fraction of 0.5-3%.We also use an updated version of a radiative-convective climate model to calculate the upper atmospheric conditions of planets warmer than the present Earth. In our simulations, cold, dry stratospheres are predicted at lower surface temperatures. However, onset of moist greenhouse water-loss limit to habitability emerges when the surface temperature reaches above 350 K. This result places constraint on a more accurate calculation of the inner edge of the habitable zone around Sun-like stars.

  19. Influence of the radiation pressure on the planetary exospheres: density profiles, escape flux and atmospheric stability

    NASA Astrophysics Data System (ADS)

    Beth, A.; Garnier, P.; Toublanc, D.; Dandouras, I.; Mazelle, C.

    2015-10-01

    The uppermost layer of the atmosphere, the exosphere,is not well-known in its global structure since the densities are very low compared to instrument detection capabilities. Because of rare collisions and high Knudsen numbers, the motion of light species (H,H2, ...)in the corona is essentially determined by the external forces : the gravitation from the planet, the radiation pressure, as well the stellar gravity. In this work, we calculate rigorously and analytically,based on the Hamiltonian mechanics and Liouville theorem, the impact of the radiation pressure and gravitation from the planet on the structure of the exosphere. This approach was partially used by Bishop and Chamberlain (1989) but only in the 2D case : we extend it to the 3D case. Assuming a collisionless exosphere and a constant radiation pressure near the planet, we determine the density profiles for ballistic particles (the main contribution for densities in the lower exosphere) for light species as a function of the angle with respect to the Sun direction. We also obtain an analytical formula for the escape flux at the subsolar point, which can be compared with the Jeans' escape flux. Finally, we study the effect of the radiation pressure on the zero velocity curves, position of the Roche lobe and Hill's region for the well-known Three-Body problem especially for Hot Jupiters and discuss about the validity of our model. The goal is to bring some constraints on modelling of exoplanet atmospheres.

  20. PLANETARY CONSTRUCTION ZONES IN OCCULTATION: DISCOVERY OF AN EXTRASOLAR RING SYSTEM TRANSITING A YOUNG SUN-LIKE STAR AND FUTURE PROSPECTS FOR DETECTING ECLIPSES BY CIRCUMSECONDARY AND CIRCUMPLANETARY DISKS

    SciTech Connect

    Mamajek, Eric E.; Quillen, Alice C.; Pecaut, Mark J.; Moolekamp, Fred; Scott, Erin L.; Kenworthy, Matthew A.; Cameron, Andrew Collier; Parley, Neil R.

    2012-03-15

    estimated total ring mass is {approx}8-0.4 M{sub Moon} (if the rings have optical opacity similar to Saturn's rings), and the edge of the outermost detected ring has orbital radius {approx}0.4-0.09 AU. In the new era of time-domain astronomy opened by surveys like SuperWASP, ASAS, etc., and soon to be revolutionized by Large Synoptic Survey Telescope, discovering and characterizing eclipses by circumplanetary and circumsecondary disks will provide us with observational constraints on the conditions that spawn satellite systems around gas giant planets and planetary systems around stars.

  1. SO_2 Absorption Cross Sections and N_2 VUV Oscillator Strengths for Planetary Atmosphere Studies

    NASA Astrophysics Data System (ADS)

    Smith, Peter L.; Stark, G.; Rufus, J.; Pickering, J. C.; Cox, G.; Huber, K. P.

    1998-09-01

    The determination of the chemical composition of the atmosphere of Io from Hubble Space Telescope observations in the 190-220 nm wavelength region requires knowledge of the photoabsorption cross sections of SO_2 at temperatures ranging from about 110 K to 300 K. We are engaged in a laboratory program to measure SO_2 absorption cross sections with very high resolving power (lambda /delta lambda =~ 450,000) and at a range of temperatures appropriate to the Io atmosphere. Previous photoabsorption measurements, with lambda /delta lambda =~ 100,000, have been unable to resolve the very congested SO_2 spectrum, and, thus, to elucidate the temperature dependence of the cross sections. Our measurements are being performed at Imperial College, London, using an ultraviolet Fourier transform spectrometer. We will present our recently completed room temperature measurements of SO_2 cross sections in the 190-220 nm region and plans for extending these to ~ 195 K. Analyses of Voyager VUV occultation measurements of the N_2-rich atmospheres of Titan and Triton have been hampered by the lack of fundamental spectroscopic data for N_2, in particular, by the lack of reliable f-values and line widths for electronic bands of N_2 in the 80-100 nm wavelength region. We are continuing our program of measurements of band oscillator strengths for the many (approximately 100) N_2 bands between 80 and 100 nm. We report new f-values, derived from data obtained at the Photon Factory (Tsukuba, Japan) synchrotron radiation facility with lambda /delta lambda =~ 130,000, of 37 bands in the 80-86 nm region and 21 bands in the 90-95 nm region. We have also begun the compilation of a searchable archive of N_2 data on the World Wide Web; see http://cfa-www.harvard. edu/amp/data/n2/n2home.html. The archive, covering the spectroscopy of N_2 between 80 and 100 nm, will include published and unpublished (14) N_2, (14) N(15) N, and (15) N_2 line lists and spectroscopic identifications, excited state energy

  2. Planetary quarantine

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Those areas of future missions which will be impacted by planetary quarantine (PQ) constraints were identified. The specific objectives for this reporting period were (1) to perform an analysis of the effects of PQ on an outer planet atmospheric probe, and (2) to prepare a quantitative illustration of spacecraft microbial reduction resulting from exposure to space environments. The Jupiter Orbiter Probe mission was used as a model for both of these efforts.

  3. Water vapor from a lunar breccia - Implications for evolving planetary atmospheres.

    NASA Technical Reports Server (NTRS)

    Cadenhead, D. A.; Buergel, W. G.

    1973-01-01

    The exposure of a typical complex lunar breccia to hydrogen after a through outgassing produces a fully reduced surface state. Subsequent outgassing over a wide temperature range results in the production of water vapor formed from the chemisorbed hydrogen and oxygen from the lunar sample; the proposed mechanism has been confirmed in terms of the chemisorption of deuterium and the release of heavy water. Since the conditions of the experiments are consistent with those on the lunar surface, it is postulated that water vapor will be produced on the moon through the interaction of the solar wind with lunar soil. It is also proposed that such a process could play an important role in the early history of many planets where an oxygen-rich soil is exposed to a reducing atmosphere.

  4. Water vapor from a lunar breccia: implications for evolving planetary atmospheres.

    PubMed

    Cadenhead, D A; Buergel, W G

    1973-06-15

    The exposure of a typical complex lunar breccia to hydrogen after a thorough outgassing produces a fully reduced surface state. Subsequent outgassing over a wide temperature range results in the production of water vapor formed from the chemisorbed hydrogen and oxygen from the lunar sample; the proposed mechanism has been confirmed in terms of the chemisorption of deuterium and the release of heavy water. Since the conditions of the experiments are consistent with those on the lunar surface, it is postulated that water vapor will be produced on the moon through the interaction of the solar wind with lunar soil. It is also proposed that such a process could play an important role in the early history of many planets where an oxygen-rich soil is exposed to a reducing atmosphere.

  5. Analysis of the Chemical Composition of the Atmospheres of Stars with Debris Disks and Planetary Systems

    NASA Astrophysics Data System (ADS)

    Rojas, M.; Drake, N. A.; Chavero, C.; Pereira, C. B.; Kholtygin, A. F.; Solovyov, D. I.

    2013-12-01

    Spectroscopic studies of seven low mass stars in spectral classes F, G, and K are presented. Four of these (HD 1581, HD 10700, HD 17925, and HD 22484) have debris disks and for two of them (HD 22049 and HD 222582(A + B)) planets are observed. Neither a debris disk nor planets have been observed for one the program stars (HD 20766). High resolution spectral observations of the program stars were made at the 2.2-m telescope of the European Southern Observatory (ESO) during 2008 with the FEROS spectrograph (R = 48000, spectral range 3800-9200 Å). The fundamental parameters of the stars are determined, including effective temperature, acceleration of gravity at the stars' surface, microturbulence velocity, metallicity, and the abundances of volatile and refractory elements in their atmospheres. The positions of all these stars are indicated on a Hertzsprung-Russell diagram.

  6. Effects of turbulence on average refraction angles in occultations by planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Eshleman, V. R.; Haugstad, B. S.

    1978-01-01

    Four separable effects of atmospheric turbulence on average refraction angles in occultation experiments are derived from a simplified analysis, and related to more general formulations by B. S. Haugstad. The major contributors are shown to be due to gradients in height of the strength of the turbulence, and the sense of the resulting changes in refraction angles is explained in terms of Fermat's principle. Because the results of analyses of such gradient effects by W. B. Hubbard and J. R. Jokipii are expressed in other ways, a special effort is made to compare all of the predictions on a common basis. We conclude that there are fundamental differences, and use arguments based on energy conservation and Fermat's principle to help characterize the discrepancies.

  7. Impact induced dehydration of serpentine and the evolution of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Lange, M. A.; Ahrens, T. J.

    1982-01-01

    Results of shock recovery experiments carried out on antigorite serpentine Mg3Si2O5(OH)4 are reported. The main objective of the present study is the determination of critical shock pressures for partial and complete dehydration of serpentine under shock loading. It is pointed out that serpentine and serpentine-like layer silicates are the major water-bearing phases in carbonaceous chondrites. It appears that these minerals, and a poorly defined cometary contribution, were the most likely water-bearing phases in accreting planetesimals which led to the formation of the terrestrial planets. The obtained results imply that the process of impact induced devolatilization of volatile bearing minerals during accretion is likely to have occurred on earth. The findings lend support to the model of a terrestrial atmosphere/hydrosphere forming during the later stages of accretion of the earth.

  8. First Light from Extrasolar Planets and Implications for Astrobiology

    NASA Technical Reports Server (NTRS)

    Richardson, L. Jeremy; Seager, Sara; Harrington, Joseph; Deming, Drake

    2005-01-01

    The first light from an extrasolar planet was recently detected. These results, obtained for two transiting extrasolar planets at different infrared wavelengths, open a new era in the field of extrasolar planet detection and characterization because for the first time we can now detect planets beyond the solar system directly. Using the Spitzer Space Telescope at 24 microns, we observed the modulation of combined light (star plus planet) from the HD 209458 system as the planet disappeared behind the star during secondary eclipse and later re-emerged, thereby isolating the light from the planet. We obtained a planet-to-star ratio of 0.26% at 24 microns, corresponding to a brightness temperature of 1130 + / - 150 K. We will describe this result in detail, explain what it can tell us about the atmosphere of HD 209458 b, and discuss implications for the field of astrobiology. These results represent a significant step on the path to detecting terrestrial planets around other stars and in understanding their atmospheres in terms of composition and temperature.

  9. Secular Resonances In Planetary Systems

    NASA Astrophysics Data System (ADS)

    Malhotra, Renu

    2006-06-01

    Secular effects introduce very low frequencies in planetary systems. The consequences are quite varied. They include mundane effects on the planetary ephemerides and on Earthly seasons, but also more esoteric effects such as apsidal alignment or anti-alignment, fine-splitting of mean motion resonances, broadening of chaotic zones, and dramatic orbital instabilities. Secular effects may shape the overall architecture of mature planetary systems by determining the long term stability of major and minor planetary bodies. This talk will be partly tutorial and partly a review of secular resonance phenomena here in the solar system and elsewhere in extra-solar systems. I acknowledge research support from NASA-Origins of Solar Systems and NASA-Outer Planets research programs.

  10. Laboratory measurements and modeling of molecular photoabsorption in the ultraviolet for planetary atmospheres applications: diatomic sulfur and sulfur monoxide

    NASA Astrophysics Data System (ADS)

    Stark, Glenn

    2016-07-01

    Our research program comprises the measurement and modeling of ultraviolet molecular photoabsorption cross sections with the highest practical resolution. It supports efforts to interpret and model observations of planetary atmospheres. Measurement and modeling efforts on diatomic sulfur (S _{2}) and sulfur monoxide (SO) are in progress. S _{2}: Interpretations of atmospheric (Io, Jupiter, cometary comae) S _{2} absorption features are hindered by a complete lack of laboratory cross section data in the ultraviolet. We are working to quantify the photoabsorption spectrum of S _{2} from 240 to 300 nm based on laboratory measurements and theoretical calculations. We have constructed an experimental apparatus to produce a stable column of S _{2} vapor at a temperature of 800 K. High-resolution measurements of the absorption spectrum of the strong B - X system of S _{2} were completed using the NIST VUV-FTS at Gaithersburg, Maryland. These measurements are currently being incorporated into a coupled-channel model of the absorption spectrum of S _{2} to quantify the contributions from individual band features and to establish the mechanisms responsible for the strong predissociation signature of the B - X system. A successful coupled channels model can then be used to calculate the B - X absorption spectrum at any temperature. SO: There has been a long-standing need for high-resolution cross sections of sulfur monoxide radicals in the ultraviolet and vacuum ultraviolet regions, where the molecule strongly predissociates, for modeling the atmospheres of Io and Venus, and most recently for understanding sulfur isotope effects in the ancient (pre-O _{2}) atmosphere of Earth. We have produced a measurable column of SO in a continuous-flow DC discharge cell, using SO _{2} as a parent molecule. Photoabsorption measurements were recently recorded on the DESIRS beamline of the SOLEIL synchrotron, taking advantage of the high-resolution VUV-FTS on that beamline. A number of

  11. NESSI: the New Mexico Tech Extrasolar Spectroscopic Survey Instrument

    NASA Astrophysics Data System (ADS)

    Jurgenson, C.; Santoro, F.; Creech-Eakman, M.; Houairi, K.; Bloemhard, H.; Vasisht, G.; Swain, M.; Deroo, P.; Moore, C.; Schmidt, L.; Boston, P.; Rodeheffer, D.; Chen, P.

    2010-07-01

    Less than 20 years after the discovery of the first extrasolar planet, exoplanetology is rapidly growing with more than one discovery every week on average since 2007. An important step in exoplanetology is the chemical characterization of exoplanet atmospheres. It has recently been shown that molecular signatures of transiting exoplanets can be studied from the ground. To advance this idea and prepare more ambitious missions such as THESIS, a dedicated spectrometer named the New Mexico Tech Extrasolar Spectroscopic Survey Instrument (NESSI) is being built at New Mexico Tech in collaboration with the NASA Jet Propulsion Laboratory. NESSI is a purpose-built multi-object spectrograph that operates in the J, H, and K-bands with a resolution of R = 1000 in each, as well as a lower resolution of R = 250 across the entire J/H/K region.

  12. Elaboration of collisional-radiative models for flows related to planetary entries into the Earth and Mars atmospheres

    NASA Astrophysics Data System (ADS)

    Bultel, Arnaud; Annaloro, Julien

    2013-04-01

    The most relevant way to predict the excited state number density in a nonequilibrium plasma is to elaborate a collisional-radiative (CR) model taking into account most of the collisional and radiative elementary processes. Three examples of such an elaboration are given in this paper in the case of various plasma flows related to planetary atmospheric entries. The case of theoretical determination of nitrogen atom ionization or recombination global rate coefficients under electron impact is addressed first. The global rate coefficient can be implemented in multidimensional computational fluid dynamics calculations. The case of relaxation after a shock front crossing a gas of N2 molecules treated in the framework of the Rankine-Hugoniot assumptions is also studied. The vibrational and electronic specific CR model elaborated in this case allows one to understand how the plasma reaches equilibrium and to estimate the role of the radiative losses. These radiative losses play a significant role at low pressure in the third case studied. This case concerns CO2 plasma jets inductively generated in high enthalpy wind tunnels used as ground test facilities. We focus our attention on the behaviour of CO and C2 electronic excited states, the radiative signature of which can be particularly significant in this type of plasma. These three cases illustrate the elaboration of CR models and their coupling with balance equations.

  13. Vibrational Spectroscopy of Ions and Radicals Present in the Interstellar Medium and in Planetary Atmospheres: A Theoretical Study

    NASA Technical Reports Server (NTRS)

    Chaban, Galina M.

    2004-01-01

    Anharmonic vibrational frequencies and intensities are calculated for OH(H2O)n and H(H2O)n radicals (that form on icy particles of the interstellar medium), HCO radical (the main intermediate in the synthesis of organic molecules in space), NH2(-) and C2H(-) anions, H5(+) cation, and other systems relevant to interstellar chemistry. In addition to pure ions and radicals, their complexes with water are studied to assess the effects of water environment on infrared spectra. The calculations are performed using the correlation-corrected vibrational self-consistent field (CC-VSCF) method with ab initio potential surfaces at the MP2 and CCSD(T) levels. Fundamental, overtone, and combination excitations are computed. The results are in good agreement with available experimental data and provide reliable predictions for vibrational excitations not yet measured in laboratory experiments. The data should be useful for interpretation of astronomically observed spectra and identification of ions and radicals present in the interstellar medium and in planetary atmospheres.

  14. Planetcam: A Visible And Near Infrared Lucky-imaging Camera To Study Planetary Atmospheres And Solar System Objects

    NASA Astrophysics Data System (ADS)

    Sanchez-Lavega, Agustin; Rojas, J.; Hueso, R.; Perez-Hoyos, S.; de Bilbao, L.; Murga, G.; Ariño, J.; Mendikoa, I.

    2012-10-01

    PlanetCam is a two-channel fast-acquisition and low-noise camera designed for a multispectral study of the atmospheres of the planets (Venus, Mars, Jupiter, Saturn, Uranus and Neptune) and the satellite Titan at high temporal and spatial resolutions simultaneously invisible (0.4-1 μm) and NIR (1-2.5 μm) channels. This is accomplished by means of a dichroic beam splitter that separates both beams directing them into two different detectors. Each detector has filter wheels corresponding to the characteristic absorption bands of each planetary atmosphere. Images are acquired and processed using the “lucky imaging” technique in which several thousand images of the same object are obtained in a short time interval, coregistered and ordered in terms of image quality to reconstruct a high-resolution ideally diffraction limited image of the object. Those images will be also calibrated in terms of intensity and absolute reflectivity. The camera will be tested at the 50.2 cm telescope of the Aula EspaZio Gela (Bilbao) and then commissioned at the 1.05 m at Pic-duMidi Observatory (Franca) and at the 1.23 m telescope at Calar Alto Observatory in Spain. Among the initially planned research targets are: (1) The vertical structure of the clouds and hazes in the planets and their scales of variability; (2) The meteorology, dynamics and global winds and their scales of variability in the planets. PlanetCam is also expected to perform studies of other Solar System and astrophysical objects. Acknowledgments: This work was supported by the Spanish MICIIN project AYA2009-10701 with FEDER funds, by Grupos Gobierno Vasco IT-464-07 and by Universidad País Vasco UPV/EHU through program UFI11/55.

  15. ExoMol: Large-scale production of line lists for molecules important for modelling of planetary atmospheres