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Sample records for extrasolar planetary atmospheres

  1. Extrasolar Planetary Transits

    NASA Astrophysics Data System (ADS)

    Cameron, Andrew Collier

    An extrasolar planet will transit the visible hemisphere of its host star if its orbital plane lies sufficiently close to the observer's line of sight. The resulting periodic dips in stellar flux reveal key system parameters, including the density of the host star and, if radial-velocity observations are available, the surface gravitational acceleration of the planet. In this chapter I present the essential methodology for modelling the time-dependent flux variation during a transit, and its use in determining the posterior probability distribution for the physical parameters of the system. Large-scale searches for transiting systems are an efficient way of discovering planets whose bulk densities, and hence compositions, can be accessed if their masses can also be determined. I present algorithms for detrending large ensembles of light curves, for searching for transit-like signals among them. I also discuss methods for identifying diluted stellar eclipsing binaries mimicking planetary transit signals, and validation of transit candidates too faint for radial-velocity follow-up. I review the use of time-resolved spectrophotometry and high-resolution spectroscopy during transits to identify the molecular constituents of exoplanetary atmospheres.

  2. Extrasolar planetary systems.

    NASA Technical Reports Server (NTRS)

    Huang, S.-S.

    1973-01-01

    The terms 'planet' and 'planet-like objects' are defined. The observational search for extrasolar planetary systems is described, as performable by earthbound optical telescopes, by space probes, by long baseline radio interferometry, and finally by inference from the reception of signals sent by intelligent beings in other worlds. It is shown that any planetary system must be preceded by a rotating disk of gas and dust around a central mass. A brief review of the theories of the formation of the solar system is given, along with a proposed scheme for classification of these theories. The evidence for magnetic activity in the early stages of stellar evolution is presented. The magnetic braking theories of solar and stellar rotation are discussed, and an estimate is made for the frequency of occurrence of planetary systems in the universe.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. Understanding the Atmospheres of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Marley, Mark S.; Fortney, J.

    2007-10-01

    With the direct measurement of thermal emission (and perhaps soon reflected light) from the 'hot Jupiters', extrasolar planetary science is transitioning from discovery to characterization. Familiar attributes of solar system giant planet atmospheres, including hot stratospheres, clouds, redistribution of heat by winds, and perhaps even non-equilibrium molecular abundances and photochemical products have been recognized and modeled in some of these exotic atmospheres. Despite the fact that atmospheric dynamics undoubtedly plays a major role in controlling the thermal structures of these planets, one-dimensional radiative-convective equilibrium models are still exceptionally useful for understanding the baseline atmospheric physics and resultant thermal structure. Our group's apparently successful prediction of a hot stratosphere on planet HD 149026b is emblematic of the utility of 1D models. In the talk we will review our efforts to model the vertical structure of several of the hot Jupiters, focusing on the processes that play major roles in influencing the atmospheric chemical and temperature profiles. We will highlight processes (e.g., photochemistry acting on S-, P-, N-, and O- as well as C-bearing molecules) that are ripe for further modeling. Given that measurements of thermal emission in various Spitzer mid-infrared bands will soon be published for 10 planets, unprecedented opportunities for comparative exoplanetary science are now at hand.

  10. 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,

  11. Atmospheric circulation of eccentric extrasolar giant planets

    NASA Astrophysics Data System (ADS)

    Lewis, Nikole Kae

    This dissertation explores the three-dimensional coupling between radiative and dynamical processes in the atmospheres of eccentric extrasolar giant planets GJ436b, HAT-P-2b, and HD80606b. Extrasolar planets on eccentric orbits are subject to time-variable heating and probable non-synchronous rotation, which results in significant variations in global circulation and thermal patterns as a function of orbital phase. Atmospheric simulations for the low eccentricity (e=0.15) Neptune sized planet GJ436b reveal that when Neptune-like atmospheric compositions are assumed day/night temperature contrasts and equatorial jet speeds are significantly increased relative to models that assume a solar-like composition. Comparisons between our theoretical light curves and recent observations support a high metallicity atmosphere with disequilibrium carbon chemistry for GJ436b. The analysis of full-orbit light curve observations at 3.6 and 4.5 microns of the HAT-P-2 system reveal swings in the planet's temperature of more than 900 K during its significantly eccentric ( e=0.5) orbit with a four to six hour offset between periapse passage and the peak of the planet's observed flux. Comparisons between our atmospheric model of HAT-P-2b and the observed light curves indicate an increased carbon to oxygen ratio in HAT-P-2b's atmosphere compared to solar values. Atmospheric simulations of the highly eccentric (e=0.9) HD80606b show that flash-heating events completely alter planetary thermal and jet structures and that assumptions about the rotation period of this planet could affect the shape of light curve observations near periapse. Our simulations of HD80606b also show the development an atmospheric shock on the nightside of the planet that is associated with an observable thermal signature in our theoretical light curves. The simulations and observations presented in this dissertation mark an important step in the exploration of atmospheric circulation on the more than 300

  12. Planetary upper atmospheres

    NASA Astrophysics Data System (ADS)

    Müller-Wodarg, Ingo

    2005-10-01

    Earth and most planets in our solar system are surrounded by permanent atmospheres. Their outermost layers, the thermospheres, ionospheres and exospheres, are regions which couple the atmospheres to space, the Sun and solar wind. Furthermore, most planets possess a magnetosphere, which extends into space considerably further than the atmosphere, but through magnetosphere-ionosphere coupling processes closely interacts with it. Auroral emissions, found on Earth and other panets, are manifestations of this coupling and a mapping of distant regions in the magnetosphere into the upper atmosphere along magnetic field lines. This article compares planetary upper atmospheres in our solar system and attempts to explain their differences via fundamental properties such as atmospheric gas composition, magnetosphere structure and distance from Sun. Understanding the space environment of Earth and its coupling to the Sun, and attempting to predict its behaviour ("Space Weather") plays an important practical role in protecting satellites, upon which many aspects to todays civilisation rely. By comparing our own space environment to that of other planets we gain a deeper understanding of its physical processes and uniqueness. Increasingly, we apply our knowledge also to atmospheres of extrasolar system planets, which will help assessing the possibility of life-elsewhere in the Universe.

  13. Comparative Understanding of Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Huestis, D. L.; Atreya, S. K.; Bolton, S. J.; Bougher, S. W.; Coustenis, A.; Edgington, S. G.; Friedson, A. J.; Griffith, C. A.; Guberman, S. L.; Hammel, H. B.; Lunine, J. I.; Mendillo, M.; Moses, J.; Mueller-Wodarg, I.; Orton, G. S.; Rages, K. A.; Slanger, T. G.; Titov, D. V.; Yelle, R.

    2001-11-01

    Observing, characterizing, and understanding planetary atmospheres are key components of solar system exploration. A planet's atmosphere is the interface between the surface and external energy and mass sources. Understanding how atmospheres are formed, evolve, and respond to perturbations is essential for addressing the long-range science objectives of identifying the conditions that are favorable for producing and supporting biological activity, managing the effects of human activity on the Earth's atmosphere, and planning and evaluating observations of extra-solar planets. Our current knowledge, based on very few observations, indicates that the planets and moons in the solar system have diverse atmospheres with a number of shared characteristics. Comparing and contrasting solar system atmospheres provides the best means of addressing the broad scientific goals. Additional space missions with specific atmospheric objectives are required. At the same time, investment of additional resources is needed in the infrastructure of observation and interpretation of planetary atmospheres. The Planetary Atmospheres Community Panel is considering and prioritizing potential recommendations in two broad categories. Possible recommendations that apply to multiple planets include creation of a new Comparative Planetary Atmospheres program, establishing a mechanism for secure funding for analysis and interpretation of mission data, creation of a new "Super-Discovery" program for more ambitious planetary missions, enhancement of laboratory and theory research, and deployment of space- or ground-based telescopes dedicated to planetary observations. Possible recommendations for specific planetary missions with atmospheric goals include deep-penetration multiprobes to determine elemental compositions of giant planet atmospheres, Venus and Mars atmospheric explorer missions, and a Post-Cassini atmospheric/surface mission to Titan.

  14. 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.

  15. 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.

  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. Model Atmospheres and Spectra of Extrasolar Giant Planets

    NASA Astrophysics Data System (ADS)

    Marley, M. S.; Guillot, T.; Saumon, D.; Freedman, R. S.

    1996-09-01

    Of the known extrasolar giant planets, five have estimated effective temperatures below ~ 800K. We report on the application of a radiative-convective equilibrium model, originally developed to study the atmospheres of the solar jovian planets, to these objects (70 Vir b, 47 UMa b, Gl 411 b, 55 Cnc c, and HD 114762 b). The deposition of incident radiation from the various primaries and the estimated internal heat fluxes are included in the models. Condensible species are removed and clouds inserted where appropriate. To span the likely range of planet masses, a variety of surface gravities are considered for each object. Preliminary results suggest that water clouds are present in all these atmospheres except for 70 Vir b and HD 114762 b. Water marginally condenses in the atmosphere of the former while that of the latter should be essentially cloud free. Condensation of trace species (e.g. NH_4Cl and NH_4H_2PO_4) may produce thin hazes in these two cases. Thermochemical equilibrium favors NH_3 and CH_4 in all these atmospheres while N_2 and CO are favored in the atmospheres of the close-orbit, hot companions like 51 Peg b and upsilon And b. The reflected visible and thermal infrared spectra of these objects are dominated by water, methane, and ammonia absorption. We find that the 4 to 5 microns window in CH_4 and H_2O opacity is open for all of these objects. Consequently, as in the case of Jupiter and the brown dwarf Gliese 229 B, the emitted flux in this region is significantly greater than the blackbody flux for the planetary effective temperature. Thus this spectral region is favorable for the detection of extrasolar giant planets and brown dwarfs. Comparison of model spectra with observations would constrain the vertical temperature and cloud structure of these new atmospheres. Burrows et al. (this meeting) use these and other models to examine the evolution of extrasolar giant planets.

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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.

  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

    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.

  5. Remote Sensing of Planetary Properties and Biosignatures on Extrasolar Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    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.

    2002-06-01

    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 μm in the mid-IR and 0.5 to ~1.1 μm 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. Introduction - Solar and Extra-Solar Planetary Systems

    NASA Astrophysics Data System (ADS)

    Williams, Iwan P.

    Over the last decade, there have been many exciting advances in all fields relating to our understanding of planetary systems. There has been a significant increase in our understanding of the general process of star formation, leading to an expectation that matter will be captured in a flattened envelope or nebula surrounding the young Sun. Theoretical models had predicted this for some time, but in the last decade, firm observational evidence of this has become fairly commonplace, with β Pictoris in particular displaying all the characteristics that were expected in systems where planets formed. The discovery of extra-solar planets has also confirmed the view that planetary formation is a normal phenomenon so that our system is no longer regarded as a one off or special. Within the Solar System itself, both space exploration and improved facilities for ground-based observations have increased our knowedge of our own system dramatically. Pluto is now the only planet not to have been visited by a spacecraft, and spacecraft images also exist of asteroids and comets. In addition, it is now known that all the major planets have extensive satellite systems as well as complex ring structures. Finally, two new classes of objects have been discovered: the Centaurs orbiting between the major planets; and the Edgeworth-Kuiper objects beyond Neptune.This book is based on the lectures given at a Pre-Doctoral Summer School held in Ballyvaughn, County Clare, Ireland during 7 - 18 September 1998, supported by the European Astrophysical Doctoral Network (EADN). The aim of the School was to give an authoritative account of these new developments so that a thorough general background in the state of our knowledge would be obtained by all participants. The scientific contents of the School can be divided into a number of broad fields. The areas are: Formation of Planetary Systems; Planets and Satellites; and Small Bodies and Dust. The chapter on Dynamics by Murray spans all of

  7. Photochemistry in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Levine, J. S.; Graedel, T. E.

    1981-01-01

    Widely varying paths of evolutionary history, atmospheric processes, solar fluxes, and temperatures have produced vastly different planetary atmospheres. The similarities and differences between the earth atmosphere and those of the terrestrial planets (Venus and Mars) and of the Jovian planets are discussed in detail; consideration is also given to the photochemistry of Saturn, Uranus, Pluto, Neptune, Titan, and Triton. Changes in the earth's ancient atmosphere are described, and problems of interest in the earth's present troposphere are discussed, including the down wind effect, plume interactions, aerosol nucleation and growth, acid rain, and the fate of terpenes. Temperature fluctuations in the four principal layers of the earth's atmosphere, predicted decreases in the ozone concentration as a function of time, and spectra of particles in the earth's upper atmosphere are also presented. Finally, the vertical structure of the Venus cloud system and the thermal structure of the Jovian planets are shown graphically.

  8. The Prospects for Earth-Like Planets within Known Extrasolar Planetary Systems

    NASA Astrophysics Data System (ADS)

    Gehman, Curtis S.; Adams, Fred C.; Laughlin, Gregory

    1996-11-01

    We consider the possible existence of habitable Earth-like planets in four recently discovered extrasolar planetary systems. Such prospective planets must have orbits that are (1) dynamically stable, and (2) allow for surface temperatures compatible with liquid water. We find that three of the four new systems (51 Peg, rho^1 Cnc, and 47 UMa) are easily capable of supporting habitable planets. The fourth (70 Vir) is capable of having a habitable planet only under rather extreme circumstances. To obtain these results, we develop a probabilistic formulation for the coupled problem of orbital stability and planetary habitability. (SECTION: Extrasolar Planets)

  9. Planetary migration, accretion, and atmospheres

    NASA Astrophysics Data System (ADS)

    Dobbs-Dixon, Ian M.

    mechanisms for stopping this accretion involve either disk dispersal or gap formation. Although mass accretion may eventually be quenched by a global depletion of gas, as in the ease of Uranus and Neptune, such a mechanism is unlikely to have stalled the growth of some known planetary systems which contain relatively low-mass and close-in planets along with more massive and longer period companions. Similarly, the formation of a gap cannot fully explain the decrease in mass accretion. Several groups have shown that, even in the presence of a gap, diffusion allows rapid gas accretion to continue. Here I explore the effect of the growing tidal barrier on the flow within the protoplanetary disk. Using both analytic and numerical approaches I show that accretion rates increases rapidly with the ratio of the protoplanet's Roche to Bondi radii or equivalently to the disk thickness. Mass accretion timescales become comparable to observed disk lifetimes. In regions with loco geometric aspect ratios gas accretion is efficiently quenched with relatively low protoplanetary masses. This mechanism is important for determining the gas- giant planets' mass function, the distribution of their masses within multiple planet systems around solar type stars, and for suppressing the emergence of gas-giants around low mass stars. The final section explores the atmospheric dynamics of short-period gas-giant planets. Ubiquitous among currently observed extrasolar planetary systems these planets receive intense irradiation from their host stars that dominates the energy input into their atmospheres. Characterization of several of these planets through transit observations have revealed information on temperature, structure, and composition. Here we present three-dimensional radiative hydrodynamical simulations of atmospheric circulation on close-in gas giant planets. In contrast to previous Global Climate Models and shallow water algorithms, this method does not assume quasi hydrostatic equilibrium

  10. Extra-Solar Planetary Imager (ESPI) for Space Based Jovian Planetary Detection

    NASA Technical Reports Server (NTRS)

    Lyon, Rick G.; Melnick, Gary J.; Nisenson, Peter; Papaliolios, Costa; Ridgeway, Steve; Friedman, Edward; Gezari, Dan Y.; Harwit, Martin; Graf, Paul

    2002-01-01

    We report on out Extra-Solar Planetary Imager (ESPI) study for a recent Midex (NASA Medium Class Explorer Mission) proposal. Proposed for ESPI was a 1.5 x 1.5 square meter Jacquinot apodized square aperture telescope. The combination of apodization and a square aperture telescope significantly reduces the diffracted light from a bright central source over much of the telescope focal plane. As a result, observations of very faint astronomical objects next to bright sources with angular separations as small as 0.32 arcseconds become possible. This permits a sensitive search for exo-planets in reflected light. The system is capable of detecting a Jupiter-like planet in a relatively long-period orbit around as many as 160 to 175 stars with a signal-to-noise ratio greater than 5 in observations lasting maximally 100 hours per star. We discuss the effects of wavefront error, mirror speckle, pointing error and signal-to-noise issues, as well as the scalability of our ESPI study with respect to NASA's Terrestrial Planet Finder mission.

  11. Studies of extended planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hunten, D. M.

    1991-01-01

    The following topics are covered: (1) telescopic observations and analysis of planetary atmospheres (including the Moon and Mars) and the Io torus; (2) occultation observations; and (3) supporting laboratory studies.

  12. 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.

  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. 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

  15. 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. PMID:16710412

  16. Radial Velocity Detection of Extra-Solar Planetary Systems

    NASA Technical Reports Server (NTRS)

    Cochran, William D.

    2004-01-01

    This NASA Origins Program grant supported four closely related research programs at The University of Texas at Austin: 1) The McDonald Observatory Planetary Search (MOPS) Program, using the McDonald Observatory 2.7m Harlan Smith telescope and its 2dcoud6 spectrometer, 2) A high-precision radial-velocity survey of Hyades dwarfs, using the Keck telescope and its HIRES spectrograph, 3) A program at McDonald Observatory to obtain spectra of the parent stars of planetary systems at R = 210,000, and 4) the start of high precision radial velocity surveys using the Hobby-Eberly Telescope. The most important results from NASA support of these research programs are described below. A list of all papers published under support of this grant is included at the end.

  17. Radial Velocity Detection of Extra-Solar Planetary Systems

    NASA Technical Reports Server (NTRS)

    Cochran, William D.

    2004-01-01

    This NASA Origins Program grant supported four closely related research programs at The University of Texas at Austin: 1) The McDonald Observatory Planetary Search (MOPS) Program, using the McDonald Observatory 2.7m Harlan Smith telescope and its 2dcoude spectrometer, 2) A high-precision radial-velocity survey of Hyades dwarfs, using the Keck telescope and its HIRES spectrograph, 3) A program at McDonald Observatory to obtain spectra of the parent stars of planetary systems at R = 210,000, and 4) the start of high precision radial velocity surveys using the Hobby-Eberly Telescope. The most important results from NASA support of these research programs are described. A list of all papers published under support of this grant is included at the end.

  18. 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?

  19. 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

  20. PLANETARY MIGRATION AND ECCENTRICITY AND INCLINATION RESONANCES IN EXTRASOLAR PLANETARY SYSTEMS

    SciTech Connect

    Lee, Man Hoi; Thommes, Edward W. E-mail: ethommes@physics.uoguelph.ca

    2009-09-10

    The differential migration of two planets due to planet-disk interaction can result in capture into the 2:1 eccentricity-type mean-motion resonances. Both the sequence of 2:1 eccentricity resonances that the system is driven through by continued migration and the possibility of a subsequent capture into the 4:2 inclination resonances are sensitive to the migration rate within the range expected for type II migration due to planet-disk interaction. If the migration rate is fast, the resonant pair can evolve into a family of 2:1 eccentricity resonances different from those found by Lee. This new family has outer orbital eccentricity e {sub 2} {approx}> 0.4-0.5, asymmetric librations of both eccentricity resonance variables, and orbits that intersect if they are exactly coplanar. Although this family exists for an inner-to-outer planet mass ratio m {sub 1}/m {sub 2} {approx}> 0.2, it is possible to evolve into this family by fast migration only for m {sub 1}/m {sub 2} {approx}> 2. Thommes and Lissauer have found that a capture into the 4:2 inclination resonances is possible only for m {sub 1}/m {sub 2} {approx}< 2. We show that this capture is also possible for m {sub 1}/m {sub 2} {approx}> 2 if the migration rate is slightly slower than that adopted by Thommes and Lissauer. There is significant theoretical uncertainty in both the sign and the magnitude of the net effect of planet-disk interaction on the orbital eccentricity of a planet. If the eccentricity is damped on a timescale comparable to or shorter than the migration timescale, e {sub 2} may not be able to reach the values needed to enter either the new 2:1 eccentricity resonances or the 4:2 inclination resonances. Thus, if future observations of extrasolar planetary systems were to reveal certain combinations of mass ratio and resonant configuration, they would place a constraint on the strength of eccentricity damping during migration, as well as on the rate of the migration itself.

  1. Oscillations of relative inclination angles in compact extrasolar planetary systems

    NASA Astrophysics Data System (ADS)

    Becker, Juliette C.; Adams, Fred C.

    2016-01-01

    The Kepler mission has detected dozens of compact planetary systems with more than four transiting planets. This sample provides a collection of close-packed planetary systems with relatively little spread in the inclination angles of the inferred orbits. A large fraction of the observational sample contains limited multiplicity, begging the question whether there is a true diversity of multitransiting systems, or if some systems merely possess high mutual inclinations, allowing them to appear as single-transiting systems in a transit-based survey. This paper begins an exploration of the effectiveness of dynamical mechanisms in exciting orbital inclination within exoplanetary systems of this class. For these tightly packed systems, we determine that the orbital inclination angles are not spread out appreciably through self-excitation. In contrast, the two Kepler multiplanet systems with additional non-transiting planets are susceptible to oscillations of their inclination angles, which means their currently observed configurations could be due to planet-planet interactions alone. We also provide constraints and predictions for the expected transit duration variations for each planet. In these multiplanet compact Kepler systems, oscillations of their inclination angles are remarkably hard to excite; as a result, they tend to remain continually mutually transiting (CMT-stable). We study this issue further by augmenting the planet masses and determining the enhancement factor required for oscillations to move the systems out of transit. The oscillations of inclination found here inform the recently suggested dichotomy in the sample of Solar systems observed by Kepler.

  2. Understanding Microbial Contributions to Planetary Atmosphere

    NASA Technical Reports Server (NTRS)

    DesMarais, David J.

    2000-01-01

    Should our search of distant, extrasolar planetary atmospheres encounter evidence of life, that evidence will most likely be the gaseous products of microorganisms. Our biosphere was exclusively microbial for over 80 percent of its history and, even today, microbes strongly influence atmospheric composition. Life's greatest environmental impact arises from its capacity for harvesting energy and creating organic matter. Microorganisms catalyze the equilibration of C, S and transition metal species at temperatures where such reactions can be very slow in the absence of life. Sunlight has been harvested through photosynthesis to create enormous energy reservoirs that exist in the form of coexisting reservoirs of reduced, organic C and S stored in Earth's crust, and highly oxidized species (oxygen, sulfate and ferric iron) stored in the crust, oceans and atmosphere. Our civilization taps that storehouse of energy by burning fossil fuels. As astrobiologists, we identify the chemical consequences of distant biospheres as expressed in the atmospheres of their planets. Our approach must recognize that planets, biospheres and atmospheres evolve and change. For example, a tectonically more active early Earth hosted a thermophilic, non-photosynthetic biosphere and a mildly reducing, carbon dioxide-rich and oxygen-poor atmosphere. Microorganisms acquired energy by consuming hydrogen and sulfide and producing a broad array of reduced C and S gases, most notably, methane. Later, diverse types of bacterial photosynthesis developed that enhanced productivity but were incapable of splitting water to produce oxygen. Later, but still prior to 2.6 billion years ago, oxygenic photosynthesis developed. We can expect to encounter distant biospheres that represent various stages of evolution and that coexist with atmospheres ranging from mildly reducing to oxidizing compositions. Accordinaly, we must be prepared to interpret a broad range of atmospheric compositions, all containing

  3. 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.

  4. 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.

  5. 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.

  6. Planetary atmospheres. [reviewing recent research

    NASA Technical Reports Server (NTRS)

    Leovy, Conway

    1987-01-01

    Observations and theoretical models of planetary atmospheres published during the period 1983-1986 are reviewed, including Vega and Voyager data and results from ground-based remote sensing. Consideration is given to water-vapor and sulfur-compound distributions, electrical phenomena, and dynamics in the Venus atmosphere; dust storms, water cycles, and water and ice erosion on Mars; the compositions, temperature profiles, and dynamics of the Jovian and Saturnian atmospheres; chemical processes and zonal winds on Titan; and the radiation budgets and chemical compositions of the outer planets.

  7. Selected Examples of Solar and Extra-Solar Planetary Science with AO

    NASA Astrophysics Data System (ADS)

    Close, Laird M.; Lenzen, Rainer; Biller, Beth; Brandner, Wolfgang; Hartung, Markus

    High spatial resolution planetary science has seen a large boost from AO observations complementing space missions. Adaptive optics is particularly well suited for planetary astronomy since solar system bodies have temporal behavior well suited to multiple epochs of observation. Here we will just highlight some very recent examples: Uranus's rings (de Pater et al. 2002), volcanoes on Io (Marchis et al. 2002), the surface of 3 Juno (Baliunas et al. 2003), and binary asteroids (Merline et al. 2002). In addition, we will present "first light" sensitivities from a high contrast simultaneous differential imager (SDI) device. This device (called NACO SDI) can detect an extrasolar planet 25,000 times fainter just 0.5" from its parent star in 40 min of VLT time at 6 sigma. These are the highest contrast astronomical images taken to date.

  8. Review of methodology and technology available for the detection of extrasolar planetary systems

    NASA Technical Reports Server (NTRS)

    Tarter, J. C.; Black, D. C.; Billingham, J.

    1986-01-01

    Anyone undertaking an interstellar voyage might wish to be assured of the existence of a safe planetary harbor at the other end! Aside from the obvious interest of the participants in this Symposium, astronomers and astrophysicists are also eager to detect and study other planetary systems in order to better understand the formation of our own Solar System. Scientists involved in the search for extraterrestrial intelligence argue that planets suitable for the evolution of life may abound elsewhere within our own Milky Way Galaxy. On theoretical grounds, they are probably correct, but they lack any observational support. For in spite of decades of claimed astrometric detections of planetary companions and the recent exciting and tantalizing observations from the IRAS satellite and the IR speckle observations of Van Biesbroeck 8 and other cool stars, there is no unambiguous proof for the existence of another planetary system beyond our own. In this paper we review the various methods for detecting extrasolar planets and briefly describe the Earth and space based technology currently available and discuss the near-term plans to implement these different search techniques. In each case an attempt is made to identify the limiting source of systematic error inherent to the methodology and to assess the potential for technological improvements.

  9. Challenges of Using Earth's Atmosphere as a Proxy for Detecting Biosignatures on Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    DeMarines, J.

    2012-06-01

    Assessing the challenges associated with the detectability of primitive biosignatures present on early Earth (methane and ethane) and addressing the observational difficulties when we begin to observe extrasolar atmospheres with a TPF-O mission.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Deeg, Hans; Belmonte, Juan Antonio; Aparicio, Antonio

    2012-03-01

    Participants; Preface; Acknowledgements; 1. Extrasolar planet detection methods Laurance R. Doyle; 2. Statistical properties of exoplanets Stéphane Udry; 3. Characterizing extrasolar planets Timothy M. Brown; 4. From clouds to planet systems: formation and evolution of stars and planets Günther Wuchterl; 5. Abundances in stars with extrasolar planetary systems Garik Israelian; 6. Brown dwarfs: the bridge between stars and planets Rafael Rebolo; 7. The perspective: a panorama of the Solar System Agustín Sánchez-Lavega; 8. Habitable planets around the Sun and other stars James F. Kasting; 9. Biomarkers of extrasolar planets and their observability Franck Selsis, Jimmy Paillet and France Allard; Index.

  17. Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Deeg, Hans; Belmonte, Juan Antonio; Aparicio, Antonio

    2007-10-01

    Participants; Preface; Acknowledgements; 1. Extrasolar planet detection methods Laurance R. Doyle; 2. Statistical properties of exoplanets Stéphane Udry; 3. Characterizing extrasolar planets Timothy M. Brown; 4. From clouds to planet systems: formation and evolution of stars and planets Günther Wuchterl; 5. Abundances in stars with extrasolar planetary systems Garik Israelian; 6. Brown dwarfs: the bridge between stars and planets Rafael Rebolo; 7. The perspective: a panorama of the Solar System Agustín Sánchez-Lavega; 8. Habitable planets around the Sun and other stars James F. Kasting; 9. Biomarkers of extrasolar planets and their observability Franck Selsis, Jimmy Paillet and France Allard; Index.

  18. Isotopic ratios in planetary atmospheres.

    PubMed

    de Bergh, C

    1995-03-01

    Recent progress on measurements of isotopic ratios in planetary or satellite atmospheres include measurements of the D/H ratio in the methane of Uranus, Neptune and Titan and in the water of Mars and Venus. Implications of these measurements on our understanding of the formation and evolution of the planets and satellite are discussed. Our current knowledge of the carbon, nitrogen and oxygen isotopic ratios in the atmospheres of these planets, as well as on Jupiter and Saturn, is also reviewed. We finally show what progress can be expected in the very near future due to some new ground-based instrumentation particularly well suited to such studies, and to forthcoming space missions. PMID:11539257

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Eccentricity Evolution of Extrasolar Multiple Planetary Systems Due to the Depletion of Nascent Protostellar Disks

    NASA Astrophysics Data System (ADS)

    Nagasawa, M.; Lin, D. N. C.; Ida, S.

    2003-04-01

    Most extrasolar planets are observed to have eccentricities much larger than those in the solar system. Some of these planets have sibling planets, with comparable masses, orbiting around the same host stars. In these multiple planetary systems, eccentricity is modulated by the planets' mutual secular interaction as a consequence of angular momentum exchange between them. For mature planets, the eigenfrequencies of this modulation are determined by their mass and semimajor axis ratios. However, prior to the disk depletion, self-gravity of the planets' nascent disks dominates the precession eigenfrequencies. We examine here the initial evolution of young planets' eccentricity due to the apsidal libration or circulation induced by both the secular interaction between them and the self-gravity of their nascent disks. We show that as the latter effect declines adiabatically with disk depletion, the modulation amplitude of the planets' relative phase of periapsis is approximately invariant despite the time-asymmetrical exchange of angular momentum between planets. However, as the young planets' orbits pass through a state of secular resonance, their mean eccentricities undergo systematic quantitative changes. For applications, we analyze the eccentricity evolution of planets around υ Andromedae and HD 168443 during the epoch of protostellar disk depletion. We find that the disk depletion can change the planets' eccentricity ratio. However, the relatively large amplitude of the planets' eccentricity cannot be excited if all the planets had small initial eccentricities.

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. Studies of planetary upper atmospheres through occultations

    NASA Technical Reports Server (NTRS)

    Elliot, J. L.

    1982-01-01

    The structure, composition, dynamics and energy balance of planetary upper atmospheres through interpretation of steller occultation data from Uranus is discussed. The wave-optical problem of modelling strong scintillation for arbitrary turbulent atmospheres is studied, as well as influence of turbulence. It was concluded that quasi-global features of atmospheric structure are accurately determined by numerical inversion. Horizontally inhomogeneous structures are filtered out and have little effect on temperature profiles.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  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. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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. PMID:17407410

  4. Detection techniques for tenuous planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hoenig, S. A.

    1978-01-01

    The application of detectors developed for analysis of planetary atmospheres under partial vacuum conditions, and data obtained during dust charging studies to various industrial problems is summarized. A specialized apparatus for dust measurements on a planetary lander was designed with the capability of measuring ambient dust density as a function of particle size, as well as for observing the charge of the collected dust. the optical system operates on an intermittent basis and requires only low power. No radioactive source or delicate detection equipment is required. Advances in monitoring catalyst operation by means of exoelection emission are also reported.

  5. 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.

  6. 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.

  7. 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.).

  8. 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

  9. Ultraviolet emissions in the planetary atmospheres.

    NASA Astrophysics Data System (ADS)

    Shematovich, V. I.

    2008-12-01

    Actual state and perspectives of the observations of the plan- etary atmospheres in the ultraviolet range of wavelengths are discussed. The main features of the planetary aeronomy for terrestrial planets, giant planets and exoplanets-transits are given. The following hot problems of the plane- tary astronomy in the UV wavelength range are discussed: (i) UV observations of hot coronas of the terrestrial planets; (ii) formation and morphology of the rarefied H2O-, O2 - and O-dominant atmospheres of the icy satellites in the gi- ant planet systems; (iii) formation and evolution of the neutral gas clouds in the giant planet systems; (iv) studies of the extended hydrogen coronae of the transit-exoplanets formed due to the stellar UV and plasma wind forcing. The mathematical models such as the Monte Carlo model for the electron, proton, and heavy-ion precipitation into the planetary atmospheres are also discussed. Such models are currently used to calculate the excitation rates of the atmo- spheric UV emissions and will be used for the interpretation of the expected UV observations of the planetary atmospheres with the space observatory World Space Observatory - Ultraviolet (WSO-UV) [1, 2].

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Planetary atmospheric physics and solar physics research

    NASA Technical Reports Server (NTRS)

    1973-01-01

    An overview is presented on current and planned research activities in the major areas of solar physics, planetary atmospheres, and space astronomy. The approach to these unsolved problems involves experimental techniques, theoretical analysis, and the use of computers to analyze the data from space experiments. The point is made that the research program is characterized by each activity interacting with the other activities in the laboratory.

  18. Infrared line widths at planetary atmospheric temperatures

    NASA Technical Reports Server (NTRS)

    Varanasi, Prasad

    1988-01-01

    Recent theoretical models and measurements of the variation of collision-broadened line width with temperature in the infrared are discussed for temperatures relevant to planetary atmospheres. The present review is restricted to lines broadened by H2, N2, O2, CO2, and He, the lines formed in the atmospheres of Jupiter, Saturn, Uranus, and Neptune. The design for a low-temperature absorption cell consisting of a nickel-coated copper tube is described. The lack of an adequate theoretical model for variation of the collision-broadened line width with temperature in terms of the molecular constants of the colliding partners is pointed out.

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. Updated Review of Planetary Atmospheric Electricity

    NASA Astrophysics Data System (ADS)

    Yair, Y.; Fischer, G.; Simões, F.; Renno, N.; Zarka, P.

    This paper reviews the progress achieved in planetary atmospheric electricity, with focus on lightning observations by present operational spacecraft, aiming to fill the hiatus from the latest review published by Desch et al. (Rep. Prog. Phys. 65:955-997, 2002). The information is organized according to solid surface bodies (Earth, Venus, Mars and Titan) and gaseous planets (Jupiter, Saturn, Uranus and Neptune), and each section presents the latest results from space-based and ground-based observations as well as laboratory experiments. Finally, we review planned future space missions to Earth and other planets that will address some of the existing gaps in our knowledge.

  6. Updated Review of Planetary Atmospheric Electricity

    NASA Astrophysics Data System (ADS)

    Yair, Y.; Fischer, G.; Simões, F.; Renno, N.; Zarka, P.

    2008-06-01

    This paper reviews the progress achieved in planetary atmospheric electricity, with focus on lightning observations by present operational spacecraft, aiming to fill the hiatus from the latest review published by Desch et al. (Rep. Prog. Phys. 65:955 997, 2002). The information is organized according to solid surface bodies (Earth, Venus, Mars and Titan) and gaseous planets (Jupiter, Saturn, Uranus and Neptune), and each section presents the latest results from space-based and ground-based observations as well as laboratory experiments. Finally, we review planned future space missions to Earth and other planets that will address some of the existing gaps in our knowledge.

  7. 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

  8. 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.

  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. 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.

  11. 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

  12. Multiple transiting extrasolar planetary systems - follow-up and Kepler discoveries

    NASA Astrophysics Data System (ADS)

    Pál, A.; Borkovits, T.; Szakáts, R.

    2011-10-01

    In this work we present a method that can be used as a tool for investigating such planetary systems in the framework of classic regression analysis. The base of the method is the employment of the Lie-integration method [3] that provides the solution of the differential equations (that describe the interacting planetary dynamics) in the form of power series and therefore provides a way to exploit the properties of the integrator for further analytical computations, such as error propagation calculations. This analytical description is rather relevant in the cases of not-so-well constrained orbital elements (for instance, mutual inclination): letting these parameters be varied might yield an unexpectedly high correlation that affects badly the otherwise efficient alternative methods, such as Monte- Carlo estimations. This analytical treatment aids us to perform almost any kind of regression analysis method as simple as it would be in case of well-known and or other well-behaved functions. Based on previously developed methods for similar types of analysis of radial velocity variations in multiple planetary systems [4], we present further possible applications discussing the above mentioned aspects of multiple transiting planetary systems. These applications include creating observation strategies for follow-up of Kepler discoveries after the mission, adaptive observation scheduling focusing on the more effective refinement of selected orbital parameters and of course, precise and accurate estimation of masses, orbital elements and their respective uncertainties.

  13. 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

  14. 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

  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. 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.

  17. 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.

  18. Meteoroids in solar corona and planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Lamy, Herve; Mann, Ingrid; Lemaire, Emeritus Joseph

    We simulate the meteoroid entry into the solar corona with a model similar to the one-dimensional ablation model developed by Campbell-Brown and Koschny (2004) for the Earth's atmosphere and by McAuliffe and Christou (2005) for the case of the atmosphere of Venus. We present the results of mass deposition profiles for a wide range of masses for objects falling into the Sun. Several representative chemical compositions of these objects are also considered in-cluding refractory and volatile materials. Our main focus is in the bigger objects (mass ¿ 1 Kg) for which most of the mass is deposited in the lower layers of the solar corona. The interaction of sungrazing comets with the solar corona is studied with a two-dimensional generalization of the model. The cumulative profile of mass deposition is calculated and we look for the actual effects on the coronal heavy ions composition. In particular we discuss possible implications for the FIP (First Ionization Potential) effect and for the formation of pick-up ions that are measured in the solar wind. We consider the similarities and differences of the entry process in the Solar corona and in planetary atmospheres and we shortly address the survival probability of molecular species.

  19. 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.

  20. 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.

  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. 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.

  3. Abundances of isotopes in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Owen, T.

    1978-01-01

    Carbon and oxygen isotopes show no large anomalies on Venus (no more than 10-15%) or Mars (less than 5%); the high value of N-15/N-14 found on Mars is explained by nonthermal escape of nitrogen. The isotopes of nonradiogenic noble gases in the atmosphere of Mars exhibit abundance patterns similar to those in the primordial component of meteoritic gases and in the earth's atmosphere. This implies that gas fractionation took place in the inner solar nebula prior to planet formation. The relatively high value of Xe-129 on Mars emphasizes its deficiency on earth, implying a difference in accretion histories of volatiles for the two planets. In the outer solar system, normal isotope ratios for nitrogen and carbon on Jupiter, and for carbon on Saturn are found, but precision is low (+ or - 15% at best). Controversy exists about the correct value of D/H, with current estimates ranging from 2.3 plus or minus 1.1 to 5.1 plus or - 0.7 times 10 to the minus 5th. Planetary missions planned for the next few years should add considerably to the quantity and quality of these data.

  4. The ELODIE survey for northern extra-solar planets. III. Three planetary candidates detected with ELODIE

    NASA Astrophysics Data System (ADS)

    Naef, D.; Mayor, M.; Beuzit, J. L.; Perrier, C.; Queloz, D.; Sivan, J. P.; Udry, S.

    2004-01-01

    We present our ELODIE radial-velocity measurements of HD 74156 and 14 Her (HD 145675). These stars exhibit low-amplitude radial-velocity variations induced by the presence of low-mass companions. The radial-velocity data of HD 74156 reveal the presence of two planetary companions: a 1.86 MJup planet on a 51.64-d orbit and a 6.2 MJup planet on a long-period (≃5.5 yr) orbit. Both orbits are fairly eccentric (e = 0.64 and 0.58). The 4.7 MJup companion to 14 Her has a long period (4.9 yr) and a moderately eccentric orbit (e = 0.34). We detect an additional linear radial-velocity trend superimposed on the periodic signal for this star. We also compute updated orbital solutions for HD 209458 and 51 Peg (HD 217014). Finally, we present our ELODIE radial-velocity data and orbital solutions for 5 stars known to host planetary companions: Ups And (HD 9826), 55 Cnc (HD 75732), 47 UMa (HD 95128), 70 Vir (HD 117176) and HD 187123. We confirm the previously published orbital solutions for Ups And, 70 Vir and HD 187123. Our data are not sufficient to fully confirm the orbital solutions for 55 Cnc and 47 UMa. Based on observations made with the ELODIE echelle spectrograph mounted on the 1.93-m Telescope at the Observatoire de Haute-Provence (CNRS) and with the CORALIE echelle spectrograph mounted on the 1.2-m Euler Swiss Telescope at ESO-La Silla Observatory. The ELODIE and CORALIE measurements discussed in this paper are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/414/351

  5. 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.

  6. Planetary Atmosphere Dynamics and Radiative Transfer

    NASA Technical Reports Server (NTRS)

    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

  7. Periastron precession measurements in transiting extrasolar planetary systems at the level of general relativity

    NASA Astrophysics Data System (ADS)

    Pál, András; Kocsis, Bence

    2008-09-01

    Transiting exoplanetary systems are surpassingly important among the planetary systems since they provide the widest spectrum of information for both the planet and the host star. If a transiting planet is on an eccentric orbit, the duration of transits TD is sensitive to the orientation of the orbital ellipse relative to the line of sight. The precession of the orbit results in a systematic variation in both the duration of individual transit events and the observed period between successive transits, Pobs. The periastron of the ellipse slowly precesses due to general relativity and possibly the presence of other planets in the system. This secular precession can be detected through the long-term change in Pobs (transit timing variations, TTV) or in TD (transit duration variations, TDV). We estimate the corresponding precession measurement precision for repeated future observations of the known eccentric transiting exoplanetary systems (XO-3b, HD 147506b, GJ 436b and HD 17156b) using existing or planned space-borne instruments. The TDV measurement improves the precession detection sensitivity by orders of magnitude over the TTV measurement. We find that TDV measurements over a approximately 4yr period can typically detect the precession rate to a precision well exceeding the level predicted by general relativity.

  8. The Circumstellar Imager: Direct detection of extra-solar planetary systems

    NASA Technical Reports Server (NTRS)

    Ftaclas, Christ; Nonnenmacher, Andreas L.; Terrile, Richard J.; Pravdo, Steven H.; Gatewood, George D.; Levy, Eugene

    1994-01-01

    The Astrometric Imaging Telescope (AIT) is designed to probe the circumstellar environment by both direct imaging and indirect astrometric measurements. The Circumstellar Imager (CI) is a coronagraphic camera and is the direct imaging component of the AIT. The CI is designed to obtain high-sensitivity images of the circumstellar region. It provides crucial non-inferential information relating to the frequency, origin, and evolution of planetary systems and all forms of circumstellar matter. Such imaging is usually limited by the scattered and diffracted light halos of the star itself, which are greatly suppressed in the CI by mating a novel high-efficiency coronagraph with a phase-compensated optical system. For faint point sources in the circumstellar region, the CI will have a sensitivity in excess of 5 magnitudes fainter than the as-designed Hubble Space Telescope (HST). Laboratory data are shown for the coronagraph, which, in a diffraction-limited environment, is capable of suppressing the stellar diffraction sidelobes by several orders of magnitude without significant sacrifice of field of view. In order to realize the high rejection levels inherent in the coronagraph design, it is necessary to limit scatter in the optical systems, imposing a mid-spatial frequency figure error requirement an order of magnitude smaller than that of the HST. Experimental data directed toward meeting this requirement are also shown.

  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. 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.

  12. 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.

  13. Spectroscopic analyses of the parent stars of extrasolar planetary system candidates

    NASA Astrophysics Data System (ADS)

    Gonzalez, Guillermo

    1998-06-01

    The stars rho () 1 Cnc, rho CrB, 16 Cyg B, 51 Peg, 47 UMa, 70 Vir, and HD 114762 have recently been proposed to harbor planetary mass companions based on small amplitude radial velocity variations. From spectroscopic analyses we derive the following values of [Fe/H] for these stars: 0.29, -0.29, 0.06, 0.21, 0.01, -0.03, and -0.60 (all with an uncertainty of 0.06 dex), respectively; the [Fe/H] value for 16 Cyg A is 0.11. The four 51 Peg-like systems, upsilon And, tau Boo, rho () 1 Cnc, and 51 Peg, have a mean [Fe/H] value of 0.25. Otherwise, the abundance patterns, expressed as [X/Fe], are approximately solar. We used Fourier analysis, supplemented by line profile synthesis, to derive the following v sin i values: <1.3, 1.4 +/- 0.3, 1.7 +/- 0.4, < 0.5, and < 1.5 km s(-1) for rho () 1 Cnc, 51 Peg, 47 UMa, 70 Vir, and HD 114762, respectively. A similar analysis of the spectrum of rho CrB (with a lower resolving power) yields a value of ~ 1.5 km s() -1. Combining these data with published estimates of v sin i and rotation periods and assuming that the radial velocity variations are due to the presence of planets, we derive the following masses for the companions: >0.66, 2.9(+13.6}_{-1.3) , 0.49+/-0.03, 3.4() +3.1_-1.1, >9.4, and >10.4 cal M_J for rho () 1 Cnc, rho CrB, 51 Peg, 47 UMa, 70 Vir, and HD 114762, respectively; the mass of 16 Cyg B b, calculated using a published estimate for sin i, is 2.0() +1.1_-0.3 cal M_J. The masses of the companions to upsilon And and tau Boo, which were analyzed in a previous paper, are 0.76() +0.19_-0.03 and 5.9() +43.9_-1.8 cal M_J, respectively. We confirm previous claims that rho () 1 Cnc appears to be a subgiant. However, the theoretical isochrone-derived age is much greater than the age of the universe. At this time we have insufficient data to determine the true nature of rho () 1 Cnc, but we suggest that it may be an unresolved stellar binary viewed nearly pole-on. A search for line profile variations might help to resolve this

  14. 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.

  15. 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.

  16. Franklin Lecture: Lightning in Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Gurnett, D. A.

    2006-12-01

    A broad overview is given of lightning in planetary atmospheres. Searches for lightning using spacecraft-borne instrumentation have now been conducted at almost all of the planets in the solar system, the exceptions being Mercury, which has no appreciable atmosphere, and Pluto which has not yet been visited by a spacecraft. The techniques used include (1) imaging observations to detect optical flashes produced by lightning; (2) high-frequency radio measurements to detect the impulsive broadband radio bursts, called spherics, produced by lightning discharges; and (3) low-frequency plasma wave measurements to detect the whistling tones, called whistlers, produced by lightning. Using these techniques, lightning has been reported at five planets other than Earth. These are: Venus, Jupiter, Saturn, Uranus, and Neptune. Of these, the existence of lightning at Venus is doubtful, and the evidence of lightning at Neptune is at best marginal. Jupiter and Saturn have by far the most intense and well documented lightning activity. During the Voyager 1 flyby of Jupiter, whistlers and intense optical flashes, comparable to those from terrestrial superbolts, were observed by the plasma wave and optical imaging instruments. However, no impulsive high-frequency radio bursts were observed. Two factors may be responsible for the absence of high-frequency radio signals: (1) the very strong magnetic field of Jupiter, which blocks the escape of the extra-ordinary mode; and (2) the relatively high electron collision frequency in the ionosphere, which increases the absorption of radio waves. During the Voyager 1 and 2 flybys of Saturn many very strong high-frequency radio bursts, called Saturn Electrostatic Discharges (SEDs), were detected. Although the origin of these impulsive radio bursts was initially uncertain, strong evidence now exists that SEDs are produced by lightning. Recent optical imaging and radio measurements from the Cassini spacecraft clearly show that SEDs originate from

  17. 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.

  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. 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.

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. A New Perspective on Trapped Radiation Belts in Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Diaz, A.; Lodhi, M. A. K.; Wilson, T. L.

    2005-01-01

    The charged particle fluxes trapped in the magnetic dipole fields of certain planets in our Solar System are interesting signatures of planetary properties in space physics. They also represent a source of potentially hazardous radiation to spacecraft during planetary and interplanetary exploration. The Earth s trapped radiation belts have been studied for years and the physical mechanisms by which primary radiation from the Sun and Galaxy is captured is well understood. The higher-energy particles collide with molecules in the planetary atmosphere and initiate large cascades of secondary radiation which itself becomes trapped by the magnetic dipole field of the planet. Some of it is even backscattered as albedo neutrons.

  6. 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)

  7. 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.

  8. Scientific program in planetary atmospheric studies

    NASA Technical Reports Server (NTRS)

    Broadfoot, A. L.

    1983-01-01

    The Voyager encounters with Jupiter led to two main areas of investigation: (1) the definition of the structure and composition of the upper atmosphere and the interaction of the magnetosphere and atmosphere, and (2) the study of the plasma torus using the EUV (Extreme Ultraviolet) data in conjunction with ground-based and in-situ measurements. In the course of these investigations, the atmosphere studies were extended to a comparative study with the bound atmospheres of Saturn and Titan; and the torus study expanded to include the extended atmospheres of Titan (the H torus) and the rings of Saturn.

  9. Observations of Planetary and Satellite Atmospheres and Surfaces

    NASA Astrophysics Data System (ADS)

    Lellouch, E.

    2001-07-01

    The full opening of the submillimeter range with the operation of Herschel is expected to prove very useful for the study of planetary atmospheres and surfaces. Areas of anticipated progress include: (i) the origin and evolution of the Giant Planets, from improved determinations of the abundance of deuterium and helium (ii) the origin of the external source of oxygen in the Giant Planets and Titan (iii) several compositional and physical aspects of planetary atmospheres, especially the issue of vertical transport in Uranus and Neptune and the martian photochemistry and (iv) the thermophysical and compositional properties of planetary surfaces, including the size distribution of transneptunian objects. The high sensitivity of all instruments and the diversity of their spectral resolutions is well suited to the diversity of size and atmospheric pressure within the bodies of the Solar System.

  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. PMID:17314975

  12. 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

  13. Comparative Planetary Atmospheres of the Galilean Satellites

    NASA Astrophysics Data System (ADS)

    Strobel, Darrell F.

    We know that each of the Galilean satellites of Jupiter has a tenuous atmosphere by terrestrial standards. Io has an SO2 atmosphere with column densities ~ 1016 cm-2 in the equatorial regions and at least an order of magnitude smaller densities in the polar regions. Europa and Ganymede have O2 atmospheres with column densities in the range of (1-10) x 1014 cm-2 whereas Callisto has an CO2 atmosphere of comparable column density. I will give exploratory comparisons of the composition of these atmospheres and their production and loss rates to estimate residence times of the dominant molecules. Based on measured and calculated ionospheric density profiles the ionospheric Pedersen and Hall conductances can be computed to estimate the strengths of their electrodynamic interactions with the Io plasma torus. As a result of these interactions large electric currents flow through their ionospheres (~ 106 A) accompanied by large Joule heating rates that can be the dominant heating mechanism of their atmospheres. Production mechanisms for HST/STIS observed UV airglow/auroras will be discussed in terms of neutral composition electron densities and temperatures necessary to achieve measured brightnesses.

  14. 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.

  15. 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.

  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. HITRAN2012 and Remote Sensing of Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Gordon, I. E.; Rothman, L. S.; Li, G.

    2013-06-01

    For the recently-released HITRAN2012 edition of the database, a substantial effort was taken to extend the HITRAN database to have capabilities for studying a variety of planetary atmospheres. Spectroscopic parameters for gases and spectral bands of molecules that are germane to the studies of planetary atmospheres have been assembled. These parameters include the types of data that have already been considered for transmission and radiance algorithms, such as line position, intensity, broadening coefficients, lower-state energies, and temperature dependence values. Besides adding new bands and isotopologues to the relevant molecules that already exist in HITRAN (methane, hydrogen halides, hydrogen disulfide, etc.), a number of new molecules, namely H_2, CS, C_4H_2, HC_3N and SO_3 have been incorporated into the HITRAN2012 database. For some of the molecules, additional parameters, beyond what is currently considered for the terrestrial atmosphere, have been archived. Examples are pressure-broadened half widths due to various foreign partners. Collision-induced absorption data for a large variety of the collision partners are provided in HITRAN for the first time. Future efforts, including preparation of a new edition of the HITEMP database, will be discussed. Note that another talk is given in the "Atmospheric Species" session, describing HITRAN improvements towards remote sensing of terrestrial atmosphere. This effort is supported by the NASA Planetary Atmospheres program, under the grant NNX10AB94G. L. S. Rothman, I. E. Gordon, et al. "The HITRAN 2012 molecular spectroscopic database," JQSRT, submitted 2013.

  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. Non-LTE Gas in Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Gusev, O. A.; Kutepov, A. A.

    2003-01-01

    The new model of radiative cooling/heating of the mesosphere and lower thermosphere (MLT) in the ro-vibrational bands of atmospheric gases (CO2, O3, H2O, CO, NO, N2O and others) accounts for vibrational and rotational non-LTE, line-overlapping, and absorption and transformation of the near-infrared solar radiation. The model utilizes ALI technique for the solution of the system of kinetic equations and the DFE radiative transfer algorithm. The contributions of various band to the total cooling/heating are analyzed. The model is applied to the calculation of the MLT cooling/heating for atmospheric data retrieved from the CRISTA limb radiance measurements. Implications for modeling of the MLT region are discussed.

  1. Infrared quantitative spectroscopy and planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Flaud, J.-M.

    2009-04-01

    Optical measurements of atmospheric minor constituents are carried out using spectrometers working in the UV-visible, infrared and microwave spectral ranges. In all cases the quality of the analysis and of the interpretation of the atmospheric spectra requires the best possible knowledge of the molecular parameters of the species of interest. To illustrate this point we will concentrate on recent laboratory studies of nitric acid, chlorine nitrate and formaldehyde. Nitric acid is one of the important minor constituent of the terrestrial atmosphere. Using new and accurate experimental results concerning the spectroscopic properties of the H14NO3 and H15NO3 molecules, as well as improved theoretical methods (Perrin et al., 2004), it has been possible to generate an improved set of line parameters for these molecules in the 11.2 μm spectral region. These line parameters were used to detect for the first time the H15NO3 molecule in the atmosphere analyzing atmospheric spectra recorded by the MIPAS experiment. The retrievals of chlorine nitrate profiles are usually performed using absorption cross sections (Birk and Wagner, 2003). Following a high resolution analysis of the ν3 and ν4bands of this species in the 12.8 μm region wepropose, as a possibility, to use line by line calculation simulating its ν4Q-branch for the atmospheric temperature and pressure ranges. For the measurement of atmospheric formaldehyde concentrations, mid-infrared and ultraviolet absorptions are both used by ground, air or satellite instruments. It is then of the utmost importance to have consistent spectral parameters in these various spectral domains. Consequently the aim of the study performed at LISA (Gratien et al., 2007) was to intercalibrate formaldehyde spectra in the infrared and ultraviolet regions acquiring simultaneously UV and IR spectra using a common optical cell. The results of the work will be presented. Also high resolution infrared data derived from Perrin et al., 2003

  2. 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

  3. Infrared laboratory studies of synthetic planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Williams, D.

    1972-01-01

    The initial stages of the research were involved with a test of Burch's law of multiplicative transmittance for mixed absorbing gases when their lines are broadened by H2 and He, which are constituents of the atmospheres of the major planets. The broadening of individual lines in the CO fundamental by various gases was investigated. Line strength and half-width for individual CO lines were studied as a function of temperature. Measurements of total band absorptance as a function of absorber thickness and total effective pressure were made at various temperatures for bands of CO and N2O. Attempts were made to develop a phenomenological theory of line broadening that would account for the phenomena observed for the CO fundamental and those reported for more highly polar gases. Laboratory measurements of nitric acid vapor absorptance were compared with balloon measurements in arriving at an estimate of the quantity of nitric acid vapor present in the earth's atmosphere in the region of the ozone layer.

  4. 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

  5. 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.

  6. 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

  7. 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

  8. Ultraviolet imaging and spectroscopy of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Gerard, Jean-Claude

    1994-01-01

    The main scientific results of the participation of the Institute of Astrophysics (Belgium) in the NASA's Pioneer Venus mission are reported on. The data were obtained with the Pioneer Orbiter's Ultraviolet Spectrometer (POUVS). The instrument provided a morphological study of the nitric oxide ultraviolet night glow. Information concerning the altitude of the airglow emitting layer was also collected and used to constrain models of turbulent transport on the night side of the planet. Models of the odd nitrogen thermospheric chemistry and transport were developed to analyze the observations and derive the properties of the global circulation of Venus' upper atmosphere. Images of the Jovian ultraviolet aurora were obtained. The morphology and the time variations of the HI Ly-alpha and H2 Lyman and Werner bands were acquired at different longitudes. The observed distribution was compared with the results of the spectrometric observations made with the Voyager and the International Ultraviolet Explorer missions. Images concerning the Io surface albedo and Saturn's disk and ring's reflectivity were also obtained.

  9. Upper atmospheric planetary-wave and gravity-wave observations

    NASA Technical Reports Server (NTRS)

    Justus, C. G.; Woodrum, A.

    1973-01-01

    Previously collected data on atmospheric pressure, density, temperature and winds between 25 and 200 km from sources including Meteorological Rocket Network data, ROBIN falling sphere data, grenade release and pitot tube data, meteor winds, chemical release winds, satellite data, and others were analyzed by a daily-difference method, and results on the magnitude of atmospheric perturbations interpreted as gravity waves and planetary waves are presented. Traveling planetary-wave contributions in the 25-85 km range were found to have significant height and latitudinal variation. It was found that observed gravity-wave density perturbations and wind are related to one another in the manner predicted by gravity-wave theory. It was determined that, on the average, gravity-wave energy deposition or reflection occurs at all altitudes except the 55-75 km region of the mesosphere.

  10. 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.

  11. 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

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. Gas chromatographic concepts for the analysis of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Valentin, J. R.; Cullers, D. K.; Hall, K. W.; Krekorian, R. L.; Phillips, J. B.

    1991-01-01

    Over the last few years, new gas chromatographic (GC) concepts were developed for use on board spacecraft or any other restricted environments for determining the chemical composition of the atmosphere and surface material of various planetary bodies. Future NASA Missions include an entry probe that will be sent to Titan and various spacecraft that will land on Mars. In order to be able to properly respond to the mission science requirements and physical restrictions imposed on the instruments by these missions, GC analytical techniques are being developed. Some of these techniques include hardware and mathematical techniques that will improve GC sensitivity and increase the sampling rate of a GC descending through a planetary atmosphere. The technique of Multiplex Gas Chromatography (MGC) is an example of a technique that was studied in a simulated Titan atmosphere. In such an environment, the atmospheric pressure at instrument deployment is estimated to be a few torr. Thus, at such pressures, the small amount of sample that is acquired might not be enough to satisfy the detection requirements of the gas chromatograph. In MGC, many samples are pseudo-randomly introduced to the chromatograph without regard to elution of preceding components. The resulting data is then reduced using mathematical techniques such as cross-correlation of Fourier Transforms. Advantages realized from this technique include: improvement in detection limits of several orders of magnitude and increase in the number of analyses that can be conducted in a given period of time. Results proving the application of MGC at very low pressures emulating the same atmospheric pressures that a Titan Probe will encounter when the instruments are deployed are presented. The sample used contained hydrocarbons that are expected to be found in Titan's atmosphere. In addition, a new selective modulator was developed to monitor water under Martian atmospheric conditions. Since this modulator is selective only

  17. Theoretical studies of important processes in planetary and comet atmospheres

    NASA Technical Reports Server (NTRS)

    Guberman, Steven L.

    1991-01-01

    This is the fifth semi-annual progress report describing research on dissociative recombination reactions in planetary and comet atmospheres. The Appendix has two papers that describe NASA supported research. Both papers have been recently accepted for publication. The first paper, 'The Generation of O(S-1) from the Dissociative Recombination of O2(+)', describes in detail the Multichannel Quantum Defect (MQDT) theory used for the calculation of dissociative recombination (DR) cross sections and rates. The application to the generation of the upper state of the atomic oxygen green line emission is of great importance to the modelling of planetary atmospheres. The second paper in the Appendix, 'Dissociative Recombination of the Ground State of N2(+)', applies the methods described in the first paper to N2(+). We find remarkable agreement with the prior microwave afterglow experiments for both the total recombination rate and for its electron temperature dependence. However, the results disagree with recent merged beams results which gave cross sections that are a factor of five below the microwave afterglow experiments and the current results. DR of N2(+) is an important mechanism for generating energetic N atoms which can escape the atmosphere of Mars. Currently we are also continuing additional work on the DR of O2(+) which is aimed at calculating both the total DR rate as a function of ion vibrational level and the rate for production of O(D-1).

  18. 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.

  19. 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.

  20. 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.

  1. Circular polarization of sunlight reflected by planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Kawata, Y.

    1978-01-01

    Multiple scattering calculations are performed in order to investigate the nature of the circular polarization of sunlight reflected by planetary atmospheres. Contour diagrams as a function of size parameter and phase angle are made for the integrated light from a spherical but locally plane-parallel atmosphere of spherical particles. To investigate the origin of the circular polarization, results are also computed for second-order scattering and for a simpler semiquantitative model of scattering by two particles. Observations of the circular polarization of the planets are presently too meager for accurate deduction of cloud particle properties. However, certain very broad constraints can be placed on the properties of the dominant cloud particles on Jupiter and Saturn. The cloud particle size and refractive index deduced for the Jupiter clouds by Loskutov, Morozhenko, and Yanovitskii from analyses of the linear polarization are not consistent with the circular polarization. The few available circular polarization observations of Venus are also examined.

  2. 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.

  3. Determination of the habitable zone through planetary atmospheric absorption analysis

    NASA Astrophysics Data System (ADS)

    Poffo, D. A.; Caranti, G. M.; Comes, R. A.

    2014-03-01

    The so-called Habitable Zone (HZ) is a region around a star where a planet without atmosphere and considered as a black body, is subjected to a radiative flux appropriate to maintain liquid water on its surface. The location of this region is closely related to the physical properties of the star and in particular with its luminosity. It is important to note that being a planet within the HZ region is a necessary condition but may not be a sufficient one to be habitable. The concept of Planetary Habitability means that not only orbital conditions must be satisfied, but also that the planet itself must be able to develop and maintain a biosphere (Porto de Mello et al. 2006). This paper aims to determine the planetary HZ for a planet with similar conditions than the Earth, i.e. having an atmosphere, using a simple model based on the interactions between the star radiation and the radiation emitted by the planet with the atmosphere. The absorption spectrum for the proposed atmospheric chemical composition is calculated as a function of temperature by means of the HITRAN database. Another important factor taken into account in this model is cloud cover. Clouds act as "traps" to the long wave radiation emitted by the surface of the planet, resulting in an additional warming contributing to the greenhouse effect, but at the same time, reflect solar radiation back into space (albedo), producing surface cooling (Porto de Mello 2010). Taken these effects into account on a global level, we find a relationship between the orbital location of the planet and the average surface temperature that allows us to extend the habitable limits proposed by Kasting et al (1993).

  4. Planetary Companions to HD 12661, HD 92788, and HD 38529 and Variations in Keplerian Residuals of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Fischer, Debra A.; Marcy, Geoffrey W.; Butler, R. Paul; Vogt, Steven S.; Frink, Sabine; Apps, Kevin

    2001-04-01

    Precision Doppler observations at the Lick and Keck observatories have revealed Keplerian velocity variations in the stars HD 12661, HD 92788, and HD 38529. HD 12661 (G6 V) has an orbital period of 252.7+/-2.7 days, velocity semiamplitude K=88.4+/-2.0 m s-1, and orbital eccentricity e=0.23+/-0.024. Adopting a stellar mass of 1.07 Msolar, we infer a companion mass of Msini=2.79 MJ and a semimajor axis of a=0.79 AU. HD 92788 (G5 V) has an orbital period of 326.7+/-3.2 days, velocity semiamplitude K=99.9+/-2.4, and orbital eccentricity e=0.30+/-0.06. The adopted stellar mass of 1.06 Msolar yields a companion mass of Msini=3.34 MJ and a semimajor axis of a=0.95 AU. HD 38529 (G4 IV) has an orbital period of 14.3+/-0.8 days, velocity semiamplitude K=53.8+/-2.0 m s-1, and eccentricity e=0.27+/-0.03. The stellar mass of 1.4 Msolar sets Msini=0.77 MJ, with a semimajor axis of a=0.13 AU for this companion. In addition to the 14.3 day periodicity, the velocity residuals for HD 38529 show curvature over the three years of observations. Based on a measurement of Ca II H and K emission, all three stars are chromospherically inactive. Based on both spectral synthesis modeling and narrowband photometry, HD 12661, HD 92788, and HD 38529 all appear to be metal-rich stars, reinforcing the correlation of high metallicity in the host stars of gas giant extrasolar planets. We examine the velocity residuals to the Keplerian fits for a subsample of 12 planet-bearing stars that have been observed longer than two years at the Lick Observatory. Five of the 12 (Ups Andromedae, τ Boo, 55 Cnc, HD 217107, and HD 38529) exhibit coherent variations in the residual velocities that are consistent with additional companions. Except for Upsilon Andromedae, the source of the velocity variation remains speculative pending completion of one full orbit. GJ 876 exhibits residual velocities with high rms scatter (24 m s-1), lacking identifiable coherence. The residual velocities for six of the 12 stars (51

  5. Building a "big picture" of planetary atmospheres dynamics

    NASA Astrophysics Data System (ADS)

    Read, Peter; Wang, Yixiong

    Together with Saturn's large satellite, Titan, Earth, Mars and Venus provide four clear and increasingly well-studied examples of terrestrial-style planetary circulation systems under quite different parametric conditions. Clear trends in behaviour can be seen between these planets, especially contrasting the slowly and rapidly rotating bodies, suggesting some analogies with the studies of flow transitions and bifurcations in laboratory flow systems such as the rotating, baroclinic annulus experiment[1,2], and other simple models. This approach to comparative studies comes especially naturally to dynamicists, to whom the ability of even relatively simple, nonlinear, dynamical systems to exhibit radically different behaviours, punctuated by well characterized bifurcations as control parameters are varied, is familiar and commonplace. But is this analogy more than superficial? Does it suggest the possibility of an overarching the-oretical framework or even prototype model that could offer useful quantitative predictions of atmospheric structure, circulation and transport across a wide range of planetary parameters? If so, what are the critical parameters upon which key dynamical properties of the circulation depend? Can comparisons between the Earth and other planetary bodies provide useful insights into the Earth's circulation and climate? These questions come into even sharper focus in the light of the recent discoveries of terrestrial-style planets around other stars, about which obser-vational measurements can provide only very basic, globally integrated parameters. It is vital, therefore, to exploit and understand as fully as possible the available models of atmospheric circulation systems amenable to detailed study within our Solar System, their common aspects and key differences, and to confront them with detailed observations and measurements. In this contribution we examine ways in which numerical models of atmospheric circulation can be used to construct

  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. Characterization and evolution of distant planetary atmospheres using stellar occultations

    NASA Astrophysics Data System (ADS)

    Young, L. A.

    2008-09-01

    for understanding the energy balance in upper atmospheres, interpreting thermal emission, and studying dynamics. These vertical profiles include small-scale fluctuations generally associated with gravity waves. While the 1988 Pluto occultation light curve was remarkably smooth, more recent Pluto occultations show spikes indicative of these small-scale dynamics. When an atmospheric occultation is observed from several sites, or when a single site is near enough to the shadow center to observe solar flux refracted from multiple locations in the occulting atmosphere, it is possible to study the two- or three-dimensional structure of an atmosphere. The simplest example is the oblateness of the atmosphere derived from the shape of an isobar [7], but more complex analyses are also possible. A comparison of the temperatures at different latitudes or local times of day can shed light on the relative importance of radiative equilibrium and dynamics to the energetics of an atmosphere, as has been done for the 2006 June 12 occultation by Pluto [4]. Closely spaced sites can be used to derive the two-dimensional shape and aspect ratio of temperature and density fluctuations [5,8], aiding the identification of the generating sources of these fluctuations. Occultation observations over a long time span are used to study the long-term evolution of an atmosphere. Both Triton and Pluto have shown large changes in their pressures since the late 1980's that is almost certainly related to changes in the temperature of their surface ices. The temperatures in the Uranian upper atmosphere increased before the previous solstice, and reverted to cooler temperatures a decade later, perhaps indicative of adiabatic cooling [9]. Recent improvements in astrometric catalogs, occultation-capable cameras (with low read noise, high readout rates, and little or no dead time), and easy access to accurate timing can greatly improve the quality, spatial sampling, and frequency of occultations by planetary

  8. 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).

  9. 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

  10. The HARPS search for southern extra-solar planets. XXVIII. Up to seven planets orbiting HD 10180: probing the architecture of low-mass planetary systems

    NASA Astrophysics Data System (ADS)

    Lovis, C.; Ségransan, D.; Mayor, M.; Udry, S.; Benz, W.; Bertaux, J.-L.; Bouchy, F.; Correia, A. C. M.; Laskar, J.; Lo Curto, G.; Mordasini, C.; Pepe, F.; Queloz, D.; Santos, N. C.

    2011-04-01

    Context. Low-mass extrasolar planets are presently being discovered at an increased pace by radial velocity and transit surveys, which opens a new window on planetary systems. Aims: We are conducting a high-precision radial velocity survey with the HARPS spectrograph, which aims at characterizing the population of ice giants and super-Earths around nearby solar-type stars. This will lead to a better understanding of their formation and evolution, and will yield a global picture of planetary systems from gas giants down to telluric planets. Methods: Progress has been possible in this field thanks in particular to the sub-m s-1 radial velocity precision achieved by HARPS. We present here new high-quality measurements from this instrument. Results: We report the discovery of a planetary system comprising at least five Neptune-like planets with minimum masses ranging from 12 to 25 M⊕, orbiting the solar-type star HD 10180 at separations between 0.06 and 1.4 AU. A sixth radial velocity signal is present at a longer period, probably caused by a 65-M⊕ object. Moreover, another body with a minimum mass as low as 1.4 M⊕ may be present at 0.02 AU from the star. This is the most populated exoplanetary system known to date. The planets are in a dense but still well separated configuration, with significant secular interactions. Some of the orbital period ratios are fairly close to integer or half-integer values, but the system does not exhibit any mean-motion resonances. General relativity effects and tidal dissipation play an important role to stabilize the innermost planet and the system as a whole. Numerical integrations show long-term dynamical stability provided true masses are within a factor ~3 from minimum masses. We further note that several low-mass planetary systems exhibit a rather "packed" orbital architecture with little or no space left for additional planets. In several cases, semi-major axes are fairly regularly spaced on a logarithmic scale, giving rise

  11. Principles of Planetary Climate

    NASA Astrophysics Data System (ADS)

    Pierrehumbert, Raymond T.

    2010-12-01

    This book introduces the reader to all the basic physical building blocks of climate needed to understand the present and past climate of Earth, the climates of Solar System planets, and the climates of extrasolar planets. These building blocks include thermodynamics, infrared radiative transfer, scattering, surface heat transfer and various processes governing the evolution of atmospheric composition. Nearly four hundred problems are supplied to help consolidate the reader's understanding, and to lead the reader towards original research on planetary climate. This textbook is invaluable for advanced undergraduate or beginning graduate students in atmospheric science, Earth and planetary science, astrobiology, and physics. It also provides a superb reference text for researchers in these subjects, and is very suitable for academic researchers trained in physics or chemistry who wish to rapidly gain enough background to participate in the excitement of the new research opportunities opening in planetary climate.

  12. Orbital structure of the GJ876 extrasolar planetary system based on the latest Keck and HARPS radial velocity data

    NASA Astrophysics Data System (ADS)

    Baluev, Roman V.

    2011-10-01

    We use full available array of radial velocity data, including recently published HARPS and Keck observatory sets, to characterize the orbital configuration of the planetary system orbiting GJ876. First, we propose and describe in detail a fast method to fit perturbed orbital configuration, based on the integration of the sensitivity equations inferred by the equations of the original N-body problem. Further, we find that it is unsatisfactory to treat the available radial velocity data for GJ876 in the traditional white noise model, because the actual noise appears autocorrelated (and demonstrates non-white frequency spectrum). The time scale of this correlation is about a few days, and the contribution of the correlated noise is about 2 m/s (i.e., similar to the level of internal errors in the Keck data). We propose a variation of the maximum-likelihood algorithm to estimate the orbital configuration of the system, taking into account the red noise effects. We show, in particular, that the non-zero orbital eccentricity of the innermost planet d, obtained in previous studies, is likely a result of misinterpreted red noise in the data. In addition to offsets in some orbital parameters, the red noise also makes the fit uncertainties systematically underestimated (while they are treated in the traditional white noise model). Also, we show that the orbital eccentricity of the outermost planet is actually ill-determined, although bounded by ~0.2. Finally, we investigate possible orbital non-coplanarity of the system, and limit the mutual inclination between the planets b and c orbits by 5°-15°, depending on the angular position of the mutual orbital nodes.

  13. 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.

  14. The evolution of solar ultraviolet luminosity. [influence on planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Zahnle, K. J.; Walker, J. C. G.

    1982-01-01

    Astronomical observations of stars analogous to the sun are used to construct a tentative account of the evolution of solar UV luminosity. Evidence exists that the young sun was a much more powerful source of energetic particles and radiation than it is today, and while on the main sequence, solar activity has declined as an inverse power law of age as a consequence of angular momentum loss to the solar wind. Observations of pre-main sequence stars indicate that before the sun reached the main sequence, it may have emitted as much as ten thousand times the amount of ultraviolet radiation that it does today. The impact of the results on knowledge of photochemistry and escape of constituents of primordial planetary atmospheres is discussed.

  15. Theoretical studies of important processes in planetary and comet atmospheres

    NASA Technical Reports Server (NTRS)

    Guberman, Steven L.

    1991-01-01

    The dissociative recombination (DR) of the AB(+) molecular ion with an electron has been shown to be an important component in the detailed interpretation of planetary ionosphere data. A first principles theoretical approach is developed for calculating the DR cross sections and rates for AB(+) molecular ions. The calculations focus on O2(+) and N2(+) DR, and are the first to include the indirect DR mechanism (Ryberg vibrational levels below v = 0 level of ion) for a molecule larger than H2(+). The importance of electron capture width in calculating the cross sections and rates is also examined. Electron capture widths are given for all states of O2 that are of importance to DR (lowest 10 vibrational levels of ion). Knowledge of the details of dissociative recombination will be needed for interpretation of data from future interplanetary and comet atmospheric studies.

  16. 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.

  17. Construction of an advanced software tool for planetary atmospheric modeling

    NASA Technical Reports Server (NTRS)

    Friedland, Peter; Keller, Richard M.; Mckay, Christopher P.; Sims, Michael H.; Thompson, David E.

    1992-01-01

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

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    Chamberlain, Joseph W.; Hunten, Donald M.

    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.

  4. 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.

  5. The Atmospheric General Circulation of Synchronously Rotating Planets: Dependence on Planetary Rotation Rate

    NASA Astrophysics Data System (ADS)

    Noda, S.; Ishiwatari, M.; Nakajima, K.; Takahashi, Y. O.; Morikawa, Y.; Nishizawa, S.; Hayashi, Y.-Y.

    2011-10-01

    We numerically investigate general circulation of moist atmosphere on synchronously rotating planets to examine the dependence of the atmospheric structure on planetary rotation rate. Three representative surface temperature patterns associated with different structure of heat transport appear. However, total amount of energy transport from dayside to nightside has only weak dependence on planetary rotation rate.

  6. 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

  7. 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

  8. 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

  9. Quasi-axisymmetric circulation and superrotation in planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Mayr, H. G.; Harris, I.

    1983-05-01

    Atmospheric superrotation is ubiquitous in the solar system, and numerous theoretical models have been proposed to describe the effect. However, no model is fully accepted. Problems are primarily related to an understanding of the angular momentum and the energy budgets. In connection with the present investigation, attention is given to hybrid models, where three-dimensional models may describe eddy processes and two-dimensional symmetric models may describe the global scale circulation in the framework of a viscous medium. It is believed that the concept of an axisymmetric circulation is still useful. It is the main purpose of the current investigation to explore some of the properties of the circulation in planetary atmospheres. It is assumed that the eddy transports are downgradient or diffusive in nature. Energy and momentum are perceived to cascade from the global scale circulation driven by the sun to the smaller scale eddies which in turn determine the diffusive properties. A numerical model of the Venusian circulation is presented, and results are discussed for different conditions of static stability.

  10. 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.

  11. 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. PMID:12634780

  12. Extrasolar Storms: The Physics and Chemistry of Evolving Cloud Structures in Brown Dwarf Atmospheres

    NASA Astrophysics Data System (ADS)

    Apai, Daniel

    2012-10-01

    Condensate clouds pose the most significant challenge to the understanding of ultracool atmospheres of brown dwarfs and giant exoplanets. In three ongoing Spitzer programs we have taken advantage of Spitzer's ability to obtain high-cadence uninterrupted observations to pioneer a new technique, rotational phase mapping, and successfully explored the properties of cloud covers in ~50 brown dwarfs. Among other exciting results we found that most brown dwarfs possess heterogeneous cloud cover, often with complex surface structures. Perhaps the most perplexing behavior seen in our surveys is light curve evolution on timescales as short as 5 hours and as long as a year. This unexpected behavior offers a unique opportunity to explore the dynamics of cloud layers, but requires multi-epoch data sets. We propose here to follow up a representative set of varying brown dwarfs via multi-epoch Spitzer and HST phase mapping to carry out the first quantitative exploration of cloud cover evolution. The proposed study will establish the first time-resolved multi-wavelength light curve library for brown dwarfs. Spitzer uniquely offers precise 3-5 micron photometry and continuous coverage that allow us to detect cloud structures a fraction of the size of the Great Red Spot on Jupiter in our targets. Combined with HST grism spectroscopy during a subset of the Spitzer observations, the Spitzer phase maps will allow us to disentangle the effects of cloud formation, differential rotation, large-scale rainout and dispersal of clouds. As different wavelengths probe different pressures and different rotational phases probe different latitudes we will be able to explore the two or even three-dimensional structure of the atmospheres. We will also constrain the dynamical and radiative timescales for brown dwarfs and compare these to theoretical predictions to identify the underlying atmospheric dynamics. This program will leave a unique legacy that will propel studies of ultracool atmosphere

  13. Extrasolar Storms: The Physics and Chemistry of Evolving Cloud Structures in Brown Dwarf Atmospheres

    NASA Astrophysics Data System (ADS)

    Apai, Daniel; Buenzli, Esther; Flateau, Davin; Metchev, Stanimir; Marley, Mark; Radigan, Jacqueline; Lowrance, Patrick; Showman, Adam; Artigau, Etienne; Heinze, Aren; Burgasser, Adam; Mohanty, Subhanjoy

    2012-09-01

    Condensate clouds pose the most significant challenge to the understanding of ultracool atmospheres of brown dwarfs and giant?exoplanets. In three ongoing Spitzer programs we have?taken advantage of Spitzer's ability to obtain high-cadence uninterrupted observations to pioneer a new technique, rotational phase mapping, and successfully explored the properties of cloud covers in ~50 brown?dwarfs. Among other exciting results we found that most brown dwarfs possess heterogeneous cloud cover, often with complex surface structures. Perhaps the most perplexing behavior seen in our surveys is light curve evolution on timescales as short as 5 hours and as long as a year. This unexpected behavior offers a unique opportunity to explore the dynamics of cloud layers, but requires multi-epoch data sets. We propose here to follow up a representative set of varying brown dwarfs via multi-epoch Spitzer and HST phase mapping to carry out the first quantitative exploration of cloud cover evolution. The proposed study will establish the first time-resolved multi-wavelength light curve library for brown dwarfs. Spitzer uniquely offers precise 3-5 micron photometry and continuous coverage that allow us to detect cloud structures a fraction of the size of the Great Red Spot on Jupiter in our targets. Combined with HST grism spectroscopy during a subset of the Spitzer observations, the Spitzer phase maps will allow us to disentangle the effects of cloud formation, differential rotation, large-scale rainout and dispersal of clouds. As different wavelengths probe different pressures and different rotational phases probe different latitudes we will be able to explore the two or even three-dimensional structure of the atmospheres. We will also constrain the dynamical and radiative timescales for brown dwarfs and compare these to theoretical predictions to identify the underlying atmospheric dynamics. This program will leave a unique legacy that will propel studies of ultracool atmosphere

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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 

  20. 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.

  1. Extrasolar Planetary Imaging Coronagraph (EPIC)

    NASA Technical Reports Server (NTRS)

    Clampin, Mark

    2009-01-01

    EPIC is a NASA mission being studied to detect and characterize Jovian and superEarth planets, and, the dust/debris disks surrounding the parent star. It will be launched into a heliocentric Earth trailing orbit and operate for 5 years. EPIC would operate over the wavelength range of 480 - 960 nm with spectral resolutions of R < 50 and employs a visible nulling coronagraph (VNC) to suppress the starlight, yielding contrast ratios of greater than 9 orders of magnitude. We will discuss the science mission, and its role in the search for habitable planets.

  2. 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

  3. 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

  4. Spectral Irradiance Measurements of Simulated Lightning in Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Borucki, W. J.; McKay, C. P.; Jebbens, D.; Lakkaraju, H. S.; Vanajakshi, C. T.; Cuzzi, Jeffrey (Technical Monitor)

    1996-01-01

    Optical emissions from lightning provide information to estimate the altitude, latitude and longitude of lightning storms, the energy of the discharges, and the production of important trace species such as HCN and C2H2. Knowledge of the spectra of planetary lightning is needed to deduce the total energy dissipated by lightning (and thereby, the production of trace gases) and to help design experiments to detect and track lightning storms. Measurements of the spectral irradiance from approximately 380 to 820 nm are reported for laboratory simulations of lightning in the atmospheres of Venus, Jupiter, and Titan. In our laboratory, laser-induced plasmas (LIP) are used to simulate lightning discharges. This technique avoids contamination of the spectra by elect-ode material and maintains a safe environment while allowing the use of flammable gases, such as hydrogen and methane, found in outer planet atmospheres. The observations were made at I and 5 bars pressure for Venus and Jupiter and at 1 bar for the Titan mixture. At a pressure of one bar, our results show prominent lines from H(sub alpha), H(sub beta), H(sub gamma), and H(sub delta) lines of the Balmer Series of atomic hydrogen, a single line from Helium at 588 nm and strong continuum radiation. At pressures of 5 bars, the H(sub alpha) and H(sub beta) lines are wider, the H(sub gamma), and H(sub delta) lines merge into the continuum because of pressure broadening, and the helium line at 588 nm is no longer visible. The observed spectra of simulated lightning in the venusian atmosphere at 1 and 5 bars shows that the OI multiplet at 777.7 nm dominates the spectra, but weak features due to atomic carbon and singly excited and singly ionized oxygen atoms are also visible. Although lightning has not yet been observed on Titan, it conceivable that some form of lightning discharge could be occurring. Therefore experiments on a Titan atmosphere mixture were conducted. The most prominent features seen in the simulated

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. A Decade of Extrasolar Planets around Normal Stars

    NASA Astrophysics Data System (ADS)

    Livio, Mario; Sahu, Kailash; Valenti, Jeff

    2008-06-01

    1. Extrasolar planets: past, present, and future A. P. Boss; 2. The quest for very low-mass planets M. Mayor, F. Pepe, C. Lovis, D. Queloz and S. Udry; 3. Extrasolar planets: a galactic perspective I. N. Reid; 4. The Kepler Mission: Design, expected science results, opportunities to participate W. J. Borucki, D. Koch, G. Basri, T. Brown, D. Caldwell, E. Devore, E. Dunham, T. Gautier, J. Geary, R. Gilliland, A. Gould, S. Howell, J. Jenkins and D. Latham; 5. Observations of the atmospheres of extrasolar planets T. M. Brown, R. Alonso, M. Knölker, H. Rauer and W. Schmidt; 6. Planetary migration P. J. Armitage and W. K. M. Rice; 7. Observational constraints on dust disk lifetimes: implications for planet formation L. A. Hillenbrand; 8. The evolution of gas in disks J. Najita; 9. Planet formation J.J. Lissauer; 10. Core accretion-gas capture model for gas giant planet formation O. Hubickyj; 11. Gravitational instabilities in protoplanetary disks R. H. Durisen; 12. Conference summary: the quest for new worlds J. E. Pringle.

  13. A Decade of Extrasolar Planets around Normal Stars

    NASA Astrophysics Data System (ADS)

    Livio, Mario; Sahu, Kailash; Valenti, Jeff

    2011-04-01

    1. Extrasolar planets: past, present, and future A. P. Boss; 2. The quest for very low-mass planets M. Mayor, F. Pepe, C. Lovis, D. Queloz and S. Udry; 3. Extrasolar planets: a galactic perspective I. N. Reid; 4. The Kepler Mission: Design, expected science results, opportunities to participate W. J. Borucki, D. Koch, G. Basri, T. Brown, D. Caldwell, E. Devore, E. Dunham, T. Gautier, J. Geary, R. Gilliland, A. Gould, S. Howell, J. Jenkins and D. Latham; 5. Observations of the atmospheres of extrasolar planets T. M. Brown, R. Alonso, M. Knölker, H. Rauer and W. Schmidt; 6. Planetary migration P. J. Armitage and W. K. M. Rice; 7. Observational constraints on dust disk lifetimes: implications for planet formation L. A. Hillenbrand; 8. The evolution of gas in disks J. Najita; 9. Planet formation J.J. Lissauer; 10. Core accretion-gas capture model for gas giant planet formation O. Hubickyj; 11. Gravitational instabilities in protoplanetary disks R. H. Durisen; 12. Conference summary: the quest for new worlds J. E. Pringle.

  14. Detecting Tree-like Multicellular Life on Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    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.

  15. 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

  16. 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).

  17. 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.

  18. Planetary Motion in the Atmospheres of Red Giants

    NASA Astrophysics Data System (ADS)

    Volobueva, M. I.; Tarakanov, P. A.

    2015-09-01

    When a star reaches the red giant stage in the course of its evolution, its closest planets are in its atmosphere. Numerical gas dynamic models are constructed for hypersonic flow around planets by matter in the atmosphere of a red giant. The results are compared with analytic models for the motion of planets in the atmospheres of stars.

  19. 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).

  20. Ion precipitation in planetary upper atmospheres: test particle simulations and implications for escape

    NASA Astrophysics Data System (ADS)

    Parkinson, Christopher; Liemohn; Fang, Xiaohua

    A 3-D Monte Carlo energetic particle transport model has been developed and successfully applied to ion precipitation into planetary upper atmospheres in our solar system (viz., Earth, Mars, Jupiter, and Saturn), and can be readily be extended using a full Lorentz motion formu-lation in the absence of strong dipole planetary magnetic fields. This model can be used with a variety of other models to assess the influence of hot ion precipitation on the thermosphere and exosphere of planetary atmospheres and the subsequent sputtering and escape. For instance in the case of Mars, a pick-up ion transport model already exists to allow for particle acceleration exerted by the convection electric field used in conjunction with existing model results from the Mars Thermosphere General Circulation Model (MTGCM) and the BATS-R-US global MHD model. The loss of exospheric neutrals through ionization, in which they become pick-up ions in the solar wind, can be calculated to examine the relative contribution of the various ionization processes. Solar wind protons as well as pick-up ions from a planetary exosphere routinely enter and alter their upper atmosphere. A study of the pick-up ion escape, sputtering, ion-ization, excitation, and energy deposition will be reviewed and discussed, resulting in a robust examination of the influence of energetic ion transport on planetary upper atmospheres.

  1. 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

  2. Theory of Tumbling Bodies Entering Planetary Atmospheres with Application to Probe Vehicles and the Australian Tektites

    NASA Technical Reports Server (NTRS)

    Tobak, Murray; Peterson, Victor L.

    1964-01-01

    The tumbling motion of aerodynamically stable bodies entering planetary atmospheres is analyzed considering that the tumbling, its arrest, and the subsequent oscillatory motion are governed by the equation for the fifth Painleve' transcendent. Results based on the asymptotic behavior of the transcendent are applied to study (1) the oscillatory behavior of planetary probe vehicles in relation to aerodynamic heating and loads and (2) the dynamic behavior of the Australian tektites on entering the Earth's atmosphere, under the hypothesis that their origin was the Moon.

  3. 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.

  4. 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.

  5. 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.

  6. Atmospheric General Circulations of Synchronously Rotating Terrestrial Planets: Dependence on Planetary Rotation Rate

    NASA Astrophysics Data System (ADS)

    Noda, S.; Ishiwatari, M.; Nakajima, K.; Takahashi, Y. O.; Morikawa, Y.; Nishizawa, S.; Hayashi, Y.-Y.

    2012-04-01

    In order to investigate a variety of climates of synchronously rotating terrestrial planets, a parameter study on the dependence on planetary rotation rate Ω is performed by using a general circulation model (GCM) with simplified hydrologic and radiative processes. The planetary rotation rate is varied from zero to the Earth's value, and other parameters such as orbital parameters, planetary radius, solar constant are set to the Earth's values. The results show that there emerge four typical atmospheric states in ascending order of planetary rotation rate as follows: States in which dayside-nightside direct circulations dominate States in which weak super rotation emerges States in which strong super rotation emerges and meridionally asymmetric patterns oscillate States in which precipitation disturbances emerge in nightside midlatitudinal regions The atmospheric state is gradually accompanied by a qualitative circulation change from state (1) to state (3) with increasing Ω from zero, although Merlis and Schneider (2010) which performed similar GCM experiments lump together cases with small planetary rotation rates under the term "slowly rotating atmospheres". For cases for planetary rotation rate with the values of 0.75-0.85 times of the terrestrial value, multiple equilibrium solutions of state (3) and state (4) are obtained. It is shown that, in addition to dry atmosphere (Edson et al., 2011), moist atmospheres on synchronously rotating planet also have multiple equilibrium solutions. Although circulation patterns and amount of sensible/latent heat transport from the dayside to the nightside changes with the change of Ω, summation of sensible heat transport and latent heat transport almost remains unchanged, and the dependence of dayside to nightside temperature contrast on Ω is small.

  7. 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.

  8. 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.

  9. 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

  10. 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.