Science.gov

Sample records for extrasolar planetary atmospheres

  1. ATMOSPHERIC LENSING AND OBLATENESS EFFECTS DURING AN EXTRASOLAR PLANETARY TRANSIT

    E-print Network

    Seager, Sara

    ATMOSPHERIC LENSING AND OBLATENESS EFFECTS DURING AN EXTRASOLAR PLANETARY TRANSIT Lam Hui1-precision photometric measurements of transiting extrasolar planets promise to tell us much about the characteristics of these systems. We examine how atmospheric lensing and (projected) planet oblateness/ellipticity modify transit

  2. Ionisation in ultra-cool, cloud forming extrasolar planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Helling, Christiane; the LEAP Team

    2015-04-01

    Transit spectroscopy provides evidence that extrasolare planets are covered in clouds, a finding that has been forecast by cloud model simulations 15 years ago. Atmospheres are strongly affected by clouds through their large opacity and their chemical activity. Cloud formation models allow to predict cloud particle sizes, their chemical composition and the composition of the remaining atmospheric gas (Woitke & Helling 2004, A&A 414; Helling & Woitke 2006, A&A 455), for example, as input for radiative transfer codes like Drift-Phoenix (Witte et al. 2009; A&A 506). These cloud particles are charged and can discharge, for example in form of lighting (Helling et al. 2013, ApJ 767; Bailey et al. 2014, ApJ 784). Earth observations demonstrate that lighting effects not only the local chemistry but also the electron budget of the atmosphere. This talk will present our work on cloud formation modelling and ionisation processes in cloud forming atmospheres. An hierarchy of ionisation processes leads to a vertically inhomogenously ionised atmosphere which has implications for planetary mass loss and global circulation pattern of planetary atmospheres. Processes involved, like Cosmic Ray ionisation, do also activate the local chemistry such that large hydrocarbon molecules form (Rimmer et al. 2014, IJAsB 13).

  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. The Atmospheres of Extrasolar Planets

    E-print Network

    Mark S. Marley

    2008-09-26

    The characteristics of irradiated solar system planetary atmospheres have been studied for decades, consequently modern planetary science benefits from an exhaustive body of ground- and space-based data. The study of extrasolar planetary atmospheres, by contrast, is still in its infancy and currently rests on a few score of datapoints, mostly of the transiting planets. This short survey aims not to review this dynamic field but rather stresses the importance of a few theoretical concepts and processes for our understanding of exoplanet atmospheres. Topics covered include atmospheric structure and dynamics, cloud processes and photochemistry of planetary atmospheres. Influences on the albedos, spectra, and colors of extrasolar planets are reviewed and caution is urged in the interpretation of exoplanet colors.

  5. Atmospheres of Extrasolar Giant Planets

    E-print Network

    Mark S. Marley; Jonathan Fortney; Sara Seager; Travis Barman

    2006-02-21

    The key to understanding an extrasolar giant planet's spectrum--and hence its detectability and evolution--lies with its atmosphere. Now that direct observations of thermal emission from extrasolar giant planets are in hand, atmosphere models can be used to constrain atmospheric composition, thermal structure, and ultimately the formation and evolution of detected planets. We review the important physical processes that influence the atmospheric structure and evolution of extrasolar giant planets and consider what has already been learned from the first generation of observations and modeling. We pay particular attention to the roles of cloud structure, metallicity, and atmospheric chemistry in affecting detectable properties through Spitzer Space Telescope observations of the transiting giant planets. Our review stresses the uncertainties that ultimately limit our ability to interpret EGP observations. Finally we will conclude with a look to the future as characterization of multiple individual planets in a single stellar system leads to the study of comparative planetary architectures.

  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 eccentricities of more than 0.1, in most cases of 0.2-0.5. In conjunction with their possible migration into the inner reaches of the Solar System, this poses a threat to the very existence of the inner planets. Recent observations of gas-dust clouds in very young stars show that hydrogen dissipates rapidly, in several million years, and dissipation is completed earlier than, according to the accretion theory, the gas component of such a planet as Jupiter forms. The mass of the remaining hydrogen is usually small, much smaller than Jupiter's mass. However, the giant planets of the Solar System retain a few percent of the amount of hydrogen that should be contained in the early protoplanetary disk, creating difficulties in understanding their formation. A plausible explanation is that gravitational instabilities in the protoplanetary disk could be the mechanism of their rapid formation.

  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. 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.

  10. Extrasolar planets Lecture 2: Planetary formation theory and

    E-print Network

    Parker, Quentin A.

    end up in close orbits ·These constitute the hot inner planets. #12;This near infrared HST image showsExtrasolar planets Lecture 2: Planetary formation theory and detection techniques Prof. Quentin A Parker ASTR178 - other worlds: planets and planetary systems 1 #12;Formation of a Star and proto

  11. Uses of Linear Polarization as a Probe of Extrasolar Planet Atmospheres

    E-print Network

    S. Saar; S. Seager

    2003-05-22

    We point out some advantages of making observations of extrasolar planets in linearly polarized (LP) light. Older cool stars have quite low levels (~ 10^-4 to 10^-5) of fractional LP, while extrasolar planets can have relatively high fractional LP (~0.1). Observations in LP light can therefore significantly enhance contrast between the planet and its parent star. Data on LP as a function of planetary orbital phase can be used to diagnose the properties (e.g., composition, size, and shape) of the scatterers in the planetary atmosphere. We discuss the feasibility of LP observations of extrasolar planets.

  12. Dead Zones and Extrasolar Planetary Properties

    E-print Network

    Soko Matsumura; Ralph E. Pudritz

    2005-12-08

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

  13. 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.

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

    PubMed

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

    2001-01-01

    We present a general modeling scheme for investigating the possibility of photosynthesis-based life on extrasolar planets. The scheme focuses on the identification of the habitable zone in main-sequence-star planetary systems with planets of Earth mass and size. Our definition of habitability is based on the long-term possibility of photosynthetic biomass production as a function of mean planetary surface temperature and atmospheric CO2-content. All the astrophysical, climatological, biogeochemical, and geodynamic key processes involved in the generation of photosynthesis-driven life conditions are taken into account. Implicitly, a co-genetic origin of the central star and the orbiting planet is assumed. The numerical solution of an advanced geodynamic model yields realistic look-up diagrams for determining the limits of photosynthesis in extrasolar planetary systems, assuming minimum CO2 levels set by the demand of C4 photosynthesis. PMID:11803974

  15. Atmospheric dynamics of tidally synchronized extrasolar planets.

    PubMed

    Cho, James Y-K

    2008-12-13

    Tidally synchronized planets present a new opportunity for enriching our understanding of atmospheric dynamics on planets. Subject to an unusual forcing arrangement (steady irradiation on the same side of the planet throughout its orbit), the dynamics on these planets may be unlike that on any of the Solar System planets. Characterizing the flow pattern and temperature distribution on the extrasolar planets is necessary for reliable interpretation of data currently being collected, as well as for guiding future observations. In this paper, several fundamental concepts from atmospheric dynamics, likely to be central for characterization, are discussed. Theoretical issues that need to be addressed in the near future are also highlighted. PMID:18812298

  16. Selected topics on extrasolar planetary systems

    NASA Astrophysics Data System (ADS)

    Ford, Eric B.

    This thesis investigates the capabilities of planet searches to detect extrasolar planets and measure their mass and orbital parameters. I developed and demonstrated a new technique based on Markov chain Monte Carlo simulations to quantify the uncertainty in the orbital parameters of extrasolar planets using actual radial velocity observations. It is hoped that future astrometric searches will build upon the successes of radial velocity searches, providing new information about currently known planets and discovering new ones. In particular, the Space Interferometry Mission (SIM) will be capable of detecting low-mass planets around nearby stars. I simulated astrometric observations to evaluate the planet-finding capabilities of SIM and estimate the number of planets which SIM planet searches would detect and characterize and explore how various factors would affect SIM's sensitivity. For example, I investigated the tradeoffs between observing more stars at lower precision and observing less stars at higher precision. I also determined that the choice of observing schedule has relatively little effect on SIM's efficiency, so it is likely best to schedule observations so as to minimize overhead (e.g., slewing, measuring grid stars). Similarly, I quantified how much SIM's efficiency is reduced when a target star has an acceleration due to a wide-binary companion, concluding that it is generally preferable to target a nearby star in a wide-binary system rather than a more distant single star. Finally, I explored how the presence of two planets around a star can make it more difficult for SIM to measure the masses and orbital parameters of either planet. I find that the presence a giant planet can significantly reduce the sensitivity of SIM for measuring the low-mass mass and orbital parameters of a low-mass planet. Each of these studies will help guide decisions, so that SIM's valuable observing time can be used most productively.

  17. Planetary atmospheres and ionospheres...

    E-print Network

    Withers, Paul

    Planetary atmospheres and ionospheres... How does a solar energetic particle event disrupt the ionosphere of Mars? Paul Withers withers@bu.edu BU Astronomy Symposium Boston, MA 2011.10.14 #12;What's going on? Katy Fallows ­ How does the lower ionosphere of Mars work? Zach Girazian ­ How does the main

  18. Stationary Orbits in Resonant Extrasolar Planetary Systems

    NASA Astrophysics Data System (ADS)

    Michtchenko, T. A.; Beaugé, C.; Ferraz-Mello, S.

    2006-04-01

    We present a catalog of stable and unstable apsidal corotation resonance (ACR) for the resonant planar planetary three-body problem, including both symmetric and asymmetric solutions. Calculations are performed with a new approach based on a numerical determination of the averaged Hamiltonian function. It has the advantage of being very simple to use and, with the exception of the immediate vicinity of the collision curve, yields precise results for any values of the eccentricities and semimajor axes. The present catalog includes results for the 3/2, 3/1, and 4/1 mean-motion resonances. The 5/1 and 5/2 commensurabilities are also discussed briefly. These results complement our previous results for the 2/1 (Beaugé et al. 2006, MNRAS, 365, 1160 1170), and give a broad picture of the structure of many important planetary resonances.

  19. Atmospheric Chemistry in Extrasolar Giant Planets or The Cosmic Shoreline

    NASA Astrophysics Data System (ADS)

    Zahnle, Kevin

    2011-09-01

    Title: Atmospheric Chemistry in Extrasolar Giant Planets. Metallicity and C/O ratio are potential observables in spectra of EGPs. Both address the mode of planetary formation. Metallicity reveals itself best in molecules composed of more than one “metal” atom, such as CO2. C/O ratio is more complicated. There are parallels between the chemistry generated by 1994’s SL9 impacts on Jupiter and the chemistry of EGPs. In both, a hot gas quenches by cooling and rarefaction. In SL9, the impact-heated gas exploded, expanded, and cooled. In EGPs, quenching is a consequence of vertical mixing. Products of SL9 included S2, CS2, HCN, C2H4, CO, CO2, and carbonaceous hazes. All of these might be expected in EGPs. Close-in planets differ from SL9 in the photochemical consequences of stellar UV. Primary photolysis of H2S, NH3, and H2O creates free radicals that react with H2 to make atomic H. Abundant H attacks CH4 and promotes formation of C2H2 and HCN, which readily polymerize to make hazes. It is likely that such a haze is observed in HD 189733b. Title: Cosmic Shoreline. Volatile escape is the classic existential problem of planetary atmospheres. The problem has gained new currency now that we can begin to study escape, or the cumulative effects of escape, from extrasolar planets seen in transit. Already some intriguing patterns have emerged. In particular, transiting EGPs appear to fit a pattern seen in our own Solar System. The data show that atmospheres are found where escape velocity is high and (i) solar heating is low or (ii) impact velocities are low. In either case, the boundary between planets with and without atmospheres --- the cosmic shoreline, as it were --- is a simple power law that extends from Pluto to Jupiters and beyond.

  20. 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.

  1. 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.

  2. Determination of Habitable Zones in Extrasolar Planetary Systems: Where are Gaia's Sisters?

    E-print Network

    1 Determination of Habitable Zones in Extrasolar Planetary Systems: Where are Gaia's Sisters scheme for assessing the suitability for life of extrasolar planets is pre- sented. The scheme focuses on the identification of the "habitable zone" in main-sequence star planetary systems accommodating Earth

  3. 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 the effect of stellar distance (e.g., incident ultraviolet flux, atmospheric temperature) on the chemical properties of EGPs. The model is applied to two generic Class II and III intermediate temperature EGPs located at 3.3 and 0.27 AU from a solar-like parent star, and the results are compared with a model for Jupiter at 5.2 AU.

  4. 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.

  5. Infrared spectra of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Townes, C. H.

    1975-01-01

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

  6. 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.

  7. 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.

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

    PubMed

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

    2002-01-01

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

  9. Studies of Tenuous Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Combi, Michael R.; Beebe, Reta (Technical Monitor)

    2001-01-01

    In order to understand the physical and chemical processes which produce the tenuous planetary and planetary satellite (upper) atmospheres through interactions with their particle, field, and radiation environs, it is necessary to analyze remotely observed and spacecraft data with physically meaningful models. With this in mind, we have undertaken a coupled program of theoretical modeling and complementary data analysis regarding the global distributions of neutral and ionized gases in, and escape from, tenuous planetary atmospheres of Io and Europa. The theoretical models developed will have further applications to other tenuous atmospheres such as that of Pluto and Titan or the upper atmospheres of the terrestrial planets.

  10. Detectability of planetary rings around an extrasolar planet from reflected-light photometry

    E-print Network

    L. Arnold; J. Schneider

    2005-10-19

    The next generation of high-contrast imaging instruments will provide the first unresolved image of an extrasolar planet. While the emitted infrared light from the planet in thermal equilibrium should show almost no phase effect, the reflected visible light will vary with the orbital phase angle. We study the photometric variation of the reflected light with orbital phase of a ringed extrasolar planet. We show that a ring around an extrasolar planet, both obviously unresolved, can be detected by its specific photometric signature. Keywords: Stars: planetary systems -- Planets: rings -- Extrasolar planet characterization

  11. 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

  12. 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.

  13. On the dynamics of Extrasolar Planetary Systems under dissipation. Migration of planets

    E-print Network

    Hadjidemetriou, John D.

    On the dynamics of Extrasolar Planetary Systems under dissipation. Migration of planets John D-mail: hadjidem@auth.gr, voyatzis@auth.gr Abstract: We study the dynamics of planetary systems with two planets moving in the same plane, when frictional forces act on the two planets, in addition to the gravitational

  14. Polarization Models for Rayleigh Scattering Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Buenzli, Esther; Schmid, Hans M.; Joos, Franco

    2009-09-01

    We present Monte Carlo simulations for the polarization of light reflected from planetary atmospheres. We investigate dependencies of intensity and polarization on three main parameters: single scattering albedo, optical depth of a scattering layer, and albedo of a Lambert surface underneath. The main scattering process considered is Rayleigh scattering, but isotropic scattering and enhanced forward scattering on haze particles are also investigated. We discuss disk integrated results for all phase angles and radial profiles of the limb polarization at opposition. These results are useful to interpret available limb polarization measurements of solar system planets and to predict the polarization of extra-solar planets as a preparation for VLT/SPHERE. Most favorable for a detection are planets with an optically thick Rayleigh-scattering layer. The limb polarization of Uranus and Neptune is especially sensitive to the vertically stratified methane mixing ratio. From limb polarization measurements constraints on the polarization at large phase angles can be set.

  15. About putative Neptune-like extrasolar planetary candidates

    E-print Network

    Krzysztof Gozdziewski; Cezary Migaszewski

    2005-11-10

    We re-analyze the precision radial velocity (RV) data of HD188015, HD114729, HD190360, HD147513 and HD208487. All these stars are supposed to host Jovian companions in long-period orbits. We test a hypothesis that the residuals of the 1-planet model of the RV or an irregular scatter of the measurements about the synthetic RV curve may be explained by the existence of additional planets in short-period orbits. We perform a global search for the best fits in the orbital parameters space with genetic algorithms and simplex method. This makes it possible to verify and extend the results obtained with an application of commonly used FFT-based periodogram analysis for identifying the leading periods. Our analysis confirms the presence of a periodic component in the RV data of HD190360 which may correspond to a hot-Neptune planet. We found four new cases when the 2-planet model yields significantly better fits to the RV data than the best 1-planet solutions. If the periodic variability of the residuals of single-planet fits has indeed a planetary origin then hot-Neptune planets may exist in these extrasolar systems. We estimate their orbital periods in the range of 7-20d and minimal masses about of 20 masses od the Earth.

  16. 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.

  17. Planetary atmospheres: Microwave spectroscopic studies of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Clancy, R. Todd

    1991-01-01

    Ground-based spectroscopic observations of isotopes of CO in the atmospheres of Mars, Venus, and Titan have been collected over the 1982-1990 period. These observations have been analyzed to obtain information on the photochemistry, dynamics, and thermal profiles of these planetary atmospheres. In the cases of the mesosphere (80-100 km altitude) of Venus and the lower atmosphere (0-70 km altitude) of Mars, the primary conclusion of this research is that significant interannual variations in the global thermal and compositional structures of these atmospheres occur over 10 year periods. The Titan studies have focussed on pinning down the true atmospheric CO abundance. A more detailed summary of the results for each of these planetary atmospheres is provided.

  18. Cryptic photosynthesis, Extrasolar planetary oxygen without a surface biological signature

    E-print Network

    C. S. Cockell; L. Kaltenegger; J. A. Raven

    2009-02-19

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

  19. The extrasolar planet atmosphere and exosphere: Emission and transmission spectroscopy

    E-print Network

    Giovanna Tinetti; Jean-Philippe Beaulieu

    2008-12-10

    We have entered the phase of extrasolar planets characterization, probing their atmospheres for molecules, constraining their horizontal and vertical temperature profiles and estimating the contribution of clouds and hazes. We report here a short review of the current situation using ground based and space based observations, and present the transmission spectra of HD189733b in the spectral range 0.5-24 microns.

  20. Terrestrial Planet Formation in Extra-Solar Planetary Systems

    E-print Network

    Sean N. Raymond

    2008-01-16

    Terrestrial planets form in a series of dynamical steps from the solid component of circumstellar disks. First, km-sized planetesimals form likely via a combination of sticky collisions, turbulent concentration of solids, and gravitational collapse from micron-sized dust grains in the thin disk midplane. Second, planetesimals coalesce to form Moon- to Mars-sized protoplanets, also called "planetary embryos". Finally, full-sized terrestrial planets accrete from protoplanets and planetesimals. This final stage of accretion lasts about 10-100 Myr and is strongly affected by gravitational perturbations from any gas giant planets, which are constrained to form more quickly, during the 1-10 Myr lifetime of the gaseous component of the disk. It is during this final stage that the bulk compositions and volatile (e.g., water) contents of terrestrial planets are set, depending on their feeding zones and the amount of radial mixing that occurs. The main factors that influence terrestrial planet formation are the mass and surface density profile of the disk, and the perturbations from giant planets and binary companions if they exist. Simple accretion models predicts that low-mass stars should form small, dry planets in their habitable zones. The migration of a giant planet through a disk of rocky bodies does not completely impede terrestrial planet growth. Rather, "hot Jupiter" systems are likely to also contain exterior, very water-rich Earth-like planets, and also "hot Earths", very close-in rocky planets. Roughly one third of the known systems of extra-solar (giant) planets could allow a terrestrial planet to form in the habitable zone.

  1. Studies of Tenuous Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Combi, Michael R.

    1997-01-01

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

  2. Theoretical Spectra and Atmospheres of Extrasolar Giant Planets

    E-print Network

    David Sudarsky; Adam Burrows; Ivan Hubeny

    2003-02-19

    We present a comprehensive theory of the spectra and atmospheres of irradiated extrasolar giant planets. We explore the dependences on stellar type, orbital distance, cloud characteristics, planet mass, and surface gravity. Phase-averaged spectra for specific known extrasolar giant planets that span a wide range of the relevant parameters are calculated, plotted, and discussed. The connection between atmospheric composition and emergent spectrum is explored in detail. Furthermore, we calculate the effect of stellar insolation on brown dwarfs. We review a variety of representative observational techniques and programs for their potential for direct detection, in light of our theoretical expectations, and we calculate planet-to-star flux ratios as a function of wavelength. Our results suggest which spectral features are most diagnostic of giant planet atmospheres and reveal the best bands in which to image planets of whatever physical or orbital characteristics.

  3. 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 signatures of life. Remarkably little is known about the composition of our own earlier atmosphere, particularly prior to the rise of oxygen levels some 2.0 to 2.2 billion years ago. Thus, field and laboratory observations and theoretical simulations should be conducted to examine the relationships between the structure and function of microbial ecosystems and their gaseous products. Ecosystems that are analogs of our ancient biosphere (e.g., based upon chemosynthesis or non-oxygenic photosynthesis, thermophilic and subsurface communities, etc.) should be included. Because key environmental parameters such as temperature and levels of hydrogen, carbon dioxide and oxygen varied during planetary evolution, their consequences for microbial ecosystems should be explored.

  4. Understanding the Outer Planets and Planetary Atmospheres

    E-print Network

    Mojzsis, Stephen J.

    · Bizarre chemistry of Titan's atmosphere · Charging of dust grains on the surface of the Moon Planetary and Earth's atmosphere. The gas giants--Mars, Venus, Pluto, and various moons and comets-- all haveUnderstanding the Outer Planets and Planetary Atmospheres Planetary science focuses on many aspects

  5. Extra-solar planetary imager (ESPI) for space-based Jovian planetary detection

    NASA Astrophysics Data System (ADS)

    Lyon, Richard G.; Gezari, Daniel Y.; Melnick, Gary J.; Nisenson, Peter; Papaliolios, Costas D.; Ridgway, Stephen T.; Friedman, Edward J.; Harwit, Martin; Graf, Paul

    2003-02-01

    The Extra-Solar Planetary Imager (ESPI) is envisioned as a space based, high dynamic range, visible imager capable of detecting Jovian like planets. Initially proposed as a NASA Midex (NASA/Medium Class Explorer) mission (PI:Gary Melnick), as a space-based 1.5 x 1.5 m2 Jacquinot apodized square aperture telescope. The combination of apodization and a square aperture telescope reduces the diffracted light from a bright central source increasing the planetary to stellar contrast 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. ESPI 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 > 5 in observations lasting maximally 100 hours per star out to ~16 parsecs. We discuss the scientific ramifications, an overview of the system design including apodizing a square aperture, signal to noise issues and the effect of wavefront errors and the scalability of ESPI with respect to NASA's Terrestrial Planet Finder mission.

  6. Retrieval of atmospheric properties of extrasolar planets

    E-print Network

    Nikku, Madhusudhan, 1980-

    2009-01-01

    We present a new method to retrieve molecular abundances and temperature profiles from exoplanet atmosphere photometry and spectroscopy. Our method allows us to run millions of 1-D atmosphere models in order to cover the ...

  7. Sprites in other planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Yair, Y.; Yaniv, R.

    Lightning have been detected in clouds on other planets either by direct imaging of the optical emissions from flashes emanating through the atmosphere or else by remote sensing of electromagnetic signals such as sferics or whistlers guided by the planet's magnetosphere. While the intensity of the electrical activity on Venus may be still inconclusive, there is little doubt, based on the Voyager, Galileo and Cassini missions, that lightning are prevalent on Jupiter and Saturn, and that their total power is much stronger than on Earth (Desch et al., 2002; Gurnett et al., 2005). Sprites are a type of a transient luminous emission which accompanies powerful lightning flashes (Lyons et al. 2001). They are caused the quasi-electrostatic electric field between the charged cloud top and the planetary ionosphere. They can take weird and magnificent shapes resembling jelly-fish, carrot heads, pearls or columns. On Earth, they emit in red and blue wavelengths, mostly from molecular Nitrogen species, and span a vertical range between 50 and 90 km. The emission spectra of sprites, their height and occurrence frequency reflect the properties of the planetary atmosphere and are directly related to the intensity of the parent lightning. We present results of theoretical calculations of the expected emissions in sprites, occurring above thunderstorms in the CO2 atmosphere of Venus and the Hydrogen-Helium atmospheres of Jupiter and Saturn. Detection methodology of sprites in planetary atmospheres by orbiting spacecraft will be discussed

  8. PASCAL - Planetary Atmospheres Spectral Catalog

    NASA Astrophysics Data System (ADS)

    Rothman, Laurence; Gordon, Iouli

    2010-05-01

    Spectroscopic observation of planetary atmospheres, stellar atmospheres, comets, and the interstellar medium is the most powerful tool for extracting detailed information concerning the properties of these objects. The HITRAN molecular spectroscopic database1 has traditionally served researchers involved with terrestrial atmospheric problems, such as remote-sensing of constituents in the atmosphere, pollution monitoring at the surface, identification of sources seen through the atmosphere, and numerous environmental issues. A new thrust of the HITRAN program is to extend this longstanding database to have capabilities for studying the above-mentioned planetary and astronomical systems. The new extension is called PASCAL (Planetary Atmospheres Spectral Catalog). The methodology and structure are basically identical to the construction of the HITRAN and HITEMP databases. We will acquire and assemble spectroscopic parameters for gases and spectral bands of molecules that are germane to the studies of planetary atmospheres. 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. Additional parameters beyond what is currently considered for the terrestrial atmosphere will be archived. Examples are collision-broadened halfwidths due to various foreign partners, collision-induced absorption, and temperature dependence factors. New molecules (and their isotopic variants), not currently included in the HITRAN database, will be incorporated. That includes hydrocarbons found on Titan but not archived in HITRAN (such as C3H4, C4H2, C3H8). Other examples include sulfur-bearing molecules such as SO and CS. A further consideration will be spectral bands that arise as opportunities to study exosolar planets. The task involves acquiring the best high-resolution data, both experimental and theoretical, covering a wide spectral range from the microwave through ultraviolet. The data are frequently from multiple sources and must be merged, with special attention to the unique quantum identification of each transition. The resultant line lists are then validated and incorporated into a structured database that is easily employed by modelers. Partition sums that are necessary for applications at a wide range of temperature will also be generated. For molecules with dense spectra, especially molecules with many low-lying fundamental vibrations, the approach is to cast them into sets of pressure-temperature absorption cross-section files. In this case, we will acquire the best laboratory measurements of these gases and transform them into the standard reference files for use in the radiative-transfer codes. This effort is supported by the NASA Planetary Atmospheres program, under the grant NNX10AB94G.

  9. Planetary Science (mostly atmospheres)

    E-print Network

    Withers, Paul

    for Mars geology Marchant and colleagues Dry valleys of Antarctica Dry valleys of Antarctica #12;Ground atmospheres and aurora, UV instrumentation · Professor Dave Marchant ­ Antarctica as a geological Mars instrument teams MAVEN UV spectrometer Mars Express and Venus Express radio science Accelerometer instruments

  10. Dynamics of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Ingersoll, Andrew P.

    1989-01-01

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

  11. Dynamical Instabilities in Extrasolar Planetary Systems Kenneth K. Yu

    E-print Network

    Rasio, Frederic A.

    The existence of planets outside our solar system is one of the greatest discoveries of the 20th century are known to exist outside our solar system. These planets are Jupiter-like gas giants and are found in more multiple planets, not unlike our home system. Surprisingly, the overwhelming majority of these extrasolar

  12. Ionisation in atmospheres of Brown Dwarfs and extrasolar planets III. Breakdown conditions for mineral clouds

    E-print Network

    Helling, Ch; Stark, C; Diver, D

    2013-01-01

    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 ou...

  13. The ability of the space telescope to detect extra-solar planetary systems

    NASA Technical Reports Server (NTRS)

    Baum, W. A.

    1979-01-01

    The space telescope can plan a key role in searching for and investigating the contents of extra-solar planetary systems. For about 90 nearby stars, positional variations due to major planets would be well within the astrometric capability of the wide-field/planetary camera system. Since the centroids of star images will be determined to within a milliarcsecond down to 22d magnitude, there will be an abundance of reference stars at very small angular distances from each planetary system candidate, and they will have small enough motions of their own to provide a reference frame of the stability required.

  14. 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.

  15. Methane present in an extrasolar planet atmosphere

    E-print Network

    Mark R. Swain; Gautam Vasisht; Giovanna Tinetti

    2008-02-07

    Molecules present in exoplanetary atmospheres are expected to strongly influence the atmospheric radiation balance, trace dynamical and chemical processes, and indicate the presence of disequilibrium effects. Since molecules have the potential to reveal the exoplanet 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-Jovian planets. Since these bands overlap in wavelength, and the corresponding signatures from them are weak, decisive identification requires precision infrared spectroscopy. Here we report on a near-infrared transmission spectrum of the planet HD 189733b showing the presence of methane. Additionally, a resolved water-vapour band at 1.9 microns confirms the recent claim of water in this object. On thermochemical grounds, carbon-monoxide is expected to be abundant in the upper atmosphere of hot-Jovian exoplanets; thus 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 mechanisms that leads to an enhancement of methane.

  16. The Significance of the Sodium Detection in the Extrasolar Planet HD209458b Atmosphere

    E-print Network

    S. Seager

    2003-05-19

    The Hubble Space Telescope (HST) detection of an extrasolar planet atmosphere in 2001 was a landmark step forward for the characterization of extrasolar planets. HST detected the trace element sodium, via the neutral atomic resonance doublet at 593 nm, in the transiting extrasolar giant planet HD209458b. In this paper I discuss the significance of this first ever extrasolar planet atmosphere detection. I explain how the sodium measurement can be used as a constraint on HD209458b atmosphere models and review recent interpretations of the lower-than-expected sodium line strength.

  17. 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.

  18. 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

  19. On the possibility of detecting extrasolar planets' atmospheres with the Rossiter-McLaughlin effect

    NASA Astrophysics Data System (ADS)

    Dreizler, S.; Reiners, A.; Homeier, D.; Noll, M.

    2009-05-01

    Context: The detection of extrasolar planets' atmospheres requires very demanding observations. For planets that cannot be spatially separated from their host stars, i.e. the vast majority of planets, the transiting planets are the only ones to allow their atmospheres to be probed. This is possible from transmission spectroscopy or from measurements taken during the secondary eclipse. An alternative is to measure of the Rossiter-McLaughlin effect, which is sensitive to the size of the planetary radius. Since the radius is wavelength-dependent due to contributions of strong planetary absorption lines, this opens a path toward also probing planetary atmospheres with ground-based high-resolution spectroscopy. Aims: The major goal of our numerical simulations is to provide a reliable estimate of the amplitude of the wavelength-dependent Rossiter-McLaughlin effect. Methods: Our numerical simulations provide detailed phase-resolved synthetic spectra modeling the partly eclipsed stellar surface during the transit. With these spectra we can obtain Rossiter-McLaughlin curves for different wavelength regions and for a wavelength-dependent planetary radius. Curves from regions with high and low contributions of absorption lines within the planetary atmosphere can be compared. Observable quantities are derived from these differential effects. Results: We applied our simulations to HD 209458. Our numerical simulations show that a detailed treatment of the limb-darkening for the synthetic spectra is important for a precise analysis. Compared to a parameterized limb-darkening law, systematic errors of 6 m s-1 occur. The wavelength dependency of the planetary atmospheres over the NaD-doublet produces a differential effect in the Rossiter-McLaughlin curve of 1.5 m s-1 for a star with a rotation velocity of 4.5 km s-1, which increases to 4 m s-1 for twice the rotation velocity. Conclusions: As a tool for probing planetary atmospheres the Rossiter-McLaughlin effect requires phase-resolved, high signal-to-noise, high-resolution spectra taken with a stabilized spectrograph in order to obtain reliable results for slowly rotating (<10 m s-1) planet host stars. Stars with spectral type earlier than about F5 are a bit less demanding since the typically higher rotation velocity increases the amplitude of the effect to about 15 m s-1 for a star with v sin i = 25 km s-1.

  20. The period-ratio and mass-ratio correlation in extra-solar multiple planetary systems

    NASA Astrophysics Data System (ADS)

    Jiang, Ing-Guey; Yeh, Li-Chin; Hung, Wen-Liang

    2015-04-01

    Employing the data from orbital periods and masses of extra-solar planets in 166 multiple planetary systems, the period ratio and mass ratio of adjacent planet pairs are studied. The correlation between the period ratio and mass ratio is confirmed, with a correlation coefficient of 0.5303 with a 99 per cent confidence interval (0.3807, 0.6528). A comparison with the distribution of synthetic samples from a Monte Carlo simulation reveals the imprint of planet-planet interactions on the formation of adjacent planet pairs in multiple planetary systems.

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

    E-print Network

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

    2007-07-20

    Water is predicted to be among, if not the most abundant molecular species after hydrogen in the atmospheres of close-in extrasolar giant planets (hot-Jupiters) Several attempts have been made to detect water on an exoplanet, but have failed to find compelling evidence for it or led to claims that should be taken with caution. Here we report an analysis of recent observations of the hot-Jupiter HD189733b taken during the transit, where the planet passed in front of its parent star. We find that absorption by water vapour is the most likely cause of the wavelength-dependent variations in the effective radius of the planet at the infrared wavelengths 3.6, 5.8 and 8 microns. The larger effective radius observed at visible wavelengths may be due to either star variability or the presence of clouds/hazes. We explain the most recent thermal infrared observations of the planet during secondary transit behind the star, reporting a non-detection of water on HD189733b, as being a consequence of the nearly isothermal vertical profile of the planet.s atmosphere. Our results show that water is detectable on extrasolar planets using the primary transit technique and that the infrared should be a better wavelength region than the visible, for such searches.

  2. 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]Nottale, L. “Scale-Relativity and Quantization of Exo- planet Orbital Semi-Major Axes,” Astronomy & Astro- physics, Vol. 361, 2000, pp. 379-387.

  3. 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.

  4. 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?

  5. Oscillations of Relative Inclination Angles in Compact Extrasolar Planetary Systems

    E-print Network

    Becker, Juliette C

    2015-01-01

    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 multi transiting 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 multi-planet systems with additional non-transiting planets are susceptible to oscillations of their inclination angles, which means their currently...

  6. 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.

  7. 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.

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

    E-print Network

    C. Lovis; M. Mayor; F. Pepe; Y. Alibert; W. Benz; F. Bouchy; A. C. M. Correia; J. Laskar; C. Mordasini; D. Queloz; N. C. Santos; S. Udry; J. -L. Bertaux; J. -P. Sivan

    2007-03-01

    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.

  9. 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

  10. 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.

  11. 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 planetary system formation processes and our peculiar position in this scheme. PMID:11538135

  12. Predicting Planets in Known Extra-Solar Planetary Systems III: Forming Terrestrial Planets

    E-print Network

    Raymond, S N

    2004-01-01

    Recent results have shown that many of the known extrasolar planetary systems contain regions which are stable for both massless and massive test particles. We simulate the formation of terrestrial planets in four planetary systems: HD37124, HD38529, 55Cnc, and HD74156. In each case, Moon- to Mars-sized planetary embryos are placed in between the giant planets and evolved for 100 Myr. We find that no terrestrial planets form in HD37124 and HD74156, although in some cases 1-2 lone embryos will survive for 100 Myr. Planets form relatively easily in 55Cnc, with masses up to 0.6 Earth masses and in some cases substantial water contents. HD38529 is likely to support an asteroid belt but no terrestrial planets of significant mass.

  13. 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.

  14. A grid of polarization models for Rayleigh scattering planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Buenzli, E.; Schmid, H. M.

    2009-09-01

    Context: Reflected light from giant planets is polarized by scattering, offering the possibility of investigating atmospheric properties with polarimetry. Polarimetric measurements are available for the atmospheres of solar system planets, and instruments are being developed to detect and study the polarimetric properties of extrasolar planets. Aims: We investigate the intensity and polarization of reflected light from planets in a systematic way with a grid of model calculations. Comparison of the results with existing and future observations can be used to constrain parameters of planetary atmospheres. Methods: We present Monte Carlo simulations for planets with Rayleigh scattering atmospheres. We discuss the disk-integrated polarization for phase angles typical of extrasolar planet observations and for the limb polarization effect observable for solar system objects near opposition. The main parameters investigated are single scattering albedo, optical depth of the scattering layer, and albedo of an underlying Lambert surface for a homogeneous Rayleigh scattering atmosphere. We also investigate atmospheres with isotropic scattering and forward scattering aerosol particles, as well as models with two scattering layers. Results: The reflected intensity and polarization depend strongly on the phase angle, as well as on atmospheric properties, such as the presence of absorbers or aerosol particles, column density of Rayleigh scattering particles and cloud albedo. Most likely to be detected are planets that produce a strong polarization flux signal because of an optically thick Rayleigh scattering layer. Limb polarization depends on absorption in a different way than the polarization at large phase angles. It is especially sensitive to a vertical stratification of absorbers. From limb polarization measurements, one can set constraints on the polarization at large phase angles. Conclusions: The model grid provides a tool for extracting quantitative results from polarimetric measurements of planetary atmospheres, in particular on the scattering properties and stratification of particles in the highest atmosphere layers. Spectropolarimetry of solar system planets offers complementary information to spectroscopy and polarization flux colors can be used for a first characterization of exoplanet atmospheres. Full Table [see full text] is 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/504/259

  15. Ionization in Atmospheres of Brown Dwarfs and Extrasolar Planets. III. Breakdown Conditions for Mineral Clouds

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

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

    SciTech Connect

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

    2013-04-20

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-02-01

    As photosynthesis on Earth produces the primary signatures of life that can be detected astronomically at the global scale, a strong focus of the search for extrasolar life will be photosynthesis, particularly photosynthesis that has evolved with a different parent star. We take previously simulated planetary atmospheric compositions for Earth-like planets around observed F2V and K2V, modeled M1V and M5V stars, and around the active M4.5V star AD Leo; our scenarios use Earth's atmospheric composition as well as very low O2 content in case anoxygenic photosynthesis dominates. With a line-by-line radiative transfer model, we calculate the incident spectral photon flux densities at the surface of the planet and under water. We identify bands of available photosynthetically relevant radiation and find that photosynthetic pigments on planets around F2V stars may peak in absorbance in the blue, K2V in the red-orange, and M stars in the near-infrared, in bands at 0.93-1.1 ?m, 1.1-1.4 ?m, 1.5-1.8 ? m, and 1.8-2.5 ?m. However, underwater organisms will be restricted to wavelengths shorter than 1.4 ?m and more likely below 1.1 ?m. M star planets without oxygenic photosynthesis will have photon fluxes above 1.6 ?m 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 ?m is a possible upper cutoff for electronic transiprotions versus only vibrational energy; however, this cutoff is not strict, since such energetics depend on molecular configuration. M star planets could be a half to a tenth as productive as Earth in the visible, but exceed Earth if useful photons extend to 1.1 ?m for anoxygenic photosynthesis. Under water, organisms would still be able to survive ultraviolet flares from young M stars and acquire adequate light for growth. Key Words: Photosynthesis-Astrobiology - Photosynthetic pigments - Oxygenic photosynthesis - Anoxygenic photosynthesis - Atmospheric photochemistry - F stars-G stars - Sun - K stars - M stars - AD Leo - Atmospheric oxygen - Atmospheric radiative transfer - Chlorophyll - Bacteriochlorophyll - Photosystems - Radiation spectrum - Photosynthetically active radiation - Light harvesting - Modeling - Extrasolar planets - Earth like planets - Virtual Planetary Laboratory - Biosignatures. Astrobiology 7(1), 252 - 274.

  18. 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.

  19. Terrestrial Planet Formation in Extra-Solar Planetary Systems

    E-print Network

    Raymond, Sean N

    2008-01-01

    Terrestrial planets form in a series of dynamical steps from the solid component of circumstellar disks. First, km-sized planetesimals form likely via a combination of sticky collisions, turbulent concentration of solids, and gravitational collapse from micron-sized dust grains in the thin disk midplane. Second, planetesimals coalesce to form Moon- to Mars-sized protoplanets, also called "planetary embryos". Finally, full-sized terrestrial planets accrete from protoplanets and planetesimals. This final stage of accretion lasts about 10-100 Myr and is strongly affected by gravitational perturbations from any gas giant planets, which are constrained to form more quickly, during the 1-10 Myr lifetime of the gaseous component of the disk. It is during this final stage that the bulk compositions and volatile (e.g., water) contents of terrestrial planets are set, depending on their feeding zones and the amount of radial mixing that occurs. The main factors that influence terrestrial planet formation are the mass an...

  20. 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

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

    SciTech Connect

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

    2011-11-01

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

  2. Rocky Extrasolar Planetary Compositions Derived from Externally Polluted White Dwarfs

    NASA Astrophysics Data System (ADS)

    Klein, B.; Jura, M.; Koester, D.; Zuckerman, B.

    2011-11-01

    We report Keck High Resolution Echelle Spectrometer data and model atmosphere analysis of two helium-dominated white dwarfs, PG1225-079 and HS2253+8023, whose heavy pollutions most likely derive from the accretion of terrestrial-type planet(esimal)s. For each system, the minimum accreted mass is ~1022 g, that of a large asteroid. In PG1225-079, Mg, Cr, Mn, Fe, and Ni have abundance ratios similar to bulk Earth values, while we measure four refractory elements, Ca, Sc, Ti, and V, all at a factor of ~2-3 higher abundance than in the bulk Earth. For HS2253+8023 the swallowed material was compositionally similar to bulk Earth in being more than 85% by mass in the major element species, O, Mg, Si, and Fe, and with abundances in the distinctive proportions of mineral oxides—compelling evidence for an origin in a rocky parent body. Including previous studies we now know of four heavily polluted white dwarfs where the measured oxygen and hydrogen are consistent with the view that the parents' bodies formed with little ice, interior to any snow line in their nebular environments. The growing handful of polluted white dwarf systems with comprehensive abundance measurements form a baseline for characterizing rocky exoplanet compositions that can be compared with bulk Earth.

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

    PubMed

    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. PMID:11539063

  4. Spectral signatures of photosynthesis II: coevolution with other stars and the atmosphere on extrasolar worlds

    E-print Network

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

    2007-01-12

    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 planetary atmospheric compositions simulated by Segura, et al. (2003, 2005) for Earth-like planets around observed F2V and K2V stars, 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. 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 NIR, in bands at 0.93-1.1 microns, 1.1-1.4 microns, 1.5-1.8 microns, and 1.8-2.5 microns. In addition, we calculate wavelength restrictions for underwater organisms and depths of water at which they would be protected from UV flares in the early life of M stars. We estimate the potential productivity for both surface and underwater photosynthesis, for both oxygenic and anoxygenic photosynthesis, and for hypothetical photosynthesis in which longer wavelength, multi-photosystem series are used.

  5. Planetary atmospheres: Microwave spectroscopic and space physics

    NASA Technical Reports Server (NTRS)

    Clancy, R. Todd

    1990-01-01

    Ground-based spectroscopic observations of isotopes of CO in the atmosphere of Mars, Venus, and Titan were collected over the 1982-1990 period. These observations were analyzed to obtain information on the photochemistry, dynamics, and thermal profiles of these planetary atmospheres. In the cases of the mesosphere (80-100 km altitude) of Venus and the lower atmosphere (0-70 km altitude) of Mars, the primary conclusion of this research is that significant interannual variation in the global, thermal, and compositional structures of these atmospheres occur over 10 year periods. The Titan studies have focussed on pinning down the true atmosphere CO abundance. A more detailed summary of the results for each of these planetary atmospheres is provided.

  6. The Role of Clouds in Brown Dwarf and Extrasolar Giant Planet Atmospheres

    E-print Network

    M. S. Marley; A. S. Ackerman

    2001-03-16

    Clouds and hazes are important throughout our solar system and in the atmospheres of brown dwarfs and extrasolar giant planets. Among the brown dwarfs, clouds control the colors and spectra of the L-dwarfs; the disappearance of clouds helps herald the arrival of the T-dwarfs. The structure and composition of clouds will be among the first remote-sensing results from the direct detection of extrasolar giant planets.

  7. Spin of Planetary Probes in Atmospheric Flight

    NASA Astrophysics Data System (ADS)

    Lorenz, R. D.

    Probes that enter planetary atmospheres are often spun during entry or descent for a variety of reasons. Their spin rate histories are influenced by often subtle effects. The spin requirements, control methods and flight experience from planetary and earth entry missions are reviewed. An interaction of the probe aerodynamic wake with a drogue parachute, observed in Gemini wind tunnel tests, is discussed in connection with the anomalous spin behaviour of the Huygens probe.

  8. 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 measurements capable of detecting planets with K {approx} 5 m s{sup -1} and periods in excess of 10 years will provide constraints on this regime. Finally, we present an analysis of the predicted separation of planets in two-planet systems, and of the population of planets in mean-motion resonances (MMRs). We show that, if there are systems with {approx} Jupiter-mass planets that avoid close encounters, the planetesimal disk acts as a damping mechanism and populates MMRs at a very high rate (50%-80%). In many cases, resonant chains (in particular the 4:2:1 Laplace resonance) are set up among all three planets. We expect such resonant chains to be common among massive planets in outer planetary systems.

  9. Predicting Planets in Known Extra-Solar Planetary Systems III: Forming Terrestrial Planets

    E-print Network

    Sean N. Raymond; Rory Barnes; Nathan A. Kaib

    2006-05-15

    Recent results have shown that many of the known extrasolar planetary systems contain regions which are stable for both Earth-mass and Saturn-mass planets. Here we simulate the formation of terrestrial planets in four planetary systems -- 55 Cancri, HD 38529, HD 37124, and HD 74156 -- under the assumption that these systems of giant planets are complete and that their orbits are well-determined. Assuming the giant planets formed and migrated quickly, then terrestrial planets may form from a second generation of planetesimals. In each case, Moon- to Mars-sized planetary embryos are placed in between the giant planets and evolved for 100 Myr. We find that planets form relatively easily in 55 Cnc, with masses up to 0.6 Earth masses and in some cases substantial water contents and orbits in the habitable zone. HD 38529 is likely to support an asteroid belt but no terrestrial planets of significant mass. No terrestrial planets form in HD 37124 and HD 74156, although in some cases 1-2 lone embryos survive for 100 Myr. If migration occurred later, depleting the planetesimal disk, then massive terrestrial planets are unlikely to form in any of these systems.

  10. 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 terms of motion not needed on Venus. When the Galileo Probe encountered Jupiter, analysis and interpretation of data commenced. The early contributions of the experiment were to define (1) the basic structure of the deep atmosphere, (2) the stability of the atmosphere, (3) the upper atmospheric profiles of density, pressure, and temperature. The next major task in the Galileo Probe project was to refine, verify and extend the analysis of the data. It was the verified, and corrected data, which indicated a dry abiabatic atmosphere within measurement accuracy. Temperature in the thermosphere was measured at 900 K. Participation in the Mars atmospheric research included: (1) work as a team member of the Mars Atmosphere Working Group, (2) contribution to the Mars Exobiology Instrument workshop, (3) asssistance in planning the Mars global network and (4) assitance in planning the Soviet-French Mars mission in 1994. This included a return to the Viking Lander parachute data to refine and improve the definition of winds between 1.5 and 4 kilometer altitude at the two entry sites. The variability of the structure of Mars atmosphere was addressed, which is known to vary with season, latitude, hemisphere and dust loading of the atmosphere. This led to work on the Pathfinder project. The probe had a deployable meteorology mast that had three temperature sensors, and a wind sensor at the tip of the mast. Work on the Titan atmospheric probe was also accomplished. This included developing an experiment proposal to the European Space Agency (ESA), which was not selected. However, as an advisor in the design and preparation of the selected experiment the researcher interacted with scientist on the Huygens Probe Atmosphere Structure Experiment. The researcher also participated in the planning for the Venus Chemical Probe. The science objectives of the probe were to resolve unanswered questions concerning the minor species chemistry of Venus' atmosphere that control cloud formation, greenhouse effectiveness, and the thermal structure. The researcher also reviewed problems with the

  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. Lithium in cool stellar atmospheres: Big bang nucleosynthesis and extrasolar planets

    E-print Network

    Lithium in cool stellar atmospheres: Big bang nucleosynthesis and extrasolar planets Matthias is not produced in the big bang, has been detected in some of the brightest metal-poor stars at levels too high isotopic ratio in cool stellar atmospheres is of crucial importance for addressing questions about the big

  13. 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.

  14. Faculty Positions Department of Earth, Atmospheric, and Planetary Sciences

    E-print Network

    Kihara, Daisuke

    Faculty Positions Department of Earth, Atmospheric, and Planetary Sciences Purdue University In support of its significant existing strengths in climate and extreme weather, the Department of Earth, Atmospheric and Planetary Sciences (EAPS), within the College of Science, Purdue University, invites

  15. Origin and evolution of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Pollack, J. B.; Yung, Y. L.

    1980-01-01

    The current understanding of the origin and evolution of the atmospheres of solar system objects is reviewed. Physical processes that control this evolution are described in an attempt to develop a set of general principles that can help guide studies of specific objects. Particular emphasis is placed on the planetary and satellite atmospheres of the inner solar system objects; current hypotheses on the origin and evolution of these objects are critically considered.

  16. Solving multiple scattering problems in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Irvine, W. M.; Lenoble, J.

    1974-01-01

    Multiple scattering problems, radiative transfer problems in planetary atmospheres within extended visible portion of the spectrum, are examined. The direct and inverse problems and the extinction coefficient are defined, along with other scattering characteristics. Albedos in semi-infinite and finite atmospheres are considered, as well as surface illumination, energy deposition, and polarization. The Eddington approximation figures prominently in the calculations. Precise numerical methods and analytical solutions are included.

  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. 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.

  20. Work on Planetary Atmospheres and Planetary Atmosphere Probes

    NASA Astrophysics Data System (ADS)

    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 instrument performance, although performed greater than 5 years prior to Jupiter encounter. Capability of decoding the science data from the Experiment Data Record to be provided at encounter was developed and exercised using the tape recording of the first Cruise Checkout data. A team effort was organized to program the selection and combination of data words defining pressure, temperature, acceleration, turbulence, and engineering quantities; to apply decalibration algorithms to convert readings from digital numbers to physical quantities; and to organize the data into a suitable printout. A paper on the Galileo Atmosphere Structure Instrument was written and submitted for publication in a special issue of Space Science Reviews. At the Journal editor's request, the grantee reviewed other Probe instrument papers submitted for this special issue. Calibration data were carefully taken for all experiment sensors and accumulated over a period of 10 years. 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. This report was distributed to experiment coinvestigators and the Probe Project Office.

  1. 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.

  2. 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.

  3. Ionization in Atmospheres of Brown Dwarfs and Extrasolar Planets VI: Properties of Large-scale Discharge Events

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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 (108-1010 m3) than in a giant gas planet (104-106 m3). Our results suggest that the total dissipated energy in one event is <1012 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 CH2 at the expense of CO and CH4. 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.

  4. Photometric Detection Of An Extra-solar Planetary Transit Across The Sun-like Star HD 209458

    NASA Astrophysics Data System (ADS)

    Chirayath, V.

    2003-12-01

    I report photometric measurements of HD 209458, an extra-solar planetary system known to have an orbiting Jupiter mass planet from radial velocity measurements. The star has been observed with a 10'' Meade Schmidt-Newtonian LXD 55 telescope and a thermo-electrically cooled Nikon Coolpix 995 CCD. I detect two full transits at projected transit times defined by radial velocity measurements. An accuracy of +/- 0.01 stellar magnitudes has been achieved using the equipment described. The primary data analysis procedure used in the determination of stellar magnitude is differential aperture photometry. Also presented are derived values for the diameter of the extra-solar planetary disk. The photometric dimming observed, attributed to the transit of a planet across the stellar disk, is consistent with past photometric measurements made by considerably large observatories (Hubble, Keck I) and provides one of the first small aperture extra-solar planetary detections to date. Sponsored in part by a grant from the Southern California Academy of Sciences and cooperation from Meade Instruments Inc

  5. 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 understanding of planetary atmospheres. Ultimately, we may be able to answer these profound questions: Are we alone in the universe? What makes a planet habitable? How does life originate? And what is the destiny for life on our own planet?

  6. Space Science I: Planetary Atmospheres

    E-print Network

    Johnson, Robert E.

    . It is also clear now that the earth's atmosphere is changing and has changed. In fact it is abundantly clear to Saturn 6th Planet 2nd largest Radius ~10 x Earth's Mass ~100 x Earth's >40 Moons * #12;#12;Another View of Surfaces of Icy Satellites Hyperion 25 Rs Enceladus 4 Rs Dione 6 Rs Rs = 1 Saturn Radius: 60,300km #12

  7. 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].

  8. 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.

  9. Studies of extended planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hunten, Donald M.

    1988-01-01

    Spectroscopic observations of gases and plasmas in the Jupiter system, and related phenomena such as the recently-discovered sodium atmospheres of Mercury and the Moon were made. Cunningham's work on Jupiter spectroscopy is complete. The optical thickness of the ammonia cloud increases from about 3 in the morning to 6 at sunset. This effect seems to be due to the combination of internal heat flow and a convective region heated at the top, giving strong convection at night and none during the day. Near-simultaneous methane data are of poor quality, but are consistent with this picture. Schneider's work on the sodium environment of Io is also complete. The eclipse data extend to nearly 10 Io radii and nicely match the densities in the outer regions (to 100 Io radii) obtained from the intensity scattered in the D lines. Other data show very fast jets of sodium (up to 100 km/sec), frequently tilted out of the orbital plane. Researchers seem to be seeing neutralized ions, not from the torus itself but from atmospheric sodium ionized and then quickly neutralized. The data set on Mercurian sodium has been augmented, and supplemented by IR reflectance spectra.

  10. 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.

  11. 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.

  12. Planetary, Atmospheric, and Environmental Applications of Physics Frank Mills

    E-print Network

    Chen, Ying

    Planetary, Atmospheric, and Environmental Applications of Physics Frank Mills Atomic and Molecular Chemistry and dynamics of the Venus middle atmosphere Present chemistry and chemical evolution of Venus'mesosphere Photochemistry of the middle atmospheres of Venus and the Earth Isotopic fractionation in planetary atmospheres

  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. Thorium Abundances in Solar Twins and Analogs: Implications for the Habitability of Extrasolar Planetary Systems

    NASA Astrophysics Data System (ADS)

    Unterborn, Cayman T.; Johnson, Jennifer A.; Panero, Wendy R.

    2015-06-01

    We present the first investigation of Th abundances in solar twins and analogues to understand the possible range of this radioactive element and its effect on rocky planet interior dynamics and potential habitability. The abundances of the radioactive elements Th and U are key components of a planet’s energy budget, making up 30%-50% of the Earth’s. Radiogenic heat drives interior mantle convection and surface plate tectonics, which sustains a deep carbon and water cycle and thereby aides in creating Earth’s habitable surface. Unlike other heat sources that are dependent on the planet’s specific formation history, the radiogenic heat budget is directly related to the mantle concentration of these nuclides. As a refractory element, the stellar abundance of Th is faithfully reflected in the terrestrial planet’s concentration. We find that log {{? }Th} varies from 59% to 251% that of solar, suggesting extrasolar planetary systems may possess a greater energy budget with which to support surface to interior dynamics and thus increase their likelihood to be habitable compared to our solar system.

  15. 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.

  16. 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.

  17. Models of Polarized Light from Oceans and Atmospheres of Earth-like Extrasolar Planets

    E-print Network

    P. R. McCullough

    2006-10-17

    Specularly reflected light, or glint, from an ocean surface may provide a useful observational tool for studying extrasolar terrestrial planets. Detection of sea-surface glints would differentiate ocean-bearing terrestrial planets, i.e. those similar to Earth, from other terrestrial extrasolar planets. The brightness and degree of polarization of both sea-surface glints and atmospheric Rayleigh scattering are strong functions of the phase angle of the extrasolar planet. We modify analytic expressions for the bi-directional reflectances previously validated by satellite imagery of the Earth to account for the fractional linear polarization of sea-surface reflections and of Rayleigh scattering in the atmosphere. We compare our models with Earth's total visual light and degree of linear polarization as observed in the ashen light of the Moon, or Earthshine. We predict the spatially-integrated reflected light and its degree of polarization as functions of the diurnal cycle and orbital phase of Earth and Earth-like planets of various imagined types. The difference in polarized reflectances of Earth-like planets may increase greatly the detectability of such planets in the glare of their host star. Finally, sea-surface glints potentially may provide a practical means to map the boundaries between oceans and continents on extrasolar planets.

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

    PubMed

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

    2009-09-01

    On Earth, photosynthetic organisms are responsible for the production of virtually all the oxygen in the atmosphere. On land, vegetation reflects in the visible and leads to a "red edge," which developed about 450 million years ago on Earth and has been proposed as a biosignature for life on extrasolar planets. However, in many regions on Earth, particularly where surface conditions are extreme--in hot and cold deserts, for example--photosynthetic organisms can be driven into and under substrates where light is still sufficient for photosynthesis. These communities exhibit no detectable surface spectral signature to indicate life. The same is true of the assemblages of photosynthetic organisms at more than a few meters' depth in water bodies. These communities are widespread and dominate local photosynthetic productivity. We review known cryptic photosynthetic communities and their productivity. We have linked geomicrobiology with observational astronomy by calculating the disk-averaged spectra of cryptic habitats and identifying detectable features on an exoplanet dominated by such a biota. The hypothetical cryptic photosynthesis worlds discussed here are Earth analogues that show detectable atmospheric biosignatures like our own planet but do not exhibit a discernable biological surface feature in the disc-averaged spectrum. PMID:19778274

  19. Undergraduate Astronomy Laboratory Software: Planetary Atmosphere Evolution

    NASA Astrophysics Data System (ADS)

    Luttermoser, D. G.

    1999-12-01

    A computer simulation software package has been developed to evolve planetary atmospheres from their formation through whatever time period the user inputs. Required initial inputs are the spectral class of the star (main sequence stars are assumed) and its chemical abundance, the distance that the planet is from the star, along with the radius, mass, and albedo of the planet. Characteristics of the Earth and Sun are loaded as defaults upon start-up. Once the input is complete, the user clicks on the ``EVOLVE'' button to start the calculations. As the calculations progress, a bar chart shows the relative abundance of important molecules (eg., H2, CO2, etc.) and the thickness of the atmosphere is continually updated. Should conditions warrant, a box will indicate if lifeforms have come into existence. The user can ``PAUSE'' the evolution at any time through the maximum inputed time. The goal of this program is to teach students that the structure of planetary atmospheres result from their initial conditions, change over time, and that the formation of life is a natural occurrence without need for magic. Two versions of this software exist, one written in Visual Basic and the other in IDL. Both will be freely available off of the Web at http://www.etsu.edu/physics/.

  20. 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.

  1. 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.

  2. Search for Double Transit Extrasolar Planetary Systems: Another Transiting Planet Around OGLE-TR-111 or a False Positive Detection?

    E-print Network

    Dante Minniti

    2005-01-20

    The search for double transit planetary systems opens new possibilities for the transit searches and for studies of orbital stability, stellar irradiation, and migration scenarios, among others. We explore the OGLE lightcurves of stars with confirmed planetary companions (OGLE-TR-10, OGLE-TR-56, OGLE-TR-111, OGLE-TR-113, and OGLE-TR-132), searching for additional transits. The most promising candidate is OGLE-TR-111, where the photometric measurements and the radial velocities are consistent with the presence of a second planet. If confirmed, OGLE-TR-111 would be the first extrasolar planetary system detected by transits. The parameters of the possible new planet OGLE-TR-111c would be: period P = 16.0644 d, semimajor axis a = 0.12 AU, orbital inclination i = 88-89 deg, mass M = 0.7 M_J, radius R = 0.85 R_J, density \\rho = 1.4 g/cm^3. If confirmed, OGLE-TR-111c would be the smallest and densest extrasolar planet measured todate, truly a Jovian planet, with properties intermediate between Jupiter and Saturn, albeit with shorter period. Additional photometric and spectroscopic data would allow to discriminate between a second transiting planet around OGLE-TR-111 and a false positive detection.

  3. 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.

  4. 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.

  5. 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.

  6. 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 on O2 diffusion to evolve to mm size. pO2 in the range ~10^3-10^4 Pa is needed to exceed the threshold of cm size for complex life with circulatory physiology. The timescale to reach pO2 ~10^4 Pa, or "oxygenation time", was long on the Earth (~3.9 billion years), within almost a factor of two of the Sun's main sequence lifetime. The oxygenation time could preclude complex life on rocky planets with prodigious reducing volatiles orbiting stars that end their main sequence lives before planetary oxygenation takes place. Conversely, Earth-like planets orbiting long-lived stars are potentially favorable places for complex life.

  7. 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.

  8. 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

  9. Extrasolar planets

    PubMed Central

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

    2000-01-01

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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

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

    PubMed

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

    2007-12-01

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

  15. 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.

  16. 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.

  17. Identification of Absorption Features in an Extrasolar Planet Atmosphere

    E-print Network

    T. S. Barman

    2007-04-09

    Water absorption is identified in the atmosphere of HD209458b by comparing models for the planet's transmitted spectrum to recent, multi-wavelength, eclipse-depth measurements (from 0.3 to 1 microns) published by Knutson et al. (2007). A cloud-free model which includes solar abundances, rainout of condensates, and photoionization of sodium and potassium is in good agreement with the entire set of eclipse-depth measurements from the ultraviolet to near-infrared. Constraints are placed on condensate removal by gravitational settling, the bulk metallicity, and the redistribution of absorbed stellar flux. Comparisons are also made to the Charbonneau et al. (2002) sodium measurements.

  18. Identification of Absorption Features in an Extrasolar Planet Atmosphere

    E-print Network

    Barman, T S

    2007-01-01

    Water absorption is identified in the atmosphere of HD209458b by comparing models for the planet's transmitted spectrum to recent, multi-wavelength, eclipse-depth measurements (from 0.3 to 1 microns) published by Knutson et al. (2007). A cloud-free model which includes solar abundances, rainout of condensates, and photoionization of sodium and potassium is in good agreement with the entire set of eclipse-depth measurements from the ultraviolet to near-infrared. Constraints are placed on condensate removal by gravitational settling, the bulk metallicity, and the redistribution of absorbed stellar flux. Comparisons are also made to the Charbonneau et al. (2002) sodium measurements.

  19. Clouds in the atmospheres of extrasolar planets. IV. On the scattering greenhouse effect of CO2 ice particles: Numerical radiative transfer studies

    E-print Network

    Kitzmann, D; Rauer, H

    2013-01-01

    Owing to their wavelengths dependent absorption and scattering properties, clouds have a strong impact on the climate of planetary atmospheres. Especially, the potential greenhouse effect of CO2 ice clouds in the atmospheres of terrestrial extrasolar planets is of particular interest because it might influence the position and thus the extension of the outer boundary of the classic habitable zone around main sequence stars. We study the radiative effects of CO2 ice particles obtained by different numerical treatments to solve the radiative transfer equation. The comparison between the results of a high-order discrete ordinate method and simpler two-stream approaches reveals large deviations in terms of a potential scattering efficiency of the greenhouse effect. The two-stream methods overestimate the transmitted and reflected radiation, thereby yielding a higher scattering greenhouse effect. For the particular case of a cool M-type dwarf the CO2 ice particles show no strong effective scattering greenhouse eff...

  20. 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.

  1. Understanding other worlds: NASA's missions to find and characterize extrasolar planetary systems

    NASA Technical Reports Server (NTRS)

    Unwin, Stephen C.

    2005-01-01

    About 150 extrasolar planets, mostly much more massive the Earth, are now known from ground-based observations. Earth-mass planets are very hard, if not impossible, to detect from the ground. The study of planets like our own Earth, orbiting in a 'habitable zone' around their parent stars, will require a new generation of space-based instruments.

  2. 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.

  3. 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.

  4. 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.

  5. 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

    After centuries of wondering about the presence of other worlds outside our Solar System, the first extrasolar planets were discovered about fifteen years ago. Since the quest continued. The greatest discovery of our new line of research, exoplanetology, has probably been the large diversity that those new worlds have brought forward; a diversity in mass, in size, in orbital periods, as well as in the architecture of the systems we discover. Planets very different from those composing our system have been detected. As such, we found hot Jupiters, gas giants which orbital period is only of a few days, mini-Neptunes, bodies five to ten time the mass of the Earth but covered by a thick gas layer, super-Earths of similar masses but rocky, lava worlds, and more recently, maybe the first ocean planet. Many more surprises probably await us. This thesis has for subject this very particular planet class: the hot Jupiters. Those astonishing worlds are still badly understood. Yet, thanks to the evolution of observational techniques and of the treatment of their signals, we probably have gathered as much knowledge from these worlds, than what was known of our own gas giants prior to their visit by probes. They are laboratories for a series of intense physical phenomena caused by their proximity to their star. Notably, these planets are found in average much larger than expected. In addition to these curiosities, their presence so close to their star is abnormal, the necessary conditions for the formation of such massive bodies, this close, not being plausible. Thus it is more reasonable to explain their current orbits by a formation far from their star, followed by an orbital migration. It is on this last subject that this thesis is on: the origin of hot Jupiters. The laws of physics are universal. Therefore, using the same physical phenomena, we need to explain the existence of hot Jupiters, while explaining why the Jupiter within our Solar System is found five times the 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 the formation of planets from matter spread in the form of a primordial disc around the Sun; such

  6. 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 3?. Future observations are needed to further constrain the abundances in order to definitively identify disequilibrium in exoplanet atmospheres.

  7. PLANETARY ATMOSPHERES Winter 2003 (ATMS 555/ASTR 555, ESS 581)

    E-print Network

    Catling, David C.

    . Thermal balance. Greenhouse effect. Runaway greenhouse effect (early Venus, future Earth?). Radiative timePLANETARY ATMOSPHERES Winter 2003 (ATMS 555/ASTR 555, ESS 581) Instructor: David Catling Office will fall behind or get ahead as needed. 1. Atmospheric Structure on the Planets: The static structure (Wks

  8. 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

  9. 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 ? (atmospheric thickness), ? (rotation rate) and ? (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 ? 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 ? is sufficiently large (as for the four examples in the solar system), or if the rotation rate ? is sufficiently small. The model indicates, however, that the dynamical constraint does influence the MEP state when ? 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

  10. 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.

  11. 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.

  12. 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.

  13. 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)

  14. 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.

  15. 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.

  16. PLANETARY ATMOSPHERES Jupiter and the Outer Planets

    E-print Network

    a nitrogen atmosphere with a surface density four times that of Earth's, a global smog layer that hides­west) jets with speeds that exceed those of Earth's atmosphere. Titan, the largest moon of Saturn, has and chemical processes as Earth's atmosphere but, because of differing compositions, gravities, lower boundary

  17. 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.

  18. PICTURE: a sounding rocket experiment for direct imaging of an extrasolar planetary environment

    E-print Network

    Bifano, Thomas

    in developing this complex payload and our technical approaches. Keywords: exoplanets, exozodiacal dust, debris disks, nulling interferometer, fine pointing, wavefront control, high-contrast imaging 1. INTRODUCTION imaging of exozodiacal dust. The dust pervades the planetary habitat, thermally emitting in the infrared

  19. Comparative Planetary Atmospheric Responses to Auroral Precipitation

    NASA Astrophysics Data System (ADS)

    Tao, C.; Badman, S. V.; Fujimoto, M.

    2012-09-01

    We will review planetary-comparative multiwavelength auroral studies including our modeling approach. We test the UV emission rates from H2 and fundamental line IR emission from H3 + as functions of exospheric temperature, auroral electron energy and flux. The differences between Jupiter and Saturn emissions can be explained by the different temperatures and the possible existence of H20 in Saturn's auroral ionosphere.

  20. 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' atmosphere were derived. The demonstration of the capability of PRIDE as a radio science instrument for planetary atmospheric studies is developed in the framework of the upcoming ESA's JUICE mission to study Jupiter's system.

  1. 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.

  2. Evaporation of extrasolar planets

    E-print Network

    David Ehrenreich

    2008-07-11

    Atomic hydrogen escaping from the extrasolar giant planet HD209458b provides the largest observational signature ever detected for an extrasolar planet atmosphere. In fact, the upper atmosphere of this planet is evaporating. Observational evidences and interpretations coming from various models are reviewed. Implications for exoplanetology are discussed.

  3. Saturn's rotation period from its atmospheric planetary-wave configuration

    E-print Network

    Read, Peter L.

    LETTERS Saturn's rotation period from its atmospheric planetary-wave configuration P. L. Read1 , T III reference frame) is commonly used to infer its bulk rotation1 . Saturn's dipole magnetic field s measured 28 years ago by Voyager2 . Here we report a determination of Saturn's rotation period based

  4. Department of Earth, Atmospheric, & Planetary Sciences Geology and Geophysics Major

    E-print Network

    Gabrielov, Andrei

    Credits 5th Semester 6th Semester (3) EAS 35300 (Surface Processes) (3) EAS 35400 (Plate Tectonics) (3Department of Earth, Atmospheric, & Planetary Sciences Geology and Geophysics Major Requirements 1 Exploring Earth through Time (4) Second Science Lab sequencec , Part 1 (4) Second Science Lab sequence, Part

  5. 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 a runaway greenhouse state. PMID:22869797

  6. Asteroid observations and planetary atmospheres analysis

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    Photoelectric observations of Eros and 30 other asteroids providing information on their surface characteristics, shape, and rotation axes are reported. Photographs of 18 asteroids and 4 comets yielding accurate position information on various dates were obtained. Photometric observations were made of the Saturn satellite lapetus, and electronographic images of the Uranus and Neptune satellites were obtained experimentally with a Spectracon tube to assess photometry by that method. Planetary patrol photographs of Venus and deconvolved area scans of Uranus were taken. UBV photometry of the Galilean satellites for the period 1973-1974 was completely analyzed and accepted for publication. An improved magnitude and color index for Minas were derived from 1974 area scans. A special photomultiplier tube with a suppressor grid was incorporated into a pulse-counting photometer with special added circuitry for carrying out the observations concerning the constancy of solar system dimensions over cosmic time.

  7. 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 resonant Kuiper belt objects by a migrating Neptune remains effective if the bulk of the primordial disk was locked in bodies having sizes [Special characters omitted.] km and if the fraction of disk mass in objects with sizes [Special characters omitted.] 1000 km was less than a few percent. Coagulation simulations produce a size distribution of primordial planetesimals that easily satisfies these constraints. We conclude that stochasticity did not interfere with Neptune's ability to capture and retain KBOs in first-order resonances during its migration. (3) Photoionization heating from UV radiation incident on the atmospheres of hot Jupiters drives planetary mass loss. Observations of stellar Lyman- a absorption at high velocities (±100 km s -1 ) have suggested that the hot Jupiter HD 209458b is losing atomic hydrogen. We show that mass loss takes the form of a hydrodynamic ("Parker") wind, emitted either from the planet's dayside during lulls in the stellar wind, or from the nightside when heat is transported there by horizontal flows. A hot Jupiter loses at most ~0.06% of its mass during its host star's pre-main-sequence phase and ~0.6% of its mass during the star's main sequence lifetime. At no stage do planetary winds reach velocities of ±100 km s -1 . We conclude that while UV radiation does indeed drive winds from hot Jupiters, such winds cannot significantly alter planet ary masses during any evolutionary stage, nor can they generate the observed decrements in Lya flux in HD 209458b.

  8. Tectonic implications of radiogenic noble gases in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Turcotte, D. L.; Schubert, G.

    1988-01-01

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

  9. 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 mechanisms driving the circulation in the simulated planets. From the 3D numerical simulations we found that some hot-Jupiters atmospheres can sustain multiple dynamical steady states. The results also suggest the presence of a new mechanism that transports heat from the upper to the lower atmosphere. The presence and impact of this mechanism in the global temperature will be discussed in this presentation.

  10. 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 used to constrain electrodynamics in the future.

  11. Electrodynamics on Extrasolar Giant Planets

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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 used to constrain electrodynamics in the future.

  12. 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?

  13. PICTURE: a sounding rocket experiment for direct imaging of an extrasolar planetary environment

    NASA Astrophysics Data System (ADS)

    Mendillo, Christopher B.; Hicks, Brian A.; Cook, Timothy A.; Bifano, Thomas G.; Content, David A.; Lane, Benjamin F.; Levine, B. Martin; Rabin, Douglas; Rao, Shanti R.; Samuele, Rocco; Schmidtlin, Edouard; Shao, Michael; Wallace, J. Kent; Chakrabarti, Supriya

    2012-09-01

    The Planetary Imaging Concept Testbed Using a Rocket Experiment (PICTURE 36.225 UG) was designed to directly image the exozodiacal dust disk of ? Eridani (K2V, 3.22 pc) down to an inner radius of 1.5 AU. PICTURE carried four key enabling technologies on board a NASA sounding rocket at 4:25 MDT on October 8th, 2011: a 0.5 m light-weight primary mirror (4.5 kg), a visible nulling coronagraph (VNC) (600-750 nm), a 32x32 element MEMS deformable mirror and a milliarcsecond-class fine pointing system. Unfortunately, due to a telemetry failure, the PICTURE mission did not achieve scientific success. Nonetheless, this flight validated the flight-worthiness of the lightweight primary and the VNC. The fine pointing system, a key requirement for future planet-imaging missions, demonstrated 5.1 mas RMS in-flight pointing stability. We describe the experiment, its subsystems and flight results. We outline the challenges we faced in developing this complex payload and our technical approaches.

  14. 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.

  15. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2002-07-01

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

  17. 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.

  18. Interdisciplinary Science Concentration in Earth, Atmospheric, and Planetary Sciences College of Science SCI-INTRD-BS

    E-print Network

    Kihara, Daisuke

    Interdisciplinary Science ­ Concentration in Earth, Atmospheric, and Planetary Sciences College For Biology or STAT 51100 Statistical Methods Required Earth, Atmospheric, and Planetary Sciences Primary Area of Atmospheric Science or EAPS 22500 Science of The Atmosphere (3) EAPS 11200 Earth Through Time or any EAPS

  19. Preparing EChO space mission: laboratory simulation of planetary atmospheres

    E-print Network

    Micela, Giusi

    Preparing EChO space mission: laboratory simulation of planetary atmospheres Riccardo U. Claudi *a the optical characteristics of gases in the typical physical conditions of the planetary atmospheres and how and biological one. Insights in this direction can be achieved from laboratory studies of simulated planetary

  20. Noise propagation in the atmosphere's surface and planetary boundary layers

    SciTech Connect

    Thomson, D.W.

    1982-01-01

    Interest in the characteristics of atmospheric sound propagation has recently been renewed as a consequence of publicity regarding the sound emitted by some types of wind turbine generators. Although traditionally studies in meteorological acoustics have most frequently been concerned with analysis of the refractive effects of the stratosphere, since about 1968 as a result of the development of sodar systems for indirect atmospheric probing, substantial knowledge regarding the propagation and scattering of audible frequency sound in the lower atmosphere also has been accumulated. There have been, however, only a few studies concerned with the dependence of refractive sound propagation on the temporally and spatially variable conditions in the atmosphere's planetary boundary layer (PBL). The structure of the PBL whose depth can easily vary from 200 to 2000 m in the course of a day is strongly dependent upon not only the ambient general meteorological conditions but also details of the underlying surface (e.g., topography and land use).

  1. 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' atmosphere nor the atmospheric escape of HD 209458 b.

  2. Atmospheric and Surface Contributions to Planetary Albedo AARON DONOHOE AND DAVID S. BATTISTI

    E-print Network

    Battisti, David

    Atmospheric and Surface Contributions to Planetary Albedo AARON DONOHOE AND DAVID S. BATTISTI Department of Atmospheric Sciences, University of Washington, Seattle, Washington (Manuscript received 28 due to atmospheric reflection and a component due to surface reflection by using shortwave fluxes

  3. 10.13 Planetary Atmospheres DC Catling, University of Washington, Seattle, WA, USA

    E-print Network

    Winglee, Robert M.

    978-0-444-53802-4.00185-8 429 Treatise on Geophysics, 2nd edition, (2015), vol. 10, pp. 429 of planetary atmospheres ranges from the origin of atmospheres to the fluid dynamics of small weather systems-472 Catling, D.C. (2015) Planetary atmospheres, in G. Schubert (ed.) Treatise on Geophysics, 2nd Ed., vol. 10

  4. 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).

  5. A Spectrum of an Extrasolar Planet

    E-print Network

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

    2007-02-20

    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 micron) of the transiting extrasolar planet HD209458b. Our observations reveal a hot thermal continuum for the planetary spectrum, with approximately constant ratio to the stellar flux over this wavelength range. Superposed on this continuum is a broad emission peak centered near 9.65 micron that we attribute to emission by silicate clouds. We also find a narrow, unidentified emission feature at 7.78 micron. Models of these ``hot Jupiter'' planets predict a flux peak near 10 micron, where thermal emission from the deep atmosphere emerges relatively unimpeded by water absorption, but models dominated by water fit the observed spectrum poorly.

  6. 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.

  7. 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.

  8. Could We Detect Molecular Oxygen in the Atmosphere of a Transiting Extra-Solar Earth-Like Planet?

    E-print Network

    John K. Webb; Imma Wormleaton

    2001-10-14

    Although the extra-solar planets discovered so far are of the giant, gaseous, type, the increased sensitivity of future surveys will result in the discovery of lower mass planets. The detection of O2 in the atmosphere of a rocky extra-solar planet would be a potential indicator of a life. In this paper we address the specific issue of whether we would be able to detect the O2 A-band absorption feature in the atmosphere of a planet similar to the Earth, if it were in orbit around a nearby star. Our method is empirical, in that we use observations of the Earth's O2 A-band, with a simple geometric modification for a transiting extra-solar planet, allowing for limb-darkening of the host star. We simulate the spectrum of the host star with the superposed O2 A-band absorption of the transiting planet, assuming a spectral resolution of 7 km/s (typical of current echelle spectrographs), for a range of spectral signal-to-noise ratios. The main result is that we could reliably detect the O2 A-band of the transiting planet for host stars with radii 0.3 solar or less. However, using existing instrumentation and 8m telescopes, this requires target M stars with m(V) of approximately 10 or brighter for integration times of about 10 hours or less. The number of such stars over the sky is small. Larger aperture telescopes and/or improved instrumentation efficiency would enable surveys of M stars down to m(V) = 13 and greatly improve the chances of discovering life elsewhere.

  9. 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.

  10. 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.

  11. 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.

  12. A discrete forward-modeling method for characterizing occultation lightcurves of tenuous planetary atmospheres

    E-print Network

    Siu, Ho Chit

    2015-01-01

    We present a discrete numerical approach for forward-modeling lightcurves from stellar occultations by planetary atmospheres. Our discrete approach provides a way to arbitrarily set atmospheric properties at any radius ...

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

    E-print Network

    Bailey, R L; Hodos, G; Bilger, C; Stark, C R

    2013-01-01

    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 infuences 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 ionisation 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 downwards (as lightning) and upwards (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 ($10^8 -~10^{10}$m$^3$) than in a gi...

  14. Meteoric Ablation in Planetary Atmospheres and the Laboratory

    NASA Astrophysics Data System (ADS)

    Sternovsky, Z.; Robertson, S. H.; Horanyi, M.; Szalay, J.

    2013-12-01

    The chemistry and energetics of all planetary atmospheres are influenced by the influx of interplanetary dust particles and the layers of material deposited through ablation. Even for the well-monitored terrestrial atmosphere, the amount of the incoming cosmic material remains uncertain. Radar and lidar systems make valuable measurements of the incoming particles and the atomic and ion layers, as well as the particulate remnants. However, the measurement methods are biased due to the wide ranges of mass, velocity and composition of the incoming material. Further ambiguity is introduced through the uncertainty of some of the ablation parameters, e.g., the ionization probability. Laboratory measurements can be used to benchmark the ablation of different materials over a wide range of speeds. In this talk, we give and overview of the state of the art ablation models and the applicability of laboratory measurements to verify these models and how fundamental quantities can be measured, including ionization and luminous efficiencies. There are upcoming mission to Mars (MAVEN) and Pluto (New Horizons) that are expected to return data on the distribution of the ablated material and the effect on their atmospheres. These data could potentially be used to further constrain the ablation processes and the parameters used.

  15. 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.

  16. 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 authors acknowledge ideas and advice from the participants in the "Planetary Magnetic Fields: Planetary Interiors and Habitability" workshop organized by the Keck Institute for Space Studies. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA.

  17. NUV radii of the extrasolar planet HD 209458b

    E-print Network

    J. M. Desert; A. Vidal-Madjar; A. Lecavelier des Etangs; G. Hebrard; R. Ferlet

    2008-10-29

    Extrasolar planetary transits are powerful tools to probe their atmosphere and to extract key physical properties of planets, like their mean densities, chemical compositions, or atmospheric structures. Every 3.5 days, the transits of the gaseous planet orbiting HD209458 offer the opportunity to investigate the spectral features of its atmosphere. We present here NUV transmission spectroscopy of the transiting extrasolar planet HD209458b using HST/ACS. We show the data analysis of the seven HST orbits which were used to observe two transits of HD209458b. Due to various remaining systematics, the radius of the planet in the NUV could not be extracted with a high precison. However, we derived a radius of Rp=1.4Rjup+/-0.08 between 2800 and 3100 AA which is consistent with previous measurements in the visible.

  18. Extrasolar Planet Orbits and Eccentricities

    E-print Network

    Scott Tremaine; Nadia L. Zakamska

    2003-12-01

    The known extrasolar planets exhibit many interesting and surprising features--extremely short-period orbits, high-eccentricity orbits, mean-motion and secular resonances, etc.--and have dramatically expanded our appreciation of the diversity of possible planetary systems. In this review we summarize the orbital properties of extrasolar planets. One of the most remarkable features of extrasolar planets is their high eccentricities, far larger than seen in the solar system. We review theoretical explanations for large eccentricities and point out the successes and shortcomings of existing theories.

  19. 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

  20. Equilibration of a baroclinic planetary atmosphere in the limit of1 vanishing bottom friction2

    E-print Network

    Vallis, Geoff

    Equilibration of a baroclinic planetary atmosphere in the limit of1 vanishing bottom friction2 J C 3 Atmospheric and Oceanic Sciences Program, Princeton University, Princeton, NJ, USA4 M J5 of Mathematics, University of Exeter, Exeter, UK8 Corresponding author address: Junyi Chai, Atmospheric

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

    NASA Technical Reports Server (NTRS)

    Khare, B. N.; Sagan, C.

    1973-01-01

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

  2. 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 large-scale, seasonal phenomena observed on Earth and Mars. In the Titan-like regime the seasonal cycle in our model acts to prevent superrotation from developing, and it is necessary to increase the value of a third parameter—the atmospheric Newtonian cooling time—to achieve a superrotating climatology.

  3. 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.

  4. 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.

  5. 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.

  6. Ionization in atmospheres of Brown Dwarfs and extrasolar planets IV. The Effect of Cosmic Rays

    E-print Network

    Rimmer, Paul

    2013-01-01

    Cosmic rays provide an important source for free electrons in the 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 1 MeV < E < 1 GeV, and an analytic cosmic ray transport model for particle energies of 1 GeV < E < 1 TeV in order to investigate the cosmic ray enhancement of free electrons in substellar atmospheres of free-floating objects. The cosmic ray calculations are applied to Drift-Phoenix model atmospheres of an example brown dwarf with effective temperature Teff = 1500 K, and two example giant gas planets (Teff = 1000 K, 1500 K). For the model brown dwarf atmosphere, the electron fraction is enhanced significantly by cosmic rays when the pressure pgas < 10^-2 bar. Our example giant gas planet atmosphere suggests that the cosmic ray enhancement extends to 10^-4 - 10^-2 bar, depending on the effective temperature. For the model atmosphere of the examp...

  7. 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.

  8. 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.

  9. PAUL WITHERS NRC/NASA/ALLISON -PAGE Winds in Planetary Atmospheres

    E-print Network

    Withers, Paul

    PAUL WITHERS ­ NRC/NASA/ALLISON - PAGE Winds in Planetary Atmospheres Introduction: The basic circulation of an atmosphere is defined by its pressure, temperature, and wind fields [Holton, 1992]. Pressure of this radiative transfer process. [Chamberlain and Hunten, 1987]. Winds have very little effect on electromagnetic

  10. 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.

  11. 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

  12. 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

  13. 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 thermal ionization.

  14. The Dawes Review 3: The Atmospheres of Extrasolar Planets and Brown Dwarfs

    NASA Astrophysics Data System (ADS)

    Bailey, Jeremy

    2014-11-01

    The last few years has seen a dramatic increase in the number of exoplanets known and in the range of methods for characterising their atmospheric properties. At the same time, new discoveries of increasingly cooler brown dwarfs have pushed down their temperature range which now extends down to Y-dwarfs of < 300 K. Modelling of these atmospheres has required the development of new techniques to deal with the molecular chemistry and clouds in these objects. The atmospheres of brown dwarfs are relatively well understood, but some problems remain, in particular the behavior of clouds at the L/T transition. Observational data for exoplanet atmosphere characterisation is largely limited to giant exoplanets that are hot because they are near to their star (hot Jupiters) or because they are young and still cooling. For these planets there is good evidence for the presence of CO and H2O absorptions in the IR. Sodium absorption is observed in a number of objects. Reflected light measurements show that some giant exoplanets are very dark, indicating a cloud free atmosphere. However, there is also good evidence for clouds and haze in some other planets. It is also well established that some highly irradiated planets have inflated radii, though the mechanism for this inflation is not yet clear. Some other issues in the composition and structure of giant exoplanet atmospheres such as the occurrence of inverted temperature structures, the presence or absence of CO2 and CH4, and the occurrence of high C/O ratios are still the subject of investigation and debate.

  15. 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 ?2-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://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/575/A119

  16. Ionization in Atmospheres of Brown Dwarfs and Extrasolar Planets V: Alfv\\'{e}n Ionization

    E-print Network

    Stark, Craig R; Diver, Declan A; Rimmer, Paul B

    2013-01-01

    Observations of continuous radio and sporadic X-ray emission from low-mass objects suggest they harbour 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 Alfv\\'{e}n ionization as a mechanism for producing localized pockets of ionized gas in the atmosphere, having sufficient degrees of ionization ($\\geq10^{-7}$) that they constitute plasmas. We outline the criteria required for Alfv\\'{e}n ionization and demonstrate it's applicability in the atmospheres of low-mass objects such as giant gas planets, brown dwarfs and M-dwarfs for both solar and sub-solar metallicities. We find that Alfv\\'{e}n 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 neut...

  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 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).

  19. Microlensing Extrasolar Planets

    E-print Network

    Gaudi, B. Scott

    Microlensing Searches for Extrasolar Planets Microlensing Searches for Extrasolar Planets Microlensing Searches for Extrasolar Planets, B. Scott Gaudi, IAS Scientific Frontiers in Research on Extrasolar Planets, June 19, 2002 #12;Microlensing and PlanetsMicrolensing and Planets Microlensing Searches

  20. 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.

  1. Planetary Atmospheres Earth and the Other Terrestrial Worlds

    E-print Network

    Crenshaw, Michael

    of molecular nitrogen (N2 - 78%) and oxygen (O2 - 21%) Atmospheric Pressure Gas pressure depends on both increases the pressure. #12;2 Atmospheric Pressure · Pressure and density decrease with altitude because of Atmospheres · Create pressure that determines whether liquid water can exist on surface · Absorb and scatter

  2. 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.

  3. Evaporation of extrasolar planets

    E-print Network

    Etangs, A Lecavelier des

    2012-01-01

    This article presents a review on the observations and theoretical modeling of the evaporation of extrasolar planets. The observations and the resulting constraints on the upper atmosphere (thermosphere and exosphere) of the "hot-Jupiters". are described. The early observations of the first discovered transiting extrasolar planet, HD209458b, allowed the discovery that this planet has an extended atmosphere of escaping hydrogen. Subsequent observations showed the presence of oxygen and carbon at very high altitude. These observations give unique constraints on the escape rate and mechanism in the atmosphere of hot-Jupiters. The most recent Lyman-alpha HST observations of HD189733b and MgII observations of Wasp-12b allow for the first time comparison of the evaporation from different planets in different environments. Models to quantify the escape rate from the measured occultation depths, and an energy diagram to describe the evaporation state of hot-Jupiters are presented. Using this diagram, it is shown that...

  4. On detecting biospheres from thermodynamic disequilibrium in planetary atmospheres

    E-print Network

    Krissansen-Totton, Joshua; Catling, David C

    2015-01-01

    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 the atmospheres of Solar System planets, in which we quantify the difference in Gibbs free energy of an observed atmosphere compared to that of all the atmospheric gases reacted to equilibrium. The purely gas phase disequilibrium in Earth's atmosphere, as measured by this available Gibbs free energy, is not unusual by Solar System standards and smaller than that of Mars. However, Earth's atmosphere is in contact with a surface ocean, which means that gases can react with water, and so a multiphase calculation that includes aqueous species is required. We find that the disequilibrium in Earth's atmosphere-ocean system (in joules per mole o...

  5. Extrasolar Planets & The Power of the Dark Side

    SciTech Connect

    Charbonneau, David

    2009-04-24

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

  6. 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.

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

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    2005-01-01

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

  10. Aerosol charging processes in planetary and terrestrial atmospheres

    NASA Astrophysics Data System (ADS)

    Tripathi, S.; Michael, M.

    2015-10-01

    Interactions between the ions and aerosols cause charge exchange, which can lead to substantial aerosol charge and ion removal in the atmosphere. Aerosol charging plays an important role in various processes such as aerosol scavenging by droplets and aerosol growth by affecting aerosol-aerosol coagulation rates. Ions are removed in regions with abundant aerosol, which may modify charge flow in an atmosphere, such as that associated with an atmospheric electrical circuit. A review will be made of the charging processes and the consequences occurring in atmospheres of Mars, Venus and Titan and compared with terrestrial atmosphere [1], [2], [3],[4], [5]. Some recent results on charging of aerosols in the lower and upper atmosphere of Titan will be presented and consequences will be discussed.

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

    NASA Astrophysics Data System (ADS)

    Wang, Yixiong; Read, Peter

    2014-04-01

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

  12. 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.

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

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1998-01-01

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

  14. THERMO-RESISTIVE INSTABILITY OF HOT PLANETARY ATMOSPHERES

    SciTech Connect

    Menou, Kristen

    2012-07-20

    The atmospheres of hot Jupiters and other strongly forced exoplanets are susceptible to a thermal instability in the presence of ohmic dissipation, weak magnetic drag, and strong winds. The instability occurs in radiatively dominated atmospheric regions when the ohmic dissipation rate increases with temperature faster than the radiative (cooling) rate. The instability domain covers a specific range of atmospheric pressures and temperatures, typically P {approx} 3-300 mbar and T {approx} 1500-2500 K for hot Jupiters, which makes it a candidate mechanism to explain the dayside thermal 'inversions' inferred for a number of such exoplanets. The instability is suppressed by high levels of non-thermal photoionization, in possible agreement with a recently established observational trend. We highlight several shortcomings of the instability treatment presented here. Understanding the emergence and outcome of the instability, which should result in locally hotter atmospheres with stronger levels of drag, will require global nonlinear atmospheric models with adequate MHD prescriptions.

  15. 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 Burrows et al. and conclude that fits to this planet's dayside spectrum provide a reasonably accurate estimate of the amount of energy transported to the night side. Our 3.6 and 4.5 {mu}m phase curves are generally in good agreement with the predictions of general circulation models for this planet from Showman et al., although we require either excess drag or slower rotation rates in order to match the locations of the measured maxima and minima in the 4.5, 8.0, and 24 {mu}m bands. We find that HD 189733b's 4.5 {mu}m nightside flux is 3.3{sigma} smaller than predicted by these models, which assume that the chemistry is in local thermal equilibrium. We conclude that this discrepancy is best explained by vertical mixing, which should lead to an excess of CO and correspondingly enhanced 4.5 {mu}m absorption in this region. This result is consistent with our constraints on the planet's transmission spectrum, which also suggest excess absorption in the 4.5 {mu}m band at the day-night terminator.

  16. The ultraviolet absorption spectrum of CO - Applications to planetary atmospheres

    NASA Technical Reports Server (NTRS)

    White, H. P.; Hua, Xin-Min; Caldwell, J.; Chen, F. Z.; Judge, D. L.; Wu, C. Y. R.

    1993-01-01

    Laboratory gas-phase photoabsorption cross sections of the CO Cameron 0-0 band and the underlying pseudocontinuum have been measured at a temperature of 147 K and pressures of about 200 mbar, conditions similar to ambient in various planetary and satellite stratospheres in the solar system. A theoretical modeling program has also been used to calculate the band's spectrum. Agreement between the theoretical and the experimental spectra is very good. Models suggest that the observations of the CO Cameron band using the Hubble Space Telescope will be straightforward for Mars, but marginal for Titan.

  17. 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.

  18. Can We Probe the Atmospheric Composition of an Extrasolar Planet from its Reflection Spectrum in a High-Magnification Microlensing Event?

    E-print Network

    David S. Spiegel; Michel Zamojski; Alan Gersch; Jennifer Donovan; Zoltan Haiman

    2005-06-17

    We revisit the possibility of detecting an extrasolar planet around a background star as it crosses the fold caustic of a foreground binary lens. During such an event, the planet's flux can be magnified by a factor of ~100 or more. The detectability of the planet depends strongly on the orientation of its orbit relative to the caustic. If the source star is inside the inter-caustic region, detecting the caustic-crossing planet is difficult against the magnified flux of its parent star. In the more favorable configuration, when the star is outside the inter-caustic region when the planet crosses the caustic, a close-in Jupiter-like planet around a Sun-like star at a distance of 8 kpc is detectable in 8-minute integrations with a 10m telescope at maximal S/N~15 for phase angle ~10 degrees. In this example, we find further that the presence of methane, at its measured abundance in Jupiter, and/or water, sodium and potassium, at the abundances expected in theoretical atmosphere models of close-in Jupiters, could be inferred from a non-detection of the planet in strong broad absorption bands at 0.6-1.4 microns caused by these compounds, accompanied by a S/N~10 detection in adjacent bands. We conclude that future generations of large telescopes might be able to probe the composition of the atmospheres of distant extrasolar planets.

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

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  20. Planetary Atmosphere and Surfaces Chamber (PASC): A Platform to Address Various Challenges in Astrobiology

    NASA Astrophysics Data System (ADS)

    Mateo-Marti, Eva

    2014-08-01

    The study of planetary environments of astrobiological interest has become a major challenge. Because of the obvious technical and economical limitations on in situ planetary exploration, laboratory simulations are one of the most feasible research options to make advances both in planetary science and in developing a consistent description of the origin of life. With this objective in mind, we applied vacuum technology to the design of versatile vacuum chambers devoted to the simulation of planetary atmospheres' conditions. These vacuum chambers are able to simulate atmospheres and surface temperatures representative of the majority of planetary objects, and they are especially appropriate for studying the physical, chemical and biological changes induced in a particular sample by in situ irradiation or physical parameters in a controlled environment. Vacuum chambers are a promising potential tool in several scientific and technological fields, such as engineering, chemistry, geology and biology. They also offer the possibility of discriminating between the effects of individual physical parameters and selected combinations thereof. The implementation of our vacuum chambers in combination with analytical techniques was specifically developed to make feasible the in situ physico-chemical characterization of samples. Many wide-ranging applications in astrobiology are detailed herein to provide an understanding of the potential and flexibility of these experimental systems. Instruments and engineering technology for space applications could take advantage of our environment-simulation chambers for sensor calibration. Our systems also provide the opportunity to gain a greater understanding of the chemical reactivity of molecules on surfaces under different environments, thereby leading to a greater understanding of interface processes in prebiotic chemical reactions and facilitating studies of UV photostability and photochemistry on surfaces. Furthermore, the stability and presence of certain minerals on planetary surfaces and the potential habitability of microorganisms under various planetary environmental conditions can be studied using our apparatus. Therefore, these simulation chambers can address multiple different challenging and multidisciplinary astrobiological studies.

  1. Planetary host stars: evaluating uncertainties in cool model atmospheres

    NASA Astrophysics Data System (ADS)

    Bozhinova, I.; Helling, Ch.; Scholz, A.

    2015-06-01

    M-dwarfs are emerging in the literature as promising targets for detecting low-mass, Earth-like planets. An important step in this process is to determine the stellar parameters of the M-dwarf host star as accurately as possible. Different well-tested stellar model atmosphere simulations from different groups are widely applied to undertake this task. This paper provides a comparison of different model atmosphere families to allow a better estimate of systematic errors on host-star stellar parameter introduced by the use of one specific model atmosphere family only. We present a comparison of the ATLAS9, MARCS, PHOENIX and DRIFT-PHOENIX model atmosphere families including the M-dwarf parameter space (Teff = 2500-4000 K, log(g) = 3.0-5.0, [M/H] = -2.5to0.5). We examine the differences in the (Tgas, pgas)-structures, in synthetic photometric fluxes and in colour indices. Model atmospheres results for higher log(g) deviate considerably less between different models families than those for lower log(g) for all Teff = 2500-4000 K examined. We compiled the broad-band synthetic photometric fluxes for all available model atmospheres (incl. M-dwarfs and brown dwarfs) for the UKIRT WFCAM ZYJHK, 2MASS JHKs and Johnson UBVRI filters, and calculated related colour indices. Synthetic colours in the IR wavelengths diverge by no more than 0.15 dex amongst all model families. For all spectral bands considered, model discrepancies in colour diminish for higher Teff atmosphere simulations. We notice differences in synthetic colours between all model families and observed example data (including Kepler 42 and GJ1214).

  2. Habitability of Extrasolar Moons

    NASA Astrophysics Data System (ADS)

    Heller, R.

    2014-04-01

    Most of the roughly one hundred Kepler planets and candidates in the stellar habitable zones are much larger than Earth. Though some of them may have their bulk mass in the form of rock, many of these super-Earths are reminiscent of Uranus, Neptune, or even Saturn, and they cannot have liquid surface water. Yet, their moons may be habitable. With the first detection of an extrasolar moon on the horizon, parameterization of the effects that constrain their habitability has become a new subdiscipline of planetary research. I here summarize our recent work on the effects of planetary illumination, planet-moon eclipses, tidal heating, gas giants' magnetic environments, and orbital stability on the potential of moons to maintain liquid surface water. I also present our new targeted Search for Exomoons Escorting Kepler Exoplanets (SEEKE), which favors detection of moons orbiting planets in the stellar habitable zones of M and K stars.

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

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1985-01-01

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

  4. Intercomparison of general circulation models for hot extrasolar planets

    E-print Network

    Wirosoetisno, Djoko

    Intercomparison of general circulation models for hot extrasolar planets Article Accepted Version. (2014) Intercomparison of general circulation models for hot extrasolar planets. Icarus, 229 . pp. 355 circulation models (GCMs) which have been recently used to study hot extrasolar planet atmospheres (BOB, CAM

  5. Conditions for Organic Haze Formation in Planetary Atmospheres - A Case Study in Archean Earth

    NASA Astrophysics Data System (ADS)

    Wilson, Eric; Atreya, S.

    2012-10-01

    Atmospheric haze can serve as a vital component in the prebiotic synthesis of organic compounds. In many planetary atmospheres, haze is a product of complex organic chemistry, initiated by the deposition of ultraviolet photons, forming compounds that can serve as key components in the propagation of prebiotic chemistry. Saturn’s moon, Titan, provides the prime example of the significance of haze in a planetary atmosphere in our present-day Solar System due to its intricate chemical interaction between aromatic hydrocarbons, nitrogen-bearing species, and complex ions. Titan has long been considered as an analogue for the environment possibly experienced by Archean Earth, and recent studies demonstrate that, like Titan, early Earth may have had an organically-furnished haze layer, facilitated by an enhanced ultraviolet solar flux during this period, protecting greenhouse gases and biota early in their development from harmful ultraviolet radiationi1 and allowing the Earth to maintain temperatures necessary for their development during the faint young Sun period. This primordial haze may have had a different composition than present-day Titan due to the CO2 content and possibly large amounts of H2 in prebiotic Earthi2. Furthermore, the amount of CO2 and H2 in the early terrestrial atmosphere would have had large implications in the efficiency of organic haze formation. A photochemical model employing complex neutral and ion chemistry is used to examine the mechanisms and efficiency of haze formation in a variety of conditions, focusing on sensitivity to factors such as atmospheric composition, and atmospheric temperature profile, and vertical mixing. These results can be used to assess the impact of atmospheric haze on the evolution of planetary atmospheres in our Solar System as well as viability of organic haze formation in the atmospheres of exoplanets. 1 Trainer et al., GRL, 31, L17S08, 2004. 2 Tian et al., Science 308, 1014-1017, 2005.

  6. Regarding tracer transport in Mars' winter atmosphere in the presence of nearly stationary, forced planetary waves

    NASA Technical Reports Server (NTRS)

    Hollingsworth, Jeffrey L.; Haberle, R. M.; Houben, Howard C.

    1993-01-01

    Large-scale transport of volatiles and condensates on Mars, as well as atmospheric dust, is ultimately driven by the planet's global-scale atmospheric circulation. This circulation arises in part from the so-called mean meridional (Hadley) circulation that is associated with rising/poleward motion in low latitudes and sinking/equatorward motion in middle and high latitudes. Intimately connected to the mean circulation is an eddy-driven component due to large-scale wave activity in the planet's atmosphere. During winter this wave activity arises both from traveling weather systems (i.e., barotropic and baroclinic disturbances) and from 'forced' disturbances (e.g., the thermal tides and surface-forced planetary waves). Possible contributions to the effective (net) transport circulation from forced planetary waves are investigated.

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

    NASA Astrophysics Data System (ADS)

    Rauer, H.

    2014-03-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  9. Outer satellite atmospheres: Their nature and planetary interactions

    NASA Technical Reports Server (NTRS)

    Smyth, W. H.

    1981-01-01

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

  10. Experimental characterisation of new design thermometers for planetary atmospheric measurements

    NASA Astrophysics Data System (ADS)

    Colombatti, G.; Francesconi, A.; Lion Stoppato, P. F.; De Cecco, M.; Ferri, F.; Fulchignoni, M.; Angrilli, F.

    2000-10-01

    A new design of a platinum resistance sensor has been studied for atmospheric experiments onboard a lander mission in order to measure the vertical temperature profile of the Martian atmosphere. Laboratory tests of different prototypes of platinum resistance thermometers (PRT) have been performed and the results are presented. The prototypes are derived from the HASI TEM, the temperature sensors of the Huygens probe of the Cassini/Huygens mission. To obtain an accurate estimation of the atmospheric temperature gradient, very high spatial resolution measurements are required. This means that, for a given descent profile, a high sampling frequency is needed. Studies have been carried out to improve the sensor performance; they result in new possible structural solutions. In the new design, the sensing element (Pt wire) is suspended on very thin non-metallic fibres truss, in order to thermally decouple it from the supporting structure. Several sensors have been designed and built; laboratory tests have been conducted in a wind tunnel in order to dynamically characterise the sensors. The time response has been investigated and the time constant calculated from the asymptotic trend of the sensor response to a step-wise electric power, simulating a steep temperature gradient. The measurements of the PRT have been compared to those of numerical simulations. A prototype has also flown in a balloon flight test in order to verify its performance in Earth's atmosphere. Results from post flight analysis data of the balloon flight experiment are presented; spectral analysis of the data has evidenced the larger bandwidth of the new sensor and a higher signal to noise ratio. Improvements of HASI TEM performance are shown in terms of a shorter time constant; this allows the new sensor to be able to resolve smaller temperature variations during the descent in Mars' atmosphere.

  11. When Extrasolar Planets Transit Their Parent Stars

    E-print Network

    David Charbonneau; Timothy M. Brown; Adam Burrows; Greg Laughlin

    2006-03-14

    When extrasolar planets are observed to transit their parent stars, we are granted unprecedented access to their physical properties. It is only for transiting planets that we are permitted direct estimates of the planetary masses and radii, which provide the fundamental constraints on models of their physical structure. In particular, precise determination of the radius may indicate the presence (or absence) of a core of solid material, which in turn would speak to the canonical formation model of gas accretion onto a core of ice and rock embedded in a protoplanetary disk. Furthermore, the radii of planets in close proximity to their stars are affected by tidal effects and the intense stellar radiation. As a result, some of these "hot Jupiters" are significantly larger than Jupiter in radius. Precision follow-up studies of such objects (notably with the space-based platforms of the Hubble and Spitzer Space Telescopes) have enabled direct observation of their transmission spectra and emitted radiation. These data provide the first observational constraints on atmospheric models of these extrasolar gas giants, and permit a direct comparison with the gas giants of the Solar system. Despite significant observational challenges, numerous transit surveys and quick-look radial velocity surveys are active, and promise to deliver an ever-increasing number of these precious objects. The detection of transits of short-period Neptune-sized objects, whose existence was recently uncovered by the radial-velocity surveys, is eagerly anticipated. Ultra-precise photometry enabled by upcoming space missions offers the prospect of the first detection of an extrasolar Earth-like planet in the habitable zone of its parent star, just in time for Protostars and Planets VI.

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

    NASA Technical Reports Server (NTRS)

    Woo, R.; Ishimaru, A.

    1973-01-01

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

  13. Impact-induced degassing from antigorite and carbonates: Implications to formation of planetary atmosphere

    NASA Astrophysics Data System (ADS)

    Sekine, Toshimori; Tachi, Ryunosuke; Shibuya, Koichi; Mihara, Ryouta; Kobayashi, Takamichi

    2015-06-01

    Primitive planetary atmosphere has been thought to consist mostly of H2O and CO2 of which components were present in the building blocks of planets. The degassing dymanics of these components during impacts processes is the key to understand the origin of planetary atmosphere. According to the Hugoniot measurements, antigorite and carbonates are stable as high as 40 GPa and 100 GPa, respectively. However, meteorites are porous and can be heated to high temperatures. If the residual temperatures for porous samples are high enough for them to degas, degassing can occur at or near ambient pressure. We have investigated the degassing of serpentine (antigorite) and carbonates (CaCO3 and MgCO3) by shock recovery experiments. Impact experiments on porous powders were carried out with a propellant gun and peak pressures were estimated as the equilibrium pressure as the container. Samples were investigated by XRD, TG/DTA, SEM, and TEM. The degassing from antigorite was small below 20 GPa, but became violent at 20-60 GPa, and completed at 60 GPa. The degassing from carbonates started in a narrow pressure range (35-38 GPa) and there was no evidence for the formation of MgO and CaO. The different results between antigorite and carbonates may suggest a constrain on the origin of planetary atmosphere. Atmospheric H2O can be present frequently but CO2 will be limited only in areas subjected to strong impacts.

  14. Spectropolarimetric signatures of Earth-like extrasolar planets

    E-print Network

    D. M. Stam

    2007-07-26

    We present results of numerical simulations of the flux (irradiance), F, and the degree of polarization (i.e. the ratio of polarized to total flux), P, of light that is reflected by Earth-like extrasolar planets orbiting solar-type stars, as functions of the wavelength (from 0.3 to 1.0 micron, with 0.001 micron spectral resolution) and as functions of the planetary phase angle. We use different surface coverages for our model planets, including vegetation and a Fresnel reflecting ocean, and clear and cloudy atmospheres. Our adding-doubling radiative transfer algorithm, which fully includes multiple scattering and polarization, handles horizontally homogeneous planets only; we simulate fluxes and polarization of horizontally inhomogeneous planets by weighting results for homogeneous planets. Like the flux, F, the degree of polarization, P, of the reflected starlight is shown to depend strongly on the phase angle, on the composition and structure of the planetary atmosphere, on the reflective properties of the underlying surface, and on the wavelength, in particular in wavelength regions with gaseous absorption bands. The sensitivity of P to a planet's physical properties appears to be different than that of F. Combining flux with polarization observations thus makes for a strong tool for characterizing extrasolar planets. The calculated total and polarized fluxes will be made available through the CDS.

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

    PubMed

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

    2005-10-01

    Because of their different origins, cosmic rays can be subdivided into galactic cosmic rays and solar/stellar cosmic rays. The flux of cosmic rays to planetary surfaces is mainly determined by two planetary parameters: the atmospheric density and the strength of the internal magnetic moment. If a planet exhibits an extended magnetosphere, its surface will be protected from high-energy cosmic ray particles. We show that close-in extrasolar planets in the habitable zone of M stars are synchronously rotating with their host star because of the tidal interaction. For gravitationally locked planets the rotation period is equal to the orbital period, which is much longer than the rotation period expected for planets not subject to tidal locking. This results in a relatively small magnetic moment. We found that an Earth-like extrasolar planet, tidally locked in an orbit of 0.2 AU around an M star of 0.5 solar masses, has a rotation rate of 2% of that of the Earth. This results in a magnetic moment of less than 15% of the Earth's current magnetic moment. Therefore, close-in extrasolar planets seem not to be protected by extended Earth-like magnetospheres, and cosmic rays can reach almost the whole surface area of the upper atmosphere. Primary cosmic ray particles that interact with the atmosphere generate secondary energetic particles, a so-called cosmic ray shower. Some of the secondary particles can reach the surface of terrestrial planets when the surface pressure of the atmosphere is on the order of 1 bar or less. We propose that, depending on atmospheric pressure, biological systems on the surface of Earth-like extrasolar planets at close-in orbital distances can be strongly influenced by secondary cosmic rays. PMID:16225432

  16. Microlensing search for extrasolar planets

    E-print Network

    A. Cassan; D. Kubas

    2006-12-01

    Microlensing has recently proven to be a valuable tool to search for extrasolar planets of Neptune- to super-Earth-mass planets at orbits of few AU. Since planetary signals are of very short duration, an intense and continuous monitoring is required, which is achieved by PLANET : ``Probing Lensing Anomalies NETwork''. Up to now the detection number amounts to four, one of them being OGLE 2005-BLG-390Lb, an extrasolar planet of only ~5.5 M_earth orbiting its M-dwarf host star at ~2.6 AU. For non-planetary microlensing events observed from 1995 to 2006, we compute detection efficiency diagrams which can then be used to derive an estimate of the limit on the Galactic abundance of sub-Jupiter-mass planets, as well as relative abundance of Neptune-like planets.

  17. ON THE PERIOD DISTRIBUTION OF CLOSE-IN EXTRASOLAR GIANT PLANETS B. Scott Gaudi,1

    E-print Network

    Gaudi, B. Scott

    ON THE PERIOD DISTRIBUTION OF CLOSE-IN EXTRASOLAR GIANT PLANETS B. Scott Gaudi,1 S. Seager,2) surveys for extrasolar planets have recently uncovered a population of ``very hot Jupiters,'' planets properties of extrasolar planets. This information, in turn, provides clues to the nature of planetary

  18. Planetary Entry Probes and Mass Spectroscopy: Tools and Science Results from In Situ Studies of Planetary Atmospheres and Surfaces

    NASA Technical Reports Server (NTRS)

    Niemann, Hasso B.

    2007-01-01

    Probing the atmospheres and surfaces of the planets and their moons with fast moving entry probes has been a very useful and essential technique to obtain in situ or quasi in situ scientific data (ground truth) which could not otherwise be obtained from fly by or orbiter only missions and where balloon, aircraft or lander missions are too complex and costly. Planetary entry probe missions have been conducted successfully on Venus, Mars, Jupiter and Titan after having been first demonstrated in the Earth's atmosphere. Future missions will hopefully also include more entry probe missions back to Venus and to the outer planets. 1 he success of and science returns from past missions, the need for more and better data, and a continuously advancing technology generate confidence that future missions will be even more successful with respect to science return and technical performance. I'he pioneering and tireless work of Al Seiff and his collaborators at the NASA Ames Research Center had provided convincing evidence of the value of entry probe science and how to practically implement flight missions. Even in the most recent missions involving entry probes i.e. Galileo and Cassini/Huygens A1 contributed uniquely to the science results on atmospheric structure, turbulence and temperature on Jupiter and Titan.

  19. 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.

  20. Undergraduate Atmospheric

    E-print Network

    Rothman, Daniel

    -Exploration Planetary Science-Observation Minor Programs Earth, Atmospheric, and Planetary Sciences AstronomyUndergraduate Handbook Earth, Atmospheric and Planetary Sciences #12;EAPS Undergraduate Program, atmospheric science, oceanography, climate, planetary science, and astronomy. The Department's flexible

  1. Spectrophotometry of planetary atmosphere from the X-15 rocket airplane

    NASA Technical Reports Server (NTRS)

    Murcray, W. B.

    1973-01-01

    Nike-Apache and Nike-Tomahawk rocket flights using spectrophotometric techniques to investigate auroral activity are reported. The specific objectives were to obtain data relative to typical auroral situations, including quiet pre-breakup auroras, westward traveling surges, breakup auroras, and post-breakup auroras. It was found that excited atoms move considerable distances between excitation and emission owing to the high velocity wind conditions prevailing above 200 km. Based on the results of these observations, recommendations are made for future studies of ionized atmospheric activity at higher altitudes.

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  3. Space Weather and the Evolution of Planetary Atmospheres: A Review of our Current Understanding

    NASA Astrophysics Data System (ADS)

    Nandi, Dibyendu

    The Sun’s activity varies. This variation defines what is known as space weather - the electromagnetic and particulate environment that our space-based and Earth based technologies are subject to on short-timescales. Slower (decadal and higher timescales), long-term solar variability also forces planetary atmospheres and climate. This long-term variability is causally connected to the evolution of the Sun-as-a-Star and in turn forces the evolution of planetary atmospheres. In this talk I will present our current understanding of the origins of long-term variability of the Sun and discuss the plausible impacts that this variability might have had on the evolution of solar-system space weather and planets.

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

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1986-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  6. 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. PMID:21118020

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  9. Observations of Exoplanet Atmospheres

    NASA Astrophysics Data System (ADS)

    Crossfield, Ian J. M.

    2015-11-01

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

  10. Observations of Exoplanet Atmospheres

    E-print Network

    Crossfield, Ian J M

    2015-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1988-01-01

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

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

    SciTech Connect

    Kaltenegger, L.; Sasselov, D.

    2010-01-10

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

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

    SciTech Connect

    Shematovich, Valery I.

    2008-12-31

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

  16. Exploring Links Between Orbital Dynamics and Atmospheres in Kepler M Dwarf Planetary Systems

    NASA Astrophysics Data System (ADS)

    Ballard, Sarah

    2015-12-01

    The Solar System furnishes the most familiar planetary architecture: many planets, orbiting nearly coplanar to one another. However, the most common planetary systems in the Milky Way orbit much smaller M dwarf stars, and these may present a very different blueprint. The Kepler data set has furnished more than 100 exoplanets orbiting stars half the mass of the sun and smaller. Half of these planets reside in systems with at least one additional planet. The data much prefer a model with two distinct modes of planet formation around M dwarfs, which occur in roughly equal measure. One mode is one very similar to the Solar System in terms of multiplicity and coplanarity, and the other is very dissimilar. Given this so-called "Kepler Dichotomy," we examine the broadband transmission spectra (with data from Kepler and hundreds of hours of Spitzer observations) of dozens of M dwarf planets: half of which reside in one type of planetary system, and half in the other. Although the data set is too small and the observational uncertainty too large to characterize any one system alone, we examine ensemble trends between planetary dynamics and atmospheric content.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  18. Stellar Winds and High-Energy Radiation: Evolution and influences on planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Johnstone, C.; Tu, L.; Güdel, M.; Lüftinger, T.; Lammer, H.; Kislyakova, K.; Fichtinger, B.

    2015-10-01

    As part of the Austrian research network "Pathways to Habitability: From Disks to Active Stars, Planets and Life" (path.univie.ac.at), we study the evolution of stellar output (e.g. winds, high-energy radiation) over the lifetimes of solar-like stars and the influence of stellar output on the development of habitable planetary environments. We have developed a coupled stellar rotation-wind-radiation model that describes the long term evolution of stellar output over the course of a star's life. We show that the initial rotation rate of a star can significantly influence the evolution of winds and high-energy radiation and therefore the development of planetary atmospheres.

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

    SciTech Connect

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

    2011-12-10

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

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

    NASA Astrophysics Data System (ADS)

    Gray, Samuel Augustine

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

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

    SciTech Connect

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

    2010-05-01

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

  2. The discovering of extrasolar planets

    NASA Astrophysics Data System (ADS)

    Wu, G. J.; Chen, D. H.

    2001-08-01

    In this paper, the significance, instrumentality, and the status in searching for extra-terrestrial intelligence, in addition, the SETI program and its development, are introduced. Especially, the discovery of extrasolar planets, with its purpose, ways and means, achievement, and the future, are emphasized. Finding extrasolar planets is one of the most vogue question for discussion now. It will be one of the most plenty research field in astronomy in the 21st century. Since the first affirmance of an extrasolar planetary system in pulsar PSR1257+12, and first discovery of a planet in a main-sequence star, 51 Peg, in 1995, about half hundred of extrasolar planets have been discovered. The discovery can not detach from the searching for extra-terrestrial intelligence, but it brings forward new open problems. During the past 10 years the research has been developing rapidly. Not only in astronomy, but also in other sciences, like spaceflight, astrochemistry, astrobiology, even in philosophy, it plays an advance function.

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

    NASA Technical Reports Server (NTRS)

    Sagan, C.

    1978-01-01

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

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

    SciTech Connect

    Cruikshank, D.P.

    1986-12-01

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

  5. Photochemistry simulation of planetary atmosphere using synchrotron radiation at soleil. Application to Titan's atmosphere

    NASA Astrophysics Data System (ADS)

    Gautier, T.; Peng, Z.; Giuliani, A.; Carrasco, N.; Cernogora, G.; Mahjoub, A.; Correia, J.-J.; Szopa, C.; Pernot, P.; Buch, A.; Benilan, Y.

    2012-02-01

    We report here on the coupling of a gas reactor with a VUV beamline at the SOLEIL synchrotron radiation facility. The reactor may be irradiated window-less with gas pressure up to the atmosphere. The photochemistry is monitored by a mass spectrometer gas analyzer. This set up, termed APSIS for Atmospheric Photochemistry SImulated by Synchrotron, has been used to simulate the atmosphere of Titan and to study the formation of the photochemical smog and the formation of tholins.

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

    NASA Technical Reports Server (NTRS)

    Kostiuk, Theodor

    2010-01-01

    Remote sensing of planetary atmospheres is not complete without studies of all levels of the atmosphere, including the dense cloudy- and haze filled troposphere, relatively clear and important stratosphere and the upper atmosphere, which are the first levels to experience the effects of solar radiation. High-resolution spectroscopy can provide valuable information on these regions of the atmosphere. Ultra-high spectral resolution studies can directly measure atmospheric winds, composition, temperature and non-thermal phenomena, which describe the physics and chemistry of the atmosphere. Spectroscopy in the middle to long infrared wavelengths can also probe levels where dust of haze limit measurements at shorter wavelength or can provide ambiguous results on atmospheric species abundances or winds. A spectroscopic technique in the middle infrared wavelengths analogous to a radio receiver. infrared heterodyne spectroscopy [1], will be describe and used to illustrate the detailed study of atmospheric phenomena not readily possible with other methods. The heterodyne spectral resolution with resolving power greater than 1,000.000 measures the true line shapes of emission and absorption lines in planetary atmospheres. The information on the region of line formation is contained in the line shapes. The absolute frequency of the lines can be measured to I part in 100 ,000,000 and can be used to accurately measure the Doppler frequency shift of the lines, directly measuring the line-of-sight velocity of the gas to --Im/s precision (winds). The technical and analytical methods developed and used to measure and analyze infrared heterodyne measurements will be described. Examples of studies on Titan, Venus, Mars, Earth, and Jupiter will be presented. 'These include atmospheric dynamics on slowly rotating bodies (Titan [2] and Venus [3] and temperature, composition and chemistry on Mars 141, Venus and Earth. The discovery and studies of unique atmospheric phenomena will also be described, such as non-thermal and lasing phenomena on Mars and Venus, mid-infrared aurora on Jupiter [5], and results of small body impacts on Jupiter [6]. The heterodyne technique can also be applied for detailed study of the Earth's stratosphere and mesosphere by measuring trace constituent abundances and temporal and spatial variability as well as winds, which provide information of transport. All ground-based measurements will be described as complementary and supporting studies for on-going and future space missions [7] (Mars Express, Venus Express, Cassini Huygens, JUNO, ExoMars Trace Gas Orbiter, and the Europa Jupiter System Mission, an Earth Science Venture Class missions), Proposed instrument and technology development for a space flight infrared heterodyne spectrometer will be described.

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

    PubMed

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

    2010-01-01

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

  8. Laboratory Studies of O2 Excited States Relevant to CO2 Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Kostko, O.; Storey-Fisher, K.; Kalogerakis, K. S.

    2013-12-01

    Knowledge of the details relevant to the production of excited O2 is critical for the study and modeling of composition, energy transfer, airglow, and transport dynamics in CO2 planetary atmospheres. Significant gaps and uncertainties exist in our understanding of the above processes, and often the relevant input from laboratory measurements is missing or outdated. We are performing laser-based laboratory experiments to investigate the O-atom three-body recombination responsible for the generation of oxygen airglow in the upper atmosphere of Venus and Mars. In the laboratory, an ultraviolet light pulse from a laser photoinitiates O-atom recombination in a CO2 environment. Spectroscopic techniques are used to probe the excited O2 molecules produced following recombination and subsequent relaxation in CO2. We present our latest laboratory results and discuss their atmospheric implications. This work is supported by the National Science Foundation's (NSF) Planetary Astronomy Program under grant AST-1109372. K. Storey-Fisher participated at a Research Experiences for Undergraduates (REU) site at SRI International, co-funded by the Division of Physics of the NSF and the Department of Defense in partnership with the NSF REU program (PHY-1002892).

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Kasting, J. F.

    1996-01-01

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

  11. Infrared spectroscopy of homogeneously nucleated hydrazine aerosols - Disordered and crystalline phases. [in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Dunder, T.; Clapp, M. L.; Miller, R. E.

    1993-01-01

    It is shown that aerosols generated at low temperatures and high condensation rate spontaneously form in a highly crystalline state. The resonant absorption bands in the IR spectra of these highly crystalline particles are much sharper than any reported previously in the bulk, and reveal details in the N-H vibrational bands that have not been previously observed. A disordered phase is also observed at somewhat higher temperatures. These results are consistent with this being a supercooled liquid. The fact that the spectra associated with these two aerosol phases are quite different is important to any future attempts at detecting hydrazine aerosols in planetary atmospheres by remote sensing techniques.

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

    PubMed

    Kasting, J F

    1996-01-01

    The goal of this conference is to consider whether it is possible within the next few decades to detect Earth-like planets around other stars using telescopes or interferometers on the ground or in space. Implicit in the term "Earth-like" is the idea that such planets might be habitable by Earth-like organisms, or that they might actually be inhabited. Here, I shall address two questions from the standpoint of planetary atmosphere evolution. First, what are the chances that habitable planets exist around other stars? And, second, if inhabited planets exist, what would be the best way to detect them? PMID:11542303

  13. A Criterion for the Validity of Parker's Model in Thermal Escape Problems for Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Volkov, A. N.

    2015-10-01

    Mass escape rate of mon- and diatomic gases from a planetary atmosphere is studied based on Parker's model for a broad range of surface conditions. The escape rate is found to follow two asymptotic regimes, namely, high- and low-density regimes, with a short intermediate regime between them. Equations for the escape rate in every asymptotic regime are found theoretically. A comparison of the obtained escape rates with results of recent kinetic simulations shows that Parker's model satisfactorily predicts escape rates only in the high-density regime. Based on this finding, a criterion of applicability of Parker's model for the calculation of the mass escape rate is established.

  14. Detecting and Constraining N2 Abundances in Planetary Atmospheres Using Collisional Pairs

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    Characterizing the bulk atmosphere of a terrestrial planet is important for determining surface pressure and potential habitability. Molecular nitrogen (N2) constitutes the largest fraction of Earth's atmosphere and is likely to be a major constituent of many terrestrial exoplanet atmospheres. Due to its lack of significant absorption features, N2 is extremely difficult to remotely detect. However, N2 produces an N2-N2 collisional pair, (N2)2, which is spectrally active. Here we report the detection of (N2)2 in Earth's disk-integrated spectrum. By comparing spectra from NASA's EPOXI mission to synthetic spectra from the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional spectral Earth model, we find that (N2)2 absorption produces a ˜35% decrease in flux at 4.15 ?m. Quantifying N2 could provide a means of determining bulk atmospheric composition for terrestrial exoplanets and could rule out abiotic O2 generation, which is possible in rarefied atmospheres. To explore the potential effects of (N2)2 in exoplanet spectra, we used radiative transfer models to generate synthetic emission and transit transmission spectra of self-consistent N2-CO2-H2O atmospheres, and analytic N2-H2 and N2-H2-CO2 atmospheres. We show that (N2)2 absorption in the wings of the 4.3 ?m CO2 band is strongly dependent on N2 partial pressures above 0.5 bar and can significantly widen this band in thick N2 atmospheres. The (N2)2 transit transmission signal is up to 10 ppm for an Earth-size planet with an N2-dominated atmosphere orbiting within the habitable zone of an M5V star and could be substantially larger for planets with significant H2 mixing ratios.

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

    PubMed

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

    2013-10-11

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

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

    NASA Technical Reports Server (NTRS)

    Hunt, R. H.

    1983-01-01

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

  17. Structure of the atmosphere in an urban planetary boundary layer from lidar and radiosonde observations

    SciTech Connect

    Cooper, D.I.; Eichinger, W.E.

    1994-11-20

    The planetary boundary layer (PBL) over Mexico City was probed with a scanning backscatter lidar to characterize and evaluate the multidimensional structure of the atmosphere. Comparisons were made between radiosonde and lidar-derived PBL heights which showed the two techniques to be in close agreement. The spatial properties of the free atmosphere-PBL interface were found to be approximately the same size as the entrainment zone thickness. Below the interface the lidar observed spatially resolved structures, such as thermal plumes, convective eddies low-level jets, and entrainment into the PBL. These structures were spatially correlated with the local diabatic condition and wind stress. One highly unstable atmosphere contains a lidar-visualized convective structure rising to a height of 0.45 the inversion base, which was predicted from earlier turbulence models. Other features, such as low-level jets, were found to be associated with neutral atmospheres in the mixing layer. The analysis indicates that the transport of pollutants is not a continuous and gradient-driven process, but low frequency and spatially discontinuous. The high spatial and temporal resolution afforded by the scanning lidar depicts surface-atmosphere interactions which are neither spatially homogeneous nor horizontally uniform. 20 refs., 12 figs., 1 tab.

  18. Microlensing Searches for Extrasolar Planets

    E-print Network

    Gaudi, B. Scott

    Microlensing Searches for Extrasolar Planets Microlensing Searches for Extrasolar Planets I for Extrasolar Planets, B. Scott Gaudi, IAS #12;The Search for Extrasolar PlanetsThe Search for Extrasolar Planets Why Search for Extrasolar Planets ? Frequency of Life Clues to Star Formation Low End

  19. Atmospheric planetary boundary layers: nature, theory, modelling and role in PEEX

    NASA Astrophysics Data System (ADS)

    Zilitinkevich, Sergej

    2014-05-01

    Atmospheric planetary boundary layers (PBLs) control turbulent exchange processes linking the atmosphere with underlying land, vegetation, urban-canopy or water surfaces. The key PBL parameters are vertical turbulent fluxes of energy, matter (pollutants, greenhouse gases, aerosol particles, etc.) and momentum at the PBL lower and upper boundaries, and the PBL height. This paper presents recent advancements in our understanding the nature of PBL and calculation of the above PBL parameters for the newly discovered PBL types, namely, conventionally-neutral and long-lived stable PBLs, and accounting for large-scale self-organised structures in convective PBLs (cells and rolls in the shear-free and sheared convection, respectively). The emphasis is put on the PBL processes determining local features of weather, climate, and air quality, such as extreme weather events, heavy air-pollution episodes and local consequences of global warming.

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  1. Scientific Value of a Saturn Atmospheric Probe Mission

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  2. Numerical Modeling of Normal-Mode Oscillations in Planetary Atmospheres: Application to Saturn and Titan

    NASA Astrophysics Data System (ADS)

    Friedson, Andrew James; Ding, Leon

    2015-11-01

    We have developed a numerical model to calculate the frequencies and eigenfunctions of adiabatic, non-radial normal-mode oscillations in the gas giants and Titan. The model solves the linearized momentum, energy, and continuity equations for the perturbation displacement, pressure, and density fields and solves Poisson’s equation for the perturbation gravitational potential. The response to effects associated with planetary rotation, including the Coriolis force, centrifugal force, and deformation of the equilibrium structure, is calculated numerically. This provides the capability to accurately compute the influence of rotation on the modes, even in the limit where mode frequency approaches the rotation rate, when analytical estimates based on functional perturbation analysis become inaccurate. This aspect of the model makes it ideal for studying the potential role of low-frequency modes for driving spiral density waves in the C ring that possess relatively low pattern speeds (Hedman, M.M and P.D. Nicholson, MNRAS 444, 1369-1388). In addition, the model can be used to explore the effect of internal differential rotation on the eigenfrequencies. We will (1) present examples of applying the model to calculate the properties of normal modes in Saturn and their relationship to observed spiral density waves in the C ring, and (2) discuss how the model is used to examine the response of the superrotating atmosphere of Titan to the gravitational tide exerted by Saturn. This research was supported by a grant from the NASA Planetary Atmosphere Program.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    The dispersal of ash from a volcanic vent on any given planet is dictated by particle properties (density, shape, and size distribution), the intensity of the eruptive source, and the characteristics of the planetary environment (atmospheric structure, wind field, and gravity) into which the ash is erupted. Relating observations of potential pyroclastic deposits to source locations and eruption conditions requires a detailed quantitative understanding of the settling rates of individual particles under changing ambient conditions. For atmospheres that are well described by continuum mechanics, the conventional Newtonian description of particle motion allows particle settling velocities to be related to particle characteristics via a drag coefficient. However, under rarefied atmospheric conditions (i.e., on Mars and at high altitude on Earth), non-continuum effects become important for ash-sized particles, and an equation of motion based on statistical mechanics is required for calculating particle motion. We have developed a rigorous new treatment of particle settling under variable atmospheric conditions and applied it to Earth and Mars. When non-continuum effects are important (as dictated by the mean free path of atmospheric gas relative to the particle size), fall velocities are greater than those calculated by continuum mechanics. When continuum conditions (i.e., higher atmospheric densities) are reached during descent, our model switches to a conventional formulation that determines the appropriate drag coefficient as the particle transits varying atmospheric properties. The variation of settling velocity with altitude allows computation of particle trajectories, fall durations and downwind dispersal. Our theoretical and numerical analyses show that several key, competing factors strongly influence the downwind trajectories of ash particles and the extents of the resulting deposits. These factors include: the shape of the particles (non-spherical particles fall more slowly than spherical particle shapes commonly adopted in settling models); the formation of particle aggregates, which enhances settling rates; and the lagging of particle motion behind the ambient wind field, which results in less widely dispersed deposits. Above all, any particles experiencing non-continuum effects settle faster and are less widely dispersed than particles falling in an entirely continuum regime. Our model results demonstrate the complex interplay of these factors in the Martian environment, and our approach provides a basis for relating deposits observed in planetary datasets to candidate volcanic sources and eruption conditions. This allows for a critical reassessment of the potential for explosive volcanism to contribute to extremely widespread, fine-grained, layered deposits such as the Medusae Fossae Formation.

  4. The Search for Extrasolar Earth-like planets

    E-print Network

    S. Seager

    2003-05-19

    The search for extrasolar Earth-like planets is underway. Over 100 extrasolar giant planets are known to orbit nearby sun-like stars, including several in multiple-planet systems. These planetary systems are stepping stones for the search for Earth-like planets; the technology development, observational strategies, and science results can all be applied to Earth-like planets. Stars much less massive than the sun the most common stars in our Galaxy are being monitored for the gravitational influence of Earth-like planets. Although Earth-like planets orbiting sun-like stars are much more difficult to detect, space missions are being built to detect them indirectly due to their effects on the parent star and to quantify fundamental factors such as terrestrial planet frequency, size distribution, and mass distribution. Extremely ambitious space programs are being developed to directly detect Earth-like planets orbiting sun-like stars, and must tackle the immense technological challenge of blocking out the light of the parent star, which is brighter than the planet by six to ten orders of magnitude. Direct detection of radiation from the planet is necessary for the definitive goal of the search for Earth-like planets: the study of atmospheric spectral signatures for signs of severe disequilibrium chemistry that could be indicative of biological activity. In addition to technological development, a growing flurry of scientific activity has begun to: understand terrestrial planet formation and terrestrial planet frequency; model terrestrial-like planet atmospheres and evolution; articulate the biological signatures of our own Earth; and even to study Earth as an extrasolar planet by observation and analysis of the spatially unresolved Earth.

  5. Balloon-borne planetary atmospheric sounder tested in the terrestrial environment

    NASA Astrophysics Data System (ADS)

    Roney, Jason A.; Mourning, Rodger L.

    2007-01-01

    A prototype high altitude balloon payload dedicated to measuring wind characteristics, pressure and temperature in terrestrial atmospheric environments was developed as part of a National Aeronautics and Space Administration (NASA) Workforce Development Educational Grant. The WindSat as it became known was one of 15 conceptual projects suggested by various NASA agencies with this specific concept suggested by the Jet Propulsion Laboratory (JPL). The WindSat project was designed, built, and tested by the University of Colorado at Colorado Springs (UCCS) Space Grant program to determine the feasibility of obtaining atmospheric weather in the upper and lower atmosphere for entry, descent, and landing of planetary missions. In the first phase of the project described in this paper, the payload was designed for and tested in the terrestrial environment of Earth. The prototype is similar to a radiosonde in function; however, the prototype logs data at a frequency of 1 Hz to determine relative gusts and also records values on both ascent and descent through the atmosphere. Some preliminary results from the first two test flights of WindSat are given in this paper.

  6. The radial flow planetary reactor: low pressure versus atmospheric pressure MOVPE

    NASA Astrophysics Data System (ADS)

    Frijlink, P. M.; Nicolas, J. L.; Ambrosius, H. P. M. M.; Linders, R. W. M.; Waucquez, C.; Marchal, J. M.

    1991-12-01

    A comparison between MOVPE of III-V compounds with the radial flow planetary reactor at atmospheric pressure and at reduced pressure has been carried out by numerical simulation and experimentally. The behavior of the reactor at low pressure was found to be very similar to that at atmospheric pressure. The obtained layer thickness uniformity was also ± 1% at pressures of 100 mbar and 200 mbar. Moreover, the uniformity was found to be almost independent of total mass flow, over the range of 10 to 43 SLM. The first growth on five 3 inch diameter wafers at atmospheric pressure is reported. Optimization of the inlet section led to simultaneous uniformities of ? 1% in layer thickness abd sheet resistance. The first GaAs-(Ga,Al)As lasers grown with this reactor at 200 mbar are reported, with a threshold current density of 400 A/cm 2. The first GaAs-(Ga,In)As-(Ga,Al)As pseudomorphic HEMT material grown with this reactor at atmospheric pressure with 22% indium in the channel layer yielded devices with an average maximum transconductance of 383 mS/mm and unity current gain cut-off frequency of 64.5 GHz for a gate length of 0.25 ?m.

  7. Detecting and Constraining N$_2$ Abundances in Planetary Atmospheres Using Collisional Pairs

    E-print Network

    Schwieterman, Edward W; Meadows, Victoria S; Misra, Amit; Domagal-Goldman, Shawn

    2015-01-01

    Characterizing the bulk atmosphere of a terrestrial planet is important for determining surface pressure and potential habitability. Molecular nitrogen (N$_2$) constitutes the largest fraction of Earth$'$s atmosphere and is likely to be a major constituent of many terrestrial exoplanet atmospheres. Due to its lack of significant absorption features, N$_2$ is extremely difficult to remotely detect. However, N$_2$ produces an N$_2$-N$_2$ collisional pair, (N$_2$)$_2$, which is spectrally active. Here we report the detection of (N$_2$)$_2$ in Earth$'$s disk-integrated spectrum. By comparing spectra from NASA$'$s EPOXI mission to synthetic spectra from the NASA Astrobiology Institute$'$s Virtual Planetary Laboratory three-dimensional spectral Earth model, we find that (N$_2$)$_2$ absorption produces a ~35$\\%$ decrease in flux at 4.15 $\\mu$m. Quantifying N$_2$ could provide a means of determining bulk atmospheric composition for terrestrial exoplanets and could rule out abiotic O$_2$ generation, which is possible ...

  8. Interactives: Comets, Orbital Motions, and Virtual Ballooning to Explore Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Russell, R. M.; Johnson, R. M.; Genyuk, J.

    2009-12-01

    We will demonstrate interactives and animations from the Windows to the Universe web site (www.windows.ucar.edu) covering three topics: cometary orbits and tails, orbit shapes and orbital motions, and virtual ballooning to explore planetary atmospheres. The comet interactive illustrates the range of shapes and sizes of cometary orbits, the formation of tails when a comet nears the Sun, and the orientations of the dust and ion tails. Our suite of animations and interactives about orbits and orbital motions help learners understand the shapes (eccentricity) and sizes (semi-major axis) of orbits as well as variations in orbital velocity from perihelion to aphelion. Our Mars orbit interactive illustrates the variations in distance between Earth and Mars as the planets orbit and at successive oppositions (closest approaches), which has influenced the history of both telescopic observations of the Red Planet as well as the timing of space missions to Mars. The virtual ballooning interactive enables students to explore the structures of atmospheres by launching virtual weather balloons that send back data on the variation of pressure and temperature with altitude. Learners set the altitude ranges and sampling frequencies for their balloon-borne virtual instruments and collect data over the course of four flights. Students learn about the pressure variation with altitude, temperature vs. altitude relationships in different atmospheric layers, and how to be thoughtful and selective during experimental data collection. Students can explore the atmospheres of Mars, Venus, and Titan as well as Earth.

  9. Planetary host stars: Evaluating uncertainties in ultra-cool model atmospheres

    E-print Network

    Bozhinova, I; Scholz, A

    2014-01-01

    M-dwarfs are discussed as promising targets for detecting planet at the lower mass end of the planetary mass distribution. An important step in this process is to accurately estimate the stellar parameters of the M-dwarf host star for which the results of stellar model atmosphere simulations are used. We present a comparison of the ATLAS9, MARCS, PHOENIX and Drift-PHOENIX model atmosphere families in the M-dwarf parameter space. We examine the differences in the (T$_{\\rm gas}$, p$_{\\rm gas}$)-structures, in synthetic photometric fluxes and in colour indices. We compiled the broad-band synthetic photometric fluxes for all available M-dwarf model atmospheres for the UKIRT WFCAM ZYJHK, 2MASS JHKs and Johnson UBVRI filters, and calculated related colour indices. We find that the synthetic colours in the IR wavelengths diverge by no more than 0.15 dex amongst all model families. For all bands considered, discrepancies in colour diminish for the higher T$_{\\rm eff}$-end of model atmosphere grids. We notice signific...

  10. Theortetical Models of Extrasolar Giant Planets

    E-print Network

    A. Burrows; W. B. Hubbard; J. I. Lunine; T. Guillot; D. Saumon; M. Marley; R. S. Freedman

    1996-08-28

    The recent discoveries of giant planets around nearby stars have galvanized the planetary science community, astronomers, and the public at large. Since {\\it direct} detection is now feasible, and is suggested by the recent acquisition of Gl229 B, it is crucial for the future of extrasolar planet searches that the fluxes, evolution, and physical structure of objects from Saturn's mass to 15 Juipter masses be theoretically investigated. We discuss our first attempts to explore the characteristics of extrasolar giant planets (EGPs), in aid of both NASA's and ESA's recent plans to search for such planets around nearby stars.

  11. Extrasolar Planets: A Galactic Perspective

    E-print Network

    I. N. Reid

    2006-08-15

    The host stars of extrasolar planets tend to be metal-rich. We have examined the data for these stars for evidence of trends in other galactic parameters, without success. However, several ESP hosts are likely to be members of the thick disk population, indicating that planet formation has occurred throughout the full lifetime of the Galactic disk. We briefly consider the radial metallicity gradient and age-metallicity relation of the Galactic disk, and complete a back-of-the envelope estimate of the likely number of solar-type stars with planetary companions with 6 < R < 10 kpc.

  12. Simulating super earth atmospheres in the laboratory

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  13. Searching for exo-planetary atmospheric sodium around the active star, HD189733 with UVES

    NASA Astrophysics Data System (ADS)

    Khalafinejad, Sara; Hoeijmakers, Jens

    2015-08-01

    During an exoplanetary transit, the spectral signatures of the exoplanet atmosphere can be measured using transmission spectroscopy. Our aim is to re-investigate the transmission spectrum of the atmosphere of hot Jupiter HD189733b, which orbits a bright active star. We intend to search for absorption features of neutral calcium, sodium and potassium using different retrieval methods, and assess which is most robust against effects induced by activity of the star and other systematics.We use high-resolution optical spectra taken by the UVES instrument at the VLT during a single transit of HD1897433b. We apply three approaches to probe the transmission spectrum for planetary absorption features. The first approach is to compare the in-transit spectra with the out of transit spectra (spectral method), by directly dividing them to each other. The second is to obtain the excess depth of the transit light curve at a certain wavelength (lightcurve method). The last one is to extract the Doppler shifted spectral features of planetary atmosphere caused by the planet’s changing radial velocity as a function of orbital phase (Doppler method). In order to specifically the effect of stellar activity, these method was also applied in the context of the Ca H & K and H-alpha lines, standard activity indicators.We concluded that the lightcurve method reveals the presence of sodium however the star exhibits flaring activity during the transit. The stellar flare induces strong systematics which in certain cases may completely mask or mimic a planetary sodium signature. It should also be noted that the CaI and KI lines show no evidence of being affected by stellar activity, allowing us to directly impose upper limits to their absorption strengths. We assess methods to minimize the influence of the flare. The Doppler method relies on the time-dependent radial velocity of the planet, this method is particularly affected by the Rossiter-McLaughlin effect, and care must be taken to mitigate it. At present, this is still under development.

  14. Direct modeling of transiting planet light curves from model stellar atmospheres

    NASA Astrophysics Data System (ADS)

    Mcneil, Joseph; Neilson, H.; Ignace, R.

    2014-01-01

    Recent and new observations of extrasolar planets via the transit method are provided unparalleled measurements that enhance our understanding of both the planets and their host stars. However, analysis techniques assume simple parameters to describe the stellar intensity profile. In this work, we compare new planetary transit light curves computed directly from model stellar atmosphere intensity profiles with light curves computed using limb-darkening coefficients. This comparison highlights the need for better models of stellar intensities and atmospheres to better understand the extrasolar planets themselves, especially in the upcoming eras of TESS and PLATO.

  15. A method for the direct determination of the surface gravities of transiting extrasolar planets

    E-print Network

    John Southworth; Peter J. Wheatley; Giles Sams

    2007-04-12

    We show that the surface gravity of a transiting extrasolar planet can be calculated from only the spectroscopic orbit of its parent star and the analysis of its transit light curve. This does not require additional constraints, such as are often inferred from theoretical stellar models or model atmospheres. The planet's surface gravity can therefore be measured precisely and from only directly observable quantities. We outline the method and apply it to the case of the first known transiting extrasolar planet, HD 209458b. We find a surface gravity of g_p = 9.28 +/- 0.15 m/s, which is an order of magnitude more precise than the best available measurements of its mass, radius and density. This confirms that the planet has a much lower surface gravity that that predicted by published theoretical models of gas giant planets. We apply our method to all fourteen known transiting extrasolar planets and find a significant correlation between surface gravity and orbital period, which is related to the known correlation between mass and period. This correlation may be the underlying effect as surface gravity is a fundamental parameter in the evaporation of planetary atmospheres.

  16. CO prompt emission as a CO2 marker in comets and planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Kalogerakis, Konstantinos S.; Romanescu, Constantin; Ahmed, Musahid; Wilson, Kevin R.; Slanger, Tom G.

    2012-07-01

    Observations of CO emissions in the visible and near-infrared (NIR) have been rare for comets, and no measurements from orbiters are currently available in the visible for the dayglows of Mars or Venus. Analysis of the ultraviolet CO(a-X) Cameron bands from Mars Express dayglow observations supports the conclusion that these bands have very high rotational temperatures, some thousands of kelvins. The most plausible source for the CO rotational excitation is its generation by CO2 photodissociation. Recent laboratory measurements investigating the photodissociation of CO2 in the extreme ultraviolet (EUV) reveal strong emissions in the visible and NIR region by the triplet CO(a?, d, e) states, which we take to be a primary source for the UV CO(a-X) Cameron bands. Thus, detection of visible emissions from the triplet CO states in planetary dayglows and comets provides an upper limit to the CO2 density. The presence of CO high rotational excitation along with the intense visible and NIR band emissions should be considered as a practical way by which planetary dayglow and cometary spectra provide information on the presence of CO2. Finally, we report on existing observations of cometary atmospheres and estimate the altitude for the emitting layer of the CO triplet states in Mars and Venus.

  17. Formation of spectral lines in planetary atmospheres. III - The use of analytic scattering diagrams in computations of synthetic spectra for cloudy atmospheres.

    NASA Technical Reports Server (NTRS)

    Hunt, G. E.

    1972-01-01

    Results of some comparisons that have been made of line profiles and equivalent widths computed from atmospheric models where the scattering has been represented by the Mie theory and a simple analytic expression, the Heyney-Greenstein function. These results show that the spectroscopic features for these models are indistinguishable and demonstrate the value of using this simple analytic function in terms of the great saving in computer time when computing synthetic spectra for any cloudy planetary atmosphere.

  18. Inverse multiple scattering problems. III - Inadequacy of certain limb darkening and phase curves for retrieving atmospheric information and limitations of approximate scattering models. [for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Fymat, A. L.; Lenoble, J.

    1979-01-01

    The paper considers three complementary inverse multiple scattering problems relating to a uniquely defined atmospheric scattering model. Consideration is given to the appropriateness, for data inversion purposes, of intensities observed in diffuse reflection under a variety of experimental conditions; the uniqueness of the inverse solution is investigated. It is found that light curves representing monotonic variations, such as limb darkening curves and phase curves for a planetary (e.g., Venus) disk center are unsuitable for inferring atmospheric and scattering parameters.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

  1. Vapor pressure isotope fractionation effects in planetary atmospheres: application to deuterium

    E-print Network

    Thierry Fouchet; Emmanuel Lellouch

    1999-11-15

    The impact of the vapor pressure difference between deuterated and nondeuterated condensing molecules in planetary atmospheres is quantitatively assessed. This difference results in a loss of deuterium in the vapor phase above the condensation level. In Titan, Uranus and Neptune, the effect on CH3D is too subtle to alter current D/H ratio determinations. In Mars, the effect can induce a large depletion of HDO, starting about one scale height above the condensation level. Although the current infrared measurements of the D/H ratio appear to be almost unaffected, the intensity of disk-averaged millimetric HDO lines can be modified by about 10%. The effect is much stronger in limb sounding, and can be easily detected from orbiter observations.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

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

    PubMed

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

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

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1986-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  8. Submillimeter Remote Sensing of Planetary and Cometary Atmospheres and LRO/LCROSS Observations of the Moon

    NASA Technical Reports Server (NTRS)

    Chin, Gordon

    2011-01-01

    Submillimeter remote sensing of planetary and cometary atmospheres have been proposed for Venus and Mars while MIRO on Rosetta will observe the coma of Comet 67P/Churyumov - Cierasimenko in December 2015, UARS and AURA MLS have observed millimeter and submillimeter molecule emissions in the Earth's stratosphere for many decades, Observations of submillimeter wave molecular emissions provide a wealth of information not obtainable by alternative techniques. Submillimeter line emissions exhibit linear temperature dependence, insensitivity to aerosol scattering, extinction, and have separated transitions with well determined line-shapes. These observations have high sensitivities to trace chemical species and can; 1) Fully resolve the line profiles of molecules with high resolution, 2) Provide deterministic retrievals of species abundance, temperature, and pressure, and 3) Measure Doppler shifts of detected molecules for wind velocities.

  9. Exploring Hot Neptune Atmospheres

    NASA Astrophysics Data System (ADS)

    Fortney, Jonathan; Marley, Mark; Saumon, Didier

    2008-03-01

    The first transiting 'hot Neptune'' GJ 436b inhabits an entirely new region of phase space for extrasolar planetary atmospheres. This relatively cool, low-mass object should be the first transiting extrasolar planet to sport a methane-rich atmosphere. Like Uranus and Neptune it may also have an atmosphere highly enriched in heavy elements. Our experience with the complex atmospheres of the known hot-Jupiters has demonstrated that insights are best gained through the combination of Spitzer observations and atmospheric modeling . However, no models have investigated the atmospheres of Neptune-class exoplanets, which may well be super metal-enriched, and span a wider range in stellar insolation and atmospheric composition than we have previously encountered. GJ 436b the coldest transiting planet, is in entirely new irradiation and mass regimes and is also the target of a barrage of planned Spitzer observations. Here we propose a new generation of atmospheric modeling to understand Spitzer observations of this new planet and others like it.

  10. ExtraSolar Planets Finding Extrasolar Planets. I

    E-print Network

    Walter, Frederick M.

    ExtraSolar Planets #12;Finding Extrasolar Planets. I Direct Searches Direct searches are difficult #12;Finding Extrasolar Planets. II Transits #12;Transits Transits requires an edge-on orbit. ·Jupiter;How Transits Work #12;Finding Extrasolar Planets. III Astrometric Wobble #12;Finding Extrasolar

  11. Formation, Habitability, and Detection of Extrasolar Moons

    E-print Network

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

    2014-01-01

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

  12. EVOLUTION OF THE SOLAR ACTIVITY OVER TIME AND EFFECTS ON PLANETARY ATMOSPHERES. I. HIGH-ENERGY IRRADIANCES (11700 8)

    E-print Network

    Audard, Marc

    EVOLUTION OF THE SOLAR ACTIVITY OVER TIME AND EFFECTS ON PLANETARY ATMOSPHERES. I. HIGH the ultimate purpose of providing the spectral irradiance evolution of solar-type stars to be used in the study and have played an important role in the development of primitive life in the solar system. Some examples

  13. Internal variability of the tropical Pacific ocean Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA

    E-print Network

    Jochum, Markus

    Internal variability of the tropical Pacific ocean M. Jochum Earth, Atmospheric and Planetary model of the tropical Pacific ocean is analyzed to quantify the interannual variability caused by internal variability of ocean dynamics. It is found that along the Pacific cold tongue internal variability

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    Because thermal conduction and IR cooling are inefficient heat transfer processes, adiabatic expansion leading to molecular escape is often the dominant cooling process for energy deposited in the upper atmosphere of planetary bodies. This led to the use of the energy-limited escape (EL) approximation in which the loss rate is roughly proportional to the heating rate, Q. In applying the EL approximation, it was also frequently assumed that the adiabatic expansion resulted in the gas outflow going sonic. Johnson et al. (2013) used molecular kinetic simulations of an atmosphere with a heated layer to show this was not necessarily the case and estimated a critical heating rate, Qc. For Q greater than ~Qc a sonic point formed below the exobase where the gas properties were collision dominated. As Q increased above ~Qc sonic escape was eventually limited by the energy and number fluxes from the below the heated layer. In that case, adiabatic cooling did dominate upper atmosphere cooling, but the escape rate did not increase with increasing Q as predicted by the EL model. Instead, the escape rate remained nearly constant and the energy per molecule carried off increased nearly monotonically with Q. For heating rates from about twice Qc to more than an order of magnitude lower, the molecular escape rate was well approximated by the energy limited rate, but the upper atmospheric structure could not be described by a fluid model with a sonic point and escape was Jeans-like although the Jeans expressions was often a poor approximation. That is, molecules escape from well below the nominal exobase and collisions remained important well above it (Tucker et al. 2009; 2013) resulting in enhanced-Jeans-like escape (Volkov et al. 2011a,b; Erwin et al. 2013). Here we give a new expression for the escape rate produced by adiabatic cooling and expansion of the upper atmosphere and apply it to atmospheric loss from an early Titan atmosphere and related atmospheres.Ref.: Erwin,J.T., et al.Icarus 226,375(2013);Johnson,R.E. et al.,ApJL768, L4(6pp);Errat:ApJL774,90(2013); Tucker,O.J. et al. PSS57,1889 (2009); Tucker,O.J., et al.Icarus 222,149(2013). Volkov,A.N., et al.Ap.J.Lett.729,L24(5pp)(2011a); ibid Phys. Fluids 23(2011b)

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  16. C/O ratios in extrasolar planetesimals

    NASA Astrophysics Data System (ADS)

    Wilson, David John; Gaensicke, Boris; Farihi, Jay; Koester, Detlev

    2015-12-01

    The wide range of densities found in small exoplanets imply a variety of possible compositions and interior structures. In particular, some models predict that protoplanetary discs with C/O>0.8 may form carbon-dominated planets. The only way to directly test such predictions are studies of evolved planetary systems at white dwarfs. Analysis of planetesimal debris in white dwarf atmospheres provides a unique insight into the chemical compositions of extrasolar planets, which cannot be observed at main-sequence systems. Thus far, such studies have predominantly focused on individual objects. However, the growing sample of abundance studies now allows conclusions to be derived regarding the overall chemical abundances of (solid) exoplanet precursors in a statistically significant sample of systems. Here, we present measurements of the C/O ratio in the debris of planetesimals at 16 white dwarfs observed with the Hubble Space Telescope. These data allow us to constrain the occurrence frequency of carbon-dominated planets. We find no evidence for such carbon planets, with C/O<0.8 by number in all 16 systems.

  17. Formation, Habitability, and Detection of Extrasolar Moons

    PubMed Central

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

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  19. Aerial vehicle surveys of other planetary atmospheres and surfaces: imaging, remote-sensing, and autonomy technology requirements

    NASA Astrophysics Data System (ADS)

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

    2005-02-01

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

  20. Extrasolar planet taxonomy: a new statistical approach

    E-print Network

    Simone Marchi

    2007-05-07

    In this paper we present the guidelines for an extrasolar planet taxonomy. The discovery of an increasing number of extrasolar planets showing a vast variety of planetary parameters, like Keplerian orbital elements and environmental parameters, like stellar masses, spectral types, metallicity etc., prompts the development of a planetary taxonomy. In this work via principal component analysis followed by hierarchical clustering analysis, we report the definition of five robust groups of planets. We also discuss the physical relevance of such analysis, which may provide a valid basis for disentangling the role of the several physical parameters involved in the processes of planet formation and subsequent evolution. For instance, we were able to divide the hot Jupiters into two main groups on the basis of their stellar masses and metallicities. Moreover, for some groups, we find strong correlations between metallicity, semi-major axis and eccentricity. The implications of these findings are discussed.

  1. Detection of Extrasolar Planets by Transit Photometry

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  2. SURVEY FOR TRANSITING EXTRASOLAR PLANETS IN STELLAR SYSTEMS. III. A LIMIT ON THE FRACTION OF STARS WITH PLANETS IN THE OPEN CLUSTER NGC 1245

    E-print Network

    Gaudi, B. Scott

    SURVEY FOR TRANSITING EXTRASOLAR PLANETS IN STELLAR SYSTEMS. III. A LIMIT ON THE FRACTION OF STARS photometric search for transiting extrasolar planets in the open cluster NGC 1245. An automated transit search: individual (NGC 1245) -- planetary systems 1. INTRODUCTION Extrasolar planet detections and analysis

  3. Detection of oxygen and carbon in the hydrodynamically escaping atmosphere of the extrasolar planet HD209458b

    E-print Network

    A. Vidal-Madjar; J. -M. Désert; A. Lecavelier des Etangs; G. Hébrard; G. E. Ballester; D. Ehrenreich; R. Ferlet; J. C. McConnell; M. Mayor; C. D. Parkinson

    2004-02-02

    Four transits of the planet orbiting the star HD209458 were observed with the STIS spectrograph on board HST. The wavelength domain (1180-1710A) includes HI as well as CI, CII, CIV, NV, OI, SI, SiII, SiIII and SiIV lines. During the transits, absorptions are detected in HI, OI and CII (5+/-2%, 13+/-4.5% and 7.5+/-3.5%, respectively). No absorptions are detected for other lines. The 5% mean absorption over the whole HI Lyman alpha line is consistent with the previous detection at higher resolution (Vidal-Madjar et al. 2003). The absorption depths in OI and CII show that oxygen and carbon are present in the extended upper atmosphere of HD209458b. These species must be carried out up to the Roche lobe and beyond, most likely in a state of hydrodynamic escape.

  4. 3D climate modeling of Earth-like extrasolar planets orbiting different types of host stars

    E-print Network

    Godolt, M; Hamann-Reinus, A; Kitzmann, D; Kunze, M; Langematz, U; von Paris, P; Patzer, A B C; Rauer, H; Stracke, B

    2015-01-01

    The potential habitability of a terrestrial planet is usually defined by the possible existence of liquid water on its surface. The potential presence of liquid water depends on many factors such as, most importantly, surface temperatures. The properties of the planetary atmosphere and its interaction with the radiative energy provided by the planet's host star are thereby of decisive importance. In this study we investigate the influence of different main-sequence stars upon the climate of Earth-like extrasolar planets and their potential habitability by applying a 3D Earth climate model accounting for local and dynamical processes. The calculations have been performed for planets with Earth-like atmospheres at orbital distances where the total amount of energy received from the various host stars equals the solar constant. In contrast to previous 3D modeling studies, we include the effect of ozone radiative heating upon the vertical temperature structure of the atmospheres. The global orbital mean results o...

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

  7. HD 179949b: A Close Orbiting Extrasolar Giant Planet with a stratosphere?

    E-print Network

    J. R. Barnes; Travis S. Barman; H. R. A. Jones; C. J. Leigh; A. Collier Cameron; R. J. Barber; D. J. Pinfield

    2008-06-02

    We have carried out a search for the 2.14 micron spectroscopic signature of the close orbiting extrasolar giant planet, HD 179949b. High cadence time series spectra were obtained with the CRIRES spectrograph at VLT1 on two closely separated nights. Deconvolution yielded spectroscopic profiles with mean S/N ratios of several thousand, enabling the near infrared contrast ratios predicted for the HD 179949 system to be achieved. Recent models have predicted that the hottest planets may exhibit spectral signatures in emission due to the presence of TiO and VO which may be responsible for a temperature inversion high in the atmosphere. We have used our phase dependent orbital model and tomographic techniques to search for the planetary signature under the assumption of an absorption line dominated atmospheric spectrum, where T and V are depleted from the atmospheric model, and an emission line dominated spectrum, where TiO and VO are present. We do not detect a planet in either case, but the 2.120 - 2.174 micron wavelength region covered by our observations enables the deepest near infrared limits yet to be placed on the planet/star contrast ratio of any close orbiting extrasolar giant planet system. We are able to rule out the presence of an atmosphere dominated by absorption opacities in the case of HD 179949b at a contrast ratio of F_p/F_* ~ 1/3350, with 99 per cent confidence.

  8. Large-scale properties of lightning in extrasolar objects

    NASA Astrophysics Data System (ADS)

    Helling, Christiane; Bailey, Rachel; Hodosan, Gabriella; Bilger, Camille; Stark, Craig

    2014-05-01

    Mineral clouds play a special role as a catalyst for a variety of charge processes also in extrasolar objects. If clouds are charged, the surrounding environment becomes electrically activated, and ensembles of charged grains are electrically discharging (e.g. by lightning), which significantly infuences 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 ionisation 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 downwards (as lightning) and upwards (as sprites) through the atmospheric clouds. We evaluate the spatial extent and energetics of lightning discharges. First attempts to show the infuence of lightning on the local gas phase indicate an increase of small carbohydrate molecules like CH and CH2 at the expense of CO and CH4. Dust forming molecules are destroyed and the cloud particle properties are frozen-in unless enough time is available for complete evaporation.

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

    NASA Astrophysics Data System (ADS)

    Kirillovich, Ivan; Gubenko, Vladimir; Pavelyev, Alexander

    Internal gravity waves (IGWs) modulate the structure and circulation of the Earth’s atmosphere, producing quasi-periodic variations in the wind velocity, temperature and density. Similar effects are anticipated for the Venus and Mars since IGWs are a characteristic of stably stratified atmosphere. In this context, an original method for the determination of IGW parameters from a vertical temperature profile measurement in a planetary atmosphere has been developed [Gubenko et al., 2008, 2011, 2012]. This method does not require any additional information not contained in the profile and may be used for the analysis of profiles measured by various techniques. The criterion for the IGW identification has been formulated and argued. In the case when this criterion is satisfied, the analyzed temperature fluctuations can be considered as wave-induced. The method is based on the analysis of relative amplitudes of the wave field and on the linear IGW saturation theory in which these amplitudes are restricted by dynamical (shear) instability processes in the atmosphere. When the amplitude of an internal wave reaches the shear instability threshold, energy is assumed to be dissipated in such a way that the IGW amplitude is maintained at the instability threshold level as the wave propagates upwards. We have extended the developed technique [Gubenko et al., 2008] in order to reconstruct the complete set of wave characteristics including such important parameters as the wave kinetic and potential energy per unit mass and IGW fluxes of the energy and horizontal momentum [Gubenko et al., 2011]. We propose also an alternative method to estimate the relative amplitudes and to extract IGW parameters from an analysis of perturbations of the Brunt-Vaislala frequency squared [Gubenko et al., 2011]. An application of the developed method to the radio occultation (RO) temperature data has given the possibility to identify the IGWs in the Earth's, Martian and Venusian atmospheres and to determine the magnitudes of key wave parameters such as the intrinsic frequency, amplitudes of vertical and horizontal wind velocity perturbations, vertical and horizontal wavelengths, intrinsic vertical and horizontal phase (and group) speeds, kinetic and potential energy per unit mass, vertical fluxes of the wave energy and horizontal momentum. Vertical profiles of temperature retrieved from RO measurements of the CHAMP (Earth), Mars Global Surveyor (Mars), Magellan and Venus Express (Venus) missions are used and analyzed to identify discrete or “narrow spectral” wave events and to determine IGW characteristics in the Earth’s, Martian and Venusian atmospheres. This work was partially supported by the RFBR grant 13-02-00526-? and Program 22 of the RAS Presidium. References. Gubenko V.N., Pavelyev A.G., Andreev V.E. Determination of the intrinsic frequency and other wave parameters from a single vertical temperature or density profile measurement // J. Geophys. Res. 2008. V. 113. No.D08109, doi:10.1029/2007JD008920. Gubenko V.N., Pavelyev A.G., Salimzyanov R.R., Pavelyev A.A. Reconstruction of internal gravity wave parameters from radio occultation retrievals of vertical temperature profiles in the Earth’s atmosphere // Atmos. Meas. Tech. 2011. V. 4. No.10. P. 2153-2162, doi:10.5194/amt-4-2153-2011. Gubenko V.N., Pavelyev A.G., Salimzyanov R.R., Andreev V.E. A method for determination of internal gravity wave parameters from a vertical temperature or density profile measurement in the Earth’s atmosphere // Cosmic Res. 2012. V. 50. No.1. P. 21-31, doi: 10.1134/S0010952512010029.

  10. Search for hydrogen peroxide in the Martian atmosphere by the Planetary Fourier Spectrometer onboard Mars Express

    NASA Astrophysics Data System (ADS)

    Aoki, Shohei; Giuranna, Marco; Kasaba, Yasumasa; Nakagawa, Hiromu; Sindoni, Giuseppe; Geminale, Anna; Formisano, Vittorio

    2015-01-01

    We searched for hydrogen peroxide (H2O2) in the Martian atmosphere using data measured by the Planetary Fourier Spectrometer (PFS) onboard Mars Express during five martian years (MY27-31). It is well known that H2O2 plays a key role in the oxidizing capacity of the Martian atmosphere. However, only a few studies based on ground-based observations can be found in the literature. Here, we performed the first analysis of H2O2 using long-term measurements by a spacecraft-borne instrument. We used the ?4 band of H2O2 in the spectral range between 359 cm-1 and 382 cm-1 where strong features of H2O2 are present around 362 cm-1 and 379 cm-1. Since the features were expected to be very weak even at the strong band, sensitive data calibrations were performed and a large number of spectra were selected and averaged. We made three averaged spectra for different seasons over relatively low latitudes (50°S-50°N). We found features of H2O2 at 379 cm-1, whereas no clear features were detected at 362 cm-1 due to large amounts of uncertainty in the data. The derived mixing ratios of H2O2 were close to the detection limits: 16 ± 19 ppb at Ls = 0-120°, 35 ± 32 ppb at Ls = 120-240°, and 41 ± 28 ppb at Ls = 240-360°. The retrieved value showed the detection of H2O2 only for the third seasonal period, and the values in the other periods provided the upper limits. These long-term averaged abundances derived by the PFS generally agreed with the ones reported by ground-based observations. From our derived mixing ratio of H2O2, the lifetime of CH4 in the Martian atmosphere is estimated to be several decades in the shortest case. Our results and sporadic detections of CH4 suggest the presence of strong CH4 sinks not subject to atmospheric oxidation.

  11. The Runaway Greenhouse: implications for future climate change, geoengineering and planetary atmospheres

    E-print Network

    Goldblatt, Colin

    2012-01-01

    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 once the surface reaches ~1400K 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 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 diox...

  12. Rayleigh Scattering in Planetary Atmospheres: Corrected Tables Through Accurate Computation of X and Y Functions

    NASA Astrophysics Data System (ADS)

    Natraj, Vijay; Li, King-Fai; Yung, Yuk L.

    2009-02-01

    Tables that have been used as a reference for nearly 50 years for the intensity and polarization of reflected and transmitted light in Rayleigh scattering atmospheres have been found to be inaccurate, even to four decimal places. We convert the integral equations describing the X and Y functions into a pair of coupled integro-differential equations that can be efficiently solved numerically. Special care has been taken in evaluating Cauchy principal value integrals and their derivatives that appear in the solution of the Rayleigh scattering problem. The new approach gives results accurate to eight decimal places for the entire range of tabulation (optical thicknesses 0.02-1.0, surface reflectances 0-0.8, solar and viewing zenith angles 0°-88.85°, and relative azimuth angles 0°-180°), including the most difficult case of direct transmission in the direction of the sun. Revised tables have been created and stored electronically for easy reference by the planetary science and astrophysics community.

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

    E-print Network

    Rimmer, Paul B

    2015-01-01

    There are many open questions about prebiotic chemistry in both planetary and exoplanetary environments. The increasing number of known exoplanets and other ultra-cool, substellar objects has propelled the desire to detect life and prebiotic chemistry outside the solar system. We present an ion-neutral chemical network constructed from scratch, Stand2015, that treats hydrogen, nitrogen, carbon and oxygen chemistry accurately within a temperature range between 100 K and 30000 K. Formation pathways for glycine and other organic molecules are included. The network is complete up to H6C2N2O3. Stand2015 is successfully tested against atmospheric chemistry models for HD209458b, Jupiter and the present-day Earth using a simple 1D photochemistry/diffusion code. Our results for the early Earth agree with those of Kasting (1993) for CO2, H2, CO and O2, but do not agree for water and atomic oxygen. We use the network to simulate an experiment where varied chemical initial conditions are irradiated by UV light. The resul...

  14. Arctic Sea Ice Export Through Fram Strait and Atmospheric Planetary Waves

    NASA Technical Reports Server (NTRS)

    Cavalieri, Donald J.; Koblinsky, Chester (Technical Monitor)

    2001-01-01

    A link is found between the variability of Arctic sea ice export through Ram Strait and the phase of the longest atmospheric planetary wave (zonal wave 1) in SLP for the period 1958-1997. Previous studies have identified a link between From Strait ice export and the North Atlantic Oscillation (NAO), but this link has been described as unstable because of a lack of consistency over time scales longer than the last two decades. Inconsistent and low correlations are also found between From Strait ice export and the Arctic Oscillation (AD) index. This paper shows that the phase of zonal wave 1 explains 60% - 70% of the simulated From Strait ice export variance over the Goodyear period 1958 - 1997. Unlike the NAB and AD links, these high variances are consistent for both the first and second halves of the Goodyear period. This consistency is attributed to the sensitivity of the wave I phase at high latitudes to the presence of secondary low pressure systems in the Barents Sea that serve to drive sea ice southward through From Strait. These results provide further evidence that the phase of zonal wave 1 in SLP at high latitudes drives regional as well as hemispheric low frequency Arctic Ocean and sea ice variability.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  16. Simulating influences of QBO phases and orographic gravity wave forcing on planetary waves in the middle atmosphere

    NASA Astrophysics Data System (ADS)

    Gavrilov, Nikolai M.; Koval, Andrej V.; Pogoreltsev, Alexander I.; Savenkova, Elena N.

    2015-12-01

    Recently developed parameterization of stationary orographic gravity waves (OGWs) generated by the Earth's topography was implemented into a general circulation model of the middle and upper atmosphere. We performed numerical simulations of the zonal mean wind and amplitudes of stationary planetary waves and normal atmospheric modes with periods of 4-16 days at altitudes from the troposphere to the lower thermosphere in January for easterly and westerly phases of the quasi-biennial oscillation (QBO) including and excluding the stationary OGW parameterization. Simulations show that accounting dynamical and thermal effects of stationary OGWs can lead to substantial changes (up to 50-90 %) in the amplitudes of stationary planetary waves. Amplitudes of westward travelling normal atmospheric modes change (up to 50-90 %) at different altitudes and latitudes of the northern hemisphere due to OGW effects. Transitions from the easterly to westerly QBO phases can change planetary wave amplitudes up to ±30-90 % at middle and high latitudes. These changes in PW amplitudes are consistent with distributions of EP-flux and refractive index under different QBO phases simulated including our parameterization of stationary OGWs.

  17. Computing planetary atmospheres with algorithms derived from action thermodynamics and a novel version of the virial theorem for gravitating polyatomic molecules

    E-print Network

    Kennedy, Ivan R

    2015-01-01

    An objective revision of the Laplace barometric formula for isothermal planetary atmospheres is proposed. From Clausius virial theorem equating the root mean square kinetic energy to half the gravitational potential energy, planetary atmospheres are required to have declining temperature with altitude as a consequence of the interaction between thermodynamic heat flow and gravity. The virial action hypothesis predicts non adiabatic lapse rates in temperature yielding a practical means to calculate variations with altitude in atmospheric entropy, free energy, molecular density and pressure. Remarkably, the new formulae derived enable prediction of atmospheric profiles with physical properties closely resembling those observed on Earth, Venus and Mars. These new formulae provide an objective basis for computing the dynamic morphology of the atmosphere. Climate scientists may consider this explanatory hypothesis for self organisation of planetary atmospheres for its possible relevance for predicting global surfa...

  18. Characterization of Extrasolar Planets Using SOFIA

    NASA Technical Reports Server (NTRS)

    Deming, Drake

    2010-01-01

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

  19. Turbulence in planetary occultations. II - Effects on atmospheric profiles derived from Doppler measurements. III - Effects on atmospheric profiles derived from intensity measurements

    NASA Technical Reports Server (NTRS)

    Haugstad, B. S.

    1978-01-01

    The nature and magnitude of turbulence-induced errors in atmospheric profiles derived from Doppler measurements made during radio occultations are investigated. It is found that turbulence in planetary atmospheres induces both fluctuating and systematic errors in derived profiles, but the errors of both types are very small. Consideration of the occultation of Mariner 10 by Venus and of the Pioneer occultations by Jupiter shows that the rms fractional errors in the atmospheric profiles derived from these observations were less than 0.01 in both temperature and pressure, while the fractional systematic errors were typically of the order of 1 millionth. The extent to which atmospheric profiles derived from radio and optical intensity measurements are affected by turbulence is also examined. The results indicate that turbulence in planetary atmospheres has only a marginal effect on derived profiles in the weak-scattering limit and that the turbulence-induced errors in this case are always much larger than the corresponding errors in profiles derived from radio Doppler measurements.

  20. On the possibility of coherent cyclotron emission from extrasolar planets

    NASA Astrophysics Data System (ADS)

    Farrell, W. M.; Desch, M. D.; Zarka, P.

    1999-06-01

    A model of the coherent cyclotron emission from extrasolar planets is presented. Scaling laws known to operate in our solar system (including scaling laws of planetary magnetic fields and the radiometric Bode's law of radio power generation) are applied to the extrasolar systems. We consider the possibility that each of the extrasolar planets possesses a substantial planetary magnetic field which is in quasi-continuous interaction with the local stellar wind. Cyclotron emission from extrasolar planets is then driven by the stellar wind/magnetospheric interaction, much like the coherent cyclotron radio emission processes associated with planets in our solar system. Based on the model results, the best candidate for solar-wind-driven cyclotron emission is Tau Bootes, with an expected median amplitude of about 2 janskys (1Jy=10-26Wm-2Hz-1) at 28 MHz, an intensity level of about a factor of 100 below the current limit of detectability. However, variations in the local stellar medium could conceivably increase power levels by a factor of 100 for short periods of time. Like the solar planets, the extrasolar planets should radiate episodically, with emission reoccurring at the planetary rotation period. Thus spectral integration techniques could also be applied to improve the likelihood of detectability.

  1. The aurora as a source of planetary-scale waves in the middle atmosphere. [atmospheric turbulence caused by auroral energy absorption

    NASA Technical Reports Server (NTRS)

    Chiu, Y. T.; Straus, J. M.

    1974-01-01

    Photographs of global scale auroral forms taken by scanning radiometers onboard weather satellites in 1972 show that auroral bands exhibit well organized wave motion with typical zonal wave number of 5 or so. The scale size of these waves is in agreement with that of well organized neutral wind fields in the 150- to 200-km region during the geomagnetic storm of May 27, 1967. Further, the horizontal scale size revealed by these observations are in agreement with that of high altitude traveling ionospheric disturbances. It is conjectured that the geomagnetic storm is a source of planetary and synoptic scale neutral atmospheric waves in the middle atmosphere. Although there is, at present, no observation of substorm related waves of this scale size at mesospheric and stratospheric altitudes, the possible existence of a new source of waves of the proper scale size to trigger instabilities in middle atmospheric circulation systems may be significant in the study of lower atmospheric response to geomagnetic activity.

  2. A Lumped Element Thermal Model of Solar Flare Gradual Phase EUV Emissions for Planetary Atmosphere Studies

    NASA Astrophysics Data System (ADS)

    Thiemann, Edward; Eparvier, Francis G.

    2015-04-01

    Gradual phase solar flare EUV emissions show a time dependence related to the cooling of the flare plasma where emission lines with higher formation temperatures peak earlier than cooler emission lines. Because photon absorption height in a planetary atmosphere is wavelength dependent, being able to spectrally model this time dependence using available wavelengths is necessary to accurately characterize the temporal response of an atmosphere to a flare when high time cadence measurements of the EUV spectrum are unavailable. Furthermore, both the spectral and wavelength dependent temporal behavior of a flare impact where the total flare energy is absorbed in an atmosphere.To address this challenge, we have developed a Lumped Element Thermal Model (LETM) which can accurately model the flare gradual phase time evolution for emission lines with peak formation temperatures above 106 K based on a cooling rate derived from only two emission lines. We will show that the 13.3 nm Fe XX and 9.4 nm Fe XVIII emission lines can be used to determine a cooling rate. This cooling rate can then be used to calculate a time constant, ?i, associated with a ith EUV emission; and the ith emission’s time-response can then be modeled by passing the measured Fe XX time-series through a digital low pass filter with time constant ?i. An implication of the LETM, is that it constrains the time evolution of the volume integrated flare irradiance which is directly related to the flare emission measure. Detailed analysis suggests that the LETM provides a method to measure the flare thermal conductance and specific heat, and constrains the flare cooling rate and differential emission measure.To broaden the utility of the LETM, correlations between the emission line derived cooling rate and broadband measurements made by MAVEN EUV or other commonly available Earth assets must be found. Therefore, in addition to introducing the LETM, we will review progress towards finding correlations with properties of broadband soft x-ray measurements, as well as relevant multi-channel instruments.

  3. Transit of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Doyle, Laurance R.

    1998-01-01

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

  4. Observed properties of extrasolar planets.

    PubMed

    Howard, Andrew W

    2013-05-01

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

  5. The Realm of Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Ferlet, Roger

    2010-10-01

    In November 1995, an article published in Nature [1] put planetary sciences not only as a new hot field in both observational and theoretical astrophysics but also as a topic with a large impact toward the layman. This article was reporting the first discovery of a planet orbiting a star beyond our Sun, namely the solar-type star 51 Pegasi. Nearly four centuries after Giordano Bruno was burnt in public in Roma partly for having intuitively claimed the plurality of worlds, we were entering the extraordinary epoch in which one of the oldest inquiries of mankind-are we alone in the Universe?-can be tackled with the scientific method, leaving aside centuries of endless speculations. To date (July 2010), almost 500 extrasolar planets are known. We shall briefly review the main detection methods, together with the big surprises which arose during these last exciting fifteen years, without being exhaustive.

  6. Planetary Bow Shocks

    E-print Network

    R. A. Treumann; C. H. Jaroschek

    2008-08-12

    Our present knowledge of the properties of the various planetary bow shocks is briefly reviewed. We do not follow the astronomical ordering of the planets. We rather distinguish between magnetised and unmagnetised planets which groups Mercury and Earth with the outer giant planets of the solar system, Mars and Moon in a separate group lacking magnetic fields and dense atmospheres, and Venus together with the comets as the atmospheric celestial objects exposed to the solar wind. Asteroids would, in this classification, fall into the group together with the Moon and should behave similarly though being much smaller. Extrasolar planets are not considered as we have only remote information about their behaviour. The presentation is brief in the sense that our in situ knowledge is rather sporadic yet, depending on just a countable number of bow shock crossings from which just some basic conclusions can be drawn about size, stationarity, shape and nature of the respective shock. The only bow shock of which we have sufficient information to deal in sufficient depth with its physics is Earth's bow shock. This has been reviewed in other places in this volume and therefore is mentioned here only as the bow shock paradigm in passing.

  7. Planetary Systems and the Origins of Life

    NASA Astrophysics Data System (ADS)

    Pudritz, Ralph; Higgs, Paul; Stone, Jonathon

    2013-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  9. Laboratory studies, analysis, and interpretation of the spectra of hydrocarbons present in planetary atmospheres including cyanoacetylene, acetylene, propane, and ethane

    NASA Technical Reports Server (NTRS)

    Blass, William E.; Daunt, Stephen J.; Peters, Antoni V.; Weber, Mark C.

    1990-01-01

    Combining broadband Fourier transform spectrometers (FTS) from the McMath facility at NSO and from NRC in Ottawa and narrow band TDL data from the laboratories with computational physics techniques has produced a broad range of results for the study of planetary atmospheres. Motivation for the effort flows from the Voyager/IRIS observations and the needs of Voyager analysis for laboratory results. In addition, anticipation of the Cassini mission adds incentive to pursue studies of observed and potentially observable constituents of planetary atmospheres. Current studies include cyanoacetylene, acetylene, propane, and ethane. Particular attention is devoted to cyanoacetylen (H3CN) which is observed in the atmosphere of Titan. The results of a high resolution infrared laboratory study of the line positions of the 663, 449, and 22.5/cm fundamental bands are presented. Line position, reproducible to better than 5 MHz for the first two bands, are available for infrared astrophysical searches. Intensity and broadening studies are in progress. Acetylene is a nearly ubiquitous atmospheric constituent of the outer planets and Titan due to the nature of methane photochemistry. Results of ambient temperature absolute intensity measurements are presented for the fundamental and two two-quantum hotband in the 730/cm region. Low temperature hotband intensity and linewidth measurements are planned.

  10. Photochemical abiotic synthesis of amino-acid precursors from simulated planetary atmospheres by vacuum ultraviolet light

    SciTech Connect

    Takahashi, Jun-ichi; Masuda, Hitomi; Kaneko, Takeo; Kobayashi, Kensei; Saito, Takeshi; Hosokawa, Teruo

    2005-07-15

    For the purpose of investigating the photon energy dependence of the photoinduced abiotic synthesis of organic molecules, gas mixtures that simulate typical planetary atmospheres, including a carbon source (CO or CH{sub 4}), a nitrogen source (N{sub 2} or NH{sub 3}), and H{sub 2}O, were irradiated with synchrotron radiation through a vacuum-ultraviolet transmitting window. Three kinds of window material, fused silica, synthetic quartz, and MgF{sub 2}, were used as a high-energy-cutting filter, whose absorption-edge energies are 6.4, 8.1, and 10.5 eV, respectively. Three types of gas mixture, Titan-type (CH{sub 4}-N{sub 2}-H{sub 2}O), comet-type (CO-NH{sub 3}-H{sub 2}O), and primitive-Earth-type (CO-N{sub 2}-H{sub 2}O), were irradiated with vacuum-ultraviolet photons in the three energy ranges. After the irradiation, amino-acid formation yields in the acid-hydrolyzed solution of the product were measured with a high-performance liquid chromatograph method. From the Titan- and comet-type mixtures, amino acids were detected by irradiation with photons lower than 8.1 eV. For both mixtures, the averaged quantum yields of glycine generation in the photon energy region of 7-10.5 eV were of the order of 10{sup -5}, which was larger by about one order than that in the region 5-8 eV. On the other hand, from the primitive-Earth-type mixture, amino-acid formation was difficult to detect even with irradiation as high as 10.5 eV, even though amino acids were generated in comparable yields from the Titan- and comet-type mixtures by irradiation with soft x rays or proton beam, whose energies are much higher. These results suggest that the vacuum ultraviolet light is a more effective energy source for the generation of the precursors of bioorganic compounds in extraterrestrial environments than in primitive-Earth atmosphere.

  11. Time-Dependent Gas Kinetics in Tenuous Planetary Atmospheres: The Cometary Coma

    NASA Astrophysics Data System (ADS)

    Combi, Michael R.

    1996-09-01

    The physics of steady and non-steady gas kinetic flow in the cometary coma has been explored using a new time-dependent kinetic model, which is based on Direct Simulation Monte Carlo (DSMC) methods and has been developed to study problems where the gas is not in local thermodynamic equilibrium so the validity of hydrodynamical approaches is questionable. The model is also applicable to a class of tenuous planetary atmosphere problems in addition to comets, e.g., Io, Pluto, and the upper atmospheres of the terrestrial planets and Titan. The results for a strong 2-D axisymmetric subsolar gas jet in a moderate comet (a few times 1028molecules sec-1) show that kinetic (non-fluid) effects become important in the flanks of the jet and on the night sidein the immediate vicinity of the nucleus.Although the inner coma remains non-spherical, there is considerable flow (15%) into the night hemisphere (even in this dust-less model) and day-to-night winds with speeds in excess of 350 m sec-1are found near the terminator. Comparisons with new adaptive-grid hydrodynamic models show excellent agreement in the collisionally thick region of the jet, but more flow into the night side. A 1-D spherical steady-state model for six species (H2O, CO, OH, H2, O, and H) at Giotto Halley flyby conditions is compared with the Giotto data, and contrasted with past hybrid fluid/kinetic and recent iterative test particle kinetic models. Although the non-fluid nature of the 103-105km region of the coma is evident in all kinetic models and the qualitative behavior is similar, the ability of the DSMC model to include internal (rotational) energy causes it to yield lower kinetic temperatures for H2and OH and enables it to determine explicitly the decreasing efficiency of IR rotational cooling in the outer coma due to non-LTE effects. The capability to model time-dependent kinetics is the strength of the DSMC method. A calculation has been performed for the 7-day periodic variation of Halley and shows that the variation in gas production rate produces a consequent temporal/spatial variation in outflow velocity. It is found that the amplitude of the gas production rate variation in March 1986, when taken directly from the typical constant-velocity analysis of photometric observations of cometary radicals, underestimates the true production from the nucleus by about 20-25%. Therefore, the amplitude of the periodic variation in March should be as large as that measured for April 1986 where the velocity effects are nil.

  12. Laboratory and theoretical work in the service of planetary atmospheric research

    NASA Astrophysics Data System (ADS)

    Coustenis, Athena

    2015-08-01

    A large quantity of observations is obtained by instruments onboard space missions exploring our solar system and by large ground-based telescopes observing the planets and also the exoplanets. Spectroscopy plays a major role in this type of investigation. To analyze and exploit these observations, planetary scientists need spectroscopic data covering wide ranges in wavelength but also in temperature, pressure, distance, etc.The outer regions of our solar system in particular, including the giant gaseous planets Jupiter and Saturn and their satellites, have recently been the target of space missions such as Cassini-Huygens and several investigations from the ground. Titan, the largest moon of Saturn, in particular, offers many similarities with our own planet, among which a dense atmosphere whose major component is dinitrogen at about 95%. Combining with methane (at a few percent) and hydrogen, gives rise to a complex organic chemistry with hydrocarbons and nitriles. Oxygen compounds also exist in Titan’s atmosphere. By studying Titan, we learn about our own planet and our Solar system Solar as a whole [1,2,3]. To properly interpret the Cassini-Huygens data and in anticipation of future missions like ESA’s JUICE to the Jupiter system, spectroscopic data are crucially needed. In the field of exoplanets (over 1000 discovered to date), it also becomes urgent to have adequate data of several molecules in order to analyze the observations returned to us every day by major observatories on Earth and in the space [4,5]. I will discuss recent applications from theoretical and experimental studies on the investigation of Titan and exoplanets, with emphasis on methane. I will also present some needs for future analyses.References: [1] Campargue, A., et al. 2012. Icarus 219, 110-128. [2] Coustenis, A., et al. 2013. Astrophys. J. 799, 177, 9p. [3] Hirtzig, et al., 2013. Icarus 226, 470-486 and corrigendum 1182-1182. [4] Tinetti, G., Encrenaz, Th., Coustenis, A., 2013. Astron. Astrophys. Rev. 21, #63. [5] Encrenaz, T., et al., 2014. Experimental Astronomy, DOI: 10.1007/s10686-014-9415-0.

  13. Models of Irradiated Extrasolar Giant Planets

    E-print Network

    Adam Burrows; David Sudarsky

    2002-07-23

    We review some of the characteristics of irradiated extrasolar giant planets (EGPs), in anticipation of their direct detection from the ground and from space. Spectral measurements are the key to unlocking their structural and atmospheric characteristics and to determining the true differences between giant planets and brown dwarfs. In this spirit, the theoretical spectral and atmospheric calculations we summarize here are in support of the many searches for EGPs to be conducted in the coming decade by astronomers from around the world.

  14. ATMOSPHERIC CIRCULATION OF ECCENTRIC HOT NEPTUNE GJ436b

    SciTech Connect

    Lewis, Nikole K.; Showman, Adam P.; Fortney, Jonathan J.; Marley, Mark S.; Freedman, Richard S.; Lodders, Katharina

    2010-09-01

    GJ436b is a unique member of the transiting extrasolar planet population being one of the smallest and least irradiated and possessing an eccentric orbit. Because of its size, mass, and density, GJ436b could plausibly have an atmospheric metallicity similar to Neptune (20-60 times solar abundances), which makes it an ideal target to study the effects of atmospheric metallicity on dynamics and radiative transfer in an extrasolar planetary atmosphere. We present three-dimensional atmospheric circulation models that include realistic non-gray radiative transfer for 1, 3, 10, 30, and 50 times solar atmospheric metallicity cases of GJ436b. Low metallicity models (1 and 3 times solar) show little day/night temperature variation and strong high-latitude jets. In contrast, higher metallicity models (30 and 50 times solar) exhibit day/night temperature variations and a strong equatorial jet. Spectra and light curves produced from these simulations show strong orbital phase dependencies in the 50 times solar case and negligible variations with orbital phase in the 1 times solar case. Comparisons between the predicted planet/star flux ratio from these models and current secondary eclipse measurements support a high metallicity atmosphere (30-50 times solar abundances) with disequilibrium carbon chemistry at play for GJ436b. Regardless of the actual atmospheric composition of GJ436b, our models serve to illuminate how metallicity influences the atmospheric circulation for a broad range of warm extrasolar planets.

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

    SciTech Connect

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

    2010-06-01

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

  16. Extrasolar Trojan Planets close to Habitable Zones

    E-print Network

    R. Dvorak; E. Pilat-Lohinger; R. Schwarz; F. Freistetter

    2004-08-04

    We investigate the stability regions of hypothetical terrestrial planets around the Lagrangian equilibrium points L4 and L5 in some specific extrasolar planetary systems. The problem of their stability can be treated in the framework of the restricted three body problem where the host star and a massive Jupiter-like planet are the primary bodies and the terrestrial planet is regarded as being massless. From these theoretical investigations one cannot determine the extension of the stable zones around the equilibrium points. Using numerical experiments we determined their largeness for three test systems chosen from the table of the know extrasolar planets, where a giant planet is moving close to the so-called habitable zone around the host star in low eccentric orbits. The results show the dependence of the size and structure of this region, which shrinks significantly with the eccentricity of the known gas giant.

  17. A Possible Aeronomy of Extrasolar Terrestrial Planets

    E-print Network

    W. A. Traub; K. W. Jucks

    2002-05-22

    Terrestrial planetary systems may exist around nearby stars as the Earth-sized counterparts to the many giant planets already discovered within the solar neighborhood. In this chapter we first discuss the numerous techniques which have been suggested to search for extrasolar terrestrial planets. We then focus on the expected results from that technique in which an orbiting telescope or interferometer is used to obtain a visible or infrared spectrum of a planet, without contamination from the parent star. We show examples of such spectra for selected cases: the present Earth, the Neoproterozoic (snowball) Earth, a methane-rich Earth, and the present Mars and Venus. We conclude by discussing the implications of such spectra for the detection of life on an extrasolar terrestrial planet.

  18. Planetary Surface Instruments Workshop

    NASA Technical Reports Server (NTRS)

    Meyer, Charles (Editor); Treiman, Allan H. (Editor); Kostiuk, Theodor (Editor)

    1996-01-01

    This report on planetary surface investigations and planetary landers covers: (1) the precise chemical analysis of solids; (2) isotopes and evolved gas analyses; (3) planetary interiors; planetary atmospheres from within as measured by landers; (4) mineralogical examination of extraterrestrial bodies; (5) regoliths; and (6) field geology/processes.

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

    E-print Network

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

    2014-01-01

    Upper atmospheres of Hot Jupiters are subject to extreme radiation conditions that can result in rapid atmospheric escape. The composition and structure of the upper atmospheres of these planets are affected by the high-energy spectrum of the host star. This emission depends on stellar type and age, which are thus important factors in understanding the behaviour of exoplanetary atmospheres. In this study, we focus on Extrasolar Giant Planets (EPGs) orbiting K and M dwarf stars. XUV spectra for three different stars - epsilon Eridani, AD Leonis and AU Microscopii - are constructed using a coronal model. Neutral density and temperature profiles in the upper atmosphere of hypothetical EGPs orbiting these stars are then obtained from a fluid model, incorporating atmospheric chemistry and taking atmospheric escape into account. We find that a simple scaling based solely on the host star's X-ray emission gives large errors in mass loss rates from planetary atmospheres and so we have derived a new method to scale th...

  20. PHYS 390 Lecture 9 -Planetary atmospheres 9 -1 2001 by David Boal, Simon Fraser University. All rights reserved; further resale or copying is strictly prohibited.

    E-print Network

    Boal, David

    , atmosphere would resemble Venus) · Earth is too far away from Sun to have the runaway greenhouse effect pressure = 90 atm and surface temperature = 740 K because of greenhouse effect · probably once containedPHYS 390 Lecture 9 - Planetary atmospheres 9 - 1 © 2001 by David Boal, Simon Fraser University. All

  1. MASSACHUSETTS INSTITUTE OF TECHNOLOGY | DEpArTMENT OF EArTH, ATMOSpHErIC AND pLANETArY SCIENCES S AN UNDErGrADUATE at Carleton

    E-print Network

    Seager, Sara

    MASSACHUSETTS INSTITUTE OF TECHNOLOGY | DEpArTMENT OF EArTH, ATMOSpHErIC AND pLANETArY SCIENCES him to MIT's Department of Earth, Atmospheric and planetary Sciences (EApS) and to the Joint program, including geology, geochemistry, geophysics, geobiol- ogy, atmospheric science, oceanography, astronomy

  2. Working model of the atmosphere and near planetary space of Jupiter

    NASA Technical Reports Server (NTRS)

    Moroz, V. I. (editor)

    1978-01-01

    Basic physical characteristics of Jupiter, its gravitational field, atmosphere, electromagnetic radiation, magnetosphere, meteorite situation and satellites are presented in tables, graphs and figures. Means of observation of the atmosphere and three models of the atmosphere are presented and analyzed.

  3. A TEOM (tm) particulate monitor for comet dust, near Earth space, and planetary atmospheres

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Scientific missions to comets, near earth space, and planetary atmospheres require particulate and mass accumulation instrumentation for both scientific and navigation purposes. The Rupprecht & Patashnick tapered element oscillating microbalance can accurately measure both mass flux and mass distribution of particulates over a wide range of particle sizes and loadings. Individual particles of milligram size down to a few picograms can be resolved and counted, and the accumulation of smaller particles or molecular deposition can be accurately measured using the sensors perfected and toughened under this contract. No other sensor has the dynamic range or sensitivity attained by these picogram direct mass measurement sensors. The purpose of this contract was to develop and implement reliable and repeatable manufacturing methods; build and test prototype sensors; and outline a quality control program. A dust 'thrower' was to be designed and built, and used to verify performance. Characterization and improvement of the optical motion detection system and drive feedback circuitry was to be undertaken, with emphasis on reliability, low noise, and low power consumption. All the goals of the contract were met or exceeded. An automated glass puller was built and used to make repeatable tapered elements. Materials and assembly methods were standardized, and controllers and calibrated fixtures were developed and used in all phases of preparing, coating and assembling the sensors. Quality control and reliability resulted from the use of calibrated manufacturing equipment with measurable working parameters. Thermal and vibration testing of completed prototypes showed low temperature sensitivity and high vibration tolerance. An electrostatic dust thrower was used in vacuum to throw particles from 2 x 10(exp 6) g to 7 x 10(exp -12) g in size. Using long averaging times, particles as small as 0.7 to 4 x 10(exp 11) g were weighted to resolutions in the 5 to 9 x 10(exp -13) g range. The drive circuit and optics systems were developed beyond what was anticipated in the contract, and are now virtually flight prototypes. There is already commercial interest in the developed capability of measuring picogram mass losses and gains. One area is contamination and outgassing research, both measuring picogram losses from samples and collecting products of outgassing.

  4. Using N2-N2 Collisionally-Induced Absorption to Detect N2 and Determine Pressure in Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Schwieterman, Edward; Robinson, T. D.; Meadows, V.; Crisp, D.; Misra, A.

    2014-01-01

    Planetary habitability is determined by the stability of liquid water at the surface, which depends on surface temperature and pressure. While molecular nitrogen (N2) constitutes the bulk of Earth’s atmosphere 78% by volume) and is the biggest contributor to surface pressure, it is also extremely hard to remotely detect. In particular, N2 lacks significant absorption features in the visible to near infrared because it is a symmetric homonuclear molecule with no transitional dipole moment. However, nitrogen has a collisionally-induced absorption (CIA) feature near 4.3 ?m, nearly coincident with the 4.3 ?m CO2 band but extending to shorter wavelengths. This feature has been known to spectroscopists for some time, but has never been considered in the context of exoplanet characterization from full-disk observations. We report a direct detection of this N2-N2 CIA feature in disk-integrated spectra of Earth taken by NASA’s EPOXI mission. We use the Virtual Planetary Laboratory’s 3D, line-by-line, multiply scattering Earth Model (Robinson et al., 2011) to match the EPOXI spectrum with a synthetic spectrum that includes N2-N2 CIA (coefficients from Lafferty et al., 1996). Because N2 is stable in the atmosphere for geologically long periods and is present in large quantities in the atmospheres of Earth and Venus, it may be a major component of many terrestrial exoplanet atmospheres. Since the strength of a CIA feature goes as the square of the density of the gas, it is more sensitive to pressure than other forms of absorption. We use a self-consistent 1D climate model and a line-by-line radiative transfer model to explore different pressure scenarios from 0.2 to 10 bars assuming pure N2-CO2-H2O atmospheres. We investigate the detectability of N2 in direct beam and transmission and quantify the signal-to-noise ratio required to distinguish between the different pressure cases. For example, to detect the difference between the 1 and 2 bar models at a 5-sigma level in direct beam observations at 4 ?m (??=0.05 ?m), we find a signal-to noise ratio of 8.1 is required. For planets whose atmospheres contain primarily nitrogen, this is another tool to quantify pressure and, thus, to help constrain planetary habitability.

  5. DETECTING OCEANS ON EXTRASOLAR PLANETS USING THE GLINT EFFECT

    SciTech Connect

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

    2010-09-20

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

  6. Atmospheric Escape from Hot Jupiters

    E-print Network

    A. Lecavelier des Etangs; A. Vidal-Madjar; J. C. McConnell; G. Hebrard

    2004-03-16

    The extra-solar planet HD209458b has been found to have an extended atmosphere of escaping atomic hydrogen (Vidal-Madjar et al. 2003), suggesting that ``hot Jupiters'' closer to their parent stars could evaporate. Here we estimate the atmospheric escape (so called evaporation rate) from hot Jupiters and their corresponding life time against evaporation. The calculated evaporation rate of HD209458b is in excellent agreement with the HI Lyman-alpha observations. We find that the tidal forces and high temperatures in the upper atmosphere must be taken into account to obtain reliable estimate of the atmospheric escape. Because of the tidal forces, we show that there is a new escape mechanism at intermediate temperatures at which the exobase reaches the Roche lobe. From an energy balance, we can estimate plausible values for the planetary exospheric temperatures, and thus obtain typical life times of planets as a function of their mass and orbital distance.

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

    NASA Technical Reports Server (NTRS)

    Pravdo, Steven H.

    1991-01-01

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

  8. The Compositional Diversity of Extrasolar Terrestrial Planets: II. Migration Simulations

    E-print Network

    Carter-Bond, Jade C; Raymond, Sean N

    2012-01-01

    Prior work has found that a variety of terrestrial planetary compositions are expected to occur within known extrasolar planetary systems. However, such studies ignored the effects of giant planet migration, which is thought to be very common in extra-solar systems. Here we present calculations of the compositions of terrestrial planets that formed in dynamical simulations incorporating varying degrees of giant planet migration. We used chemical equilibrium models of the solid material present in the disks of five known planetary host stars: the Sun, GJ 777, HD4203, HD19994 and HD213240. Giant planet migration has a strong effect on the compositions of simulated terrestrial planets as the migration results large-scale mixing between terrestrial planet building blocks that condensed at a range of temperatures. This mixing acts to 1) increase the typical abundance of Mg-rich silicates in the terrestrial planets feeding zones and thus increase the frequency of planets with Earth-like compositions compared with s...

  9. Direct Imaging of Warm Extrasolar Planets

    SciTech Connect

    Macintosh, B

    2005-04-11

    One of the most exciting scientific discoveries in the last decade of the twentieth century was the first detection of planets orbiting a star other than our own. By now more than 130 extrasolar planets have been discovered indirectly, by observing the gravitational effects of the planet on the radial velocity of its parent star. This technique has fundamental limitations: it is most sensitive to planets close to their star, and it determines only a planet's orbital period and a lower limit on the planet's mass. As a result, all the planetary systems found so far are very different from our own--they have giant Jupiter-sized planets orbiting close to their star, where the terrestrial planets are found in our solar system. Such systems have overturned the conventional paradigm of planet formation, but have no room in them for habitable Earth-like planets. A powerful complement to radial velocity detections of extrasolar planets will be direct imaging--seeing photons from the planet itself. Such a detection would allow photometric measurements to determine the temperature and radius of a planet. Also, direct detection is most sensitive to planets in wide orbits, and hence more capable of seeing solar systems resembling our own, since a giant planet in a wide orbit does not preclude the presence of an Earth-like planet closer to the star. Direct detection, however, is extremely challenging. Jupiter is roughly a billion times fainter than our sun. Two techniques allowed us to overcome this formidable contrast and attempt to see giant planets directly. The first is adaptive optics (AO) which allows giant earth-based telescopes, such as the 10 meter W.M. Keck telescope, to partially overcome the blurring effects of atmospheric turbulence. The second is looking for young planets: by searching in the infrared for companions to young stars, we can see thermal emission from planets that are still warm with the heat of their formation. Together with a UCLA team that leads the field of young-star identification, we carried out a systematic near-infrared search for young planetary companions to {approx}200 young stars. We also carried out targeted high-sensitivity observations of selected stars surrounded by circumstellar dust rings. We developed advanced image processing techniques to allow detection of even fainter sources buried in the noisy halo of scattered starlight. Even with these techniques, around most of our targets our search was only sensitive to planets in orbits significantly wider than our solar system. With some carefully selected targets--very young dusty stars in the solar neighborhood--we reach sensitivities sufficient to see solar systems like our own. Although we discovered no unambiguous planets, we can significantly constrain the frequency of such planets in wide (>50 AU) orbits, which helps determine which models of planet formation remain plausible. Successful modeling of our observations has led us to the design of a next-generation AO system that will truly be capable of exploring solar systems resembling our own.

  10. A Massively Parallel Particle Code for Rarefied Ionized and Neutral Gas Flows in Earth and Planetary Atmospheres, Ionospheres and Magnetospheres

    NASA Technical Reports Server (NTRS)

    Combi, Michael R.

    2004-01-01

    In order to understand the global structure, dynamics, and physical and chemical processes occurring in the upper atmospheres, exospheres, and ionospheres of the Earth, the other planets, comets and planetary satellites and their interactions with their outer particles and fields environs, it is often necessary to address the fundamentally non-equilibrium aspects of the physical environment. These are regions where complex chemistry, energetics, and electromagnetic field influences are important. Traditional approaches are based largely on hydrodynamic or magnetohydrodynamic MHD) formulations and are very important and highly useful. However, these methods often have limitations in rarefied physical regimes where the molecular collision rates and ion gyrofrequencies are small and where interactions with ionospheres and upper neutral atmospheres are important.

  11. Homes for extraterrestrial life: extrasolar planets.

    PubMed

    Latham, D W

    2001-12-01

    Astronomers are now discovering giant planets orbiting other stars like the sun by the dozens. But none of these appears to be a small rocky planet like the earth, and thus these planets are unlikely to be capable of supporting life as we know it. The recent discovery of a system of three planets is especially significant because it supports the speculation that planetary systems, as opposed to single orbiting planets, may be common. Our ability to detect extrasolar planets will continue to improve, and space missions now in development should be able to detect earth-like planets. PMID:11797754

  12. On the temperature dependence of possible S8 infrared bands in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Khare, B. N.; Sagan, C.

    1976-01-01

    Measurements of the temperature dependence between 77 and 333 K of the infrared spectrum of cyclic octatomic sulfur are reported. It is suggested that the 23 micrometer Jovian feature is not due to 3 sub 8 and that the temperature dependence of the frequency of the 835/cm band of S sub 8 may be a useful temperature marker in planetary studies.

  13. Planetary population synthesis coupled with atmospheric escape: a statistical view of evaporation

    SciTech Connect

    Jin, Sheng; Ji, Jianghui; Mordasini, Christoph; Van Boekel, Roy; Henning, Thomas; Parmentier, Vivien E-mail: mordasini@mpia.de

    2014-11-01

    We apply hydrodynamic evaporation models to different synthetic planet populations that were obtained from a planet formation code based on the core-accretion paradigm. We investigated the evolution of the planet populations using several evaporation models, which are distinguished by the driving force of the escape flow (X-ray or EUV), the heating efficiency in energy-limited evaporation regimes, or both. Although the mass distribution of the planet populations is barely affected by evaporation, the radius distribution clearly shows a break at approximately 2 R {sub ?}. We find that evaporation can lead to a bimodal distribution of planetary sizes and to an 'evaporation valley' running diagonally downward in the orbital distance—planetary radius plane, separating bare cores from low-mass planets that have kept some primordial H/He. Furthermore, this bimodal distribution is related to the initial characteristics of the planetary populations because low-mass planetary cores can only accrete small primordial H/He envelopes and their envelope masses are proportional to their core masses. We also find that the population-wide effect of evaporation is not sensitive to the heating efficiency of energy-limited description. However, in two extreme cases, namely without evaporation or with a 100% heating efficiency in an evaporation model, the final size distributions show significant differences; these two scenarios can be ruled out from the size distribution of Kepler candidates.

  14. Electrodynamics in Giant Planet Atmospheres

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    The atmospheres of close-in extrasolar giant planets such as HD209458b are strongly ionized by the UV flux of their host stars. We show that photoionization on such planets creates a dayside ionosphere that extends from the thermosphere to the 100 mbar level. The resulting peak electron density near the 1 mbar level is higher than that encountered in any planetary ionosphere of the solar system, and the model conductivity is in fact comparable to the atmospheres of Sun-like stars. As a result, the momentum and energy balance in the upper atmosphere of HD209458b and similar planets can be strongly affected by ion drag and resistive heating arising from wind-driven electrodynamics. Despite much weaker ionization, electrodynamics is nevertheless also important on the giant planets of the solar system. We use a generic framework to constrain the conductivity regimes on close-in extrasolar planets, and compare the results with conductivites based on the same approach for Jupiter and Saturn. By using a generalized Ohm's law and assumed magnetic fields, we then demonstrate the basic effects of wind-driven ion drag in giant planet atmospheres. Our results show that ion drag is often significant in the upper atmosphere where it can also substantially alter the energy budget through resistive heating.

  15. A smoothing technique for improving atmospheric reconstruction for planetary entry probes

    E-print Network

    Withers, Paul

    atmospheric flight (Desai et al., 2011). Post-flight, these acceleration measurements can be used to determine the spacecraft's atmospheric trajectory and to analyze vehicle performance (Blanchard and Desai, 2011). They can also be used to derive the local atmospheric density along the trajectory, which is scientifically

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

    PubMed

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

    2014-09-01

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

  17. Formation, Habitability, and Detection of Extrasolar Moons

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  18. On the wavelength dependence of the effects of turbulence on average refraction angles in occultations by planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Haugstad, B. S.; Eshleman, V. R.

    1979-01-01

    The dependence of the effects of planetary atmospheric turbulence on radio or optical wavelength in occultation experiments is discussed, and the analysis of Hubbard and Jokipii (1977) is criticized. It is argued that in deriving a necessary condition for the applicability of their method, Hubbard and Jokipii neglect a factor proportional to the square of the ratio of atmospheric or local Fresnel zone radius and the inner scale of turbulence, and fail to establish sufficient conditions, thereby omitting the square of the ratio of atmospheric scale height and the local Fresnel zone radius. The total discrepancy is said to mean that the results correspond to geometrical optics instead of wave optics, as claimed, thus being inapplicable in a dicussion of wavelength dependence. Calculations based on geometrical optics show that the bias in the average bending angle depends on the wavelength in the same way as does the bias in phase path caused by turbulence in a homogeneous atmosphere. Hubbard and Jokipii comment that the criterion of Haugstad and Eshleman is incorrect and show that there is a large wave optical domain where the results are independent of wavelength.

  19. Solar cycle influence on troposphere and middle atmosphere via ozone layer in the presence of planetary waves: Simulation with ARM

    NASA Astrophysics Data System (ADS)

    Krivolutsky, A. A.; Cherepanova, L. A.; Dement'eva, A. V.

    2015-10-01

    Global circulation model of the Troposphere-Middle Atmosphere-Lower Thermosphere ARM (Atmospheric Research Model) is used to simulate the thermal and wind response to solar cycle-induced UV variations. ARM covers altitudes from 1 to 135 km and has corresponding spatial resolution: 1 km in altitude; 11.25° in longitude; 5° in latitude. Internal Gravity Waves parameterization and planetary waves (PWs) structure on the basis of observations are determined at the lower boundary of the model. Changes in UV radiation, which is absorbed by ozone and molecular oxygen, are introduced into the model to find the corresponding global wind and temperature response. Stationary PWs with zonal wave numbers 1-3 are included at lower boundary in model runs. The simulations show that atmospheric response to solar cycle has a visible nonzonal character with the amplitude of about 5 K in the troposphere for the winter season. The effect is rather smaller for summer due to the trapping PWs at lower altitudes. So, in accordance with the results of simulations, the link between the solar UV variability and the middle and low atmosphere strongly depends on the ozone and PWs activity.

  20. Kinetic Energy Release in molecular dications fragmentation after VUV and EUV ionization and escape from planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Falcinelli, Stefano; Rosi, Marzio; Candori, Pietro; Vecchiocattivi, Franco; Farrar, James M.; Pirani, Fernando; Balucani, Nadia; Alagia, Michele; Richter, Robert; Stranges, Stefano

    2014-09-01

    The measurements of the Kinetic Energy Release (KER) for various ionic species originating from two-body dissociations reactions, induced by double photoionization of CO2, C2H2 and N2O neutral molecular precursors of interest in planetary atmospheres, are reported. The KER distributions as a function of the ultraviolet (UV) photon energy in the range of 30-65 eV (Vacuum and Extreme UV photons) are extracted from the electron-ion-ion coincidence spectra obtained by using tunable synchrotron radiation coupled with ion imaging techniques. This experimental method allows assessing the probability of escape for some simple ionic species in the upper atmosphere of Mars and Titan. In fact, the KER measured for H+, C+, CH+, CH2+, N+, O+, CO+, N2+ and NO+ fragment ions are ranging between 1.0 and 5.5 eV (only for H+ the maximum value reaches 6.0 eV), and these translational energies are large enough to allow these ionic species in participating in the atmospheric escape from Mars and Titan into space (for CO+, N2+ and NO+, the measured KER of 0.5-2.5 eV, 0.5-2.8 eV and 1.0-2.5 eV, respectively, allows the possible escape only from the Titan atmosphere).

  1. Observational Studies of Transiting Extrasolar Planets

    NASA Astrophysics Data System (ADS)

    Southworth, J.

    2015-07-01

    The study of transiting extrasolar planets is only 15 years old, but has matured into a rich area of research. I review the observational aspects of this work, concentrating on the discovery of transits, the characterization of planets from photometry and spectroscopy, the Homogeneous Studies project, starspots, orbital obliquities, and the atmospheric properties of the known planets. I begin with historical context and conclude with a glance to a future of TESS, CHEOPS, Gaia and PLATO.

  2. HAT-P-15b: A 10.9 DAY EXTRASOLAR PLANET TRANSITING A SOLAR-TYPE STAR

    SciTech Connect

    Kovacs, G.; Bakos, G. A.; Hartman, J. D.; Torres, G.; Noyes, R. W.; Latham, D. W.; Sasselov, D. D.; Stefanik, R. P.; Esquerdo, G. A.; Fernandez, J. M.; Howard, A. W.; Marcy, G. W.; Isaacson, H.; Fischer, D. A.; Johnson, J. A.; Lazar, B. Beky J.; Papp, I.; Sari, P.

    2010-12-01

    We report the discovery of HAT-P-15b, a transiting extrasolar planet in the 'period valley', a relatively sparsely populated period regime of the known extrasolar planets. The host star, GSC 2883-01687, is a G5 dwarf with V= 12.16. It has a mass of 1.01 {+-} 0.04 M{sub sun}, radius of 1.08 {+-} 0.04 R{sub sun}, effective temperature 5568 {+-} 90 K, and metallicity [Fe/H] = +0.22 {+-} 0.08. The planetary companion orbits the star with a period P = 10.863502 {+-} 0.000027 days, transit epoch T{sub c} = 2454638.56019 {+-} 0.00048 (BJD), and transit duration 0.2285 {+-} 0.0015 days. It has a mass of 1.946 {+-} 0.066 M{sub J} and radius of 1.072 {+-} 0.043 R{sub J} yielding a mean density of 1.96 {+-} 0.22 g cm{sup -3}. At an age of 6.8{sup +2.5}{sub -1.6} Gyr, the planet is H/He-dominated and theoretical models require about 2% (10 M{sub +}) worth of heavy elements to reproduce its measured radius. With an estimated equilibrium temperature of {approx}820 K during transit, and {approx}1000 K at occultation, HAT-P-15b is a potential candidate to study moderately cool planetary atmospheres by transmission and occultation spectroscopy.

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

    SciTech Connect

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

    2012-11-20

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

  4. Refraction in planetary atmospheres: improved analytical expressions and comparison with a new ray-tracing algorithm

    E-print Network

    Betremieux, Yan

    2015-01-01

    Atmospheric refraction affects to various degrees exoplanet transit, lunar eclipse, as well as stellar occultation observations. Exoplanet retrieval algorithms often use analytical expressions for the column abundance along a ray traversing the atmosphere as well as for the deflection of that ray, which are first order approximations valid for low densities in a spherically symmetric homogeneous isothermal atmosphere. We derive new analytical formulae for both of these quantities, which are valid for higher densities, and use them to refine and validate a new ray tracing algorithm which can be used for arbitrary atmospheric temperature-pressure profiles. We illustrate with simple isothermal atmospheric profiles the consequences of our model for different planets: temperate Earth-like and Jovian-like planets, as well as HD189733b, and GJ1214b. We find that, for both hot exoplanets, our treatment of refraction does not make much of a difference to pressures as high as 10 atmosphere, but that it is important to ...

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

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1985-01-01

    Radio absorptivity data for the Venus middle atmosphere (1 to 6 atm, temperatures from 500 to 575K) obtained from spacecraft radio occultation experiments (at 3.6 to 13.4 cm wavelengths) and earth-based radio astronomical observations (1 to 3 cm wavelength range) are compared to laboratory observations at the latter wavelength range under simulated Venus conditions to infer abundances of microwave-absorbing atmospheric constituents, i.e. H2SO4 in a CO2 atmosphere.

  6. Laboratory evaluation of microwave absorption properties under simulated conditions for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1984-01-01

    The microwave absorbing properties of gaseous sulfuric acid (H2SO4) under Venus atmospheric conditions are investigated. The results are applied to measurements from Mariner 5, Mariner 10, and Pioneer/Venus Radio Occultation experiments, to determine abundancies of gaseous sulfuric acid in the Venus atmosphere. The microwave properties of the vapors accompanying liquid H2SO4 are studied to estimate the vapor pressure in an atmospheric model.

  7. Planetary astronomy

    NASA Technical Reports Server (NTRS)

    Morrison, David; Hunten, Donald; Ahearn, Michael F.; Belton, Michael J. S.; Black, David; Brown, Robert A.; Brown, Robert Hamilton; Cochran, Anita L.; Cruikshank, Dale P.; Depater, Imke

    1991-01-01

    The authors profile the field of astronomy, identify some of the key scientific questions that can be addressed during the decade of the 1990's, and recommend several facilities that are critically important for answering these questions. Scientific opportunities for the 1990' are discussed. Areas discussed include protoplanetary disks, an inventory of the solar system, primitive material in the solar system, the dynamics of planetary atmospheres, planetary rings and ring dynamics, the composition and structure of the atmospheres of giant planets, the volcanoes of IO, and the mineralogy of the Martian surface. Critical technology developments, proposed projects and facilities, and recommendations for research and facilities are discussed.

  8. Imaging Spectroscopy for Extrasolar Planet Detection

    E-print Network

    William B. Sparks; Holland C. Ford

    2002-09-04

    Coronagraphic imaging in combination with moderate to high spectral resolution may prove more effective in both detecting extrasolar planets and characterizing them than a standard coronagraphic imaging approach. We envisage an integral-field spectrograph coupled to a coronagraph to produce a 3D datacube. For the idealised case where the spectrum of the star is well-known and unchanging across the field, we discuss the utility of cross-correlation to seek the extrasolar planet signal, and describe a mathematical approach to completely eliminate stray light from the host star (although not its Poisson noise). For the case where the PSF is dominated by diffraction and scattering effects, and comprises a multitude of speckles within an Airy pattern typical of a space-based observation, we turn the wavelength dependence of the PSF to advantage and present a general way to eliminate the contribution from the star while preserving both the flux and spectrum of the extrasolar planet. We call this method `spectral deconvolution'. We illustrate the dramatic gains by showing an idealized simulation that results in a 20-sigma detection of a Jovian planet at 2 pc with a 2-m coronagraphic space telescope, even though the planet's peak flux is only 1% that of the PSF wings of the host star. This scales to detection of a terrestrial extrasolar planet at 2 pc with an 8-m coronagraphic Terrestrial Planet Finder (TPF) in ~7 hr (or less with appropriate spatial filtering). Data on the spectral characteristics of the extrasolar planet and hence on its atmospheric constituents and possible biomarkers are obtained naturally as part of this process.

  9. Characterization of extrasolar terrestrial planets from diurnal photometric variability.

    PubMed

    Ford, E B; Seager, S; Turner, E L

    2001-08-30

    The detection of massive planets orbiting nearby stars has become almost routine, but current techniques are as yet unable to detect terrestrial planets with masses comparable to the Earth's. Future space-based observatories to detect Earth-like planets are being planned. Terrestrial planets orbiting in the habitable zones of stars-where planetary surface conditions are compatible with the presence of liquid water-are of enormous interest because they might have global environments similar to Earth's and even harbour life. The light scattered by such a planet will vary in intensity and colour as the planet rotates; the resulting light curve will contain information about the planet's surface and atmospheric properties. Here we report a model that predicts features that should be discernible in the light curve obtained by low-precision photometry. For extrasolar planets similar to Earth, we expect daily flux variations of up to hundreds of per cent, depending sensitively on ice and cloud cover as well as seasonal variations. This suggests that the meteorological variability, composition of the surface (for example, ocean versus land fraction) and rotation period of an Earth-like planet could be derived from photometric observations. Even signatures of Earth-like plant life could be constrained or possibly, with further study, even uniquely determined. PMID:11528471

  10. International Conference on Laboratory Research for Planetary Atmospheres, 2nd, University of Virginia, Charlottesville, Oct. 21, 1990, Proceedings

    NASA Astrophysics Data System (ADS)

    Fox, Kenneth; Khanna, R. K.; Allen, J. E., Jr.; Stief, L. J.

    1991-09-01

    The present conference on laboratory research for planetary atmospheres discusses collisional cooling as an environment for planetary research, modeling of Jupiter's millimeter wave emission utilizing laboratory measurements of ammonia opacity, laboratory measurements of the millimeter wave properties of liquid sulfuric acid, and the optical constants of solid methane and ethane from 100,000 to 450/cm. Attention is given to laboratory spectra of C-13 ethane, measurements of pure CO2 absorption at high densities near 2.3 microns, pressure-induced absorption in the infrared, and new measurements of the 6190-A band of methane. Topics discussed include high-resolution low-temperature photoabsorption cross sections of C2H2, PH3, AsH3, and GeH4, alteration of the UV-visible reflectance spectra of H2O ice by ion bombardment, proton irradiated H2O + CO2 and H2O + CO ices and synthesized molecules, ion irradiation experiments relevant to cometary physics, and irradiation effects in a comet's outer layers.

  11. Work output of planetary atmospheric engines: dissipation in clouds and rain

    E-print Network

    Lorenz, Ralph D.

    . This comparison suggests moist convection on Earth and Titan is similar, but on Jupiter latent heat alone does as the original function of steam engines was to lift water, a principal output of the atmospheric heat engine of the atmospheric heat engine) appears to be due to [Brunt, 1926, 1952], who suggested on the basis of a typical

  12. CARBON-RICH MOLECULAR CHAINS IN PROTOPLANETARY AND PLANETARY ATMOSPHERES: QUANTUM MECHANISMS AND ELECTRON ATTACHMENT RATES FOR ANION FORMATION

    SciTech Connect

    Carelli, F.; Grassi, T.; Gianturco, F. A.; Satta, M.

    2013-09-10

    The elementary mechanisms through which molecular polyynes could form stable negative ions after interacting with free electrons in planetary atmospheres (e.g., Titan's) are analyzed using quantum scattering calculations and quantum structure methods. The case of radical species and of nonpolar partners are analyzed via specific examples for both the C{sub n}H and HC{sub n}H series, with n values from 4 to 12. We show that attachment processes to polar radicals are dominating the anionic production and that the mediating role of dipolar scattering states is crucial to their formation. The corresponding attachment rates are presented as calculated upper limits to their likely values and are obtained down to the low temperatures of interest. The effects of the computed rates, when used in simple evolutionary models, are also investigated and presented in detail.

  13. Analysis of stellar occultation data - Effects of photon noise and initial conditions. [planetary atmosphere temperature, pressure and density profiles from occultation light curve

    NASA Technical Reports Server (NTRS)

    French, R. G.; Elliot, J. L.; Gierasch, P. J.

    1978-01-01

    An occultation light curve can be analyzed to provide information about a planetary atmosphere. Temperature, pressure, and number density profiles for the atmosphere of Mars are derived from a series of boundary layer equations, which invert equal increments of altitude (as opposed to time) in order to predict the noise quality of the occultation. Numerical results are given for a noisy isothermal light curve, with special attention to error analysis.

  14. Exploring the Potential of Integral Field Spectroscopy for Observing Extrasolar Planet Transits: Ground-based Observations of the Atmospheric Na in HD 209458b

    NASA Astrophysics Data System (ADS)

    Arribas, Santiago; Gilliland, Ronald L.; Sparks, William B.; López-Martín, Luis; Mediavilla, Evencio; Gómez-Alvarez, Pedro

    2006-01-01

    We explore the use of integral field spectroscopy (IFS) for observing extrasolar planet transits. Although this technique should find its full potential in space-based observations (e.g., James Webb Space Telescope, Terrestrial Planet Finder), we have tested its basics with ground-based time-series observations of HD 209458b obtained with the William Herschel Telescope optical fiber system INTEGRAL during a transit in 2004 August 17/18. For this analysis we have used 5550 spectra (from a potential of ~30,000) obtained in 150 exposures during a period of more than 7 hr. We have found that IFS offers three fundamental advantages with respect to previously used methods (based on imaging or standard slit spectroscopy). First, it improves the effective signal-to-noise ratio in photon-limited observations by distributing the light coming from the star into the two dimensions of the detector. Second, this type of IFS data allows us to ``autocalibrate'' instrumental and background effects. Third, since the star image characteristics (i.e., seeing, spatial shifts, etc.) as well as its photometric properties are extracted from the same data cube, it is possible to decorrelate photometric instabilities induced by point-spread function (or instrument) variations. These data have also allowed us to explore the accuracy limits of ground-based relative spectrophotometry. This was done using a photometric index that probes the Na D lines, for which we obtained a nominal 1 ? error of ~1.0 × 10-4. This result, based on observations of only one transit, indicates that this type of ground observation can constrain the characterization of the transmission spectrum of extrasolar planets, especially if they cover multiple transits under good weather conditions. The present observations are compatible with no extra Na D depression during the transit. Although this result seems to be inconsistent with the recently reported Hubble Space Telescope STIS findings, we point out its limited statistical meaning: the results disagree within 1 ?, but agree within 2 ?. This method requires careful and specific reductions, and details about this process are given. We also give some recommendations to instrument developers in order to enhance the efficiency of the method.

  15. Photometric stellar variation due to extra-solar comets

    E-print Network

    A. Lecavelier des Etangs; A. Vidal-Madjar; R. Ferlet

    1998-12-21

    We performed numerical simulations of stellar occultations by extra-solar cometary tails. We find that extra-solar comets can be detected by the apparent photometric variations of the central stars. In most cases, the light curve shows a very peculiar ``rounded triangular'' shape. However, in some other cases, the curve can mimic a planetary occultation. Photometric variations due to comet occultations are mainly achromatic. Nevertheless, if comets with small periastrons have smaller particles, these occultations could be chromatic with a larger extinction in the blue by few percents. We also estimate the number of detections expected in a large photometric survey at high accuracy. By the observation of several tens of thousand of stars, it should be possible to detect several hundreds of occultation per year. We thus conclude that a spatial photometric survey would detect a large number of extra-solar comets. This would allow to explore the time evolution of cometary activity, and consequently would probe structure and evolution of extra-solar planetary systems.

  16. * Corresponding author. Present address: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. Fax: #617-253-4464.

    E-print Network

    Khatiwala, Samar

    * Corresponding author. Present address: Department of Earth, Atmospheric and Planetary Sciences. Visbeck, P. Schlosser Lamont}Doherty Earth Observatory and Department of Earth and Environmental Sciences and the transit-time probability density function (PDF) with the aim of improving our understanding

  17. Extrasolar comets : dynamics and composition

    NASA Astrophysics Data System (ADS)

    Lecavelier des Etangs, Alain; Wilson, Paul Anthony; Kiefer, Flavien

    2015-12-01

    Extrasolar comets, or exocomets, are detected using transit spectroscopy in young planetary systems.Spectroscopic observations of ? Pictoris revealed a high rate of transits, allowing statistical analysis of exocomets populations. Using more than 1,000 archival spectra, we obtained a sample of several hundreds of signatures of exocomets transiting the disk of the parent star. Statistical analysis of the observed properties of these exocomets allowed the identification of two populations with different physical and dynamical properties. One family consists of exocomets producing shallow absorption lines at high radial velocities (>40 km/s), which can be attributed to old exhausted comets trapped in a mean motion resonance with a massive planet, possibly ? Pic b. The second family consists of exocomets which produce deep absorption lines at low radial velocities (˜ 15 km/s), which could be related to the recent fragmentation of one or a few parent bodies.Most recently, our last HST/COS observations of ? Pic yielded the first detection of exocomets in the far-UV. Several new species were detected for the first time in exocomets, including HI, CII, NI, OI and all the ionization states of Si. Measuring the abundance of the key species such as Hydrogen, Carbon, Nitrogen and Oxygen in evaporating exocomets allows us to trace the condensation and evaporation processes present in the late stages of planetary formation. Moreover, the measured radial velocities of these exocomets are consistent with the two dynamical populations previously identified. Most importantly, correlations between the dynamical properties and abundances seems to show up. In short, these two families of exocomets have different dynamical properties, and their origin could be determined by studying their chemical composition. I will present the latest results on that subject, and provide an overview of other systems for which signatures of exocomets have been observed.

  18. Outer satellite atmospheres: Their extended nature and planetary interactions. [sodium cloud of Io, hydrogen torus of Titan, and comet atmospheres

    NASA Technical Reports Server (NTRS)

    Smyth, W. H.

    1980-01-01

    Highly developed numerical models are applied to interpret extended-atmosphere data for the sodium cloud of Io and the hydrogen torus of Titan. Solar radiation pressure was identified and verified by model calculations as the mechanism to explain two different east-west asymmetries observed in the sodium cloud. Analysis of sodium line profile data, suggesting that a Jupiter magnetospheric wind may be responsible for high speed sodium atoms emitted from Io, and preliminary modeling of the interaction of the Io plasma torus and Io's sodium cloud are also reported. Models presented for Titan's hydrogen torus are consistent both with the recent Pioneer 11 measurements and earlier Earth-orbiting observations by the Copernicus satellite. Progress is reported on developing models for extended gas and dust atmospheres of comets.

  19. Outer satellite atmospheres: Their nature and planetary interactions. [atmospheric models for Amalthea, Ganymede, Callisto, and Titan are presented

    NASA Technical Reports Server (NTRS)

    Smyth, W. H.

    1978-01-01

    Results show that Amalthea is likely to form a tightly-bound partial toroidal-shaped hydrogen cloud about its planet, while Ganymede, Callisto and Titan may have rather large, complete and nearly symmetric toroidal-shaped clouds. The toroidal cloud for Amalthea compares favorably with spacecraft data of Pioneer 10 for a satellite escape flux of order 10 to the 11th power atoms/sq cm/sec. Model results for Ganymede, Callisto and Titan suggest that these extended hydrogen atmospheres are likely to be detected by the Voyager spacecrafts and that Titan's cloud might also be detected by the Pioneer 11 spacecraft. Ions created because of atoms lost through ionization processes from these four extended hydrogen atmospheres and from the sodium cloud of Io are discussed.

  20. Earth as an Exoplanet: Lessons in Recognizing Planetary Habitability

    NASA Astrophysics Data System (ADS)

    Meadows, Victoria; Robinson, Tyler; Misra, Amit; Ennico, Kimberly; Sparks, William B.; Claire, Mark; Crisp, David; Schwieterman, Edward; Bussey, D. Ben J.; Breiner, Jonathan

    2015-01-01

    Earth will always be our best-studied example of a habitable world. While extrasolar planets are unlikely to look exactly like Earth, they may share key characteristics, such as oceans, clouds and surface inhomogeneity. Earth's globally-averaged characteristics can therefore help us to recognize planetary habitability in data-limited exoplanet observations. One of the most straightforward ways to detect habitability will be via detection of 'glint', specular reflectance from an ocean (Robinson et al., 2010). Other methods include undertaking a census of atmospheric greenhouse gases, or attempting to measure planetary surface temperature and pressure, to determine if liquid water would be feasible on the planetary surface. Here we present recent research on detecting planetary habitability, led by the NASA Astrobiology Institute's Virtual Planetary Laboratory Team. This work includes a collaboration with the NASA Lunar Science Institute on the detection of ocean glint and ozone absorption using Lunar Crater Observation and Sensing Satellite (LCROSS) Earth observations (Robinson et al., 2014). This data/model comparison provides the first observational test of a technique that could be used to determine exoplanet habitability from disk-integrated observations at visible and near-infrared wavelengths. We find that the VPL spectral Earth model is in excellent agreement with the LCROSS Earth data, and can be used to reliably predict Earth's appearance at a range of phases relevant to exoplanet observations. Determining atmospheric surface pressure and temperature directly for a potentially habitable planet will be challenging due to the lack of spatial-resolution, presence of clouds, and difficulty in spectrally detecting many bulk constituents of terrestrial atmospheres. Additionally, Rayleigh scattering can be masked by absorbing gases and absorption from the underlying surface. However, new techniques using molecular dimers of oxygen (Misra et al., 2014) and nitrogen (Schwieterman et al., 2014) may provide an alternative means to determine terrestrial atmospheric pressure for both transit transmission and direct imaging observations.

  1. Pervasive orbital eccentricities dictate the habitability of extrasolar earths.

    PubMed

    Kita, Ryosuke; Rasio, Frederic; Takeda, Genya

    2010-09-01

    The long-term habitability of Earth-like planets requires low orbital eccentricities. A secular perturbation from a distant stellar companion is a very important mechanism in exciting planetary eccentricities, as many of the extrasolar planetary systems are associated with stellar companions. Although the orbital evolution of an Earth-like planet in a stellar binary system is well understood, the effect of a binary perturbation on a more realistic system containing additional gas-giant planets has been very little studied. Here, we provide analytic criteria confirmed by a large ensemble of numerical integrations that identify the initial orbital parameters leading to eccentric orbits. We show that an extrasolar earth is likely to experience a broad range of orbital evolution dictated by the location of a gas-giant planet, which necessitates more focused studies on the effect of eccentricity on the potential for life. PMID:20879864

  2. Microwave studies of planetary atmospheres. [by Mariner 2 Space Probe for Jupiter and Venus

    NASA Technical Reports Server (NTRS)

    Jones, D. E.

    1975-01-01

    Data from microwave observations of the atmospheres of Jupiter and Venus are examined. Radar features with corresponding coordinates of longitude and lattitude are given, along with scans of Mariner 2 radiometer beams.

  3. Planetary and Space Science 55 (2007) 18451876 Huygens' entry and descent through Titan's atmosphere--Methodology

    E-print Network

    Atkinson, David H.

    2007-01-01

    's atmosphere--Methodology and results of the trajectory reconstruction Bobby Kazeminejada,b,Ã, David H of Titan, the largest moon in the Saturnian system (Lebreton and Matson, 2002; Lebreton et al., 2005

  4. The final fate of planetary systems

    NASA Astrophysics Data System (ADS)

    Gaensicke, Boris

    2015-12-01

    The discovery of the first extra-solar planet around a main-sequence star in 1995 has changed the way we think about the Universe: our solar system is not unique. Twenty years later, we know that planetary systems are ubiquitous, orbit stars spanning a wide range in mass, and form in an astonishing variety of architectures. Yet, one fascinating aspect of planetary systems has received relatively little attention so far: their ultimate fate.Most planet hosts will eventually evolve into white dwarfs, Earth-sized stellar embers, and the outer parts of their planetary systems (in the solar system, Mars and beyond) can survive largely intact for billions of years. While scattered and tidally disrupted planetesimals are directly detected at a small number of white dwarfs in the form infrared excess, the most powerful probe for detecting evolved planetary systems is metal pollution of the otherwise pristine H/He atmospheres.I will present the results of a multi-cycle HST survey that has obtained COS observations of 136 white dwarfs. These ultraviolet spectra are exquisitely sensitive to the presence of metals contaminating the white atmosphere. Our sophisticated model atmosphere analysis demonstrates that at least 27% of all targets are currently accreting planetary debris, and an additional 29% have very likely done so in the past. These numbers suggest that planet formation around A-stars (the dominant progenitors of today's white dwarf population) is similarly efficient as around FGK stars.In addition to post-main sequence planetary system demographics, spectroscopy of the debris-polluted white dwarf atmospheres provides a direct window into the bulk composition of exo-planetesimals, analogous to the way we use of meteorites to determine solar-system abundances. Our ultraviolet spectroscopy is particularly sensitive to the detection of Si, a dominant rock-forming species, and we identify up to ten additional volatile and refractory elements in the most strongly contaminated white dwarfs. The derived bulk abundances unambiguously demonstrate the predominantly rocky nature of the accreted material, with two exceptions where we detect volatile-rich debris. The relative abundance ratios suggest a wide range of parent bodies, including both primitive asteroids and fragments from differentiated planetesimals. The growing number of detailed debris abundances can provide important observational constraints on planet formation models.

  5. Planetary atmosphere representation for Monte-Carlo simulation of aerospace vehicle trajectories

    NASA Technical Reports Server (NTRS)

    Dutton, K.; Moerder, D.; Queen, E.; Suit, W.

    1990-01-01

    Methods of simulating large scale random atmospheric variations are examined for use in Monte Carlo simulations of hypervelocity vehicles. Random density, temperature, and pressure variations have a significant impact on the performance of such vehicles. Methods for generating random atmosphere profiles are described and compared in the context of a Monte Carlo simulation of the Aeroassist Flight Experiment (AFE). It is seen that these techniques result in statistically significant differences in key simulation point statistics.

  6. A Grant from NASA's Office of Space Station Science, Planetary Atmosphere's Program to Boston University

    NASA Technical Reports Server (NTRS)

    Yelle, Roger V.

    2000-01-01

    In the past three years of this program we have made contributions to a variety of subjects in research on Jupiter's Atmosphere, the Ultraviolet Spectroscopy of Jupiter, the abundance of CH4 in Pluto's atmosphere, and the emissivity of Pluto's Surface. We also performed work on two projects related to Titan, and an analysis of the visible spectrum of a brown dwarf. The highpoints are briefly summarized and a list of papers supported partly or wholly by this program is also provided.

  7. Refraction in planetary atmospheres: improved analytical expressions and comparison with a new ray-tracing algorithm

    NASA Astrophysics Data System (ADS)

    Bétrémieux, Yan; Kaltenegger, Lisa

    2015-08-01

    Atmospheric refraction affects to various degrees exoplanet transit, lunar eclipse, as well as stellar occultation observations. Exoplanet retrieval algorithms often use analytical expressions for the column abundance along a ray traversing the atmosphere as well as for the deflection of that ray, which are first-order approximations valid for low densities in a spherically symmetric homogeneous isothermal atmosphere. We derive new analytical formulae for both of these quantities, which are valid for higher densities, and use them to refine and validate a new ray-tracing algorithm which can be used for arbitrary atmospheric temperature-pressure profiles. We illustrate with simple isothermal atmospheric profiles the consequences of our model for different planets: temperate Earth-like and Jovian-like planets, as well as HD 189733b, and GJ1214b. We find that, for both hot exoplanets, our treatment of refraction does not make much of a difference to pressures as high as 10 atm, but that it is important to consider the variation of gravity with altitude for GJ1214b. However, we find that the temperate atmospheres have an apparent scaleheight significantly smaller than their actual density scaleheight at densities larger than 1 amagat, thus increasing the difficulty of detecting spectral features originating in these regions. These denser atmospheric regions form a refractive boundary layer where column abundances and ray deflection increases dramatically with decreasing impact parameter. This refractive boundary layer mimics a surface, and none of the techniques mentioned above can probe atmospheric regions denser than about 4 amagat on these temperate planets.

  8. Earth-like habitats in planetary systems

    NASA Astrophysics Data System (ADS)

    Fritz, J.; Bitsch, B.; Kührt, E.; Morbidelli, A.; Tornow, C.; Wünnemann, K.; Fernandes, V. A.; Grenfell, J. L.; Rauer, H.; Wagner, R.; Werner, S. C.

    2014-08-01

    Understanding the concept of habitability is clearly related to an evolutionary knowledge of the particular planet-in-question. However, additional indications so-called "systemic aspects" of the planetary system as a whole governs a particular planet's claim on habitability. In this paper we focus on such systemic aspects and discuss their relevance to the formation of an "Earth-like" habitable planet. This contribution summarizes our results obtained by lunar sample work and numerical models within the framework of the Research Alliance "Planetary Evolution and Life". We consider various scenarios which simulate the dynamical evolution of the Solar System and discuss the consequences for the likelihood of forming an Earth-like world orbiting another star. Our model approach is constrained by observations of the modern Solar System and the knowledge of its history. Results suggest that on the one hand the long-term presence of terrestrial planets is jeopardized due to gravitational interactions if giant planets are present. On the other hand the habitability of inner rocky planets may be supported in those planetary systems hosting giant planets. Gravitational interactions within a complex multiple-body structure including giant planets may supply terrestrial planets with materials which formed in the colder region of the proto-planetary disk. During these processes, water, the prime requisite for habitability, is delivered to the inner system. This may occur either during the main accretion phase of terrestrial planets or via impacts during a post-accretion bombardment. Results for both processes are summarized and discussed with reference to the lunar crater record. Starting from a scenario involving migration of the giant planets this contribution discusses the delivery of water to Earth, the modification of atmospheres by impacts in a planetary system context and the likelihood of the existence of extrasolar Earth-like habitable worlds.

  9. Extrasolar Planet Inferometric Survey (EPIcS)

    NASA Technical Reports Server (NTRS)

    Shao, Michael; Baliunas, Sallie; Boden, Andrew; Kulkarni, Shrinivas; Lin, Douglas N. C.; Loredo, Tom; Queloz, Didier; Shaklan, Stuart; Tremaine, Scott; Wolszczan, Alexander

    2004-01-01

    The discovery of the nature of the solar system was a crowning achievement of Renaissance science. The quest to evaluate the properties of extrasolar planetary systems is central to both the intellectual understanding of our origins and the cultural understanding of humanity's place in the Universe; thus it is appropriate that the goals and objectives of NASA's breakthrough Origins program emphasize the study of planetary systems, with a focus on the search for habitable planets. We propose an ambitious research program that will use SIM - the first major mission of the Origins program - to explore planetary systems in our Galactic neighborhood. Our program is a novel two-tiered SIM survey of nearby stars that exploits the capabilities of SIM to achieve two scientific objectives: (i) to identify Earth-like planets in habitable regions around nearby Sunlike stars: and (ii) to explore the nature and evolution of planetary systems in their full variety. The first of these objectives was recently recommended by the Astronomy and Astrophysics Survey Committee (the McKee-Taylor Committee) as a prerequisite for the development of the Terrestrial Planet Finder mission later in the decade. Our program combines this two-part survey with preparatory and contemporaneous research designed to maximize the scientific return from the limited and thus precious observing resources of SIM.

  10. Saturn's magnetospheric planetary period oscillations, neutral atmosphere circulation, and thunderstorm activity: Implications, or otherwise, for physical links

    NASA Astrophysics Data System (ADS)

    Cowley, S. W. H.; Provan, G.

    2013-11-01

    that the planetary period oscillations (PPOs) observed in Saturn's magnetosphere may be driven or influenced by neutral atmospheric perturbations motivate an exploratory comparison of PPO rotation periods with available tropospheric and stratospheric determinations. Nonpolar atmospheric rotation periods occupy the range ~10.2-10.7 h associated with the latitudinal jet structure, are similar north and south, and are independent of season, while PPO periods lie in a narrower partly overlapping range ~10.6-10.8 h, are persistently shorter north than south, and undergo a seasonal cycle. In this cycle, widely separated north-south PPO periods during southern summer converge across equinox to values lying within the atmospheric west jet band, remaining well-separated from east jet periods. Closest convergence occurred 1 year post equinox, contemporaneously with the switch in seasonal thunderstorm activity from Southern to Northern Hemispheres. Since most large-scale atmospheric phenomena are related to the west jets, rotating with closely similar periods, they also rotate with periods close to the PPOs under post equinoctial conditions but not otherwise. Specifically, post equinox northern PPOs rotate with a period close to the southern thunderstorms, as well as the north polar spot and hexagon features, while the post equinox southern PPOs rotate with a period close to the pre-equinox northern "string of pearls" and the first colocated post equinox northern thunderstorm, the Great White Spot event. However, even under these conditions, no consistent correspondences in period are found at a detailed level, which taken together with the lack of correspondence at other times does not suggest a direct physical link exists between these phenomena.

  11. Are there physical links between Saturn's magnetospheric planetary period oscillations, neutral atmosphere circulation, and thunderstorm activity? (Invited)

    NASA Astrophysics Data System (ADS)

    Provan, G.; Cowley, S. W.

    2013-12-01

    Suggestions that the planetary period oscillations (PPOs) observed in Saturn's magnetosphere may be driven or influenced by neutral atmospheric perturbations, motivates an exploratory comparison of PPO rotation periods with available tropospheric and stratospheric determinations. Non-polar atmospheric rotation periods occupy the range ~10.2-10.7 h associated with the latitudinal jet structure, are similar north and south, and independent of season, while PPO periods lie in a narrower partly overlapping range ~10.6-10.8 h, are persistently shorter north than south, and undergo a seasonal cycle. In this cycle, widely-separated north-south PPO periods during southern summer converge across equinox to values lying within the atmospheric west jet band, remaining well-separated from east jet periods. Closest convergence occurred one year post-equinox, contemporaneously with the switch in seasonal thunderstorm activity from southern to northern hemispheres. Since most large-scale atmospheric phenomena are related to the west jets, rotating with closely similar periods, they also rotate with periods close to the PPOs under post-equinoctial conditions, but not otherwise. Specifically, post-equinox northern PPOs rotate with a period close to the southern thunderstorms, as well as the north polar spot and hexagon features, while the post equinox southern PPOs rotate with a period close to the pre-equinox northern ';string of pearls' and the first co-located post-equinox northern thunderstorm, the Great White Spot event. However, even under these conditions no consistent correspondences in period are found at a detailed level, which taken together with the lack of correspondence at other times, does not suggest a direct physical link exists between these phenomena.

  12. Spectral properties of condensed phases of disulfur monoxide, polysulfur oxide, and irradiated sulfur. [in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hapke, Bruce; Graham, Francis

    1989-01-01

    The spectral reflectances of S2O, as well as the polysulfur oxide (PSO) condensate dissociation products of SO2 and condensates of elemental sulfur irradiated with UV light and X-rays, have been ascertained in the 200-1700 nm range with a view to the relevance of these compounds to the interpretation of planetary data. While S2O is a dark red solid, PSO is a pale yellow one that absorbs strongly in the UV but exhibits no bands in either the visible or near IR. Elemental S produces strong bands in the UV, and while it is normally white at room temperature, UV irradiation causes it to turn yellow. X-ray irradiation of S turns it orange.

  13. Perturbative approach to the astrometric microlensing due to an extrasolar planet

    E-print Network

    Hideki Asada

    2002-03-25

    We have developed a perturbative approach to microlensing due to an extrasolar planetary lens. In particular, we have found analytic formulae for triple images. We have used the formulae to investigate the astrometric microlensing due to the extrasolar planetary lens, in expectation of dramatic improvements in the precision of the future astrometric measurements. For a weak lensing case, we have shown how the maximum angular size and the typical time scale of the anomalous shift of the lightcentroid are dependent on the mass ratio and angular separation between the star and the planet.

  14. Estimating the height of the planetary boundary layer for transport and diffusion atmospheric models: A four algorithm comparison

    SciTech Connect

    Russ, R.L.; Dean, D.; Walters, M.K.

    1999-07-01

    The authors present the results of a performance evaluation of four algorithms that determine the height of the Planetary Boundary Layer (PBL) against both forecasted and observed PBL heights derived by human analysis (taken to be the forecasted and observed truth). The PBL height determines the direction and speed of pollution movement, as well as the vertical depth over which the effluent will be mixed, and therefore is important for accurate transport and diffusion modeling. Three of these algorithms are methods used by the Short-range Layered Atmospheric Model (SLAM). Although designed to be used with observed upper-air data, these three methods have been adapted to utilize forecast soundings from the Regional Atmospheric Modeling System (RAMS) forecast model. The fourth method relies on the properties of turbulent kinetic energy (TKE) predicted by the RAMS forecast model to determine PBL heights. The results of the study indicate that two of the three SLAM model algorithms, and the RAMS TKE derived PBL heights all produce reasonable results compared to those derived by human analysis. The results suggest an ensemble approach in which the transport and diffusion calculations are performed using each of the three algorithms may produce the best results.

  15. Zeppelin NT - Measurement Platform for the Exploration of Atmospheric Chemistry and Dynamics in the Planetary Boundary Layer

    NASA Astrophysics Data System (ADS)

    Hofzumahaus, Andreas; Holland, Frank; Oebel, Andreas; Rohrer, Franz; Mentel, Thomas; Kiendler-Scharr, Astrid; Wahner, Andreas; Brauchle, Artur; Steinlein, Klaus; Gritzbach, Robert

    2014-05-01

    The planetary boundary layer (PBL) is the chemically most active and complex part of the atmosphere where freshly emitted reactive trace gases, tropospheric radicals, atmospheric oxidation products and aerosols exhibit a large variability and spatial gradients. In order to investigate the chemical degradation of trace gases and the formation of secondary pollutants in the PBL, a commercial Zeppelin NT was modified to be used as an airborne measurement platform for chemical and physical observations with high spatial resolution. The Zeppelin NT was developed by Zeppelin Luftschifftechnik (ZLT) and is operated by Deutsche Zeppelin Reederei (DZR) in Friedrichshafen, Germany. The modification was performed in cooperation between Forschungszentrum Jülich and ZLT. The airship has a length of 75 m, can lift about 1 ton of scientific payload and can be manoeuvered with high precision by propeller engines. The modified Zeppelin can carry measurement instruments mounted on a platform on top of the Zeppelin, or inside the gondola beneath the airship. Three different instrument packages were developed to investigate a. gas-phase oxidation processes involving free radicals (OH, HO2) b. formation of secondary organic aerosols (SOA) c. new particle formation (nucleation) The presentation will describe the modified airship and provide an overview of its technical performance. Examples of its application during the recent PEGASOS flight campaigns in Europe will be given.

  16. The outer limit of the life supporting zone of exoplanets having CO2-rich atmospheres: Virtual exoplanets and Kepler planetary candidates

    NASA Astrophysics Data System (ADS)

    Neubauer, David; Leitner, Johannes J.; Firneis, Maria Gertrude; Hitzenberger, Regina

    2013-08-01

    CO2 rich atmospheres have been considered for the outer limit of the classic water habitable zone. Here we provide a database for the outer limit of the life supporting zone consisting of a sulfuric acid, a water and a water/ammonia mixture (15 wt% ammonia) habitable zone for virtual exoplanets having CO2-rich atmospheres and orbiting G-, K-, or M-dwarf stars. We used recent CO2 line and continuum absorption data for CO2 pressures up to 100 bar for our simulations. Scenarios for different stellar spectra, stellar fluxes, planetary surface albedos, atmospheric pressures and planetary masses are explored. One notable result is that the surface temperature does not strongly increase if CO2 pressure is larger than approximately 25 bar, due to increased Rayleigh scattering or CO2 condensation at the surface and a thereby reduced greenhouse effect in these cases. The database is created for virtual exoplanets and applied to Kepler planetary candidates. All of the considered planetary candidates likely lie within the outer limit of the life supporting zone.

  17. Studies of the chemistry of vibrationally and electronically excited species in planetary upper atmospheres

    NASA Technical Reports Server (NTRS)

    Fox, J. L.

    1984-01-01

    The vibrational distribution of O2(+) in the atmospheres of Venus and Mars was investigated to compare with analogous values in the Earth's atmosphere. The dipole moment of the Z(2) Pi sub u - X(2) Pi sub g transition of O2(+) is calculated as a function of internuclear distance. The band absorption oscillator strengths and band transition probabilities of the second negative system are derived. The vibrational distribution of O2(+) in the ionosphere of Venus is calculated for a model based on data from the Pioneer Venus neutral mass spectrometer.

  18. To Cool is to Accrete: Analytic Scalings for Nebular Accretion of Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Lee, Eve J.; Chiang, Eugene

    2015-09-01

    Planets acquire atmospheres from their parent circumstellar disks. We derive a general analytic expression for how the atmospheric mass grows with time t as a function of the underlying core mass {M}{core} and nebular conditions, including the gas metallicity Z. Planets accrete as much gas as can cool: an atmosphere's doubling time is given by its Kelvin-Helmholtz time. Dusty atmospheres behave differently from atmospheres made dust-free by grain growth and sedimentation. The gas-to-core mass ratio (GCR) of a dusty atmosphere scales as GCR \\propto {t}0.4{M}{core}1.7{Z}-0.4{? }{rcb}3.4, where {? }{rcb}\\propto 1/(1-Z) (for Z not too close to 1) is the mean molecular weight at the innermost radiative-convective boundary. This scaling applies across all orbital distances and nebular conditions for dusty atmospheres; their radiative-convective boundaries, which regulate cooling, are not set by the external environment, but rather by the internal microphysics of dust sublimation, H2 dissociation, and the formation of H-. By contrast, dust-free atmospheres have their radiative boundaries at temperatures {T}{rcb} close to nebular temperatures {T}{out}, and grow faster at larger orbital distances where cooler temperatures, and by extension lower opacities, prevail. At 0.1 AU in a gas-poor nebula, GCR \\propto {t}0.4{T}{rcb}-1.9{M}{core}1.6{Z}-0.4{? }{rcb}3.3, while beyond 1 AU in a gas-rich nebula, GCR \\propto {t}0.4{T}{rcb}-1.5{M}{core}1{Z}-0.4{? }{rcb}2.2. We confirm our analytic scalings against detailed numerical models for objects ranging in mass from Mars (0.1{M}\\oplus ) to the most extreme super-Earths (10-20{M}\\oplus ), and explain why heating from planetesimal accretion cannot prevent the latter from undergoing runaway gas accretion.

  19. Commission 53: Extrasolar Planets

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  20. Planet Formation and the Characteristics of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

    An overview of current theories of planetary growth, emphasizing the formation of extrasolar planets, is presented. Models of planet formation are based upon observations of the Solar System, extrasolar planets, and young stars and their environments. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets begin their growth like terrestrial planets, but if they become massive enough before the protoplanetary disk dissipates, then they are able to accumulate substantial amounts of gas. These models predict that rocky planets should form in orbit about most single stars. It is uncertain whether or not gas giant planet formation is common, because most protoplanetary disks may dissipate before solid planetary cores can grow large enough to gravitationally trap substantial quantities of gas. A potential hazard to planetary systems is radial decay of planetary orbits resulting from interactions with material within the disk. Planets more massive than Earth have the potential to decay the fastest, and may be able to sweep up smaller planets in their path. The implications of the giant planets found in recent radial velocity searches for the abundances of habitable planets are discussed.

  1. he entry of a space vehicle into a planet-ary atmosphere is violent and dramatic.

    E-print Network

    Lorenz, Ralph D.

    atmosphere of Saturn's moon Titan by the Huygens probe in early 2005, can be detected by astronomical emissions from the planets, such as aurorae on Jupiter and Saturn (figure 2). The question then arises an entry at Mars or Venus may in fact be more challenging (requiring a much better radiomet- ric resolution

  2. Planetary and Space Science 56 (2008) 12 Surfaces and atmospheres of the outer planets,

    E-print Network

    Atreya, Sushil

    2008-01-01

    during the PS3.02 and PS3.03 sessions of the European Geosciences Union (EGU) meeting in Vienna, Austria and the rings. In particular, there are several studies reported here from session PS3.02 on the Kronian icy PS3.03 included presentations on the neutral atmospheres of the outer planets and Titan--the largest

  3. Low-temperature Kinetic Studies of OH Radical Reactions Relevant to Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Townsend, T. M.; Antiñolo, M.; Ballesteros, B.; Jimenez, E.; Canosa, A.

    2011-05-01

    In the solar system, the temperature (T) of the atmosphere of giant planets or their satellites is only several tens of Kelvin (K). The temperature of the tropopause of Titan (satellite of Saturn) and the surface of Mars is 70 K and 210 K, respectively. In the Earth's atmosphere, T decreases from 298 K (surface) to 210 K close to the T-inversion region (tropopause). The principal oxidants in the Earth's lower atmosphere are ozone, the hydroxyl (OH) radical and hydrogen peroxide. A number of critical atmospheric chemical problems depend on the Earth's oxidising capacity, which is essentially the global burden of these oxidants. In the interstellar clouds and circumstellar envelopes, OH radicals have also been detected. As the chemistry of atmospheres is highly influenced by temperature, the knowledge of the T-dependence of the rate coefficients for OH-reactions (k) is the key to understanding the underlying molecular mechanisms. In general, these reactions take place on a short temporal scale. Therefore, a detection technique with high temporal resolution is required. Measurements of k at low temperatures can be achieved by maintaining a thermalised environment using either cryogenic cooling (T>200 K) or supersonic gas expansion with a Laval nozzle (several tens of K). The pulsed laser photolysis technique coupled with laser induced fluorescence detection has been widely used in our laboratory to determine the rate coefficients of OH-reactions with different volatile organic compounds, such as alcohols (1), saturated and unsaturated aliphatic aldehydes (2), linear ketones (3), as a function of temperature (260 350 K). An experimental system based on the CRESU (Cinetique de Reaction en Ecoulement Supersonique Uniforme or Reaction Kinetics in a Uniform Supersonic Flow) technique is currently under construction. This technique will allow the performance of kinetic studies of OH-reactions of astrophysical interest at temperatures lower than 200 K.

  4. Impact of variations of gravitational acceleration on the general circulation of the planetary atmosphere

    NASA Astrophysics Data System (ADS)

    Kilic, Cevahir; Raible, Christoph C.; Stocker, Thomas F.

    2015-04-01

    Instrumentation to detect new planets has been continually developed over the last decades. Thus, exoplanets can be characterised in terms of physical parameters, such as size and mass, as well as identify possible atmospheres. The increasing number of newly detected planets raises issues of possible other habitable worlds. In this study, the atmospheric dynamics of potential habitable planets is investigated using a three-dimensional atmospheric general circulation model (Planet Simulator) of intermediate complexity (Lunkeit et al. 2011). A set of sensitivity simulations varying the gravitational acceleration from 1/4g0 to 5g0 (with g0 = 9.81ms-2) are performed in an aquaplanet configuration. Except of that all simulations are performed with Earth-like initial conditions, which reach after 4 to 10 years a steady-state. The gravitation of a terrestrial planet significantly influences atmospheric dynamics. Up to 1g0, the meridional atmospheric circulation is driven by a three-cell structure on one hemisphere: a thermally direct cell between 0°and ±30°(Hadley cell), a thermally indirect cell between ±30°and ±60°(Ferrel cell) and a third cell (polar cell), which is also a thermally direct cell. Further, all cells illustrated by the mass stream function become more intense with increasing gravity from 1/4g0 to 1g0. However, for experiments greater than 1g0 the general atmospheric circulation begins to change fundamentally. The thermally indirect cell becomes weaker and vanishes completely with 3g0, whereas both direct thermal cells enhance and merge around 3g0. Hence, one strong thermally direct cell remains, which becomes stronger with increasing gravity acceleration (> 3g0). To understand the physical processes leading to a one-cell structure, the main drivers are considered separately: diabatic heating, meridional eddy fluxes of heat and momentum, and zonal shear. The results show that all main processes enhance with increasing gravity up to 1g0. For g > g0, both eddy processes, heat and momentum flux, become weaker, whereas the contribution of diabatic heating and zonal shear still increase. The increase of zonal shear is explained by a denser air due to increased gravity. The increase of the diabatic heating caused by an increasing Brunt-Väisälä frequency and the weakening of the eddy processes at the same time lead to a direct thermally driven circulation from the equator to the poles, i.e., a one-cell structure on each hemisphere. References Lunkeit, F., et al., Planet Simulator - Reference Manual Version 16, Meteorological Institute, University of Hamburg, 2011.

  5. Electronic excitation and isentropic coefficients of high temperature planetary atmosphere plasmas

    SciTech Connect

    Colonna, Gianpiero; Capitelli, Mario

    2012-07-15

    In this paper, we have discussed the effects of electronically excited states of atomic species in affecting the isentropic coefficients of plasmas, focusing on mixtures representing the atmospheres of Jupiter, Mars, and Earth. General behaviors have been rationalized on the basis of simplified approaches. The contribution of the electronically excited states has been evidenced by comparing results obtained considering only the ground state and those obtained using either Fermi or Griem cutoff criteria.

  6. Evaporation of ice in planetary atmospheres: Ice-covered rivers on Mars

    NASA Technical Reports Server (NTRS)

    Wallace, D.; Sagan, C.

    1978-01-01

    The evaporation rate of water ice on the surface of a planet with an atmosphere involves an equilibrium between solar heating and radiative and evaporative cooling of the ice layer. The thickness of the ice is governed principally by the solar flux which penetrates the ice layer and then is conducted back to the surface. Evaporation from the surface is governed by wind and free convection. In the absence of wind, eddy diffusion is caused by the lower density of water vapor in comparison to the density of the Martian atmosphere. For mean martian insolations, the evaporation rate above the ice is approximately 10 to the minus 8th power gm/sq cm/s. Evaporation rates are calculated for a wide range of frictional velocities, atmospheric pressures, and insolations and it seems clear that at least some subset of observed Martian channels may have formed as ice-chocked rivers. Typical equilibrium thicknesses of such ice covers are approximately 10m to 30 m; typical surface temperatures are 210 to 235 K.

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

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1991-01-01

    Laboratory measurements of microwave and millimeter wave properties of the simulated atmosphere of the outer planets and their satellites has continued. One of the focuses is on the development of a radiative transfer model of the Jovian atmosphere at wavelengths from 1 mm to 10 cm. This modeling effort led to laboratory measurements of the millimeter wave opacity of hydrogen sulfide (H2S) under simulated Jovian conditions. Descriptions of the modeling effort, the Laboratory experiment, and the observations are presented. Correlative studies of measurements with Pioneer-Venus radio occultation measurements with longer wavelength emission measurements have provided new ways for characterizing temporal and spatial variations in the abundance of both gases H2SO4 and SO2, and for modeling their roles in the subcloud atmosphere. Laboratory measurements were conducted on 1.35 cm (and 13 cm) opacity of gaseous SO2 and absorptivity of gaseous SO2 at the 3.2 mm wavelength under simulated Venus conditions. Laboratory measurements were completed on millimeter wave dielectric properties of liquid H2SO4, in order to model the effects of the opacity of the clouds of Venus onto millimeter wave emission spectrum.

  8. Elemental compositions of two extrasolar rocky planetesimals

    SciTech Connect

    Xu, S.; Jura, M.; Klein, B.; Zuckerman, B.; Koester, D. E-mail: jura@astro.ucla.edu E-mail: ben@astro.ucla.edu

    2014-03-10

    We report Keck/HIRES and Hubble Space Telescope/COS spectroscopic studies of extrasolar rocky planetesimals accreted onto two hydrogen atmosphere white dwarfs, G29-38 and GD 133. In G29-38, eight elements are detected, including C, O, Mg, Si, Ca, Ti, Cr, and Fe while in GD 133, O, Si, Ca, and marginally Mg are seen. These two extrasolar planetesimals show a pattern of refractory enhancement and volatile depletion. For G29-38, the observed composition can be best interpreted as a blend of a chondritic object with some refractory-rich material, a result from post-nebular processing. Water is very depleted in the parent body accreted onto G29-38, based on the derived oxygen abundance. The inferred total mass accretion rate in GD 133 is the lowest of all known dusty white dwarfs, possibly due to non-steady state accretion. We continue to find that a variety of extrasolar planetesimals all resemble to zeroth order the elemental composition of bulk Earth.

  9. Detecting Extrasolar Planets with Integral Field Spectroscopy

    E-print Network

    A. Berton; R. G. Gratton; M. Feldt; T. Henning; S. Desidera; M. Turatto; H. M. Schmid; R. Waters

    2006-05-11

    Observations of extrasolar planets using Integral Field Spectroscopy (IFS), if coupled with an extreme Adaptive Optics system and analyzed with a Simultaneous Differential Imaging technique (SDI), are a powerful tool to detect and characterize extrasolar planets directly; they enhance the signal of the planet and, at the same time, reduces the impact of stellar light and consequently important noise sources like speckles. In order to verify the efficiency of such a technique, we developed a simulation code able to test the capabilities of this IFS-SDI technique for different kinds of planets and telescopes, modelling the atmospheric and instrumental noise sources. The first results obtained by the simulations show that many significant extrasolar planet detections are indeed possible using the present 8m-class telescopes within a few hours of exposure time. The procedure adopted to simulate IFS observations is presented here in detail, explaining in particular how we obtain estimates of the speckle noise, Adaptive Optics corrections, specific instrumental features, and how we test the efficiency of the SDI technique to increase the signal-to-noise ratio of the planet detection. The most important results achieved by simulations of various objects, from 1 M_J to brown dwarfs of 30 M_J, for observations with an 8 meter telescope, are then presented and discussed.

  10. Theory for planetary exospheres: III. Radiation pressure effect on the Circular Restricted Three Body Problem and its implication on planetary atmospheres

    E-print Network

    Beth, Arnaud; Toublanc, Dominique; Dandouras, Iannis; Mazelle, Christian

    2015-01-01

    The planetary exospheres are poorly known in their outer parts, since the neutral densities are low compared with the instruments detection capabilities. The exospheric models are thus often the main source of information at such high altitudes. We present a new way to take into account analytically the additional effect of the stellar radiation pressure on planetary exospheres. In a series of papers, we present with an Hamiltonian approach the effect of the radiation pressure on dynamical trajectories, density profiles and escaping thermal flux. Our work is a generalization of the study by Bishop and Chamberlain (1989). In this third paper, we investigate the effect of the stellar radiation pressure on the Circular Restricted Three Body Problem (CR3BP), called also the photogravitational CR3BP, and its implication on the escape and the stability of planetary exospheres, especially for Hot Jupiters. In particular, we describe the transformation of the equipotentials and the location of the Lagrange points, an...

  11. High-Contrast Imaging using Adaptive Optics for Extrasolar Planet Detection

    SciTech Connect

    Evans, J W

    2006-08-18

    Direct imaging of extrasolar planets is an important, but challenging, next step in planetary science. Most planets identified to date have been detected indirectly--not by emitted or reflected light but through the effect of the planet on the parent star. For example, radial velocity techniques measure the doppler shift in the spectrum of the star produced by the presence of a planet. Indirect techniques only probe about 15% of the orbital parameter space of our solar system. Direct methods would probe new parameter space, and the detected light can be analyzed spectroscopically, providing new information about detected planets. High contrast adaptive optics systems, also known as Extreme Adaptive Optics (ExAO), will require contrasts of between 10{sup -6} and 10{sup -7} at angles of 4-24 {lambda}/D on an 8-m class telescope to image young Jupiter-like planets still warm with the heat of formation. Contrast is defined as the intensity ratio of the dark wings of the image, where a planet might be, to the bright core of the star. Such instruments will be technically challenging, requiring high order adaptive optics with > 2000 actuators and improved diffraction suppression. Contrast is ultimately limited by residual static wavefront errors, so an extrasolar planet imager will require wavefront control with an accuracy of better than 1 nm rms within the low- to mid-spatial frequency range. Laboratory demonstrations are critical to instrument development. The ExAO testbed at the Laboratory for Adaptive Optics was designed with low wavefront error and precision optical metrology, which is used to explore contrast limits and develop the technology needed for an extrasolar planet imager. A state-of-the-art, 1024-actuator micro-electrical-mechanical-systems (MEMS) deformable mirror was installed and characterized to provide active wavefront control and test this novel technology. I present 6.5 x 10{sup -8} contrast measurements with a prolate shaped pupil and flat mirror demonstrating that the testbed can operate in the necessary contrast regime. Wavefront measurements and simulations indicate that contrast is limited by wavefront error, not diffraction. I demonstrate feasibility of the MEMS deformable mirror for meeting the stringent residual wavefront error requirements of an extrasolar planet imager with closed-loop results of 0.54 nm rms within controllable spatial frequencies. Individual contributors to final wavefront quality have been identified and characterized. I also present contrast measurements of 2 x 10{sup -7} made with the MEMS device and identify amplitude errors as the limiting error source. Closed-loop performance and simulated far-field measurements using a Kolmogorov phase plate to introduce atmosphere-like optical errors are also presented.

  12. Extrasolar Planets in the Classroom

    ERIC Educational Resources Information Center

    George, Samuel J.

    2011-01-01

    The field of extrasolar planets is still, in comparison with other astrophysical topics, in its infancy. There have been about 300 or so extrasolar planets detected and their detection has been accomplished by various different techniques. Here we present a simple laboratory experiment to show how planets are detected using the transit technique.…

  13. Multiplex gas chromatography: an alternative concept for gas chromatographic analysis of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Valentin, J. R.

    1989-01-01

    Gas chromatography (GC) is a powerful technique for analyzing gaseous mixtures. Applied to the earth's atmosphere, GC can be used to determine the permanent gases--such as carbon dioxide, nitrogen, and oxygen--and to analyze organic pollutants in air. The U.S. National Aeronautics and Space Administration (NASA) has used GC in spacecraft missions to Mars (the Viking Biology Gas Exchange Experiment [GEX] and the Viking Gas Chromatograph-Mass Spectrometer [GC-MS]) and to Venus (the Pioneer Venus Gas Chromatograph [PVGC] on board the Pioneer Venus sounder probe) for determining the atmospheric constituents of these two planets. Even though conventional GC was very useful in the Viking and Pioneer missions, spacecraft constraints and limitations intrinsic to the technique prevented the collection of more samples. With the Venus probe, for instance, each measurement took a relatively long time to complete (10 min), and successive samples could not be introduced until the previous samples had left the column. Therefore, while the probe descended through the Venusian atmosphere, only three samples were acquired at widely separated altitudes. With the Viking mission, the sampling rate was not a serious problem because samples were acquired over a period of one year. However, the detection limit was a major disadvantage. The GC-MS could not detect simple hydrocarbons and simple alcohols below 0.1 ppm, and the GEX could not detect them below 1 ppm. For more complex molecules, the detection limits were at the parts-per-billion level for both instruments. Finally, in both the Viking and Pioneer missions, the relatively slow rate of data acquisition limited the number of analyses, and consequently, the amount of information returned. Similar constraints are expected in future NASA missions. For instance, gas chromatographic instrumentation is being developed to collect and analyze organic gases and aerosols in the atmosphere of Titan (one of Saturn's satellites). The Titan-Cassini entry probe, which is being jointly planned by NASA and the European Space Agency (ESA), might be launched as early as 1994. As in the Pioneer mission, limited time--perhaps only 3-4 h--will be available for the completion of all analyses while the probe descends through the atmosphere. A conventional GC or GC-MS system would be able to analyze no more than two aerosol and two gas samples during the probe's descent. Conventional GC also is limited by the sensitivity of the detector and by the sample volume. For the Titan mission, the sensitivity problems will be worse because the atmospheric pressure at the time of instrument deployment is expected to be < 3 torr. Consequently, the sample volume might not be large enough to satisfy the detector sensitivity requirements. Because of such limitations, alternative GC analysis techniques have been investigated for future NASA missions. Multiplex gas chromatography has been investigated as a possible candidate for chemical analysis within a spacecraft or other restricted environment, and chemical modulators have been developed and used when needed with this technique to reduce the size and weight of the instrumentation. Also, several new multiplex techniques have been developed for use in specific applications.

  14. Multiplex gas chromatography: an alternative concept for gas chromatographic analysis of planetary atmospheres.

    PubMed

    Valentin, J R

    1989-03-01

    Gas chromatography (GC) is a powerful technique for analyzing gaseous mixtures. Applied to the earth's atmosphere, GC can be used to determine the permanent gases--such as carbon dioxide, nitrogen, and oxygen--and to analyze organic pollutants in air. The U.S. National Aeronautics and Space Administration (NASA) has used GC in spacecraft missions to Mars (the Viking Biology Gas Exchange Experiment [GEX] and the Viking Gas Chromatograph-Mass Spectrometer [GC-MS]) and to Venus (the Pioneer Venus Gas Chromatograph [PVGC] on board the Pioneer Venus sounder probe) for determining the atmospheric constituents of these two planets. Even though conventional GC was very useful in the Viking and Pioneer missions, spacecraft constraints and limitations intrinsic to the technique prevented the collection of more samples. With the Venus probe, for instance, each measurement took a relatively long time to complete (10 min), and successive samples could not be introduced until the previous samples had left the column. Therefore, while the probe descended through the Venusian atmosphere, only three samples were acquired at widely separated altitudes. With the Viking mission, the sampling rate was not a serious problem because samples were acquired over a period of one year. However, the detection limit was a major disadvantage. The GC-MS could not detect simple hydrocarbons and simple alcohols below 0.1 ppm, and the GEX could not detect them below 1 ppm. For more complex molecules, the detection limits were at the parts-per-billion level for both instruments. Finally, in both the Viking and Pioneer missions, the relatively slow rate of data acquisition limited the number of analyses, and consequently, the amount of information returned. Similar constraints are expected in future NASA missions. For instance, gas chromatographic instrumentation is being developed to collect and analyze organic gases and aerosols in the atmosphere of Titan (one of Saturn's satellites). The Titan-Cassini entry probe, which is being jointly planned by NASA and the European Space Agency (ESA), might be launched as early as 1994. As in the Pioneer mission, limited time--perhaps only 3-4 h--will be available for the completion of all analyses while the probe descends through the atmosphere. A conventional GC or GC-MS system would be able to analyze no more than two aerosol and two gas samples during the probe's descent. Conventional GC also is limited by the sensitivity of the detector and by the sample volume. For the Titan mission, the sensitivity problems will be worse because the atmospheric pressure at the time of instrument deployment is expected to be < 3 torr. Consequently, the sample volume might not be large enough to satisfy the detector sensitivity requirements. Because of such limitations, alternative GC analysis techniques have been investigated for future NASA missions. Multiplex gas chromatography has been investigated as a possible candidate for chemical analysis within a spacecraft or other restricted environment, and chemical modulators have been developed and used when needed with this technique to reduce the size and weight of the instrumentation. Also, several new multiplex techniques have been developed for use in specific applications. PMID:11539794

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

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1987-01-01

    Laboratory measurements were conducted to evaluate properties of atmospheric gases under simulated conditions for the outer planets. A significant addition to this effort was the capability to make such measurements at millimeter wavelengths. Measurements should soon be completed on the millimeter wave absorption from ammonia under Jovian conditions. Also studied will be the feasibility of measuring the microwave and millimeter wave properties of phosphine (PH3) under simulated Jovian conditions. Further analysis and application of the laboratory results to microwave and millimeter wave absorption data for the outer planet, such as Voyager Radio Occultation experiments, will be pursued.

  16. Parameterization of linear wave chemical transport in planetary atmospheres by eddy diffusion

    NASA Technical Reports Server (NTRS)

    Strobel, D. F.

    1981-01-01

    Two-dimensional transport by linear waves is parameterized by wave velocity and temperature correlations and nonconservative properties of the atmosphere in a residual Eulerian framework. Explicit expressions derived for the eddy tracer flux vector are written in eddy diffusion tensor form, but it is demonstrated that strong coupling of chemistry and temperature through the rate constants, as is the case for ozone, requires additional terms proportional to the mixing ratio and not to its gradient. A variety of limiting cases are discussed. In the residual Eulerian framework the K(yz), K(zy) components are nonzero for a nonconservative atmosphere and/or a reactive tracer. Tracers have common transport coefficients in the limit where their chemistry is negligible in comparison to transience. It is shown that the usual one-dimensional vertical eddy diffusion continuity equation is rigorously valid only when the temperature dependence of the rate constants is negligible and the tracer has strong vertical stratification relative to its horizontal variability.

  17. Influence of the radiation pressure on the planetary exospheres: density profiles, escape flux and atmospheric stability

    NASA Astrophysics Data System (ADS)

    Beth, A.; Garnier, P.; Toublanc, D.; Dandouras, I.; Mazelle, C.

    2015-10-01

    The uppermost layer of the atmosphere, the exosphere,is not well-known in its global structure since the densities are very low compared to instrument detection capabilities. Because of rare collisions and high Knudsen numbers, the motion of light species (H,H2, ...)in the corona is essentially determined by the external forces : the gravitation from the planet, the radiation pressure, as well the stellar gravity. In this work, we calculate rigorously and analytically,based on the Hamiltonian mechanics and Liouville theorem, the impact of the radiation pressure and gravitation from the planet on the structure of the exosphere. This approach was partially used by Bishop and Chamberlain (1989) but only in the 2D case : we extend it to the 3D case. Assuming a collisionless exosphere and a constant radiation pressure near the planet, we determine the density profiles for ballistic particles (the main contribution for densities in the lower exosphere) for light species as a function of the angle with respect to the Sun direction. We also obtain an analytical formula for the escape flux at the subsolar point, which can be compared with the Jeans' escape flux. Finally, we study the effect of the radiation pressure on the zero velocity curves, position of the Roche lobe and Hill's region for the well-known Three-Body problem especially for Hot Jupiters and discuss about the validity of our model. The goal is to bring some constraints on modelling of exoplanet atmospheres.

  18. From Sub-Neptunes to Earth-like Exoplanets: Modeling Optically Thick and Thin Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Chen, Howard; Rogers, Leslie; Kasting, James

    2016-01-01

    Exoplanet surveys have revealed a wide diversity of planet properties in the Milky Way. Here, we present the results from two projects modeling planet atmospheres; one considering the hydrogen/helium envelopes of sub-Neptune-mass planets, and the other, the climate of Earth-like planets.First, we modify the state-of-the-art stellar evolution code Modules for Experimental Astrophysics (MESA) to model the thermal evolution of gaseous Sub-Neptune sized planets. Including photo-evaporation, we find a resulting convergent evolution trend that could potentially imprint itself on the close-in planet population as a preferred H/He mass fraction of 0.5-3%.We also use an updated version of a radiative-convective climate model to calculate the upper atmospheric conditions of planets warmer than the present Earth. In our simulations, cold, dry stratospheres are predicted at lower surface temperatures. However, onset of moist greenhouse water-loss limit to habitability emerges when the surface temperature reaches above 350 K. This result places constraint on a more accurate calculation of the inner edge of the habitable zone around Sun-like stars.

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

    E-print Network

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

    2015-01-01

    The atmosphere of a transiting planet shields the stellar radiation providing us with a powerful method to estimate its size and density. In particular, because of their high ionization energy, atoms with high atomic number (Z) absorb short-wavelength radiation in the upper atmosphere, undetectable with observations in visible light. One implication is that the planet should appear larger during a primary transit observed in high energy bands than in the optical band. The last Venus transit in 2012 offered a unique opportunity to study this effect. The transit has been monitored by solar space observations from Hinode and Solar Dynamics Observatory (SDO). We measure the radius of Venus during the transit in three different bands with subpixel accuracy: optical (4500A), UV (1600A, 1700A), Extreme UltraViolet (EUV, 171-335A) and soft X-rays (about 10A). We find that, while the Venus optical radius is about 80 km larger than the solid body radius (the expected opacity mainly due to clouds and haze), the radius i...

  20. ExoMol: Large-scale production of line lists for molecules important for modelling of planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Yurchenko, S.; Tennyson, J.

    2013-09-01

    The spectral characterization of astrophysical objects cool enough to form polyatomic molecules (the atmospheres of planets, brown dwarfs, planetary discs etc.) requires a huge amount of fundamental molecular data. With a few exceptions the existing molecular line lists are not sufficiently accurate and complete. The aim of ExoMol [1] is to generate comprehensive line lists for all molecules likely to be observable in exoplanet atmospheres in the foreseeable future (see www.exomol.com for more details). We identified the following 40 species that are important sources of opacity in (exo)planets and brown dwarfs and where there is currently a lack of fundamental data on wavelength and temperature-dependent absorption: • Diatomics: AlO, AlH, BeH, CaH, C2, CrH, FeH, HF, HCl, KCl, MgH, MgO, NaH, NaCl, NiH, O2,SiO, SiH, S2, SH, TiH, TiO, VO, YO • Triatomics: C3, H2S, SO2 • Tetratomics: H2CO, H2CS, HCCH, HOOH, PH3,SO3 • Pentatomics: CH4, HNO3 • Larger molecules: C2H4, C2H6, C3H8, P2H2, P2H4 The production of comprehensive and very large rotation-vibration and rotation-vibration-electronic line lists requires a mixture of first principles quantum mechanical methods and empirical tuning based on laboratory spectroscopic data and makes extensive use of state-of-the-art computing. These and other aspects of molecular line lists, their production and astrophysical applications will be discussed. The contribution will make specific reference to molecules for which line lists have recently been completed or are nearing completion: phosphine, hydrogen sulphide, hydrogen peroxide, methane, formaldehyde, nitric acid as well as to a number of diatomic molecules of astrophysical importance, see Fig. 1.

  1. Vibrational Spectroscopy of Ions and Radicals Present in the Interstellar Medium and in Planetary Atmospheres: A Theoretical Study

    NASA Technical Reports Server (NTRS)

    Chaban, Galina M.

    2004-01-01

    Anharmonic vibrational frequencies and intensities are calculated for OH(H2O)n and H(H2O)n radicals (that form on icy particles of the interstellar medium), HCO radical (the main intermediate in the synthesis of organic molecules in space), NH2(-) and C2H(-) anions, H5(+) cation, and other systems relevant to interstellar chemistry. In addition to pure ions and radicals, their complexes with water are studied to assess the effects of water environment on infrared spectra. The calculations are performed using the correlation-corrected vibrational self-consistent field (CC-VSCF) method with ab initio potential surfaces at the MP2 and CCSD(T) levels. Fundamental, overtone, and combination excitations are computed. The results are in good agreement with available experimental data and provide reliable predictions for vibrational excitations not yet measured in laboratory experiments. The data should be useful for interpretation of astronomically observed spectra and identification of ions and radicals present in the interstellar medium and in planetary atmospheres.

  2. PHOTOMETRIC ORBITS OF EXTRASOLAR PLANETS

    SciTech Connect

    Brown, Robert A.

    2009-09-10

    We define and analyze the photometric orbit (PhO) of an extrasolar planet observed in reflected light. In our definition, the PhO is a Keplerian entity with six parameters: semimajor axis, eccentricity, mean anomaly at some particular time, argument of periastron, inclination angle, and effective radius, which is the square root of the geometric albedo times the planetary radius. Preliminarily, we assume a Lambertian phase function. We study in detail the case of short-period giant planets (SPGPs) and observational parameters relevant to the Kepler mission: 20 ppm photometry with normal errors, 6.5 hr cadence, and three-year duration. We define a relevant 'planetary population of interest' in terms of probability distributions of the PhO parameters. We perform Monte Carlo experiments to estimate the ability to detect planets and to recover PhO parameters from light curves. We calibrate the completeness of a periodogram search technique, and find structure caused by degeneracy. We recover full orbital solutions from synthetic Kepler data sets and estimate the median errors in recovered PhO parameters. We treat in depth a case of a Jupiter body-double. For the stated assumptions, we find that Kepler should obtain orbital solutions for many of the 100-760 SPGP that Jenkins and Doyle estimate Kepler will discover. Because most or all of these discoveries will be followed up by ground-based radial velocity observations, the estimates of inclination angle from the PhO may enable the calculation of true companion masses: Kepler photometry may break the 'msin i' degeneracy. PhO observations may be difficult. There is uncertainty about how low the albedos of SPGPs actually are, about their phase functions, and about a possible noise floor due to systematic errors from instrumental and stellar sources. Nevertheless, simple detection of SPGPs in reflected light should be robust in the regime of Kepler photometry, and estimates of all six orbital parameters may be feasible in at least a subset of cases.

  3. Direct imaging of extra-solar planets

    SciTech Connect

    Olivier, S.S.; Max, V.E.; Brase, J.M.; Caffano, C.J.; Gavel, D.T.; Macintosh, B.A.

    1997-03-01

    Direct imaging of extra-solar planets may be possible with the new generation of large ground-based telescopes equipped with state- of- the-art adaptive optics (AO) systems to compensate for the blurring effect of the Earth`s atmosphere. The first of these systems is scheduled to begin operation in 1998 on the 10 in Keck II telescope. In this paper, general formulas for high-contrast imaging with AO systems are presented and used to calculate the sensitivity of the Keck AO system. The results of these calculations show that the Keck AO system should achieve the sensitivity necessary to detect giant planets around several nearby bright stars.

  4. Effects of turbulence on average refraction angles in occultations by planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Eshleman, V. R.; Haugstad, B. S.

    1978-01-01

    Four separable effects of atmospheric turbulence on average refraction angles in occultation experiments are derived from a simplified analysis, and related to more general formulations by B. S. Haugstad. The major contributors are shown to be due to gradients in height of the strength of the turbulence, and the sense of the resulting changes in refraction angles is explained in terms of Fermat's principle. Because the results of analyses of such gradient effects by W. B. Hubbard and J. R. Jokipii are expressed in other ways, a special effort is made to compare all of the predictions on a common basis. We conclude that there are fundamental differences, and use arguments based on energy conservation and Fermat's principle to help characterize the discrepancies.

  5. Water vapor from a lunar breccia - Implications for evolving planetary atmospheres.

    NASA Technical Reports Server (NTRS)

    Cadenhead, D. A.; Buergel, W. G.

    1973-01-01

    The exposure of a typical complex lunar breccia to hydrogen after a through outgassing produces a fully reduced surface state. Subsequent outgassing over a wide temperature range results in the production of water vapor formed from the chemisorbed hydrogen and oxygen from the lunar sample; the proposed mechanism has been confirmed in terms of the chemisorption of deuterium and the release of heavy water. Since the conditions of the experiments are consistent with those on the lunar surface, it is postulated that water vapor will be produced on the moon through the interaction of the solar wind with lunar soil. It is also proposed that such a process could play an important role in the early history of many planets where an oxygen-rich soil is exposed to a reducing atmosphere.

  6. Impact induced dehydration of serpentine and the evolution of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Lange, M. A.; Ahrens, T. J.

    1982-01-01

    Results of shock recovery experiments carried out on antigorite serpentine Mg3Si2O5(OH)4 are reported. The main objective of the present study is the determination of critical shock pressures for partial and complete dehydration of serpentine under shock loading. It is pointed out that serpentine and serpentine-like layer silicates are the major water-bearing phases in carbonaceous chondrites. It appears that these minerals, and a poorly defined cometary contribution, were the most likely water-bearing phases in accreting planetesimals which led to the formation of the terrestrial planets. The obtained results imply that the process of impact induced devolatilization of volatile bearing minerals during accretion is likely to have occurred on earth. The findings lend support to the model of a terrestrial atmosphere/hydrosphere forming during the later stages of accretion of the earth.

  7. Shock-induced CO2 loss from CaCO3: Implications for early planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Lange, M. A.; Ahrens, T. J.

    1984-01-01

    Recovered samples from shock recovery experiments on single crystal calcite were subjected to thermogravimetric analysis to determine the amount of post-shock CO2, the decarbonization interval and the activation energy, for the removal of remaining CO2 in shock-loaded calcite. Comparison of post-shock CO2 with that initially present determines shock-induced CO2 loss as a function of shock pressure. Incipient to complete CO2 loss occurs over a pressure range of approximately 10 to approximately 70 GPa. Optical and scanning electron microscopy reveal structural changes, which are related to the shock-loading. The occurrence of dark, diffuse areas, which can be resolved as highly vesicular areas as observed with a scanning electron microscope are interpreted as representing quenched partial melts, into which shock-released CO2 was injected. The experimental results are used to constrain models of shock-produced, primary CO2 atmospheres on the accreting terrestrial planets.

  8. Water vapor from a lunar breccia: implications for evolving planetary atmospheres.

    PubMed

    Cadenhead, D A; Buergel, W G

    1973-06-15

    The exposure of a typical complex lunar breccia to hydrogen after a thorough outgassing produces a fully reduced surface state. Subsequent outgassing over a wide temperature range results in the production of water vapor formed from the chemisorbed hydrogen and oxygen from the lunar sample; the proposed mechanism has been confirmed in terms of the chemisorption of deuterium and the release of heavy water. Since the conditions of the experiments are consistent with those on the lunar surface, it is postulated that water vapor will be produced on the moon through the interaction of the solar wind with lunar soil. It is also proposed that such a process could play an important role in the early history of many planets where an oxygen-rich soil is exposed to a reducing atmosphere. PMID:17743599

  9. Optical Spectra of Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.; Hubeny, Ivan; Sudarsky, David; Burrows, Adam

    2004-01-01

    The flux distribution of a planet relative to its host star is a critical quantity for planning space observatories to detect and characterize extrasolar giant planets (EGP's). In this paper, we present optical planet-star contrasts of Jupiter-mass planets as a function of stellar type, orbital distance, and planetary cloud characteristics. As originally shown by Sudarsky et al. (2000, 2003), the phaseaveraged brightness of an EGP does not necessarily decrease monotonically with greater orbital distance because of changes in its albedo and absorption spectrum at lower temperatures. We apply our results to Eclipse, a 1.8-m optical telescope + coronograph to be proposed as a NASA Discovery mission later this year.

  10. Venus as a laboratory for studying planetary surface, interior, and atmospheric evolution

    NASA Astrophysics Data System (ADS)

    Smrekar, S. E.; Hensley, S.; Helbert, J.

    2013-12-01

    As Earth's twin, Venus offers a laboratory for understanding what makes our home planet unique in our solar system. The Decadal Survey points to the role of Venus in answering questions such as the supply of water and its role in atmospheric evolution, its availability to support life, and the role of geology and dynamics in controlling volatiles and climate. On Earth, the mechanism of plate tectonics drives the deformation and volcanism that allows volatiles to escape from the interior to the atmosphere and be recycled into the interior. Magellan revealed that Venus lacks plate tectonics. The number and distribution of impact craters lead to the idea Venus resurfaced very rapidly, and inspired numerous models of lithospheric foundering and episodic plate tectonics. However we have no evidence that Venus ever experienced a plate tectonic regime. How is surface deformation affected if no volatiles are recycled into the interior? Although Venus is considered a ';stagnant' lid planet (lacking plate motion) today, we have evidence for recent volcanism. The VIRTIS instrument on Venus Express mapped the southern hemisphere at 1.02 microns, revealing areas likely to be unweathered, recent volcanic flows. Additionally, numerous studies have shown that the crater population is consistent with ongoing, regional resurfacing. How does deformation and volcanism occur in the absence of plates? At what rate is the planet resurfacing and thus outgassing? Does lithospheric recycling occur with plate tectonics? In the 25 years since Magellan, the design of Synthetic Aperture Radar has advanced tremendously, allowing order of magnitude improvements in altimetry and imaging. With these advanced tools, we can explore Venus' past and current tectonic states. Tesserae are highly deformed plateaus, thought to be possible remnants of Venus' earlier tectonic state. How did they form? Are they low in silica, like Earth's continents, indicating the presence of abundant water? Does the plains volcanism cover an earlier tectonic surface, or perhaps cover ancient impact basins? Was there an abrupt transition in tectonic style, perhaps due to degassing of the crust or a more gradual shift? What is the nature of Venus' modern tectonics? Is the lithosphere still deforming? Is there recent or active volcanism? Is volcanism confined to hotspots, areas above mantle plumes? Has plains volcanism ceased? What are the implications for volatile history? These questions can be addressed via a combination of high resolution altimetry, imaging, and surface emissivity mapping.

  11. Stability of Satellites Around Close-in Extrasolar Giant Planets

    E-print Network

    Jason W. Barnes; D. P. O'Brien

    2002-05-02

    We investigate the long-term dynamical stability of hypothetical moons orbiting extrasolar giant planets. Stellar tides brake a planet's rotation and, together with tidal migration, act to remove satellites; this process limits the lifetimes of larger moons in extrasolar planetary systems. Because more massive satellites are removed more quickly than less massive ones, we are able to derive an upper mass limit for those satellites that might have survived to the present day. For example, we estimate that no primordial satellites with masses greater than 7 x 10^{-7} M_Earth$ (~ \\70km radius for rho=3 g cm^{-3}) could have survived around the transiting planet HD209458b for the age of the system. No meaningful mass limits can be placed on moons orbiting Jovian planets more than ~0.6 AU from their parent stars. Earth-like moons of Jovian planets could exist for 5 Gyr in systems where the stellar mass is greater than 0.15 M_Sun. Transits show the most promise for the discovery of extrasolar moons -- we discuss prospects for satellite detection via transits using space-based photometric surveys and the limits on the planetary tidal dissipation factor Q that a discovery would imply.

  12. Microfabricated silicon leak for sampling planetary atmospheres with a mass spectrometer

    SciTech Connect

    Jamieson, B. G.; Lynch, B. A.; Harpold, D. N.; Niemann, H. B.; Shappirio, M. D.; Mahaffy, P. R.

    2007-06-15

    A microfabricated silicon mass spectrometer inlet leak has been designed, fabricated, and tested. This leak achieves a much lower conductance in a smaller volume than is possible with commonly available metal or glass capillary tubing. It will also be shown that it is possible to integrate significant additional functionality, such as inlet heaters and valves, into a silicon microleak with very little additional mass. The fabricated leak is compatible with high temperature (up to 500 deg. C) and high pressure (up to 100 bars) conditions, as would be encountered on a Venus atmospheric probe. These leaks behave in reasonable agreement with their theoretically calculated conductance, although this differs between devices and from the predicted value by as much as a factor of 2. This variation is believed to be the result of nonuniformity in the silicon etching process which is characterized in this work. Future versions of this device can compensate for characterized process variations in order to produce devices in closer agreement with designed conductance values. The integration of an inlet heater into the leak device has also been demonstrated in this work.

  13. Impact induced dehydration of serpentine and the evolution of planetary atmospheres

    SciTech Connect

    Lange, M.A.; Ahrens, T.J.

    1982-11-15

    Shock recovery experiments in the 25 to 45 GPa range on antigorite serpentine determine the amount of shock-induced loss of structural water as a function of shock pressure. Infrared absorption spectra of shock recovered samples demonstrate systematic changes in the amount of structural water and molecular, surface adsorbed water. These yield qualitative estimates of shock-induced water loss and demonstrate that a portion of the shock release structural water is readsorbed on interfacial grain surfaces. Determination of the post-shock water content of the shocked samples relates shock-induced water loss and shock pressure. Based on the present results and theoretical predictions, we conclude that shock pressures of from 20 to approx.60 GPa induce incipient to complete water loss, respectively. This result agrees closely with theoretical estimates for total dehydration. The dehydration interval and the activation energies for dehydration in shocked samples decrease systematically with increasing shock pressure as experienced by the sample. We believe the present experiments are applicable to describing dehydration processes of serpentine-like minerals in the accretional environment of the terrestrial planets. We conclude that complete loss of structural water in serpentine could have occurred from accretional impacts of approx.3 km/sec when earth and Venus have grown to about 50% of their final size. Accreting planetesimals, impacting Mars, never reached velocities sufficient for complete dehydration of serpentine. Our results support a model in which an impact generated atmosphere/hydrosphere forms while the earth is accreting.

  14. Microfabricated silicon leak for sampling planetary atmospheres with a mass spectrometer.

    PubMed

    Jamieson, B G; Lynch, B A; Harpold, D N; Niemann, H B; Shappirio, M D; Mahaffy, P R

    2007-06-01

    A microfabricated silicon mass spectrometer inlet leak has been designed, fabricated, and tested. This leak achieves a much lower conductance in a smaller volume than is possible with commonly available metal or glass capillary tubing. It will also be shown that it is possible to integrate significant additional functionality, such as inlet heaters and valves, into a silicon microleak with very little additional mass. The fabricated leak is compatible with high temperature (up to 500 degrees C) and high pressure (up to 100 bars) conditions, as would be encountered on a Venus atmospheric probe. These leaks behave in reasonable agreement with their theoretically calculated conductance, although this differs between devices and from the predicted value by as much as a factor of 2. This variation is believed to be the result of nonuniformity in the silicon etching process which is characterized in this work. Future versions of this device can compensate for characterized process variations in order to produce devices in closer agreement with designed conductance values. The integration of an inlet heater into the leak device has also been demonstrated in this work. PMID:17614640

  15. Collision-induced Absorption in the Infrared: A Data Base for Modelling Planetary and Stellar Atmospheres

    NASA Technical Reports Server (NTRS)

    Borysow, Aleksandra

    1998-01-01

    Accurate knowledge of certain collision-induced absorption continua of molecular pairs such as H2-H2, H2-He, H2-CH4, CO2-CO2, etc., is a prerequisite for most spectral analyses and modelling attempts of atmospheres of planets and cold stars. We collect and regularly update simple, state of the art computer programs for the calculation of the absorption coefficient of such molecular pairs over a broad range of temperatures and frequencies, for the various rotovibrational bands. The computational results are in agreement with the existing laboratory measurements of such absorption continua, recorded with a spectral resolution of a few wavenumbers, but reliable computational results may be expected even in the far wings, and at temperatures for which laboratory measurements do not exist. Detailed information is given concerning the systems thus studied, the temperature and frequency ranges considered, the rotovibrational bands thus modelled, and how one may obtain copies of the FORTRAN77 computer programs by e-mail.

  16. New laboratory measurements on ammonia's inversion spectrum, with implications for planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Spilker, Thomas R.

    1993-01-01

    Microwave spectral measurements have been performed on pure room-temperature gaseous ammonia at frequencies from 1.75 to 18 GHz (1.7-17 cm), at 50-, 100-, and 300-torr pressures. These measurements are part of a laboratory program to measure the microwave absorption spectrum of ammonia, under conditions applicable to giant planet atmospheres, now in progress at the Jet Propulsion Laboratory. The pure ammonia data reported here agree well with previous data by Bleaney and Loubser (1950) at 100 and 300 torrs, and with predictions of the absorptivity formalism published by Berge and Gulkis. Success with pure ammonia but failure with mixtures of ammonia in hydrogen and helium (Spilker, 1990) indicates that the Berge and Gulkis formalism does not correctly handle foreign-gas effects on ammonia inversion lines. This may require modifying conclusions of radio astronomical and radio occultation studies that used this formalism. Notably, a suggested depletion of ammonia and superabundance of hydrogen sulfide may have been exaggerated as a result of inaccuracies in the Berge and Gulkis formalism.

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

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.

    1988-01-01

    In the first half of this grant year, laboratory measurements were conducted on the millimeter-wave properties of atmospheric gases under simulated conditions for the outer planet. Significant improvements in the current system have made it possible to accurately characterize the opacity from gaseous NH3 at longer millimeter wavelengths (7 to 10 mm) under simulated Jovian conditions. In the second half of the grant year, it is hoped to extend such measurements to even shorter millimeter-wavelengths. Further analysis and application of the laboratory results to microwave and millimeter-wave absorption data for the outer planets, such as results from Voyager Radio Occultation experiments and earth-based radio astronomical observations will be continued. The analysis of available multispectral microwave opacity data from Venus, including data from the most recent radio astronomical ovservations in the 1.3 to 3.6 cm wavelength range and newly obtained Pioneer-Venus Radio Occulatation measurements at 13 cm, using the laboratory measurements as an interpretative tool will be pursued.

  18. Planetary quarantine

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Those areas of future missions which will be impacted by planetary quarantine (PQ) constraints were identified. The specific objectives for this reporting period were (1) to perform an analysis of the effects of PQ on an outer planet atmospheric probe, and (2) to prepare a quantitative illustration of spacecraft microbial reduction resulting from exposure to space environments. The Jupiter Orbiter Probe mission was used as a model for both of these efforts.

  19. Cloud formation in substellar atmospheres

    E-print Network

    Christiane Helling

    2008-09-26

    Clouds seem like an every-day experience. But -- do we know how clouds form on brown dwarfs and extra-solar planets? How do they look like? Can we see them? What are they composed of? Cloud formation is an old-fashioned but still outstanding problem for the Earth atmosphere, and it has turned into a challenge for the modelling of brown dwarf and exo-planetary atmospheres. Cloud formation imposes strong feedbacks on the atmospheric structure, not only due to the clouds own opacity, but also due to the depletion of the gas phase, possibly leaving behind a dynamic and still supersaturated atmosphere. I summarise the different approaches taken to model cloud formation in substellar atmospheres and workout their differences. Focusing on the phase-non-equilibrium approach to cloud formation, I demonstrate the inside we gain from detailed micro-physical modelling on for instance the material composition and grain size distribution inside the cloud layer on a Brown Dwarf atmosphere. A comparison study on four different cloud approaches in Brown Dwarf atmosphere simulations demonstrates possible uncertainties in interpretation of observational data.

  20. 3D climate modeling of Earth-like extrasolar planets orbiting different types of host stars

    NASA Astrophysics Data System (ADS)

    Godolt, M.; Grenfell, J. L.; Hamann-Reinus, A.; Kitzmann, D.; Kunze, M.; Langematz, U.; von Paris, P.; Patzer, A. B. C.; Rauer, H.; Stracke, B.

    2015-06-01

    The potential habitability of a terrestrial planet is usually defined by the possible existence of liquid water on its surface, since life as we know it needs liquid water at least during a part of its life cycle. The potential presence of liquid water on a planetary surface depends on many factors such as, most importantly, surface temperatures. The properties of the planetary atmosphere and its interaction with the radiative energy provided by the planet's host star are thereby of decisive importance. In this study we investigate the influence of different main-sequence stars (F, G, and K-type stars) upon the climate of Earth-like extrasolar planets and their potential habitability by applying a state-of-the-art three-dimensional (3D) Earth climate model accounting for local and dynamical processes. The calculations have been performed for planets with Earth-like atmospheres at orbital distances (and corresponding orbital periods) where the total amount of energy received from the various host stars equals the solar constant. In contrast to previous 3D modeling studies, we include the effect of ozone radiative heating upon the vertical temperature structure of the atmospheres. The global orbital mean results obtained have been compared to those of a one-dimensional (1D) radiative convective climate model to investigate the approximation of global mean 3D results by those of 1D models. The different stellar spectral energy distributions lead to different surface temperatures and due to ozone heating to very different vertical temperature structures. As previous 1D studies we find higher surface temperatures for the Earth-like planet around the K-type star, and lower temperatures for the planet around the F-type star compared to an Earth-like planet around the Sun. However, this effect is more pronounced in the 3D model results than in the 1D model because the 3D model accounts for feedback processes such as the ice-albedo and the water vapor feedback. Whether the 1D model may approximate the global mean of the 3D model results strongly depends on the choice of the relative humidity profile in the 1D model, which is used to determine the water vapor profile. Hence, possible changes in the hydrological cycle need to be accounted for when estimating the potential habitability of an extrasolar planet.

  1. Earth as an Extrasolar Planet: Earth Model Validation Using EPOXI Earth Observations

    PubMed Central

    Meadows, Victoria S.; Crisp, David; Deming, Drake; A'Hearn, Michael F.; Charbonneau, David; Livengood, Timothy A.; Seager, Sara; Barry, Richard K.; Hearty, Thomas; Hewagama, Tilak; Lisse, Carey M.; McFadden, Lucy A.; Wellnitz, Dennis D.

    2011-01-01

    Abstract The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole-disk Earth model simulations used to better understand remotely detectable extrasolar planet characteristics. We have used these data to upgrade, correct, and validate the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model. This comprehensive model now includes specular reflectance from the ocean and explicitly includes atmospheric effects such as Rayleigh scattering, gas absorption, and temperature structure. We have used this model to generate spatially and temporally resolved synthetic spectra and images of Earth for the dates of EPOXI observation. Model parameters were varied to yield an optimum fit to the data. We found that a minimum spatial resolution of ?100 pixels on the visible disk, and four categories of water clouds, which were defined by using observed cloud positions and optical thicknesses, were needed to yield acceptable fits. The validated model provides a simultaneous fit to Earth's lightcurve, absolute brightness, and spectral data, with a root-mean-square (RMS) error of typically less than 3% for the multiwavelength lightcurves and residuals of ?10% for the absolute brightness throughout the visible and NIR spectral range. We have extended our validation into the mid-infrared by comparing the model to high spectral resolution observations of Earth from the Atmospheric Infrared Sounder, obtaining a fit with residuals of ?7% and brightness temperature errors of less than 1?K in the atmospheric window. For the purpose of understanding the observable characteristics of the distant Earth at arbitrary viewing geometry and observing cadence, our validated forward model can be used to simulate Earth's time-dependent brightness and spectral properties for wavelengths from the far ultraviolet to the far infrared. Key Words: Astrobiology—Extrasolar terrestrial planets—Habitability—Planetary science—Radiative transfer. Astrobiology 11, 393–408. PMID:21631250

  2. Earth as an extrasolar planet: Earth model validation using EPOXI earth observations.

    PubMed

    Robinson, Tyler D; Meadows, Victoria S; Crisp, David; Deming, Drake; A'hearn, Michael F; Charbonneau, David; Livengood, Timothy A; Seager, Sara; Barry, Richard K; Hearty, Thomas; Hewagama, Tilak; Lisse, Carey M; McFadden, Lucy A; Wellnitz, Dennis D

    2011-06-01

    The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole-disk Earth model simulations used to better understand remotely detectable extrasolar planet characteristics. We have used these data to upgrade, correct, and validate the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model. This comprehensive model now includes specular reflectance from the ocean and explicitly includes atmospheric effects such as Rayleigh scattering, gas absorption, and temperature structure. We have used this model to generate spatially and temporally resolved synthetic spectra and images of Earth for the dates of EPOXI observation. Model parameters were varied to yield an optimum fit to the data. We found that a minimum spatial resolution of ?100 pixels on the visible disk, and four categories of water clouds, which were defined by using observed cloud positions and optical thicknesses, were needed to yield acceptable fits. The validated model provides a simultaneous fit to Earth's lightcurve, absolute brightness, and spectral data, with a root-mean-square (RMS) error of typically less than 3% for the multiwavelength lightcurves and residuals of ?10% for the absolute brightness throughout the visible and NIR spectral range. We have extended our validation into the mid-infrared by comparing the model to high spectral resolution observations of Earth from the Atmospheric Infrared Sounder, obtaining a fit with residuals of ?7% and brightness temperature errors of less than 1?K in the atmospheric window. For the purpose of understanding the observable characteristics of the distant Earth at arbitrary viewing geometry and observing cadence, our validated forward model can be used to simulate Earth's time-dependent brightness and spectral properties for wavelengths from the far ultraviolet to the far infrared. Key Words: Astrobiology-Extrasolar terrestrial planets-Habitability-Planetary science-Radiative transfer. Astrobiology 11, 393-408. PMID:21631250

  3. The transport of nitric oxide in the upper atmosphere by planetary waves and the zonal mean circulation

    NASA Technical Reports Server (NTRS)

    Jones, G. A.; Avery, S. K.

    1982-01-01

    A time-dependent numerical model was developed and used to study the interaction between planetary waves, the zonal mean circulation, and the trace constituent nitric oxide in the region between 55 km and 120 km. The factors which contribute to the structure of the nitric oxide distribution were examined, and the sensitivity of the distribution to changes in planetary wave amplitude was investigated. Wave-induced changes in the mean nitric oxide concentration were examined as a possible mechanism for the observed winter anomaly. Results indicate that vertically-propagating planetary waves induce a wave-like structure in the nitric oxide distribution and that at certain levels, transports of nitric oxide by planetary waves could significantly affect the mean nitric oxide distribution. The magnitude and direction of these transports at a given level was found to depend not only on the amplitude of the planetary wave, but also on the loss rate of nitric oxide at that level.

  4. A model for eastward and westward jets in laboratory experiments and planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Marcus, P. S.; Lee, C.

    1998-06-01

    Flows in a rotating annular tank [J. Sommeria, S. D. Meyers, and H. L. Swinney, Nonlinear Topics in Ocean Physics, edited by A. Osborne (North Holland, Amsterdam, 1991); Nature (London) 337, 58 (1989); T. H. Solomon, W. J. Holloway, and H. L. Swinney, Phys. Fluids A 5, 1971 (1993); J. Sommeria, S. D. Meyers, and H. L. Swinney, Nature (London) 331, 689 (1989)] with a sloping bottom (that simulates a barotropic atmosphere's Coriolis force with a topographic ?-effect [J. Pedlosky, Geophysical Fluid Dynamics, 2nd ed. (Springer, Berlin, 1986)]) produce eastward and westward jets, i.e., azimuthal flows moving in the same or opposite direction as the annulus' rotation. Flows are forced by pumping fluid in and out of two concentric slits in the bottom boundary, and the direction of the jets depends on the direction of the pumping. The eastward and westward jets differ, with the former narrow, strong, and wavy. The jets of Jupiter and Saturn have the same east-west asymmetry [P. S. Marcus, Ann. Rev. Astron. Astro. 431, 523 (1993)]. Numerical simulations show that the azimuthally-averaged flow differs substantially from the non-averaged flow which has sharp gradients in the potential vorticity q. They also show that the maxima of the eastward jets and Rossby waves are located where the gradients of q are large, and the maxima of the westward jets and vortex chains are located where they are weak. As the forcing is increased the drift velocities of the two chains of vortices of the eastward jet lock together; whereas the two chains of the westward jet do not. Inspired by a previously published, [P. S. Marcus, Ann. Rev. Astron. Astro. 431, 523 (1993)] piece-wise constant-q model of the Jovian jets and based on numerical simulations, a new model of the experimental flow that is characterized by regions of undisturbed flow and bands of nearly uniform q separated by sharp gradients is presented. It explains the asymmetry of the laboratory jets and quantitatively describes all of the wave and vortex behavior in the experiments including the locking of the vortex chains of the eastward jet. The simulations and new model contradict the predictions of a competing, older model of the laboratory flow that is based on a Bickley jet; this raises concerns about previous calculations of Lagrangian mixing in the laboratory experiments that used the Bickley model for the fluid velocity. The new model, simulations and laboratory experiments all show that jets can be formed by the mixing and homogenization of q. The relevance of this to the jets of Jupiter is discussed.

  5. CO Emissions from Cometary and Planetary Atmospheres as a Marker for CO2

    NASA Astrophysics Data System (ADS)

    Kalogerakis, K.; Romanescu, C.; Ahmed, M.; Wilson, K. R.; Slanger, T. G.

    2012-12-01

    Photodissociation of CO2 in the atmosphere of Mars leads to dayglow emissions in the 190-250 nm region from the CO(a-X) Cameron bands, the 290-nm CO2+ (B-X) band, the 300-400 nm CO2+ (A-X) system, and the 297-nm O(1S-3P) line [1]. Very recently, detectors on Venus Express have shown the same emissions at that planet with an order of magnitude higher intensity [2], approximately 2 MR on the limb. It has been generally assumed that production of the CO(a) state is direct, i.e., CO2 is photodissociated by photons with wavelengths less than the 108-nm threshold to produce CO(a) + O(3P). Experiments at the Advanced Light Source (ALS) in Berkeley indicate that this scenario is incorrect, and that CO(a) production arises mainly from cascading from higher CO triplet states with a threshold of 100 nm [3]. The cascading process results in initial emission in the visible and infrared (IR), followed by the Cameron band emission. As a result, there are discrepancies between the observations and models and, furthermore, there has never been an attempt to monitor the strong unquenched CO dayglow emission in the visible and IR at Mars/Venus. On the other hand, cometary spectra in these wavelength regions are obtained from the ground, and a serious effort should be made to identify the very complex CO bands. [1] C. A. Barth et al., J. Geophys. Res. 76, 2213-2227 (1971). [2] J.-L. Bertaux et al., Geophys. Res. Abstracts, 14, EGU 2012-8097 (2012). [3] K. S. Kalogerakis et al., Icarus 220, 205-210 (2012). The ALS experiments were performed under grant NNX06AB82G from the NASA Outer Planets Research Program to SRI International. Partial support for K.S. Kalogerakis from NSF grants AST-0709173 and AST-1109372 is also acknowledged. M. Ahmed, K.R. Wilson, and the ALS are supported by the Director, Office of Energy Research, Office of Basic Energy Sciences, Chemical Sciences Division of the U.S. Department of Energy under contract No. DE-AC02-05CH11231.

  6. An investigation of low-frequency planetary wave forcing and predictability in a simple global atmospheric circulation model

    SciTech Connect

    Stewart, D.A.

    1992-01-01

    Dynamically consistent data generated by a simple 2-level global spectral model are used in conjunction with a diagnostic method to study the forcing of large-scale low-frequency (LF) atmospheric fluctuations. Run in perpetual January mode at moderate spatial resolution (i.e., R15 truncation), the model realistically simulates pertinent features of the observed time-mean climate and variability. The diagnostic method consists of calculating, from the R15 model output, the terms of the governing equations of a hypothetical low-order model that simulates only the slowly-evolving planetary-scale flow. The right hand sides of these low-pass-filtered equations are expressed in terms of resolved forcing and unresolved forcing, with the former representing autonomous processes involving only the large-scale LF components of the flow, and the latter containing the effects of high-frequency (HF) transient eddies. The roles of resolved and unresolved forcing during the various stages of composite positive and negative persistent anomalies are assessed. During anomaly maintenance, HF transient eddies anchor anomalies against downstream propagation and resist local decay. In contrast, the thermal forcing of the HF eddies acts in a destructive sense. Applying the diagnostic method to the onset stage suggests that autonomous processes typically determine the local growth of both positive and negative anomalies, consistent with interpreting their origin as a large-scale instability. The development of anomalies in HF transient eddy forcing, in general, stem from the evolution of the large-scale flow, rather than acting independently to initiate the large-scale anomaly development. Relationships between the resolved and unresolved forcing gleaned from the diagnostic phase of the study are exploited in the development of a quasi-stochastic parameterization of the latter in terms of the former.

  7. Amateur - professional collaborations in Giant Planets Atmospheres Research through the Planetary Virtual Observatory of the International Outer Planets Watch (PVOL - IOPW)

    NASA Astrophysics Data System (ADS)

    Hueso, R.; Legarreta, J.; Sánchez-Lavega, A.

    2015-10-01

    The atmospheres node of the International Outer Planets Watch (IOPW) maintains a large database of observations of the Giant Planets called Planetary Virtual Observatory Laboratory (PVOL) [1]. This image repository is contributed by amateur astronomers worldwide and its images keep a record of atmospheric activity on Jupiter, Saturn and Uranus over the years. PVOL was created as an unfunded project that has been online since 2004. Its data content has been growing ever since then, now containing about 25,000 image files that cover the period 2000-2015. The main characteristic of PVOL, when compared with other amateur images repositories, is that it is built as a database with different searching tools. This characteristic has made PVOL an important research tool over the years for various scientific teams. Here we update the description of the data in PVOL and we discuss new development plans in the context of the Virtual European Solar and Planetary Access (VESPA) collaboration which will bring life to a Virtual Observatory for Planetary Sciences. The database is available in the following address:

  8. Extrasolar Carbon Planets

    E-print Network

    Marc J. Kuchner; S. Seager

    2005-05-02

    We suggest that some extrasolar planets planets and low-mass white dwarf planets are especially good candidate members of this new class of planets, but these objects could also conceivably form around stars like the Sun. This planet-formation pathway requires only a factor of two local enhancement of the protoplanetary disk's C/O ratio above solar, a condition that pileups of carbonaceous grains may create in ordinary protoplanetary disks. Hot, Neptune-mass carbon planets should show a significant paucity of water vapor in their spectra compared to hot planets with solar abundances. Cooler, less massive carbon planets may show hydrocarbon-rich spectra and tar-covered surfaces. The high sublimation temperatures of diamond, SiC, and other carbon compounds could protect these planets from carbon depletion at high temperatures.

  9. Taxonomy of the extrasolar planet.

    PubMed

    Plávalová, Eva

    2012-04-01

    When a star is described as a spectral class G2V, we know that the star is similar to our Sun. We know its approximate mass, temperature, age, and size. When working with an extrasolar planet database, it is very useful to have a taxonomy scale (classification) such as, for example, the Harvard classification for stars. The taxonomy has to be easily interpreted and present the most relevant information about extrasolar planets. I propose an extrasolar planet taxonomy scale with four parameters. The first parameter concerns the mass of an extrasolar planet in the form of units of the mass of other known planets, where M represents the mass of Mercury, E that of Earth, N Neptune, and J Jupiter. The second parameter is the planet's distance from its parent star (semimajor axis) described in a logarithm with base 10. The third parameter is the mean Dyson temperature of the extrasolar planet, for which I established four main temperature classes: F represents the Freezing class, W the Water class, G the Gaseous class, and R the Roasters class. I devised one additional class, however: P, the Pulsar class, which concerns extrasolar planets orbiting pulsar stars. The fourth parameter is eccentricity. If the attributes of the surface of the extrasolar planet are known, we are able to establish this additional parameter where t represents a terrestrial planet, g a gaseous planet, and i an ice planet. According to this taxonomy scale, for example, Earth is 1E0W0t, Neptune is 1N1.5F0i, and extrasolar planet 55 Cnc e is 9E-1.8R1. PMID:22506608

  10. Atmosphere Expansion and Mass Loss of Close-orbit Giant Exoplanets Heated by Stellar XUV. II. Effects of Planetary Magnetic Field; Structuring of Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Khodachenko, M. L.; Shaikhislamov, I. F.; Lammer, H.; Prokopov, P. A.

    2015-11-01

    This is the second paper in a series where we build a self-consistent model to simulate the mass-loss process of a close-orbit magnetized giant exoplanet, so-called hot Jupiter (HJ). In this paper we generalize the hydrodynamic (HD) model of an HJ's expanding hydrogen atmosphere, proposed in the first paper, to include the effects of intrinsic planetary magnetic field. The proposed self-consistent axisymmetric 2D magnetohydrodynamics model incorporates radiative heating and ionization of the atmospheric gas, basic hydrogen chemistry for the appropriate account of major species composing HJ's upper atmosphere and related radiative energy deposition, and {{{H}}}3+ and Ly? cooling processes. The model also takes into account a realistic solar-type X-ray/EUV spectrum for calculation of intensity and column density distribution of the radiative energy input, as well as gravitational and rotational forces acting in a tidally locked planet–star system. An interaction between the expanding atmospheric plasma and an intrinsic planetary magnetic dipole field leads to the formation of a current-carrying magnetodisk that plays an important role for topology and scaling of the planetary magnetosphere. A cyclic character of the magnetodisk behavior, composed of consequent phases of the disk formation followed by the magnetic reconnection with the ejection of a ring-type plasmoid, has been discovered and investigated. We found that the mass-loss rate of an HD 209458b analog planet is weakly affected by the equatorial surface field <0.3 G, but is suppressed by an order of magnitude at the field of 1 G.

  11. The Twenty-Fifth Lunar and Planetary Science Conference. Part 1: A-G

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Papers from the conference are presented, and the topics covered include the following: planetary geology, meteorites, planetary composition, meteoritic composition, planetary craters, lunar craters, meteorite craters, petrology, petrography, volcanology, planetary crusts, geochronology, geomorphism, mineralogy, lithology, planetary atmospheres, impact melts, volcanoes, planetary evolution, tectonics, planetary mapping, asteroids, comets, lunar soil, lunar rocks, lunar geology, metamorphism, chemical composition, meteorite craters, and planetary mantles.

  12. Secular Resonances In Planetary Systems

    NASA Astrophysics Data System (ADS)

    Malhotra, Renu

    2006-06-01

    Secular effects introduce very low frequencies in planetary systems. The consequences are quite varied. They include mundane effects on the planetary ephemerides and on Earthly seasons, but also more esoteric effects such as apsidal alignment or anti-alignment, fine-splitting of mean motion resonances, broadening of chaotic zones, and dramatic orbital instabilities. Secular effects may shape the overall architecture of mature planetary systems by determining the long term stability of major and minor planetary bodies. This talk will be partly tutorial and partly a review of secular resonance phenomena here in the solar system and elsewhere in extra-solar systems. I acknowledge research support from NASA-Origins of Solar Systems and NASA-Outer Planets research programs.

  13. Jupiter-like planets as dynamical barriers to inward-migrating super-Earths: a new understanding of the origin of Uranus and Neptune and predictions for extrasolar planetary systems

    NASA Astrophysics Data System (ADS)

    Morbidelli, Alessandro; Izidoro Da Costa, Andre'; Raymond, Sean

    2014-11-01

    Planets of 1-4 times Earth's size on orbits shorter than 100 days exist around 30-50% of all Sun-like stars. These ``hot super-Earths'' (or ``mini-Neptunes''), or their building blocks, might have formed on wider orbits and migrated inward due to interactions with the gaseous protoplanetary disk. The Solar System is statistically unusual in its lack of hot super-Earths. Here, we use a suite of dynamical simulations to show that gas-giant planets act as barriers to the inward migration of super-Earths initially placed on more distant orbits. Jupiter's early formation may have prevented Uranus and Neptune (and perhaps Saturn's core) from becoming hot super-Earths. It may actually have been crucial to the very formation of Uranus and Neptune. In fact, the large spin obliquities of these two planets argue that they experienced a stage of giant impacts from multi-Earth mass planetary embryos. We show that the dynamical barrier offered by Jupiter favors the mutual accretion of multiple migrating planetary embryos, favoring the formation of a few massive objects like Uranus and Neptune. Our model predicts that the populations of hot super-Earth systems and Jupiter-like planets should be anti-correlated: gas giants (especially if they form early) should be rare in systems with many hot super-Earths. Testing this prediction will constitute a crucial assessment of the validity of the migration hypothesis for the origin of close-in super-Earths.

  14. EXTRASOLAR PLANETS Awhiffofmethane

    E-print Network

    - pheres in our Solar System: those of Earth, Mars, Titan and the gas giants, Jupiter, Saturn, Uranus our Solar System. It was made possible by the fact that HD 189733b is a transiting planet -- one whose us about planetary behaviour? The methane abun- dances on Jupiter, Saturn and both Uranus and Neptune

  15. Microlensing search for extrasolar planets: observational strategy, discoveries and implications

    E-print Network

    Arnaud Cassan; Takahiro Sumi; Daniel Kubas

    2007-11-29

    Microlensing has proven to be a valuable tool to search for extrasolar planets of Jovian- to Super-Earth-mass planets at orbits of a few AU. Since planetary signals are of very short duration, an intense and continuous monitoring is required. This is achieved by ground-based networks of telescopes (PLANET/RoboNET, microFUN) following up targets, which are identified as microlensing events by single dedicated telescopes (OGLE, MOA). Microlensing has led to four already published detections of extrasolar planets, one of them being OGLE-2005-BLG-390Lb, a planet of only ~5.5 M_earth orbiting its M-dwarf host star at ~2.6 AU. Very recent observations (May--September 2007) provided more planetary candidates, still under study, that will double the number of detections. For non-planetary microlensing events observed from 1995 to 2006 we compute detection efficiency diagrams, which can then be used to derive an estimate of the Galactic abundance of cool planets in the mass regime from Jupiters to Sub-Neptunes.

  16. Mean Motion Resonances and the Origins of Extrasolar Orbital Architectures

    NASA Astrophysics Data System (ADS)

    Batygin, Konstantin; Morbidelli, Alessandro

    2015-08-01

    The early stages of dynamical evolution of planetary systems are often shaped by dissipative processes that drive orbital migration. In multi-planet systems, convergent amassing of orbits inevitably leads to encounters with rational period ratios, which may result in establishment of mean motion resonances. The success or failure of resonant capture yields exceedingly different subsequent evolutions, and thus plays a central role in determining the ensuing orbital architecture of planetary systems. In this talk, we will show how an integrable Hamiltonian formalism for planetary resonances that allows both secondary bodies to have finite masses and eccentricities, can be used to construct a comprehensive theory for resonant capture. Employing the developed analytical model, we shall examine the origins of the dominantly non-resonant orbital distribution of sub-Jovian extrasolar planets, and demonstrate that the commonly observed extrasolar orbital structure can be understood if planet pairs encounter mean motion commensurabilities on slightly eccentric (e ~ 0.02) orbits. Accordingly, we speculate that resonant capture among low-mass planets is typically rendered unsuccessful due to subtle axial asymmetries inherent to the global structure of protoplanetary disks.

  17. Planetary atmospheres program

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Chemical and physical models of the Jovian subnebula are addressed. Halide cloud condensation and volatile element inventories on Venus and considered. Computation methods for isolated grain condensation behavior are examined.

  18. Dynamics of Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Ingersoll, Andrew P.

    2002-01-01

    The PI had nineteen papers either published or in press in 1999 through early 2002. Ten of these (Thomas et al. 1999, Geisler et al. 1999, Vasavada et al. 1999, Little et al. t999, Gierasch et al. 2000, Ingersoll et al. 2000, Thomas et al. 2000, Dyudina et al. 2001, Chang et al. 2001, Wang and Ingersoll 2002) were largely supported by the Mars Global Surveyor project and the Galileo project. The other nine papers were largely supported under this grant, and are listed in boldface below. Six of the nine are research papers. Their titles and abstracts are reproduced below. The New Solar System chapter and the Meteorology at the Millennium chapter are review articles, and the World Book Encyclopedia chapter is a popular article. Their title pages and abstracts are also reproduced below.

  19. Planetary atmospheres program

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Non-solar compositional models of the troposphere of Jupiter, halide cloud condensation and volatile element inventories on Venus, and shock-wave processing of interstellar cloud materials are discussed.

  20. Origins of Structure in Planetary Systems

    NASA Astrophysics Data System (ADS)

    Murray-Clay, Ruth

    2016-01-01

    Observations confirm that planet formation is a ubiquitous process that produces a diversity of planetary systems. However, a class of solar system analogs has yet to be identified among the thousands of currently known planets and candidates, the overwhelming majority of which are more easily detectable than direct counterparts of the Sun's worlds. To understand whether our solar system's history was unusual and, more generally, to properly characterize the galactic population of extrasolar planets, we must identify how differences in formation environment translate into different planetary system architectures. In this talk, I will consider our solar system in the context of theoretical advances in planet formation driven by the study of extrasolar planets. Along the way, I will discuss several examples of physical processes operating at different stages of planet formation that imprint observable structures on the dynamical and compositional demographics of planetary systems.