Model Atmospheres for Stars and Brown Dwarfs : A Big Step Forwards !
Centre de Recherche Astrophysique de Lyon, France
We present a new grid of model atmosphere and synthetic spectra for stars and brown dwarfs which include the most complete and up-to-date opacity database for elements, molecules and condensed particles, NLTE for hydrogen to iron, a cloud model, and advective mixing based upon radiation hydrodynamic simulations by Ludwig et al. (2002, 2006), and Freytag et al. (2010). The new models explain the spectral properties of very low mass stars and brown dwarfs (http://phoenix.ens-lyon.fr/simulator/).
Global Simulations of a Young Extrasolar Planet in Presence of Cloud Formation and Rotation : Implications for Their Spectral Signatures.
Centre de Recherche Astrophysique de Lyon, France
We present preliminary results of global simulations of a planet under the interaction of rotation and cloud formation. We discuss the resulting spectral properties, the cloud surface distribution, and eventual variability signatures. This works extends our previous works on the subject (Barman, Hauschildt & Allard 2001, 2002, 2005, Barman 2007).
Breaking the “Great Silence”: the game of active SETI
IST Austria, Austria
SETI surveys have rarely engaged in active messaging. A simple game (prisoners dilemma) explains this: each player (civilization) can passively search (defect), or also broadcast (cooperate). The best strategy is defection. A model is presented that considers civilizations a) only interested in knowing whether there are other civilizations, b) keen on two-way communication, or c) willing to take advantage and exploit ours. I evaluate active SETI’s risks, chances of success, and expected gains.
Exoplanet characterisation with (future) ground-based telescopes
European Southern Observatory, Germany
I will introduce the next generation of extremely large telescopes (ELTs) and describe their goals with respect to the characterisation of exoplanets and the study of the formation of planetary systems. As the project scientist for the European ELT, I will present the recent studies showing the potential and limitations of that generation of ground-based telescopes with respect to direct detection and characterisation of Earth-like planets in habitable zones.
The Amazing Atacama Desert: How to Survive with no Water
1Pontificia Universidad Catolica de Chile, Chile; 2CENIMA, Universidad Arturo Prat, Iquique, Chile.; 3Pontificia Universidad Catolica de Chile, Chile; 4Pontificia Universidad Catolica de Chile, Chile; 5Pontificia Universidad Catolica de Chile, Chile
On earth there are several analog models being studied in order to understand what we could find elsewhere. One of these analogs is the Atacama Desert, focus of our research. One of the main aspects to be understood here is how life evolved to live with minimum amounts of water, and how it became so efficient in its use. Presently, we are trying to understand how photosynthetic microorganisms like cyanobacteria and microalgae cope with this by studying different habitats in the Atacama.
Search for the Water 22 GHz MASER Line in Planetary Systems ( The ITASEL project)
1IFSI-INAF, Italy; 2IRA-INAF, Italy; 3JIVE, The Netherlands; 4ASI, Italy
After the discovery 1994 of the first water MASER emission in the atmosphere of Jupiter induced by a cometary impact, we started to use the 22 GHz (1.35 cm) line as a diagnostic tool for cometary and for planetary water search outside our solar system. By using two different fast multichannel spectrometers coupled to the 32 m radiotelescopes of Medicina and Noto we investigated 35 targets up to 50 LY from the Sun. Here we report the promising results on: Eps Eri, Lalande 21185 and Gliese 876.
Microphysics of the Deposition of Energy by Cosmic Rays on Microorganisms
1Laboratorio de Astrobiologia - Instituto de Astronomia, Geofisica e Ciencias Atmosfericas - Universidade de Sao Paulo; 2Instituto de Fisica Teorica - Universidade Estadual Paulista; 3Universidade Federal do ABC - Santo Andre
We present numerical calculations for the microscopic effects of particulate radiation on microorganisms, aiming to understand the characteristics of damages caused by background cosmic rays and by particles accelerated in high energy astrophysical events, such as SNe and GRBs. We intend to explain observed phenomena like the increased mortality off the primary track of particles and extend our understanding of cell damages to higher energies or experimentally unavailable particles.
Looking for Life in High Temperature Worlds
Space research institute of Russian Academy of Science, Russian Federation
There is evidence that life would adapt to the high temperatures of exoplanets in low orbits. The known rhizobia use the high energy metabolism reaching 10 eV. Similar to extrasolar planet’s is the temperature on Venus, 740 K. Strange dark strikes of a regular shape can be seen on stones in the images transmitted in 1975 by Venera landers. May these strikes be Venusian plants? The illuminance 5-7 klx at the Venusian surface is enough for the photosynthesis of these hypothetic plants.
Metallicities of planet-hosting G-stars and their implications for terrestrial-like planets – a statistical analysis
University of Vienna, Research Platform: ExoLife/Institute for Astronomy, Vienna, Austria
We have used an uncompressed density model and defined two internal layers (core and mantle) for the exoplanets of interest to be able to estimate the sizes of their cores and mantles. Based on the estimated iron contents of Earth-size and super-Earth exoplanets we have investigated the statistics on the metallicities of known G-stars which host planets in order to make predications on potential extrasolar planets still waiting for their discovery.
Once in a Pale Blue Dot: Simulated Observations of an Extrasolar Earth-Moon System
1University of Washington Astronomy Department, United States of America; 2University of Washington Astrobiology Program; 3NASA Astrobiology Institute
The presence of a moon orbiting an exoplanet has important consequences for the characterization and understanding of the host planet. Modeled observations of an unresolved Earth-Moon system demonstrate that an undetected satellite can confound interpretations of the spectrum of a habitable exoplanet. By acquiring thermal infrared observations of a planet-moon system at different phases (i.e., illumination fractions), it may be possible to detect Moon-like companions to terrestrial exoplanets.
Habitability of Gliese 581d: atmospheric models and spectra
1Universidad Nacional Autónoma de México, Mexico; 2Max Planck Institute for Astronomy, Germany; 3Imperial College London, UK; 4Virtual Planetary Laboratory, NASA Astrobiology Institute
Gl581d has a minimum mass of 7 M_Earth and is the first detected potentially habitable Super-Earth. We derive spectroscopic features for atmospheres with and without biology assuming an Earth-like composition for this planet. We calculate the surface temperature assuming a high oxygen atmosphere analogous to present Earth’s and high CO2 atmospheres with and without biotic oxygen concentrations.
The Moon to see our Earth as a single dot or in transit: biosignatures from atmosphere and ground in the visible spectrum
Observatoire de Haute Provence - OAMP - CNRS USR2207, France
In the near future, we will be able to characterize super-Earth or Earth-like planets from direct spectroscopy or spectrally resolved transit photometry. These complementary approaches respectively allow to analyze the reflectivity of the planet and the transmission of its atmosphere. We present results from Earthshine and lunar eclipse observations to investigate the reflectivity and atmospheric transmission of the Earth considered as an extrasolar planet where life has developed.
Detecting Extrasolar Planetary Habitability: Sensitivity to Surface Temperature
1University of Washington, United States of America; 2NASA Astrobiology Institute
Determining whether an unresolved exoplanet can support liquid water on its surface will be an extremely challenging task, but is a necessary step in constraining planetary habitability. We present an exploration of challenges and limitations likely to be encountered in photometrically and spectroscopically determining surface temperatures of Earthlike planets, including the quantitative effects of clouds and gases. We also discuss the optimum wavelengths for temperature observation.
The Organic-Mediated Habitable Zone
1NASA Headquarters, United States of America; 2Virtual Planetary Laboratory; 3University of Washington Astronomy Department
In this presentation, we will discuss how organic-rich planetary atmospheres can extend both the inner and outer edges of the traditional habitable zone (Kasting, 1997) around a star. At the outer edge, methane and other organics increase the magnitude of the greenhouse effect. At the inner edge of the habitable zone, organic haze particles can shield the planet from incoming stellar radiation. This work will have an affect on current exoplanet searches and future characterization efforts.
Measuring the Habitability of Earth and Earth-like Exoplanets from Diurnal and Seasonal Light Curves
University of Puerto Rico at Arecibo, Puerto Rico
In the next two decades, missions to study exoplanets will be able to detect and sample the light of individual Earth-like exoplanets. Our main goal is to establish a methodology to help assess the habitability of Earth-like exoplanets from the limited information of photometric observations. In our analysis we traced the evolution of terrestrial habitability in the last million years as a model to interpret the light curves of Earth-like exoplanets.
Evaporating exoplanets as cradles for the development of microbial life
Laboratoire de Meteorologie Dynamique, France
Via simple models of atmospheric escape and greenhouse warming, I assess the idea that super-Earth exoplanets with evaporating hydrogen atmospheres could represent transiently favourable environments for the formation of life.
Extrasolar Planet Research at U de Chile
Universidad de Chile, Chile
I will present the latest publications and current status on projects lead by researchers and doctoral candidates at Universidad de Chile in the area of extrasolar planets. Making use of the privileged access to world-class telescopes, the research efforts are focused in ground-based observations. Long- and short-term projects are currently underway.
Tidal equilibrium and the habitability of extrasolar planets
1Leibniz-Institut für Astrophysik Potsdam (AIP), Germany; 2GrK 1351 “Extrasolar planets and their host stars”, Hamburger Sternwarte, Germany; 3cole Normale Supérieure de Lyon, France; 4University of Washington, Seattle, USA; 5Virtual Planetary Laboratory, USA
The gravitational interaction between a planet and its host star induces a steady change in the physical parameters of the system. It will decrease the angle between the planetary equator and the orbital plane (the obliquity) to 0°. Because both the rotation rate and the obliquity strongly affect the planetary climate, we show that tidal synchronization, tidal coplanarization and tidal heating urge a revision of the traditional concept of the ‘habitable zone’, especially for low-mass stars.
EChO, the Exoplanet Characterization Observatory
1LESIA - Observatoire de Paris, France; 2University College London, UK; 3Institut d'Astrophysique de Paris, France; 4Max-Planck Institut für Astronomie, Heidelberg, Germany; 5Eidgenossische Technische Hochschule Zurich, Switzerland; 6INAF, Osservatorio di Palermo, Italy; 7Institut de Ciencies de l’Espai, Barcelona, Spain; 8SRON Netherlands Institute for Space Research, Utrecht, Netherlands; 9Jet Propulsion Laboratory, Pasadena, USA
EChO is a space mission dedicated to the investigation of exoplanetary atmospheres. By providing high resolution, simultaneous multi-wavelength spectroscopic observations on a stable platform that will allow very long exposures, it will help us place our Solar System in context and address the suitability of planets for the presence of life. EChO is under study as a potential M3 mission in the frame of ESA’s Cosmic Vision program, with a target launch date of 2020.
Extremophile Desiccation Resistance: Thermally Stable Proteins in Rotifer Resting Eggs
Georgia Institute of Technology, United States of America
With adaptations to extreme environments, extremophiles expand our understanding of the boundaries of habitable conditions. One of the biggest challenges facing eukaryote extremophiles is the loss of water leading to desiccation. Two thermally stable proteins were identified in rotifer resting eggs; these proteins are hypothesized to associate with ribosomes during desiccation, protecting them from damage and then dissociate upon rehydration.
Potential Biosignatures in Super-Earth Atmospheres: Photochemical Responses
1Technische Universität Berlin (TUB), Germany; 2Inst. Planetary Research, DLR, Berlin-Adlershof, Germany; 3Alfred-Wegener Inst. für Polar- und Meeresforschung, Potsdam, Germany
Spectral characterisation of Super-Earth atmospheres for planets orbiting in the Habitable Zone (HZ) of M-stars is a key focus in exoplanet science. We assume a planet with an earthlike biomass and planetary development. We apply a climate-photochemical column model, varying planetary gravity (1g to 3g) and class (M0 to M7) of the central M-star. The spectral signals have been presented in Rauer et al. (2011). Here, we present a deeper analysis of the chemical processes in the planetary atmospheres.
Can Quasar Host Galaxies Support Life?
Shawnee State University, United States of America
What kinds of galaxies can support planets and life? In this study, we consider the effects of an active nucleus—in particular, the radiation environment and the influence of jets on the galaxy’s gas content. Bright elliptical galaxies are the ones most likely to have undergone major galactic mergers and an active phase with radio jets, which quenches star and planet formation. Existing planets would be subjected to the ionizing radiation environment produced by the quasar.
Hot Jupiters photo-thermo-chemistry: from experimental measurements to numerical modelling
1Laboratoire d'Astrophysique de Bordeaux, France; 2Laboratoire Réactions et Génie des Procédés, France; 3Laboratoire Interuniversitaire des Systèmes Atmosphériques, France
Exoplanet atmospheres current characterized are hot, subjected to very high UV fluxes and undergo strong circulation; a situation radically different from what is found in the atmospheres of our own Solar System and which requires the creation of a new generation of modelling tools. In that frame, we have measured VUV photoabsorption cross-sections at high temperatures for key species and we have developped a new photothermochemical model combining thermochemistry to non-equilibrium processes.