Recipe for a Habitable Planet
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The Search for Another Earth – Part II
GENERAL ARTICLE The Search for Another Earth – Part II Sujan Sengupta In the first part, we discussed the various methods for the detection of planets outside the solar system known as the exoplanets. In this part, we will describe various kinds of exoplanets. The habitable planets discovered so far and the present status of our search for a habitable planet similar to the Earth will also be discussed. Sujan Sengupta is an 1. Introduction astrophysicist at Indian Institute of Astrophysics, Bengaluru. He works on the The first confirmed exoplanet around a solar type of star, 51 Pe- detection, characterisation 1 gasi b was discovered in 1995 using the radial velocity method. and habitability of extra-solar Subsequently, a large number of exoplanets were discovered by planets and extra-solar this method, and a few were discovered using transit and gravi- moons. tational lensing methods. Ground-based telescopes were used for these discoveries and the search region was confined to about 300 light-years from the Earth. On December 27, 2006, the European Space Agency launched 1The movement of the star a space telescope called CoRoT (Convection, Rotation and plan- towards the observer due to etary Transits) and on March 6, 2009, NASA launched another the gravitational effect of the space telescope called Kepler2 to hunt for exoplanets. Conse- planet. See Sujan Sengupta, The Search for Another Earth, quently, the search extended to about 3000 light-years. Both Resonance, Vol.21, No.7, these telescopes used the transit method in order to detect exo- pp.641–652, 2016. planets. Although Kepler’s field of view was only 105 square de- grees along the Cygnus arm of the Milky Way Galaxy, it detected a whooping 2326 exoplanets out of a total 3493 discovered till 2Kepler Telescope has a pri- date. -
The Subsurface Habitability of Small, Icy Exomoons J
A&A 636, A50 (2020) Astronomy https://doi.org/10.1051/0004-6361/201937035 & © ESO 2020 Astrophysics The subsurface habitability of small, icy exomoons J. N. K. Y. Tjoa1,?, M. Mueller1,2,3, and F. F. S. van der Tak1,2 1 Kapteyn Astronomical Institute, University of Groningen, Landleven 12, 9747 AD Groningen, The Netherlands e-mail: [email protected] 2 SRON Netherlands Institute for Space Research, Landleven 12, 9747 AD Groningen, The Netherlands 3 Leiden Observatory, Leiden University, Niels Bohrweg 2, 2300 RA Leiden, The Netherlands Received 1 November 2019 / Accepted 8 March 2020 ABSTRACT Context. Assuming our Solar System as typical, exomoons may outnumber exoplanets. If their habitability fraction is similar, they would thus constitute the largest portion of habitable real estate in the Universe. Icy moons in our Solar System, such as Europa and Enceladus, have already been shown to possess liquid water, a prerequisite for life on Earth. Aims. We intend to investigate under what thermal and orbital circumstances small, icy moons may sustain subsurface oceans and thus be “subsurface habitable”. We pay specific attention to tidal heating, which may keep a moon liquid far beyond the conservative habitable zone. Methods. We made use of a phenomenological approach to tidal heating. We computed the orbit averaged flux from both stellar and planetary (both thermal and reflected stellar) illumination. We then calculated subsurface temperatures depending on illumination and thermal conduction to the surface through the ice shell and an insulating layer of regolith. We adopted a conduction only model, ignoring volcanism and ice shell convection as an outlet for internal heat. -
Comparative Habitability of Transiting Exoplanets
Draft version October 1, 2015 A Preprint typeset using LTEX style emulateapj v. 04/17/13 COMPARATIVE HABITABILITY OF TRANSITING EXOPLANETS Rory Barnes1,2,3, Victoria S. Meadows1,2, Nicole Evans1,2 Draft version October 1, 2015 ABSTRACT Exoplanet habitability is traditionally assessed by comparing a planet’s semi-major axis to the location of its host star’s “habitable zone,” the shell around a star for which Earth-like planets can possess liquid surface water. The Kepler space telescope has discovered numerous planet candidates near the habitable zone, and many more are expected from missions such as K2, TESS and PLATO. These candidates often require significant follow-up observations for validation, so prioritizing planets for habitability from transit data has become an important aspect of the search for life in the universe. We propose a method to compare transiting planets for their potential to support life based on transit data, stellar properties and previously reported limits on planetary emitted flux. For a planet in radiative equilibrium, the emitted flux increases with eccentricity, but decreases with albedo. As these parameters are often unconstrained, there is an “eccentricity-albedo degeneracy” for the habitability of transiting exoplanets. Our method mitigates this degeneracy, includes a penalty for large-radius planets, uses terrestrial mass-radius relationships, and, when available, constraints on eccentricity to compute a number we call the “habitability index for transiting exoplanets” that represents the relative probability that an exoplanet could support liquid surface water. We calculate it for Kepler Objects of Interest and find that planets that receive between 60–90% of the Earth’s incident radiation, assuming circular orbits, are most likely to be habitable. -
Exoplanet Community Report
JPL Publication 09‐3 Exoplanet Community Report Edited by: P. R. Lawson, W. A. Traub and S. C. Unwin National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California March 2009 The work described in this publication was performed at a number of organizations, including the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). Publication was provided by the Jet Propulsion Laboratory. Compiling and publication support was provided by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not constitute or imply its endorsement by the United States Government, or the Jet Propulsion Laboratory, California Institute of Technology. © 2009. All rights reserved. The exoplanet community’s top priority is that a line of probeclass missions for exoplanets be established, leading to a flagship mission at the earliest opportunity. iii Contents 1 EXECUTIVE SUMMARY.................................................................................................................. 1 1.1 INTRODUCTION...............................................................................................................................................1 1.2 EXOPLANET FORUM 2008: THE PROCESS OF CONSENSUS BEGINS.....................................................2 -
Using an Energy Balance Model to Determine Exoplanetary Climates
Using an Energy Balance Model to Determine Exoplanetary Climates that Support Liquid Water By Macgregor Sullivan Presented to the Faculty of Wheaton College in Partial Fulfillment of the Requirements for Graduation with Departmental Honors in Physics May 14, 2018 1 Abstract The purpose of this thesis is to modify an energy balance atmospheric model created by R. Pierrehumbert (Pierrehumbert 2011). His energy balance model gave an estimate of Gliese 581g’s, a tidally locked exoplanet, atmosphere. Using an energy balance model, the surface and air temperatures can be found for a planet in equilibrium, when the amount incoming energy is equal to the amount of outgoing energy. Starting from Pierrehumbert’s model, we have added for a greenhouse effect and an ice-albedo feedback. We have also modified the model to test a rotating planet (similar to Earth) in addition to a tidally locked planet. This model, by varying the planet’s surface pressure, stellar flux, and the atmosphere's emissivity, can find which conditions leads to the planet having the temperatures needed to support liquid water. Surface pressure affects how efficient the planet is at redistributing heat leading to uniform temperatures across its surface. As the incoming stellar flux or the emissivity increase, the planet’s surface temperatures rise due the increase in absorbed energy from the planet’s surface. We have also found that the orbital distances that are able to support liquid water depend heavily on the pressure of the planet’s atmosphere. In future work, this model will produce the planet’s IR emission to determine if the planet is detectable using telescopes like the James Webb Space Telescope. -
PLANETARY CANDIDATES OBSERVED by Kepler. VIII. a FULLY AUTOMATED CATALOG with MEASURED COMPLETENESS and RELIABILITY BASED on DATA RELEASE 25
Draft version October 13, 2017 Typeset using LATEX twocolumn style in AASTeX61 PLANETARY CANDIDATES OBSERVED BY Kepler. VIII. A FULLY AUTOMATED CATALOG WITH MEASURED COMPLETENESS AND RELIABILITY BASED ON DATA RELEASE 25 Susan E. Thompson,1, 2, 3, ∗ Jeffrey L. Coughlin,2, 1 Kelsey Hoffman,1 Fergal Mullally,1, 2, 4 Jessie L. Christiansen,5 Christopher J. Burke,2, 1, 6 Steve Bryson,2 Natalie Batalha,2 Michael R. Haas,2, y Joseph Catanzarite,1, 2 Jason F. Rowe,7 Geert Barentsen,8 Douglas A. Caldwell,1, 2 Bruce D. Clarke,1, 2 Jon M. Jenkins,2 Jie Li,1 David W. Latham,9 Jack J. Lissauer,2 Savita Mathur,10 Robert L. Morris,1, 2 Shawn E. Seader,11 Jeffrey C. Smith,1, 2 Todd C. Klaus,2 Joseph D. Twicken,1, 2 Jeffrey E. Van Cleve,1 Bill Wohler,1, 2 Rachel Akeson,5 David R. Ciardi,5 William D. Cochran,12 Christopher E. Henze,2 Steve B. Howell,2 Daniel Huber,13, 14, 1, 15 Andrej Prša,16 Solange V. Ramírez,5 Timothy D. Morton,17 Thomas Barclay,18 Jennifer R. Campbell,2, 19 William J. Chaplin,20, 15 David Charbonneau,9 Jørgen Christensen-Dalsgaard,15 Jessie L. Dotson,2 Laurance Doyle,21, 1 Edward W. Dunham,22 Andrea K. Dupree,9 Eric B. Ford,23, 24, 25, 26 John C. Geary,9 Forrest R. Girouard,27, 2 Howard Isaacson,28 Hans Kjeldsen,15 Elisa V. Quintana,18 Darin Ragozzine,29 Avi Shporer,30 Victor Silva Aguirre,15 Jason H. Steffen,31 Martin Still,8 Peter Tenenbaum,1, 2 William F. -
Erosion of an Exoplanetary Atmosphere Caused by Stellar Winds J
A&A 630, A52 (2019) https://doi.org/10.1051/0004-6361/201935543 Astronomy & © ESO 2019 Astrophysics Erosion of an exoplanetary atmosphere caused by stellar winds J. M. Rodríguez-Mozos1 and A. Moya2,3 1 University of Granada (UGR), Department of Theoretical Physics and Cosmology, 18071 Granada, Spain 2 School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK e-mail: [email protected]; [email protected] 3 Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark Received 26 March 2019 / Accepted 8 August 2019 ABSTRACT Aims. We present a formalism for a first-order estimation of the magnetosphere radius of exoplanets orbiting stars in the range from 0.08 to 1.3 M . With this radius, we estimate the atmospheric surface that is not protected from stellar winds. We have analyzed this unprotected surface for the most extreme environment for exoplanets: GKM-type and very low-mass stars at the two limits of the habitable zone. The estimated unprotected surface makes it possible to define a likelihood for an exoplanet to retain its atmosphere. This function can be incorporated into the new habitability index SEPHI. Methods. Using different formulations in the literature in addition to stellar and exoplanet physical characteristics, we estimated the stellar magnetic induction, the main characteristics of the stellar wind, and the different star-planet interaction regions (sub- and super- Alfvénic, sub- and supersonic). With this information, we can estimate the radius of the exoplanet magnetopause and thus the exoplanet unprotected surface. -
Arxiv:2010.01074V2 [Astro-Ph.EP] 14 Jan 2021 Four Years
Draft version January 18, 2021 Typeset using LATEX twocolumn style in AASTeX63 Refining the transit timing and photometric analysis of TRAPPIST-1: Masses, radii, densities, dynamics, and ephemerides. Eric Agol ,1 Caroline Dorn ,2 Simon L. Grimm ,3 Martin Turbet ,4 Elsa Ducrot ,5 Laetitia Delrez ,6, 4, 5 Michaël Gillon ,5 Brice-Olivier Demory ,3 Artem Burdanov ,7 Khalid Barkaoui ,8, 5 Zouhair Benkhaldoun ,8 Emeline Bolmont ,4 Adam Burgasser ,9 Sean Carey ,10 Julien de Wit ,7 Daniel Fabrycky ,11 Daniel Foreman-Mackey ,12 Jonas Haldemann ,13 David M. Hernandez ,14 James Ingalls ,10 Emmanuel Jehin ,6 Zachary Langford ,1 Jérémy Leconte ,15 Susan M. Lederer ,16 Rodrigo Luger ,12 Renu Malhotra ,17 Victoria S. Meadows ,1 Brett M. Morris ,3 Francisco J. Pozuelos ,6, 5 Didier Queloz ,18 Sean N. Raymond ,15 Franck Selsis ,15 Marko Sestovic ,3 Amaury H.M.J. Triaud ,19 and Valerie Van Grootel 6 1Astronomy Department and Virtual Planetary Laboratory, University of Washington, Seattle, WA 98195 USA 2University of Zurich, Institute of Computational Sciences, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland 3Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, CH-3012, Bern, Switzerland 4Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, CH-1290 Sauverny, Switzerland 5Astrobiology Research Unit, Université de Liège, Allée du 6 Août 19C, B-4000 Liège, Belgium 6Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, B-4000 Liège, Belgium 7Department -
Abstracts of Extreme Solar Systems 4 (Reykjavik, Iceland)
Abstracts of Extreme Solar Systems 4 (Reykjavik, Iceland) American Astronomical Society August, 2019 100 — New Discoveries scope (JWST), as well as other large ground-based and space-based telescopes coming online in the next 100.01 — Review of TESS’s First Year Survey and two decades. Future Plans The status of the TESS mission as it completes its first year of survey operations in July 2019 will bere- George Ricker1 viewed. The opportunities enabled by TESS’s unique 1 Kavli Institute, MIT (Cambridge, Massachusetts, United States) lunar-resonant orbit for an extended mission lasting more than a decade will also be presented. Successfully launched in April 2018, NASA’s Tran- siting Exoplanet Survey Satellite (TESS) is well on its way to discovering thousands of exoplanets in orbit 100.02 — The Gemini Planet Imager Exoplanet Sur- around the brightest stars in the sky. During its ini- vey: Giant Planet and Brown Dwarf Demographics tial two-year survey mission, TESS will monitor more from 10-100 AU than 200,000 bright stars in the solar neighborhood at Eric Nielsen1; Robert De Rosa1; Bruce Macintosh1; a two minute cadence for drops in brightness caused Jason Wang2; Jean-Baptiste Ruffio1; Eugene Chiang3; by planetary transits. This first-ever spaceborne all- Mark Marley4; Didier Saumon5; Dmitry Savransky6; sky transit survey is identifying planets ranging in Daniel Fabrycky7; Quinn Konopacky8; Jennifer size from Earth-sized to gas giants, orbiting a wide Patience9; Vanessa Bailey10 variety of host stars, from cool M dwarfs to hot O/B 1 KIPAC, Stanford University (Stanford, California, United States) giants. 2 Jet Propulsion Laboratory, California Institute of Technology TESS stars are typically 30–100 times brighter than (Pasadena, California, United States) those surveyed by the Kepler satellite; thus, TESS 3 Astronomy, California Institute of Technology (Pasadena, Califor- planets are proving far easier to characterize with nia, United States) follow-up observations than those from prior mis- 4 Astronomy, U.C. -
Near-Resonance in a System of Sub-Neptunes from TESS
Near-resonance in a System of Sub-Neptunes from TESS The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Quinn, Samuel N., et al.,"Near-resonance in a System of Sub- Neptunes from TESS." Astronomical Journal 158, 5 (November 2019): no. 177 doi 10.3847/1538-3881/AB3F2B ©2019 Author(s) As Published 10.3847/1538-3881/AB3F2B Publisher American Astronomical Society Version Final published version Citable link https://hdl.handle.net/1721.1/124708 Terms of Use Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The Astronomical Journal, 158:177 (16pp), 2019 November https://doi.org/10.3847/1538-3881/ab3f2b © 2019. The American Astronomical Society. All rights reserved. Near-resonance in a System of Sub-Neptunes from TESS Samuel N. Quinn1 , Juliette C. Becker2 , Joseph E. Rodriguez1 , Sam Hadden1 , Chelsea X. Huang3,45 , Timothy D. Morton4 ,FredC.Adams2 , David Armstrong5,6 ,JasonD.Eastman1 , Jonathan Horner7 ,StephenR.Kane8 , Jack J. Lissauer9, Joseph D. Twicken10 , Andrew Vanderburg11,46 , Rob Wittenmyer7 ,GeorgeR.Ricker3, Roland K. Vanderspek3 , David W. Latham1 , Sara Seager3,12,13,JoshuaN.Winn14 , Jon M. Jenkins9 ,EricAgol15 , Khalid Barkaoui16,17, Charles A. Beichman18, François Bouchy19,L.G.Bouma14 , Artem Burdanov20, Jennifer Campbell47, Roberto Carlino21, Scott M. Cartwright22, David Charbonneau1 , Jessie L. Christiansen18 , David Ciardi18, Karen A. Collins1 , Kevin I. Collins23,DennisM.Conti24,IanJ.M.Crossfield3, Tansu Daylan3,48 , Jason Dittmann3 , John Doty25, Diana Dragomir3,49 , Elsa Ducrot17, Michael Gillon17 , Ana Glidden3,12 , Robert F. -
Circulation Patterns, Climate Moist Bistability, and Habitability
3D climate modeling of close-in land planets: Circulation patterns, climate moist bistability, and habitability The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Leconte, J., F. Forget, B. Charnay, R. Wordsworth, F. Selsis, E. Millour, and A. Spiga. 2013. “3D Climate Modeling of Close-in Land Planets: Circulation Patterns, Climate Moist Bistability, and Habitability.” Astronomy & Astrophysics 554 (June): A69. doi:10.1051/0004-6361/201321042. http:// dx.doi.org/10.1051/0004-6361/201321042. Published Version doi:10.1051/0004-6361/201321042 Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:27846337 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Open Access Policy Articles, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#OAP Astronomy & Astrophysics manuscript no. gliese_v5 c ESO 2013 March 29, 2013 3D climate modeling of close-in land planets: Circulation patterns, climate moist bistability and habitability Jérémy Leconte1, Francois Forget1, Benjamin Charnay1, Robin Wordsworth2, Franck Selsis3; 4, and Ehouarn Millour1 1 LMD, Institut Pierre-Simon Laplace, Université P. et M. Curie, BP99, 75005, Paris, France e-mail: [email protected] 2 Department of Geological Sciences, University of Chicago, 5734 S Ellis Avenue, Chicago, IL 60622, USA 3 Université de Bordeaux, Observatoire Aquitain des Sciences de l’Univers, BP 89, 33271 Floirac Cedex, France 4 CNRS, UMR 5804, Laboratoire d’Astrophysique de Bordeaux, BP 89, 33271 Floirac Cedex, France Accepted 27 March 2013 ABSTRACT The inner edge of the classical habitable zone is often defined by the critical flux needed to trigger the runaway greenhouse instability. -
Habitable Climate Scenarios for Proxima Centauri B with a Dynamic Ocean
HABITABLE CLIMATE SCENARIOS FOR PROXIMA CENTAURI B WITH A DYNAMIC OCEAN Anthony D. Del Genio1, Michael J. Way1, David S. Amundsen1,2, Igor Aleinov1,3, Maxwell Kelley1,4, Nancy Y. Kiang1, and Thomas L. Clune5 1NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025 2Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027 3 Center for Climate Systems Research, Columbia University, New York, NY 10027 4Trinnovim, LLC, 2880 Broadway, New York, NY 10025 5NASA Goddard Space Flight Center, Greenbelt, MD 20771 Submitted to Astrobiology September 6, 2017 Revised, April 3, 2018; second revision, May 18, 2018 Corresponding author: Anthony D. Del Genio NASA Goddard Institute for Space Studies 2880 Broadway, New York, NY 10025 Phone: 212-678-5588; Fax: 212-678-5552 Email: [email protected] Running title: Habitability of Proxima Centauri b 1 ABSTRACT The nearby exoplanet Proxima Centauri b will be a prime future target for characterization, despite questions about its retention of water. Climate models with static oceans suggest that Proxima b could harbor a small dayside surface ocean despite its weak instellation. We present the first climate simulations of Proxima b with a dynamic ocean. We find that an ocean-covered Proxima b could have a much broader area of surface liquid water but at much colder temperatures than previously suggested, due to ocean heat transport and/or depression of the freezing point by salinity. Elevated greenhouse gas concentrations do not necessarily produce more open ocean because of dynamic regime transitions between a state with an equatorial Rossby-Kelvin wave pattern and a state with a day-night circulation.