Lisa Kaltenegger and Later on I Appreciate It,” He Says
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Colors of Extreme Exo-Earth Environments
Colors of Extreme Exo-Earth Environments Siddharth Hegde1,* and Lisa Kaltenegger1,2 1Max Planck Institute for Astronomy, Heidelberg, Germany; 2Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA. *E-mail: [email protected]; [email protected] Abstract The search for extrasolar planets has already detected rocky planets and several planetary candidates with minimum masses that are consistent with rocky planets in the habitable zone of their host stars. A low-resolution spectrum in the form of a color-color diagram of an exoplanet is likely to be one of the first post-detection quantities to be measured for the case of direct detection. In this paper, we explore potentially detectable surface features on rocky exoplanets and their connection to, and importance as, a habitat for extremophiles, as known on Earth. Extremophiles provide us with the minimum known envelope of environmental limits for life on our planet. The color of a planet reveals information on its properties, especially for surface features of rocky planets with clear atmospheres. We use filter photometry in the visible waveband as a first step in the characterization of rocky exoplanets to prioritize targets for follow-up spectroscopy. Many surface environments on Earth have characteristic albedos and occupy a different color space in the visible waveband (0.4-0.9 !m) that can be distinguished remotely. These detectable surface features can be linked to the extreme niches that support extremophiles on Earth and provide a link between geomicrobiology and observational astronomy. This paper explores how filter photometry can serve as a first step in characterizing Earth-like exoplanets for an aerobic as well as an anaerobic atmosphere, thereby prioritizing targets to search for atmospheric biosignatures. -
Thea Kozakis
Thea Kozakis Present Address Email: [email protected] Space Sciences Building Room 514 Phone: (908) 892-6384 Ithaca, NY 14853 Education Masters Astrophysics; Cornell University, Ithaca, NY Graduate Student in Astronomy and Space Sciences, minor in Earth and Atmospheric Sciences B.S. Physics, B.S. Astrophysics; College of Charleston, Charleston, SC Double major (B.S.) in Astrophysics and Physics, May 2013, summa cum laude Minor in Mathematics Research Dr. Lisa Kaltenegger, Carl Sagan Institute, Cornell University, Spring 2015 - present Projects Studying biosignatures of habitable zone planets orbiting white dwarfs using a • coupled climate-photochemistry atmospheric model Searching the Kepler field for evolved stars using GALEX UV data • Dr. James Lloyd, Cornell University, Fall 2013 - present UV/rotation analysis of Kepler field stars • Study the age-rotation-activity relationship of 20,000 Kepler field stars using UV data from GALEX and publicly available rotation⇠ periods Dr. Joseph Carson, College of Charleston, Spring 2011 - Summer 2013 SEEDS Exoplanet Survey • Led data reduction e↵orts for the SEEDS High-Mass stars group using the Subaru Telescope’s HiCIAO adaptive optics instrument to directly image exoplanets Hubble DICE Survey • Developed data reduction pipeline for Hubble STIS data to image exoplanets and debris disks around young stars Publications Direct Imaging Discovery of a ‘Super-Jupiter’ Around the late B-Type Star • And, J. Carson, C. Thalmann, M. Janson, T. Kozakis, et al., 2013, Astro- physical Journal Letters, 763, 32 -
High-Resolution Spectra and Biosignatures of Earth-Like Planets Transiting White Dwarfs
High-resolution Spectra and Biosignatures of Earth-like Planets Transiting White Dwarfs Thea Kozakis, Zifan Lin, Lisa Kaltenegger Carl Sagan Institute, Cornell University, Ithaca, New York, USA ABSTRACT With the first observations of debris disks as well as proposed planets around white dwarfs, the question of how rocky planets around such stellar remnants can be char- acterized and probed for signs of life becomes tangible. White dwarfs are similar in size to Earth and have relatively stable environments for billions of years after initial cooling, making them intriguing targets for exoplanet searches and terrestrial planet atmospheric characterization. Their small size and the resulting large planet transit signal allows observations with next generation telescopes to probe the atmosphere of such rocky planets, if they exist. We model high-resolution transmission spectra for planets orbiting white dwarfs from as they cool from 6,000-4,000 K, for i) planets re- ceiving equivalent irradiation to modern Earth, and ii) planets orbiting at the distance around a cooling white dwarf which allows for the longest continuous time in the hab- itable zone. All high-resolution transmission spectra will be publicly available online upon publication of this study and can be used as a tool to prepare and interpret up- coming observations with JWST, the Extremely Large Telescopes as well as mission concepts like Origins, HabEx, and LUVOIR. Subject headings: White dwarf stars, Habitable zone, Habitable planets, Stellar evolution, Exoplanet atmospheres, Astrobiology, Biosignatures, Transmission spectroscopy, Extrasolar rocky planets 1. Introduction Zwart 2016; Malamud & Perets 2016) indi- cate debris disks or planets around a high The first discovery of a planetestimal or- percentage of WDs of up to 50% (Schreiber arXiv:2001.00049v3 [astro-ph.EP] 17 Jan 2020 biting a white dwarf (WD) in 2015 (Van- et al. -
Model Spectra of the First Potentially Habitable Super-Earth - Gl581d
Model Spectra of the First Potentially Habitable Super-Earth - Gl581d Lisa Kaltenegger Harvard Smithsonian Center for Astrophysics, 60 Garden st., 02138 MA Cambridge, USA also MPIA, Koenigstuhl 17, 69117 Heidelberg, Germany [email protected] Antígona Segura Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México Subhanjoy Mohanty Imperial College London, 1010 Blackett Lab., Prince Consort Road, London SW7 2AZ, UK Abstract Gl581d has a minimum mass of 7 MEarth and is the first detected potentially habitable rocky Super-Earth. Our models confirm that a habitable atmosphere can exist on Gl581d. We derive spectroscopic features for atmospheres, assuming an Earth-like composition for this planet, from high oxygen atmosphere analogous to Earth’s to high CO2 atmospheres with and without biotic oxygen concentrations. We find that a minimum CO2 partial pressure of about 7 bar, in an atmosphere with a total surface pressure of 7.6 bar, are needed to maintain a mean surface temperature above freezing on Gl581d. We model transmission and emergent synthetic spectra from 0.4µm to 40µm and show where indicators of biological activities in such a planet’s atmosphere could be observed by future ground- and space-based telescopes. The model we present here only represents one possible nature – an Earth-like composition - of a planet like Gl581d in a wide parameter space. Future observations of atmospheric features can be used to examine if our concept of habitability and its dependence on the carbonate-silicate cycle is correct, and assess whether Gl581d is indeed a habitable super-Earth. Subject headings: astrobiology, Planets and satellites: atmospheres, composition, detection, individual: Gl581d, Earth, Instrumentation: spectrographs 1. -
Earth's Own Evolution Used As Guide to Hunt Exoplanets 26 March 2020, by Blaine Friedlander
Earth's own evolution used as guide to hunt exoplanets 26 March 2020, by Blaine Friedlander "Using our own Earth as the key, we modeled five distinct Earth epochs to provide a template for how we can characterize a potential exo-Earth—from a young, prebiotic Earth to our modern world," she said. "The models also allow us to explore at what point in Earth's evolution a distant observer could identify life on the universe's 'pale blue dots' and other worlds like them." Kaltenegger and her team created atmospheric models that match the Earth of 3.9 billion years ago, a prebiotic Earth, when carbon dioxide densely cloaked the young planet. A second This artistic depiction shows exoplanet Kepler-62f, a throwback model chemically depicts a planet free of rocky super-Earth size planet, located about 1,200 light- oxygen, an anoxic Earth, going back 3.5 billion years from Earth in the constellation Lyra. Kepler-62f years. Three other models reveal the rise of oxygen may be what a prebiotic Earth may have looked like. in the atmosphere from a 0.2% concentration to Other exoplanets may look similar. Credit: NASA modern-day levels of 21%. Ames/JPL-Caltech "Our Earth and the air we breathe have changed drastically since Earth formed 4.5 billions years ago," Kaltenegger said, "and for the first time, this Cornell astronomers have created five models paper addresses how astronomers trying to find representing key points from our planet's evolution, worlds like ours, could spot young to modern Earth- like chemical snapshots through Earth's own like planets in transit, using our own Earth's history geologic epochs. -
The Astrophysical Journal HABITABLE ZONES of POST
The Astrophysical Journal HABITABLE ZONES OF POST-MAIN SEQUENCE STARS Ramses M. Ramirez1,2 and Lisa Kaltenegger1,3 1Carl Sagan Institute, Cornell University, Ithaca, NY 2Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, NY 3Department of Astronomy, Cornell University, Ithaca, NY ABSTRACT Once a star leaves the main sequence and becomes a red giant, its Habitable Zone (HZ) moves outward, promoting detectable habitable conditions at larger orbital distances. We use a one-dimensional radiative-convective climate and stellar evolutionary models to calculate post-MS HZ distances for a grid of stars from 3,700K to 10,000K (~M1 to A5 stellar types) for different stellar metallicities. The post-MS HZ limits are comparable to the distances of known directly imaged planets. We model the stellar as well as planetary atmospheric mass loss during the Red Giant Branch (RGB) and Asymptotic Giant Branch (AGB) phases for super-Moons to super-Earths. A planet can stay between 200 million years up to 9 Gyr in the post-MS HZ for our hottest and coldest grid stars, respectively, assuming solar metallicity. These numbers increase for increased stellar metallicity. Total atmospheric erosion only occurs for planets in close-in orbits. The post-MS HZ orbital distances are within detection capabilities of direct imaging techniques. Key words: planets and satellites: atmospheres, planets and satellites: detection, planet-star interactions, stars: post-main-sequence, stars: winds, outflows 1. Introduction that may promote habitability (Stern 2003). The recent discovery of sub-Earth sized planets Here, we calculate the post-main-sequence around an 11 billion year old star (Campante et boundaries of the Habitable Zone as well as al. -
The Habitable Zone and Extreme Planetary Orbits Authors
Title: The Habitable Zone and Extreme Planetary Orbits Authors: Stephen R. Kane, Dawn M. Gelino Affiliation: NASA Exoplanet Science Institute, Caltech, MS 100-22, 770 South Wilson Avenue, Pasadena, CA 91125, USA Correspondence: Stephen Kane, Address: NASA Exoplanet Science Institute, Caltech, MS 100-22, 770 South Wilson Avenue, Pasadena, CA 91125, USA, Phone: +1-626-395-1948, Fax: +1-626-397-7181, Email: [email protected] Running title: Extreme Planetary Orbits Abstract: The Habitable Zone for a given star describes the range of circumstellar distances from the star within which a planet could have liquid water on its surface, which depends upon the stellar properties. Here we describe the development of the Habitable Zone concept, its application to our own Solar System, and its subsequent application to exoplanetary systems. We further apply this to planets in extreme eccentric orbits and show how they may still retain life- bearing properties depending upon the percentage of the total orbit which is spent within the Habitable Zone. Keywords: Extra-solar Planets, Habitable Zone, Astrobiology 1. Introduction The detection of exoplanets has undergone extraordinary growth over the past couple of decades since sub-stellar companions were detected around HD 114762 (Latham et al 1989), pulsars (Wolszczan & Frail 1992), and 51 Peg (Mayor & Queloz 1995). From there the field rapidly expanded from the exclusivity of exoplanet detection to include exoplanet characterization. This has been largely facilitated by the discovery of transiting planets which allows unique opportunities to study the transmission and absorption properties of their atmospheres during primary transit (Agol et al 2010, Knutson et al 2007) and secondary eclipse (Charbonneau et al 2005, Richardson et al 2007). -
How to Characterize Habitable Worlds and Signs of Life
Annual Review of Astronomy and Astrophysics HOW TO CHARACTERIZE HABITABLE WORLDS AND SIGNS OF LIFE Lisa Kaltenegger Department of Astronomy and Carl Sagan Institute, Cornell University, Ithaca, New York 14853; email: [email protected] Published in Annual Review of Astronomy and Astrophysics 2017. 55:433–85 https://doi.org/10.1146/annurev-astro-082214-122238 KEYWORDS: Earth, exoplanets, habitability, habitable zone, search for life ABSTRACT The detection of exoplanets orbiting other stars has revolutionized our view of the cosmos. First results suggest that it is teeming with a fascinating diversity of rocky planets, including those in the habitable zone. Even our closest star, Proxima Centauri, harbors a small planet in its habitable zone, Proxima b. With the next generation of telescopes, we will be able to peer into the atmospheres of rocky planets and get a glimpse into other worlds. Using our own planet and its wide range of biota as a Rosetta stone, we explore how we could detect habitability and signs of life on exoplanets over interstellar distances. Current telescopes are not yet powerful enough to characterize habitable exoplanets, but the next generation of telescopes that is already being built will have the capabilities to characterize close-by habitable worlds. The discussion on what makes a planet a habitat and how to detect signs of life is lively. This review will show the latest results, the challenges of how to identify and characterize such habitable worlds, and how near- future telescopes will revolutionize the field. For the first time in human history, we have developed the technology to detect potential habitable worlds. -
Darwin – a Mission to Detect, and Search for Life On, Extrasolar Planets
Darwin – A Mission to Detect, and Search for Life on, Extrasolar Planets Charles S Cockell 1 CEPSAR, The Open University, Milton Keynes, MK7 6AA, UK. Tel : 01908 652588. Email: [email protected] Alain Léger IAS, bat 121, Universite Paris-Sud, F-91405, Paris, France Malcolm Fridlund Astrophysics Mission Division, European Space Agency, ESTEC, SCI-SA PO Box 299, Keplerlaan 1 NL 2200AG, Noordwijk, Netherlands. Tom Herbst Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg, Germany Lisa Kaltenegger Harvard-Smithsonian Center for Astrophysics. 60 Garden St. MS20, Cambridge , MA 02138, USA Olivier Absil Laboratoire d'Astrophysique de Grenoble, CNRS, Université Joseph Fourier, UMR 5571, BP53, F-38041 Grenoble, France Charles Beichman Michelson Science Center, California Inst. Of Technology, Pasedena, CA 91125, USA Willy Benz Physikalisches Institut, University of Berne, Switzerland Michel Blanc Observatoire Midi-Pyrénées, 14, Av. E. Belin, Toulouse, France Andre Brack Centre de Biophysique Moleculaire, CNPS, Rue Charles Sadron, 45071 Orleans cedex 2, France Alain Chelli Laboratoire d'Astrophysique de Grenoble, CNRS, Université Joseph Fourier, UMR 5571, BP53, F-38041 Grenoble, France Luigi Colangeli INAF - Osservatorio Astronoomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy Hervé Cottin Laboratoire Interuniversitaire des Systèmes Atmosphériques Universités Paris 12, Paris 7, CNRS UMR 7583 91, av. Di Général de Gaulle, 94010 Créteil Cedex, France Vincent Coudé du Foresto LESIA - Observatoire de Paris, 5 place -
This Article Appeared in a Journal Published by Elsevier. the Attached
This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier’s archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright Author's personal copy Available online at www.sciencedirect.com C. R. Palevol 8 (2009) 679–691 General palaeontology (Palaeobiochemistry) Characterizing habitable extrasolar planets using spectral fingerprints Lisa Kaltenegger a,∗, Franck Selsis b a Harvard Smithsonian Center for Astrophysics, 60, Garden Street, 02138 MA Cambridge, USA b Laboratoire d’astrophysique de Bordeaux (CNRS, Université Bordeaux-1), BP 89, 33271 Floirac cedex, France Received 9 January 2009; accepted after revision 3 July 2009 Available online 4 November 2009 Written on invitation of the Editorial Board Abstract The detection and characterization of an Earth-like planet is approaching rapidly thanks to radial velocity (RV) surveys (e.g. HARPS) and transit searches (Corot, Kepler). A rough characterization of these planets will be already achievable in 2014 with the James Webb Space Telescope, and more detailed spectral studies will be obtained by future large ground based telescopes (ELT, TNT, GMT), and dedicated space-based missions like Darwin, Terrestrial Planet Finder, New World Observer. -
Update on the Quest for an Earth-Like Planet Update on the Quest for An
LEAD ARTICLE by Hugh Ross, PhD UpdateUpdate onon thethe QuestQuest forfor anan Earth-LikeEarth-Like PlanetPlanet uring the Middle Ages and especially in DArthurian legend, the quest for the Holy Grail, the cup from which Jesus drank at the Last Supper, became the consuming passion of nobles. They were driven by belief that the cup possessed miraculous healing powers. Today, many astronomers passionately pursue a different Holy Grail. Their quest—to find a planet sufficiently like Earth to support life, perhaps even advanced life. The discovery of such a planet could, some believe, hold the power to deliver humanity from our cosmic loneliness, from our isolated existence on this pale blue dot. NEW REASONS TO BELIEVE | 4 | VOL 3/NO 4 | November 2011 GEOPHYSICS Hugh Ross Many of these modern-day Galahads and Lancelots, been able to measure the characteristics of nearly 700 aware that life arose as soon as the late heavy confirmed planets (at the date of this publication).6 bombardment subsided enough for liquid water to remain, assume that wherever liquid water exists, Of these confirmed and measured planets, 373 are life exists also. Such reasoning explains astronomer at least as massive as Jupiter or more so (Jupiter = Steven Vogt’s excitement at a recent news conference 317.4 Earth masses); 239 are less massive than Jupiter announcing the (presumed) discovery of Gliese 581g, but more massive than Uranus (Uranus =14.5 Earth a planet with a predicted surface temperature (at two masses); 77 are “super Earths,” more massive than Earth longitudes only) that would allow for the presence of but less massive than Uranus. -
Lisa Kaltenegger
Publication List L. Kaltenegger PUBLICATION LIST LISA KALTENEGGER Max Planck Institute for Astronomy e-mail: [email protected], [email protected] Koenigstuhl 17 URL: http://www.mpia.de/homes/kaltenegger 69117 Heidelberg, Germany also CfA, 60 Garden street, 02138 Ma Cambridge FIVE SAMPLE MAJOR PAPERS 1. Kaltenegger, L et al., Spectral Evolution of an Earth-like Planet, ApJ 658, 598, 2007 This paper changed the way the scientific community thinks about, and models rocky exoplanets, as well as what observes consider as input for design specifications of new instruments. It pioneered the study of observable spectra “spectral fingerprints” of Earth through geological times using fossil records as proxy for evolutionary stages of an exoEarths. 2. Kaltenegger, L & Traub, W., Transits of Earth-Like Planets, ApJ, 698, 1, pp. 519-527, 2009 This paper used shuttle data to produce the first Earth’s spectrum in transit geometry - the first spectral fingerprint of our Earth transiting the Sun and for the first time quantitatively evaluates future mission needs for JWST for the Exo-Earth science case. 3. Kaltenegger, L., Characterizing Habitable Exo-Moons, ApJL, 711, L1-L6, 2010 This paper address for the first time what it would take to figure out if a exomoon is habitable using spectroscopy while considering dynamical constraints on the moon’s orbit. 4. Kaltenegger L., et al.,Characterizing Volcano planets, ApJ, 140, 5, 1370, 2010 This paper established the idea that we can detect signatures of volcanism on exoplanets to establish if it is geologically active, and therefore can maintain surface habitability. 5. Kaltenegger L., et al., Characterizing Model Spectra of the First Potentially Habitable Super- Earth—Gl581d, ApJ, 733, 1, 2011 This paper explores whether Gl 581d could in principle provide habitable environments and how those could be observed using spectroscopy in transit and secondary eclipse.