Detecting Exoplanet Transit

Total Page:16

File Type:pdf, Size:1020Kb

Detecting Exoplanet Transit Exoplanets Detecting Exoplanet Transit Edge on Face on Lab 5: Detecting Exoplanet Transit Lab 5: Detecting Exoplanet Transit • Due: March 13 (Wed) 11:59pm (e-submission) • Target: GJ 1214 b • Data: from ACAM on the William Herschel Telescope • Lectures on Exoplanets and Differential Photometry • Group Presentations: Preferred Dates & Format? Exoplanets Extra-solar Planets (Exoplanets) How Do We Detect? Exoplanet discoveries per year 2,000 confirmed exoplanets discovered so far! Exoplanets So how do we detect them? ● Direct Imaging ● Stellar Motions − velocities, timing, astrometry ● Light curve − transient planets Direct Imaging • Currently heating up with adaptive optics, high contrast imaging systems • Earth-like planet around a sun-like star is 10 billion times fainter than its star • Need to find a faint object very close to a bright star Beta Pictoris HR 8799 Direct Imaging • Only about ~ 20 planets directly imaged (2017) • Technically challenging Stellar Motions • Radial velocity, timing, astrometry Stellar Motions Radial Velocity Comparisons 1995 • Best measurements now at a level of 0.5 m/s (a slow walk) Stellar Motions Radial Velocity Comparisons • 51 Pegasi b – First planet around sun-like star • P = 4.23 days! Hot Jupiter Exoplanets How do we detect exoplanets? Light Curve Method: Transient Planets A transient planet changes blocks the light from a star = eclipse! ● Eclipse depth in terms of planet radius and star radius? Exoplanets How do we detect exoplanets? Light Curve Method: Transient Planets A transient planet changes blocks the light from a star = eclipse! ● Eclipse depth in terms of planet radius and star radius? ● Transit probability in terms of star radius and distance between the planet and star? Exoplanets How do we detect exoplanets? Light Curve Method: Transient Planets A transient planet changes blocks the light from a star = eclipse! ● Eclipse depth in terms of planet and star radii? ● Transit probability in terms of star radius and distance between the planet and star? Light Curve – Transiting Planets HD 209458 Precision Photometry Transit Transit Secondary Eclipse Orbital Period Can reach 10 parts-per-million accuracy for the brightest stars from space. Exoplanets How do we detect exoplanets? Light Curve Method: Transient Planets A transient planet changes blocks the light from a star = eclipse! Challenges and Advantages of Detecting Transient Planets? Exoplanets How do we detect exoplanets? Light Curve Method: Transient Planets Large Transit Planet Survey: OGLE, Kepler, Corot, … Exoplanets How do we detect exoplanets? Transient Planets The Kepler Project The Kepler Mission: Field FOV The Kepler Mission The Kepler Mission The Kepler Mission Exoplanets How do we detect exoplanets? Transient Planets Example: HD209458b (1999) Small telescope discovery Hubble Space Telescope data Exoplanets How do we detect exoplanets? Transient Planets “Information on planet atmosphere!” Exoplanets How do we detect exoplanets? Transient Planets “Information on planet atmosphere!” Example: HD209458b (1999) Exoplanets How do we detect exoplanets? Transient Planets “Information on planet atmosphere!” Example: HD209458b (1999) Exoplanets How do we detect exoplanets? Transient Planets “Information on planet atmosphere!” Exoplanet Density Measurement: o Density is critical to understanding the nature of planets Density measurement: Useful Diagrams Density measurement: Example Kepler-78 Star KIC 8435766 (Kepler-78) Constellation Cygnus h m s Right ascension (α) 19 34 58 Declination (δ) +44° 26′ 54″ Apparent magnitude (mV) 12 Radius (r) 0.73±0.15 R☉ Temperature (T) 5143 (± 70) K Metallicity [Fe/H] -0.08 (± 0.13) A planet was discovered in 2013 by analyzing data from Kepler space telescope. The planet was found not only transiting the star, but its occultation and reflected light from the parent star due to orbital phases were also detected. Density measurement: Example Kepler-78b (formerly known as KIC 8435766 b) is an exoplanet orbiting around the star Kepler-78. Mass (m) 1.69-1.85 M⊕ Radius (r) 1.12 R⊕ Bond Albedo (%) 20-60 % -3 Density (ρ) 5.3-5.6 g cm Exoplanet Density Measurement: o Density is critical to understanding the nature of planets o Part of Lab 5 is to measure the density of a transiting planet What do we learn from transit light curve analyses? o Transit Probability, Depth, Duration and Period o Limb Darkening Effect, Ingress and Egress Transit Probability, Depth, Duration: Simple Case o Transit Probability R*/a Geometrical 2 o Transit Depth (Rp/R* ) Configuration o Transit Duration (R*/a)P Geometry & Time ( Mass) Transit Probability, Depth, Duration: Simple Case Solid angle traced out by the two extreme transit configurations = Transit Probability = Blue Circles: two extreme planet-orbit inclinations, above and below which the planet does not transit. 2R*/a: angle separation between the two extreme orbits Transit Probability, Depth, Duration: Simple Case Condition for full transit: Condition for grazing transit: (i: inclination – see next slides) True Anomaly (): angle between direction of periapsis (B) and the current position of a planet (P) on an ellipse (= angular parameter that defines the position of a planet in a Keplerian orbit) Keplerian Planet Orbit Larger star and/or closer planet gives a high transit probability For an eccentric orbit (e: eccentricity): Higher probability with a large eccentricity Observer Edge on (i = 90), so always transit Face on (i = 0), so no transit i : the angle between the angular-momentum vector of the planet’s orbit and the line of sight. Transit Duration: time during which any part of the planet obscures the disc of the star, depends on how the planet transits the host star. Transit Length: length the planet has to travel across the disk of the star Transit Depth Ingress Egress Transit Depth Limb Darkening Transit Depth A small planet (e.g., Earth) requires high-precision photometry for the planet to be detected due to its shallow transit depth..
Recommended publications
  • Modelling and the Transit of Venus
    Modelling and the transit of Venus Dave Quinn University of Queensland <[email protected]> Ron Berry University of Queensland <[email protected]> Introduction enior secondary mathematics students could justifiably question the rele- Svance of subject matter they are being required to understand. One response to this is to place the learning experience within a context that clearly demonstrates a non-trivial application of the material, and which thereby provides a definite purpose for the mathematical tools under consid- eration. This neatly complements a requirement of mathematics syllabi (for example, Queensland Board of Senior Secondary School Studies, 2001), which are placing increasing emphasis on the ability of students to apply mathematical thinking to the task of modelling real situations. Success in this endeavour requires that a process for developing a mathematical model be taught explicitly (Galbraith & Clatworthy, 1991), and that sufficient opportu- nities are provided to students to engage them in that process so that when they are confronted by an apparently complex situation they have the think- ing and operational skills, as well as the disposition, to enable them to proceed. The modelling process can be seen as an iterative sequence of stages (not ) necessarily distinctly delineated) that convert a physical situation into a math- 1 ( ematical formulation that allows relationships to be defined, variables to be 0 2 l manipulated, and results to be obtained, which can then be interpreted and a n r verified as to their accuracy (Galbraith & Clatworthy, 1991; Mason & Davis, u o J 1991). The process is iterative because often, at this point, limitations, inac- s c i t curacies and/or invalid assumptions are identified which necessitate a m refinement of the model, or perhaps even a reassessment of the question for e h t which we are seeking an answer.
    [Show full text]
  • Predictable Patterns in Planetary Transit Timing Variations and Transit Duration Variations Due to Exomoons
    Astronomy & Astrophysics manuscript no. ms c ESO 2016 June 21, 2016 Predictable patterns in planetary transit timing variations and transit duration variations due to exomoons René Heller1, Michael Hippke2, Ben Placek3, Daniel Angerhausen4, 5, and Eric Agol6, 7 1 Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany; [email protected] 2 Luiter Straße 21b, 47506 Neukirchen-Vluyn, Germany; [email protected] 3 Center for Science and Technology, Schenectady County Community College, Schenectady, NY 12305, USA; [email protected] 4 NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA; [email protected] 5 USRA NASA Postdoctoral Program Fellow, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, USA 6 Astronomy Department, University of Washington, Seattle, WA 98195, USA; [email protected] 7 NASA Astrobiology Institute’s Virtual Planetary Laboratory, Seattle, WA 98195, USA Received 22 March 2016; Accepted 12 April 2016 ABSTRACT We present new ways to identify single and multiple moons around extrasolar planets using planetary transit timing variations (TTVs) and transit duration variations (TDVs). For planets with one moon, measurements from successive transits exhibit a hitherto unde- scribed pattern in the TTV-TDV diagram, originating from the stroboscopic sampling of the planet’s orbit around the planet–moon barycenter. This pattern is fully determined and analytically predictable after three consecutive transits. The more measurements become available, the more the TTV-TDV diagram approaches an ellipse. For planets with multi-moons in orbital mean motion reso- nance (MMR), like the Galilean moon system, the pattern is much more complex and addressed numerically in this report.
    [Show full text]
  • A Disintegrating Minor Planet Transiting a White Dwarf!
    A Disintegrating Minor Planet Transiting a White Dwarf! Andrew Vanderburg1, John Asher Johnson1, Saul Rappaport2, Allyson Bieryla1, Jonathan Irwin1, John Arban Lewis1, David Kipping1,3, Warren R. Brown1, Patrick Dufour4, David R. Ciardi5, Ruth Angus1,6, Laura Schaefer1, David W. Latham1, David Charbonneau1, Charles Beichman5, Jason Eastman1, Nate McCrady7, Robert A. Wittenmyer8, & Jason T. Wright9,10. ! White dwarfs are the end state of most stars, including We initiated follow-up ground-based photometry to the Sun, after they exhaust their nuclear fuel. Between better time-resolve the transits seen in the K2 data (Figure 1/4 and 1/2 of white dwarfs have elements heavier than S1). We observed WD 1145+017 frequently over the course helium in their atmospheres1,2, even though these of about a month with the 1.2-meter telescope at the Fred L. elements should rapidly settle into the stellar interiors Whipple Observatory (FLWO) on Mt. Hopkins, Arizona; unless they are occasionally replenished3–5. The one of the 0.7-meter MINERVA telescopes, also at FLWO; abundance ratios of heavy elements in white dwarf and four of the eight 0.4-meter telescopes that compose the atmospheres are similar to rocky bodies in the Solar MEarth-South Array at Cerro Tololo Inter-American system6,7. This and the existence of warm dusty debris Observatory in Chile. Most of these data showed no disks8–13 around about 4% of white dwarfs14–16 suggest interesting or significant signals, but on two nights we that rocky debris from white dwarf progenitors’ observed deep (up to 40%), short-duration (5 minutes), planetary systems occasionally pollute the stars’ asymmetric transits separated by the dominant 4.5 hour atmospheres17.
    [Show full text]
  • Contents JUPITER Transits
    1 Contents JUPITER Transits..........................................................................................................5 JUPITER Conjunct Sun..............................................................................................6 JUPITER Opposite Sun............................................................................................10 JUPITER Sextile Sun...............................................................................................14 JUPITER Square Sun...............................................................................................17 JUPITER Trine Sun..................................................................................................20 JUPITER Conjunct Moon.........................................................................................23 JUPITER Opposite Moon.........................................................................................28 JUPITER Sextile Moon.............................................................................................32 JUPITER Square Moon............................................................................................36 JUPITER Trine Moon................................................................................................40 JUPITER Conjunct Mercury.....................................................................................45 JUPITER Opposite Mercury.....................................................................................48 JUPITER Sextile Mercury........................................................................................51
    [Show full text]
  • A Warm Terrestrial Planet with Half the Mass of Venus Transiting a Nearby Star∗
    Astronomy & Astrophysics manuscript no. toi175 c ESO 2021 July 13, 2021 A warm terrestrial planet with half the mass of Venus transiting a nearby star∗ y Olivier D. S. Demangeon1; 2 , M. R. Zapatero Osorio10, Y. Alibert6, S. C. C. Barros1; 2, V. Adibekyan1; 2, H. M. Tabernero10; 1, A. Antoniadis-Karnavas1; 2, J. D. Camacho1; 2, A. Suárez Mascareño7; 8, M. Oshagh7; 8, G. Micela15, S. G. Sousa1, C. Lovis5, F. A. Pepe5, R. Rebolo7; 8; 9, S. Cristiani11, N. C. Santos1; 2, R. Allart19; 5, C. Allende Prieto7; 8, D. Bossini1, F. Bouchy5, A. Cabral3; 4, M. Damasso12, P. Di Marcantonio11, V. D’Odorico11; 16, D. Ehrenreich5, J. Faria1; 2, P. Figueira17; 1, R. Génova Santos7; 8, J. Haldemann6, N. Hara5, J. I. González Hernández7; 8, B. Lavie5, J. Lillo-Box10, G. Lo Curto18, C. J. A. P. Martins1, D. Mégevand5, A. Mehner17, P. Molaro11; 16, N. J. Nunes3, E. Pallé7; 8, L. Pasquini18, E. Poretti13; 14, A. Sozzetti12, and S. Udry5 1 Instituto de Astrofísica e Ciências do Espaço, CAUP, Universidade do Porto, Rua das Estrelas, 4150-762, Porto, Portugal 2 Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua Campo Alegre, 4169-007, Porto, Portugal 3 Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, PT1749-016 Lisboa, Portugal 4 Departamento de Física da Faculdade de Ciências da Universidade de Lisboa, Edifício C8, 1749-016 Lisboa, Portugal 5 Observatoire de Genève, Université de Genève, Chemin Pegasi, 51, 1290 Sauverny, Switzerland 6 Physics Institute, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland 7 Instituto de Astrofísica de Canarias (IAC), Calle Vía Láctea s/n, E-38205 La Laguna, Tenerife, Spain 8 Departamento de Astrofísica, Universidad de La Laguna (ULL), E-38206 La Laguna, Tenerife, Spain 9 Consejo Superior de Investigaciones Cientícas, Spain 10 Centro de Astrobiología (CSIC-INTA), Crta.
    [Show full text]
  • Correlations Between Planetary Transit Timing Variations, Transit Duration Variations and Brightness fluctuations Due to Exomoons
    Correlations between planetary transit timing variations, transit duration variations and brightness fluctuations due to exomoons April 4, 2017 K:E:Naydenkin1 and D:S:Kaparulin2 1 Academic Lyceum of Tomsk, High school of Physics and Math, Vavilova 8 [email protected] 2 Tomsk State University, Physics Faculty, Lenina av. 50 [email protected] Abstract Modern theoretical estimates show that with the help of real equipment we are able to detect large satellites of exoplanets (about the size of the Ganymede), although, numerical attempts of direct exomoon detection were unsuccessful. Lots of methods for finding the satellites of exoplanets for various reasons have not yielded results. Some of the proposed methods are oriented on a more accurate telescopes than those exist today. In this work, we propose a method based on relationship between the transit tim- ing variation (TTV) and the brightness fluctuations (BF) before and after the planetary transit. With the help of a numerical simulation of the Earth- Moon system transits, we have constructed data on the BF and the TTV for arXiv:1704.00202v1 [astro-ph.IM] 1 Apr 2017 any configuration of an individual transit. The experimental charts obtained indicate an easily detectable near linear dependence. Even with an artificial increase in orbital speed of the Moon and high-level errors in measurements the patterns suggest an accurate correlation. A significant advantage of the method is its convenience for multiple moons systems due to an additive properties of the TTV and the BF. Its also important that mean motion res- onance (MMR) in system have no affect on ability of satellites detection.
    [Show full text]
  • Detection of Exoplanets Using the Transit Method
    Detection of Exoplanets Using the Transit Method De nnis A fanase v , T h e Geo rg e W a s h i n g t o n Un i vers i t y *, Washington, DC 20052 [email protected] Abstract I conducted differential photometry on a star GSC 3281-0800, a known host to exoplanet HAT-P-32b, using analysis software AstroImageJ. I plotted the measurements from a series of images taken during the transit, via ADU count given from an earth-based digital CCD camera. I was able to establish a definite light curve and learn more about the properties of this exoplanet. * Columbian College of Arts and Sciences, 2020 Introduction Exoplanets are the planets found outside of the solar system. Since the first exoplanet was discovered in 1992, a number of methods for detection have been established. Specific to this paper, I will be evaluating the star known as HAT-P-32 (also catalogued as GSC 3281- 0800) and its exoplanet HAT-P-32b using the transit method. Figure 1. Light curve when planet passes in front of a star. When a planet passes in front of a star, the brightness of that star as Transit Method observed by us becomes dimmer; which I have conducted my research on depends on the size of the planet. The detecting exoplanets with the transit data we observe will show a dip in flux method. This method relies on taking if a planet is transiting the star we are the light flux of the target star and observing, as shown in Fig.
    [Show full text]
  • New Front of Exoplanetary Science: High Dispersion Coronagraphy (HDC)
    New Front of Exoplanetary Science: High Dispersion Coronagraphy (HDC) Ji Wang Caltech Transmission Spectroscopy Fischer et al. 2016 8/1/17 Knutson et al. 2007 Cloud and Haze Sing et al. 2011 Sing et al. 2016 Kreidberg et al. 2014 8/1/17 High Resolution Spectroscopy Wyttenbach et al. 2015 HD 189733b See also Khalafinejad et al. 2016 Atmospheric Composition From High- Resolution Spectroscopy HD 209458, Snellen et al. 2010 8/1/17 Planet Rotation – Beta Pic b Snellen et al. 2014 Dashed - Instrument Profile Solid – Measured Line Profile Doppler Imaging – Luhman 16 A & B DeViation from mean line profile Vs. time CCloud map of Lunman 16 B Luhman 16 B (Crossfield et al. 2014) Detection of H2O and CO on HR 8799 c Keck OSIRIS Konopacky et al. 2013 8/1/17 High Dispersion Coronagraphy Snellen et al. 2015 Keck NIRSPEC Keck NIRC2 Vortex 8/1/17 Keck Planet Imager and Characterizer PI: D. Mawet (Caltech) • Upgrade to Keck II AO and instrument suite: – L-band Vortex coronagraph in NIRC2 - deployed – IR PyWFS – funded (NSF) – SMF link to upgraded NIRSPEC (FIU) - funded (HSF & NSF) – High contrast FIU – seeking funding – MODIUS: New fiber-fed, Multi-Object Diffraction limited IR Ultra-high resolution (R~150k-200k) Spectrograph – design study encouraged by KSSC • Pathfinder to ELT planet imager exploring new high contrast imaging/spectroscopy instrument paradigms: – Decouple search and discoVery from characterization: specialized module/strategy for each task – New hybrid coronagraph designs: e.g. apodized vortex – Wavefront control: e.g. speckle nulling on SMF HDC Instruments • CRIRES • SPHERE + ESPRESSO • SCExAO + IRD • MagAO-X + RHEA • Keck Planet Imager and Characterizer (KPIC) Science cases for HDC • Planet detection and confirmation at moderate contrast from ground • Detecting molecular species in planet atmospheres • Measuring planet rotation • Measuring cloud map for brown dwarfs and exoplanets HDC Simulator Template Matching Mawet et al.
    [Show full text]
  • Fast Transit: Mars & Beyond
    Fast Transit: mars & beyond final Report Space Studies Program 2019 Team Project Final Report Fast Transit: mars & beyond final Report Internationali l Space Universityi i Space Studies Program 2019 © International Space University. All Rights Reserved. i International Space University Fast Transit: Mars & Beyond Cover images of Mars, Earth, and Moon courtesy of NASA. Spacecraft render designed and produced using CAD. While all care has been taken in the preparation of this report, ISU does not take any responsibility for the accuracy of its content. The 2019 Space Studies Program of the International Space University was hosted by the International Space University, Strasbourg, France. Electronic copies of the Final Report and the Executive Summary can be downloaded from the ISU Library website at http://isulibrary.isunet.edu/ International Space University Strasbourg Central Campus Parc d’Innovation 1 rue Jean-Dominique Cassini 67400 Illkirch-Graffenstaden France Tel +33 (0)3 88 65 54 30 Fax +33 (0)3 88 65 54 47 e-mail: [email protected] website: www.isunet.edu ii Space Studies Program 2019 ACKNOWLEDGEMENTS Our Team Project (TP) has been an international, interdisciplinary and intercultural journey which would not have been possible without the following people: Geoff Steeves, our chair, and Jaroslaw “JJ” Jaworski, our associate chair, provided guidance and motivation throughout our TP and helped us maintain our sanity. Øystein Borgersen and Pablo Melendres Claros, our teaching associates, worked hard with us through many long days and late nights. Our staff editors: on-site editor Ryan Clement, remote editor Merryl Azriel, and graphics editor Andrée-Anne Parent, helped us better communicate our ideas.
    [Show full text]
  • When Extrasolar Planets Transit Their Parent Stars 701
    Charbonneau et al.: When Extrasolar Planets Transit Their Parent Stars 701 When Extrasolar Planets Transit Their Parent Stars David Charbonneau Harvard-Smithsonian Center for Astrophysics Timothy M. Brown High Altitude Observatory Adam Burrows University of Arizona Greg Laughlin University of California, Santa Cruz When extrasolar planets are observed to transit their parent stars, we are granted unprece- dented 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 proto- planetary 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 spacebased 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 tran- sits of short-period Neptune-sized objects, whose existence was recently uncovered by the radial- velocity surveys, is eagerly anticipated.
    [Show full text]
  • Atmospheric Mass Loss of Extrasolar Planets Orbiting Magnetically Active
    MNRAS 000, 1–?? (2017) Preprint 8 August 2018 Compiled using MNRAS LATEX style file v3.0 Atmospheric mass loss of extrasolar planets orbiting magnetically active host stars Lalitha Sairam,1⋆ J. H. M. M. Schmitt,2 and Spandan Dash3 1Indian Institute of Astrophysics, II Block, Koramangala, Bangalore 560 034, India 2Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg 3Indian Institute of Science, C.V Raman Avenue, Yeshwantpur, Bangalore 560 012, India Accepted XXX. Received YYY; in original form ZZZ ABSTRACT Magnetic stellar activity of exoplanet hosts can lead to the production of large amounts of high-energy emission, which irradiates extrasolar planets, located in the immediate vicinity of such stars. This radiation is absorbed in the planets’ upper atmospheres, which consequently heat up and evaporate, possibly leading to an irradiation-induced mass-loss. We present a study of the high-energy emission in the four magnetically ac- tive planet-bearing host stars Kepler-63, Kepler-210, WASP-19, and HAT-P-11, based on new XMM-Newton observations. We find that the X-ray luminosities of these stars are rather high with orders of magnitude above the level of the active Sun. The total XUV irradiation of these planets is expected to be stronger than that of well stud- ied hot Jupiters. Using the estimated XUV luminosities as the energy input to the planetary atmospheres, we obtain upper limits for the total mass loss in these hot Jupiters. Key words: stars: activity – stars: coronae – stars: low-mass, late-type, planetary systems – stars: individual: Kepler-63, Kepler-210, WASP-19, HAT-P-11 1 INTRODUCTION through Jeans escape, the observations of atmospheric mass loss in HD 209458 b (Vidal-Madjar et al.
    [Show full text]
  • Mass-Loss Rates for Transiting Exoplanets Energy Diagram Enable to Estimate the Observable Transit Signa- Ture of Evaporating Planets (E.G., Ehrenreich Et Al
    Astronomy & Astrophysics manuscript no. massloss˙vA1 c ESO 2018 November 2, 2018 Mass-loss rates for transiting exoplanets D. Ehrenreich1 & J.-M. D´esert2 1 Institut de plan´etologie et d’astrophysique de Grenoble (IPAG), Universit´eJoseph Fourier-Grenoble 1, CNRS (UMR 5274), BP 53 38041 Grenoble CEDEX 9, France, e-mail: [email protected] 2 Harvard-Smithsonian Center for Astrophysics, 60 Garden street, Cambridge, Massachusetts 02138, USA, e-mail: [email protected] ABSTRACT Exoplanets at small orbital distances from their host stars are submitted to intense levels of energetic radiations, X-rays and extreme ultraviolet (EUV). Depending on the masses and densities of the planets and on the atmospheric heating efficiencies, the stellar energetic inputs can lead to atmospheric mass loss. These evaporation processes are observable in the ultraviolet during planetary transits. The aim of the present work is to quantify the mass-loss rates (m ˙ ), heating efficiencies (η), and lifetimes for the whole sample of transiting exoplanets, now including hot jupiters, hot neptunes, and hot super-earths. The mass-loss rates and lifetimes are estimated from an “energy diagram” for exoplanets, which compares the planet gravitational potential energy to the stellar X/EUV energy deposited in the atmosphere. We estimate the mass-loss rates of all detected transiting planets to be within 106 to 1013 g s−1 for various conservative assumptions. High heating efficiencies would imply that hot exoplanets such the gas giants WASP-12b and WASP-17b could be completely evaporated within 1 Gyr. We further show that the heating efficiency can be constrained whenm ˙ is inferred from observations and the stellar X/EUV luminosity is known.
    [Show full text]