DOCSLIB.ORG

Dr. Avi Mandell (NASA) “Somewhere, Something Incredible Is Waiting to Be Known.” - Carl Sagan

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Dr. Avi Mandell (NASA) “Somewhere, Something Incredible Is Waiting to Be Known.” - Carl Sagan The Age of Exoplanets: From First Discoveries to the Search for Living Worlds Dr. Avi Mandell (NASA) “Somewhere, something incredible is waiting to be known.” - Carl Sagan How will the discovery of a distant planet teeming with life change our perspective on our own planet – and on ourselves? Planets 101: Our Solar SysteM Planets 101: Our Solar SysteM First Planet Around a Sun-Like Star Discovered in 1995 Notable Facts About 1995: • Bill Clinton is in his 3rd year of the Presidency • Ebay opens for business •DVDs are first introduced •Big event for the coffee-drinking world… Invention of the Frappucino! The First Planets were Discovered by Measuring The Motions of Stars 51 Peg b • Uses the change in star’s light due to the Doppler effect Mayor & Queloz, Movie: eso1035g.mov November 1995 Dr. Michel Mayor & Dr. Didier Queloz Geneva Observatory Spectrum of Starlight from Dr. Geoff Marcy & Parent Star Dr. R. Paul Butler San Francisco State Univ. Timeline of Exoplanet Discoveries Known Exoplanets, 1995: 0 Planet Mass Jup. Neptune Earth Mercury Earth Jupiter Distance to the Star Timeline of Exoplanet Discoveries Known Exoplanets, 1996: 6 Planet Mass Jup. First Confirmed RV Planet: 51 Peg b Neptune Earth Mercury Earth Jupiter Distance to the Star Timeline of Exoplanet Discoveries Known Exoplanets, 1996: 6 2000: 38 Planet Mass First Transiting Planet: Jup. HD 209458 b First Confirmed RV Planet: 51 Peg b Neptune Earth Mercury Earth Jupiter Distance to the Star The Most Planets have been Discovered by Measuring The Shadows on Stars Movie: OccultationGraphH264FullSize.mov Timeline of Exoplanet Discoveries Known Exoplanets, 2000: 38 2005: 155 2008: 260 2012: 579 Planet Mass Jup. Neptune Earth Mercury Earth Jupiter Distance to the Star Revolutionizing Exoplanet Discovery: The Kepler Space Telescope • Launched in March 2009 • Stared at one patch of the sky (~150,000 stars) for a total of 5 years and watched for planetary transits Revolutionizing Exoplanet Discovery: The Kepler Space Telescope Kepler Has Discovered 4,696 Planet Candidates as of July 2015 Statistics of Planetary Systems: The Kepler Space Telescope Candidate Planets Feb 2012 Statistics of Planetary Systems: The Kepler Space Telescope Candidate Planets Feb 2012 Io M E Kepler’s Super-Earth Planets: Neptune-Like or Earth-Like? Kepler-11 e Kepler-11 d Kepler-11 c Kep-11 f Kepler-11 b *confirmed planets Lissauer et al. 2011 Kepler’s Super-Earth Planets: Neptune-Like or Earth-Like? The Temperate Sweet Spot: The Habitable Zone Water Water Boils Freezes Finding Nearby Transiting Earth-Like Planets We need planets that are rocky and nearby… “Good planets are hard to find, and hard planets are good to find” Before 2009 50% Fe 100% H2O Berta-Thompson et al. 2015 Finding Nearby Transiting Earth-Like Planets We need planets that are rocky and nearby… “Good planets are hard to find, and hard planets are good to find” AfterBefore 2009 2009 50% Fe 100% H2O Berta-Thompson et al. 2015 What Does a Living Planet’s Atmosphere Look (or Smell) Like? How Do We Learn About The Atmospheres of Transiting Planets? • Transits provide the – As starlight passes – The more absorption, opportunity to probe through the the larger a planet’s the absorption in a atmosphere of a planet, radius appears, and the planet’s atmosphere atoms and molecules higher the altitude that absorb at different the transmitted light wavelengths passes through Apparent Planet Size Revolutionizing Exoplanet Atmospheres: The James Webb Space Telescope • Expected launch in 2018, first light in early 2019 • More than 100x more sensitive than any previous IR telescope Simulated Habitable Super-Earth (Teq ~ 300K) around an M-star at 20 pc with JWST H2O H2O CO2 Abs. Abs. Abs. Deming et al. 2009 How to See Earth-Sized planets around Sun-like Stars Coronographic Imaging Remaining light Light is focused… at edge and center… Problem: The final image: Initial Stellar almost all starlight is removed, Illumination – revealing the planet Too bright! planet? planet! … and mostly … is blocked again! star blocked (Simulated image) Occulting Spot Adapted from Lyot Stop Lyot.org How to See Earth-Sized planets around Sun-like Stars Coronographic Imaging Remaining light Light is focused… at edge and center… Problem: The final image: Beta Pictoris b almost all starlight is removed, Initial Stellar Illumination – revealing the planet ~ 8MJ, ~ 10 AU Too bright! planet? planet! … and mostly … is blocked again! star blocked (Simulated image) Occulting Spot Adapted from Lyot Stop Lyot.org Bonnefoy et al. 2011 – Optimal technique for finding colder planets at larger distances from their parent star – Earth-like planets will require HR 8799 b,c,d,e All planets ~ 8 M technology 10,000x more precise J than the current best performance Marois et al. 2010 Marching Towards The Ultimate Goal: Measuring the Atmosphere on a Living Planet Timeline of Exoplanet Discovery 1990 Hubble Launched First Exoplanet Found 2000 First Transiting ExPl. Spitzer Launched First Light from an ExPl. Kepler Launched 2010 First Spectrum of a Super-Earth First Earth-sized ExPl Found First Habitable Earth-sized ExPl ? JWST Planned Launch 2020 First Spectrum of a Habitable M-Earth? 2030 N. Gen. Telescope Launched? First Spectrum of a Habitable Earth? Marching Towards The Ultimate Goal: Measuring the Atmosphere on a Living Planet • Timeline of Exoplanet Discovery The goal is to acquire both an image and a spectrum of a nearby Earth-sized planet, in order 1990 Hubble Launched to search for definitive signs of life First Exoplanet Found Thermal Emission at 300K 2000 First Transiting ExPl. Spitzer Launched First Light from an ExPl. Water Kepler Launched Ozone 2010 Absorb. First Spectrum of a Super-Earth Absorb. First Earth-sized ExPl Found PlanetBrightness Methane First Habitable Earth-sized ExPl ? Absorb. Carbon Diox. Absorb. JWST Planned Launch 2020 First Spectrum of a Habitable M-Earth? 6 8 10 12 14 Wavelength (μm) Robinson et al. 2011 Bacteria Plants & Algae 2030 N. Gen. Telescope Launched? First Spectrum of a Habitable Earth? Liquid Water.
Load more

Recommended publications
  • Arxiv:2009.06280V1 [Astro-Ph.EP] 14 Sep 2020
    Astronomy & Astrophysics manuscript no. vis_hd20_hd18 c ESO 2020 September 15, 2020 Discriminating between hazy and clear hot-Jupiter atmospheres with CARMENES A. Sánchez-López1, M. López-Puertas2, I. A. G. Snellen1, E. Nagel3, F. F. Bauer2, E. Pallé4; 5, L. Tal-Or6; 9, P. J. Amado2, J. A. Caballero7, S. Czesla8, L. Nortmann9, A. Reiners9, I. Ribas10; 11, A. Quirrenbach12, J. Aceituno13, V. J. S. Béjar4; 5, N. Casasayas-Barris4; 5, Th. Henning14, K. Molaverdikhani14, D. Montes15, M. Stangret4; 5, M. R. Zapatero Osorio16, and M. Zechmeister9 1 Leiden Observatory, Leiden University, Postbus 9513, 2300 RA, Leiden, The Netherlands e-mail: [email protected] 2 Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain 3 Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany 4 Instituto de Astrofísica de Canarias (IAC), Calle Vía Láctea s/n, 38200 La Laguna, Tenerife, Spain 5 Departamento de Astrofísica, Universidad de La Laguna, 38026 La Laguna, Tenerife, Spain 6 Department of Physics, Ariel University, Ariel 40700, Israel 7 Centro de Astrobiología (CSIC-INTA), ESAC, Camino bajo del castillo s/n, 28692 Villanueva de la Cañada, Madrid, Spain 8 Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany 9 Institut für Astrophysik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany 10 Institut de Ciències de l’Espai (CSIC-IEEC), Campus UAB, c/ de Can Magrans s/n, 08193 Bellaterra, Barcelona, Spain 11 Institut d’Estudis Espacials
    [Show full text]
  • The Astronomy Department of the University of Geneva (UNIGE) and Its Exoplanet Team
    Département D'Astronomie Chemin des Mailletess 5 Université De Genève CH-5290 Versoix Sauverny Switzerland +45 22 379 22 00 [email protected] www.unige.ch/sciences/astro/en/ The Astronomy Department of the University of Geneva (UNIGE) and its Exoplanet Team About the Astronomy Department The Department of Astronomy of the University of Geneva (UNIGE) is located on the commune of Versoixs 5 km from the Geneva city center. The main buidings (l’Observatoire) are in the forest on the site of Sauvernys km from the town of Versoix. Another sites Ecogias closer to town hosts most of our space developments. Grounded in 5772 as the Geneva Observatory the insttute became the Department of Astronomy of UNIGE in 5973. Todays a group of approximately 5 0 people are employeds including scientstss PhD candidatess studentss technical staf (computer and electronics specialistss mechanics)s as well as administratve staf. The Astronomy Department manages a permanent astronomical observaton statonn a 5s2 m telescope on the site of La Silla (ESOs Chile). Observatons are also regularly obtained with the other ESO facilitess from the 5.93m telescope on the site of St-Michel (Observatory of Haute Provences OHPs France)s and from La Palma (Canary Islandss Spain). Astronomy Department Research Overview Research in the Department of Astronomy is described according to the Roadmap for Astronomy in Switzerland 2007-2056 four main themesn Exoplanetary systems Stars formaton evoluton Galaxies Universe Extreme Universe Main Building of the Astronomy Department in Versoix/Geneva 5 Département D'Astronomie Chemin des Mailletess 5 Université De Genève CH-5290 Versoix Sauverny Switzerland +45 22 379 22 00 [email protected] www.unige.ch/sciences/astro/en/ Research at the Exoplanetary Group The discovery of planets orbitng other stars (exoplanets) has been one of the major breakthroughs in astronomy of the past decades.
    [Show full text]
  • Evidence of Energy-, Recombination-, and Photon-Limited Escape Regimes in Giant Planet H/He Atmospheres M
    A&A 648, L7 (2021) Astronomy https://doi.org/10.1051/0004-6361/202140423 & c ESO 2021 Astrophysics LETTER TO THE EDITOR Evidence of energy-, recombination-, and photon-limited escape regimes in giant planet H/He atmospheres M. Lampón1, M. López-Puertas1, S. Czesla2, A. Sánchez-López3, L. M. Lara1, M. Salz2, J. Sanz-Forcada4, K. Molaverdikhani5,6, A. Quirrenbach6, E. Pallé7,8, J. A. Caballero4, Th. Henning5, L. Nortmann9, P. J. Amado1, D. Montes10, A. Reiners9, and I. Ribas11,12 1 Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain e-mail: [email protected] 2 Hamburger Sternwarte, Universität Hamburg,Gojenbergsweg 112, 21029 Hamburg, Germany 3 Leiden Observatory, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands 4 Centro de Astrobiología (CSIC-INTA), ESAC, Camino bajo del castillo s/n, 28692, Villanueva de la Cañada Madrid, Spain 5 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany 6 Landessternwarte, Zentrum für Astronomie der Universität Heidelberg, Königstuhl 12, 69117 Heidelberg, Germany 7 Instituto de Astrofísica de Canarias (IAC), Calle Vía Láctea s/n, 38200, La Laguna Tenerife, Spain 8 Departamento de Astrofísica, Universidad de La Laguna, 38026, La Laguna Tenerife, Spain 9 Institut für Astrophysik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany 10 Departamento de Física de la Tierra y Astrofísica & IPARCOS-UCM (Instituto de Física de Partículas y del Cosmos de la UCM), Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain 11 Institut de Ciències de l’Espai (CSIC-IEEC), Campus UAB, c/ de Can Magrans s/n, 08193 Bellaterra, Barcelona, Spain 12 Institut d’Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain Received 26 January 2021 / Accepted 19 March 2021 ABSTRACT Hydrodynamic escape is the most efficient atmospheric mechanism of planetary mass loss and has a large impact on planetary evolution.
    [Show full text]
  • CV En Didier Queloz.Pdf
    1 CURRICULUM VITAE Didier Queloz July 2012 Date of birth 23 February 1966 Nationality Swiss Current Position Professor, Geneva University, Geneva Observatory 51ch des Maillettes, CH-1290 Sauverny Switzerland Academic degrees 1990 Master in physics, Geneva University 1992 Astronomy and Astrophysics Certificate (DEA) 1995 PhD with Prof M. Mayor “Research by cross-correlation techniques”, Geneva University Awards § Science quotation (1995) for Discovery of the first extra-solar planet as on of the 10 most important discovery of the year § “Vacheron Constantin” prize (1996) for best phD of the Geneva science faculty § “Balzers” prize from the Swiss Physical Society (1996) for the discovery of the planet orbiting the star 51Peg § IAU Medal of honor (1996) commission 51 Bioastronomy § “Prix de la ville de Genève” 2011, Science category § BBVA Foundation Frontiers of Knowledge Awards 2011 § Honorary degrees from Employments 1996-1997 Post-doc, Geneva University 1997-1999 Distinguished visiting scientist, Jet Propulsion Lab, CA, USA 2000-2002 Research associate (“maitre assistant”), Geneva University 2003-2007 Faculty (“MER”), Geneva University 2008 Professor (PAD), Geneva University Professional service and committees • ESA Scientific Advisory group for IRSI-DARWIN (1997-2001) • IAU “radial velocity commission” (1997-2006) 2 • Board of the science advisory councilors of the OHP (1997-2000) • Study science team for PRIMA (ESO) (1998-2000) • ESO Observation Program Committee (OPC) (ESO telescope allocation) (2000-2001) • ESA Astronomical Working
    [Show full text]
  • A Three-Planet Extrasolar System
    quires that common properties in all the Acknowledgements Koch A. et al. 2006a, The Messenger 123, 38 dSphs be identified – we must therefore Koch A. et al. 2006b, AJ 131, 895 Mark I. Wilkinson acknowledges the Particle Physics Majewski S. R. et al. 2005, AJ 130, 2677 carry out similar studies of all dSphs. and Astronomy Research Council of the United Martin N. et al. 2006, MNRAS 367, L69 Kingdom for financial support. Andreas Koch and Mateo M. et al. 1993, AJ 105, 510 Finally, in the area of dynamical model- Eva K. Grebel thank the Swiss National Science Mateo M. 1997, ASP Conf. Ser. 116, 259 ling, identifying correlations between the Foundation for financial support. Mateo M. et al. 1998, AJ 116, 2315 Monelli M. et al. 2003, AJ 126, 218 kinematics and abundances of the stel- Munoz R. R. et al. 2005, ApJ 631, L137 lar populations in dSphs (e.g. Tolstoy et References Shetrone M. D. et al. 2001, ApJ 548, 592 al. 2006) is likely to provide important Tolstoy E. et al. 2006, The Messenger 123, 33 new information about the formation and Aaronson M. 1983, ApJ 266, L11 Wilkinson M. I. et al. 2002, MNRAS 330, 778 Belokurov V. et al. 2006, ApJL, submitted, Wilkinson M. I. et al. 2004, MNRAS 611, L21 evolution of these objects, which in turn astro-ph/0604355 Wilkinson M. I. et al. 2006, in proceedings of XXIst will further constrain models of any astro- Goerdt T. et al. 2006, MNNRAS 368, 1073 IAP meeting, EDP sciences, astro-ph/0602186 physical feedback on their dark matter.
    [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]
  • Who Really Discovered the First Exoplanet?
    Who Really Discovered the First Exoplanet? Two Swiss astronomers got a well-deserved Nobel for finding an exoplanet, but there’s an intriguing backstory By Josh Winn The year 1995, like 1492, was the dawn of an age of discovery. The new explorers, instead of using seagoing vessels to discover continents, use telescopes to discover planets revolving around distant stars. Thousands of these extrasolar planets, a term usually shortened to “exoplanets,” have been found, including a few potentially Earth- like worlds, along with bizarre objects that bear no resemblance to any of the planets in our solar system. Two of these exoplanet explorers, Michel Mayor and Didier Queloz, were recently awarded half of the Nobel Prize in Physics for the discovery they made in 1995. My colleagues and I are united in our admiration for their pioneering work, and in our pride to be continuing what they began. But there is something peculiar about the Nobel Prize citation. It says: “for the discovery of an exoplanet orbiting a solar-type star.” Shouldn’t it say the first exoplanet? After all, hundreds of astronomers have discovered an exoplanet. I’ve helped find a few. Even high school students and amateur astronomers have discovered them. Did the Nobel Committee make a typographical error? No, they did not, and thereby hangs a tale. Just as it is problematic to decide who discovered America (Christopher Columbus? John Cabot? Leif Erikson? Amerigo Vespucci, whose name is the one that stuck? Those who came on foot from Siberia tens of thousands of years ago?) it is difficult to say who discovered the first exoplanet.
    [Show full text]
  • A Catalog of Rotational and Radial Velocities for Evolved Stars V
    A&A 561, A126 (2014) Astronomy DOI: 10.1051/0004-6361/201220762 & c ESO 2014 Astrophysics A catalog of rotational and radial velocities for evolved stars V. Southern stars, J. R. De Medeiros1,S.Alves1,S.Udry2, J. Andersen3,4,B.Nordström3, and M. Mayor2 1 Departamento de Física, Universidade Federal do Rio Grande do Norte, Campus Universitário, 59072-970 Natal, RN, Brasil e-mail: [email protected] 2 Observatoire de Genève, Université de Genève, Chemin des Maillettes 51, 1290 Sauverny, Switzerland 3 The Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen, Denmark 4 Nordic Optical Telescope, Apartado 474, 38700 Santa Cruz de La Palma, Spain Received 19 November 2012 / Accepted 10 December 2013 ABSTRACT Rotational and radial velocities have been measured for 1589 evolved stars of spectral types F, G, and K and luminosity classes IV, III, II, and Ib, based on observations carried out with the CORAVEL spectrometers. The precision in radial velocity is better than 0.30 km s−1 per observation, whereas rotational velocity uncertainties are typically 1.0 km s−1 for subgiants and giants and 2.0 km s−1 for class II giants and Ib supergiants. Key words. stars: late-type – stars: fundamental parameters – binaries: spectroscopic – techniques: radial velocities – catalogs – stars: evolution 1. Introduction enabling reliable investigations of stellar rotational character- istics in different regions of the H−Rdiagram(Carlberg et al. Over the past two decades, observations have been carried out at 2011; Cortés et al. 2009; Melo et al. 2001), the relation- the Geneva Observatory, Switzerland, and the Federal University ship between rotation and different stellar properties (Monaco of Rio Grande do Norte, Brazil, to accurately measure projected v et al.
    [Show full text]
  • REPO RT SFROMOBSE RV ERSA Study of the Activity of G and K
    R E P O RT S F R O M O B S E RV E R S A Study of the Activity of G and K Giants Through Their Precise Radial Velocity; Breaking the 10-m/sec Accuracy with FEROS J. SETIAWAN 1, L. PASQUINI 2, L. DA SILVA3, A. HATZES4, O. VON DER LÜHE1, A. KAUFER2, L. GIRARDI 5, R. DE LA REZA3, J.R. DE MEDEIROS6 1Kiepenheuer-Institut für Sonnenphysik, Freiburg (Breisgau), Germany; 2European Southern Observatory 3Observatorio Nacional, Rio de Janeiro, Brazil; 4Thüringer Landessternwarte Tautenburg, Tautenburg, Germany 5Dipartimento di Astronomia, Università di Padova, Padova, Italy 6Universidade Federal do Rio Grande do Norte, Natal, Brazil 1. Scientific Background giant stars and their progenitors. In par- ible stellar surface (as a result of stellar ticular, when combining accurate dis- rotation), they will also induce variabili- Asteroseismology is an indispensa- tances (e.g. from HIPPARCOS), the ty in the core of deep lines, as the Ca II ble tool that uses the properties of stel- spectroscopic determination of the H and K, which are formed in the chro- lar oscillations to probe the internal chemical composition and gravity along mosphere (see e.g. Pasquini et al. structure of stars. This can provide a di- with the oscillation spectrum, the stellar 1988, Pasquini 1992). Since FEROS rect test of stellar structure and evolu- evolutionary models will be required to allows the simultaneous recording of tion theory. Precise stellar radial veloc- fit all these observations. This could the most relevant chromospheric lines, ity (RV) measurements made in recent provide an unprecedented test bench it will be possible to test directly from years have not only discovered the first for the theories of the stellar evolution.
    [Show full text]
  • Introduction
    Introduction Onething is certain about this book: by thetimeyou readit, parts of it will be out of date. Thestudy of exoplanets,planets orbitingaround starsother than theSun, is anew andfast-moving field.Important newdiscoveries areannounced on a weekly basis. This is arguablythe most exciting andfastest-growing field in astrophysics.Teamsofastronomersare competing to be thefirsttofind habitable planets likeour ownEarth, andare constantly discovering ahostofunexpected andamazingly detailed characteristics of thenew worlds. Since1995, when the first exoplanet wasdiscoveredorbitingaSun-like star,over 400 of them have been identified.Acomprehensive review of thefield of exoplanets is beyond thescope of this book, so we have chosen to focus on thesubset of exoplanets that are observedtotransittheir hoststar (Figure 1). Figure1 An artist’simpression of thetransitofHD209458 bacrossits star. Thesetransitingplanets areofparamount importancetoour understanding of the formation andevolutionofplanets.During atransit, theapparent brightness of the hoststar drops by afraction that is proportionaltothe area of theplanet: thus we can measure thesizes of transitingplanets,eventhough we cannot seethe planets themselves.Indeed,the transitingexoplanets arethe onlyplanets outside our own Solar System with known sizes.Knowing aplanet’ssize allows its density to be deduced andits bulk compositiontobeinferred.Furthermore, by performing precisespectroscopicmeasurements during andout of transit, theatmospheric compositionofthe planet can be detected.Spectroscopicmeasurements
    [Show full text]
  • THE STELLAR VARIABILITY from HIPPARCOS PHOTOMETRY M. GRENON Geneva Observatory 1290 Sauverny, Switzerland 1. Introduction During
    THE STELLAR VARIABILITY FROM HIPPARCOS PHOTOMETRY M. GRENON Geneva Observatory 1290 Sauverny, Switzerland 1. Introduction During the development of the Hipparcos satellite, the opportunity to use the star mapper to perform a whole sky two colour intermediate accuracy photometric survey, and the main-mission detector for high accuracy photometry of target stars was identified. The instrument was optimised and the pre-launch calibrations performed to pre-determine the pass-bands with an accuracy suf­ ficient to cope, in-orbit, with the foreseen aging of the detection chains. Photometry became an important by-product of the mission, very complementary to the astrometric results. It was the first opportunity to monitor the sky during 3-4 years without selection biases and with a precision similar to that achieved from the ground with the best classical techniques. A systematic detection of small amplitude variables was the expected return. 2. The correction of the aging effect The radiation by cosmic and solar particles induced transmission losses mainly in the green to violet part of the spectrum. Since the Hp band is broad, AA 380-900 nm, the effect was a chromatic change of the band, and hence of the Hp magnitude as large as 0.6 and 0.2 mag over the mission for V-I = 0 and 7 mag respectively. Photometric reductions were performed twice a day using a subset of the 29000 standard stars. Zero-point errors on the magnitude scale were then less than 0.001 mag for each data set. Correction of chromatic drifts requires the knowledge of the star colour; consequently error on it induces a linear trend in the Hp time series.
    [Show full text]
  • List of Participants
    LIST OF PARTICIPANTS H. ABLES, US Naval Observatory, Flagstaff, USA M. ANDRACACOU, Dept. of Astronomy, University of Athens, Greece E. ANTONOPOULOU, Dept. of Astronomy, University of Athens, Greece I. APPENZELLER, Landessternwarte Konigstuhl, Heidelberg, Germany T. ARMANDROFF, Yale University Observatory, New Haven, CT, USA M. AZZOPARDI, European Southern Observatory, München, Germany G. BERTELLI, Istituto di Astronomia, Padova, Italy G. BODIFEE, Astrofysisch Instituut, University of Brussels, Belgium. Β. BOHANNAN, university of Colorado, Boulder, USA J. BREYSACHER, European Southern Observatory, München, Germany A. CAMPBELL, Institute of Astronomy, Cambridge, England C. CHIOSI, Istituto di Astronomia, Padova, Italy M. CHRYSSOVERGIS, University of Athens, Greece Y. CHU, Astronomy Dept., University of Illinois, Urbana, USA P. CONTI, University of Colorado, Boulder, USA A. DAPERGOLAS, National Observatory Athens, Greece J.P. DE GREVE, Astrofysisch Instituut, University of Brussels, Belgium. M. DE GROOT, Armagh Observatory, Northern Ireland C. DE JAGER, Space Research Laboratory, Utrecht, the Netherlands C. DE LOORE, Astrofysisch Instituut, University of Brussels, Belgium. P. DUBOIS, Observatoire de Strasbourg, France M. FEAST, South African Astronomical Observatory, South Africa W. FREEDMAN, Mount Wilson and Los Campanos Observatory, Pasadena, California, USA E. GAVRYUSEVA, Inst, for Nuclear Research, Acad, of Sciences, Moscow, U.S.S.R. J. GRAHAM, Joint Institute for Laboratory Astrophysics University of Colorado and National Bureau of Standards, USA. L. GREGG10, Istituto di Astronomia, Padova, Italy. D. HATZIDIMITRIOÜ, National Observatory Athens, Greece P. HELLINGS, Astrofysisch Instituut, University of Brussels, Belgium. D. HILLIER, Mt. Stromlo Observatory, Woden P.O., Australia P. HODGE, Astronomy Dept. University of Washington, Seattle USA J. HOESSEL, Space Telescope Science Institute, Baltimore, USA I. HOWARTH, Dept.
    [Show full text]