The Exoplanets Revolution

Casoli Fabienne, Thérèse Encrenaz, Lequeux James

Description

More than 4300 planets around nearby stars! Who could have imagined this extraordinary harvest only thirty years ago? As the vast majority of stars are surrounded by planets, we can surmise that there must be more than a hundred billion planets in our Galaxy. The Solar system is therefore very far from unique. However, it looks quite different from most of the external systems that we know today, but the variety of planetary systems is such that it is difficult to conclude that the Solar System is truly particular. Understanding how diverse planet systems were formed and how they evolved, studying the nature of exoplanets and their atmospheres, are challenges that hundreds of researchers around the world are working on. Does any of these planets harbor life? We do not yet have an answer, but the new means of observation and analysis that astronomers have and will soon have at their disposal are so powerful that they could give a first answer in a few decades, and perhaps even in a few years if we are lucky.
This book gives a comprehensive vision of this complex and fascinating area of research, presented in a simple and lively way.

Sujets

• Sciences expérimentales
• Astronomie et astrophysique
• Astronomie
• Astrophysique
• Space Science
• Sciences et techniques
• Astronomy
• Science
• Physique
• Physical attractiveness

Informations

• Publié par: EDP Sciences
• Date de parution: 29 juillet 2020
• Nombre de lectures: 1
• EAN13: 9782759822119
• Langue: English
• Poids de l'ouvrage: 3 Mo

Extrait

www.edpsciences.org

The Exoplanet Revolution

The Exoplanet Revolution

J. Lequeux,

James Lequeux, Thérèse Encrenaz and Fabienne Casoli

CURRENT NATURAL SCIENCES

The Exoplanet Revolution

James Lequeux, Thérèse Encrenaz and Fabienne Casoli

ore than 4300 planets around nearby stars! Who could have îmagîned thîs bîllîon M planets în our Galaxy. The Solar system îs thereore very ar rom unîque. However, ît extraordînary harvest only thîrty years ago? As the vast majorîty o stars are surrounded by planets, we can surmîse that there must be more than a hundred looks quîte dîferent rom most o the external systems that we know today, but the varîety o planetary systems îs such that ît îs dîIcult to conclude that the Solar System îs truly partîcular. Understandîng how dîverse planet systems were ormed and how they evolved, studyîng the nature o exoplanets and theîr atmospheres, are challenges that hundreds o researchers around the world are workîng on. Does any o these planets harbor lîe? We do not yet have an answer, but the new means o observatîon and analysîs that astronomers have and wîll soon have at theîr dîsposal are so powerul that they could gîve a irst answer în a ew decades, and perhaps even în a ew years î we are lucky. Thîs book gîves a comprehensîve vîsîon o thîs complex and ascînatîng area o research, presented în a sîmple and lîvely way.

James Lequeuxîs an emerîtus astronomer at the Parîs Observatory. Hîs domaîns o expertîse are the înterstellar matter and the evolutîon o stars and galaxîes. He has dîrected the Marseîlles Observatory. He has wrîtten many books on the hîstory o astronomy, and several popular books.

Thérèse Encrenazîs an expert în planetary atmospheres. She has dîrected the Department o Space Research at the Parîs Observatory and was adjunct Presîdent o thîs Observatory. She has wrîtten many textbooks and popular books.

Fabienne Casoliîs Presîdent o the Parîs Observatory. Her specîalty îs radîoastronomy. She has been adjunct dîrector o the French Natîonal Center or Space Studîes and o the Natîonal ïnstîtute o Scîences o the Unîverse, and dîrected the ïnstîtute o Space Astronomy în Orsay.

www.edpsciences.org

9 782759 822102

ISBN :9782759822102

CURRENT NATURAL SCIENCES

J. Lequeux, T. Encrenaz and F. Casoli

The Exoplanet Revolution

C U R R E N T N A T U R A L S C I E N C E S EDP Sciences

Cover image: a planet just formed in the disk of gas and dust surrounding the dwarf star PDS 70. In this near-infrared, high-resolution image, the planet is seen as a bright point inside the remains of the disk. The star itself, at the center, is occulted by a mask. © European Southern Observatory, A. Müller et al. Printed in France © 2020, EDP Sciences, 17 avenue du Hoggar, BP 112, Parc d’activités de Courtabœuf, 91944 Les Ulis Cedex A This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, re-use of illustrations, recitation, broad-casting, reproduction on microfilms or in other ways, and storage in data bank. Duplication of this publication or parts thereof is only permitted under the provisions of the French Copyright law of March 11, 1957. Violations fall under the prosecution act of the French Copyright law. ISBN (print): 978-2-7598-2210-2 - ISBN (ebook): 978-2-7598-2211-9

Table of Contents

Introduction Chapter 1. The prehistory of exoplanets Fîst îdéas and spécûlatîons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thé évolûtîon of concépts on thé fomatîon of thé Sola Systém . . . . . . Thé dîscovéy of potoplanétay dîsks . . . . . . . . . . . . . . . . . . . . . . . . . Thé fîst attémpts to détéct éxoplanéts . . . . . . . . . . . . . . . . . . . . . . . . Bîblîoaphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 2. The first detections An ûnéxpéctéd dîscovéy: planéts aoûnd a pûlsa! . . . . . . . . . . . . . . . . 1995: Thé fîst planét aoûnd a sta lîké oûs! . . . . . . . . . . . . . . . . . . . Thé sûccéss of vélocîméty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bîblîoaphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 3. The method of transits What îs a planétay tansît? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Obsévatîons fom thé Eath . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thé Spacé Aé . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thé CoRoT mîssîon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thé Képlé Mîssîon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pîmay and Séconday Tansîts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tansmîssîon spéctoscopy (pîmay tansît) . . . . . . . . . . . . . . . . Emîssîon spéctoscopy (séconday tansît) . . . . . . . . . . . . . . . . . . Gavîtatîonal tansîts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bîblîoaphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 4. Detecting and viewing exoplanets Advantaés and lîmîtatîons of îndîéct méthods of détéctîon . . . . . . . . . Thé tansît méthod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Exoplanéts détéctéd as avîtatîonal mîcolénsés . . . . . . . . . . . . . Exoplanéts détéctéd by vélocîméty o astométy . . . . . . . . . . . . Dîéct obsévatîon: a véy dîffîcûlt poblém . . . . . . . . . . . . . . . . . . . . . Coonoaphy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thé black-fîné întéféomété . . . . . . . . . . . . . . . . . . . . . . . . . How to obtaîn péféct îmaés: adaptîvé optîcs . . . . . . . . . . . . . . . Combînéd coonoaphy and adaptîvé optîcs . . . . . . . . . . . . . . . . A néw tack fo thé fûtûé: thé séach fo éxoplanéts în thé adîo domaîn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bîblîoaphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1 5 5 8 11 12 17 19 19 21 27 31 33 33 36 37 37 38 40 41 43 44 46

47 47 47 48 49 50 51 52 53 55

57 57

IV

Thé Exoplanét Révolûtîon

Chapter 5. The variety of exoplanets Thé oûtstandîn ésûlts of thé last twénty yéas. . . . . . . . . . . . . . . . . . A mûltîtûdé of éxoplanéts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gîant éxoplanéts véy closé to théî stas . . . . . . . . . . . . . . . . . . Obîts of all kînds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Many mûltîplé systéms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Planéts aoûnd doûblé stas . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thé dîfféént classés of éxoplanéts . . . . . . . . . . . . . . . . . . . . . . . . . . . Hot and Cold Jûpîtés . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sûpé-Eaths and Néptûnés . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eaths and Habîtablé Planéts . . . . . . . . . . . . . . . . . . . . . . . . . . Bîblîoaphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 6. The birth of stars and protoplanetary disks Potostas, jéts and dîsks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thé potoplanétay dîsks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thé îcé lînés în potoplanétay dîsks . . . . . . . . . . . . . . . . . . . . . . . . . . Planét-dîsk întéactîons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bîblîoaphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 7. Formation and evolution of planetary systems Thé fomatîon of planéts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thé évolûtîon of planétay systéms: what doés thé Sola Systém téach ûs? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Why no sûpé-Eaths în thé Sola Systém? . . . . . . . . . . . . . . . . . . . . . Expélléd planéts, îsolatéd éxoplanéts . . . . . . . . . . . . . . . . . . . . . . . . . What fûtûé fo thé Sola Systém? . . . . . . . . . . . . . . . . . . . . . . . . . . . What conséqûéncés fo oû ûndéstandîn of éxoplanétay systéms?. . . . Bîblîoaphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 8. The physical nature of exoplanets Thé obsévablés . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thé fîst méasûéménts of thé atmosphéîc composîtîon of hot Jûpîtés . . Possîblé caûsés of dépatûé fom thémochémîcal éqûîlîbîûm. . . . . . . . Cloûds and mîsts on éxoplanéts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Spéctoscopîc méasûéménts of sûpé-Eaths and éxo-Néptûnés în tansît Spéctoscopy of éxoplanéts fom thé oûnd . . . . . . . . . . . . . . . . . . . . Phasé cûvés and atmosphéîc cîcûlatîon of éxoplanéts . . . . . . . . . . . . Bîblîoaphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 9. Around Exoplanets Thé éxocométs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gîant îns aoûnd an éxoplanét? . . . . . . . . . . . . . . . . . . . . . . . . . . . . A satéllîté? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bîblîoaphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 10. Life on exoplanets? What îs lîfé? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thé émééncé of lîfé on Eath. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lîfé élséwhéé în thé Sola Systém? . . . . . . . . . . . . . . . . . . . . . . . . . . How to détéct lîfé on éxoplanéts? . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bîblîoaphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

59 59 59 59 60 61 62 62 64 67 70 73

75 75 78 82 84 87 89 89

92 98 98 100 102 104

107 107 111 114 116 116 118 120 121

123 124 127 129 130

131 132 133 141 144 149

Tablé of Conténts

Chapter 11. Exploring Exoplanets: What Prospects? Habîtablé planéts, înhabîtéd planéts: a dîffîcûlt poblém . . . . . . . . . . . . Moé planéts, and smallé onés, to éxploé thé dîvésîty of planétay systéms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Néw lîht on îant planéts: astométy and îmaéy . . . . . . . . . . . . . . . Stûdyîn thé atmosphéés of éxoplanéts . . . . . . . . . . . . . . . . . . . . . . . Towads analos of thé Eath-Sûn systém: afté 2030? . . . . . . . . . . . . . Alpha Céntaûî: othé planéts?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 12. Communicating with other worlds? Thé pobabîlîty of éxîsténcé of advancéd cîvîlîzatîons on othé planéts . . Thé SETI Pojécts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Méssaés to thé Unîvésé . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bîblîoaphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Appendix 1: The planets of the Solar System

Appendix 2: A Selection of Exoplanets

Appendix 3: Some useful data

Appendix 4: The nomenclature of stars and exoplanets Glossary Acronyms Index

V

151 151

154 159 162 165 167

169 169 171 174 177

179 181 189 191 193 199 203

Introduction

Amon thé éat astonomîcal dîscovéîés of thé last céntûy, thé most éxcîtîn în thé éyés of thé énéal pûblîc was ûndoûbtédly that of a planét aoûnd anothé sta than thé Sûn. It datés back to 1995. To say thé tûth, ît was éxpéctéd that sûch a dîscovéy woûld occû somé day, bécaûsé théé was no éason why thé Sola Systém shoûld bé thé only oné of îts kînd. Fom thé tîmé of Antîqûîty, thén wîth Nîcolas dé Cûés and Gîodano Bûno at thé énd of thé sîxtéénth céntûy, théé was spécûlatîon aboût thé possîbîlîty of planétay systéms sîmîla to oûs aoûnd othé stas. It was only nécéssay that thé téchnîqûés of obsévatîon had poésséd sûffîcîéntly to allow thé dîscovéy. Thîs îs what dîffééntîatés thé dîscovéy of thé éxtasola planéts, as wéll as that of thé Hîs boson în 2012 and thé avîtatîonal wavés în 2015, fom that of thé ûnéxpéctéd astonomîcal objécts that aé thé dak matté (dîscovééd în 1937), thé X-ay soûcés (1965), thé qûasas (1963), thé fossîl adîatîon fom thé Unîvésé (1965), thé pûlsas (1965) and thé soûcés of amma-ay bûsts (1968), to namé only thé most spéctacûla. Thé sûpîsé was qûîté dîfféént: thé néw planét, whîch has a mass closé to that of Jûpîté, avîtatés aoûnd thé sta 51 Péasî în only foû days and îs twénty tîmés léss dîstant fom thîs sta than thé Eath îs fom thé Sûn, whîch makés ît a véy hot objéct. Théé îs nothîn sîmîla în thé Sola Systém, whîch was îmmédîatély déadéd fom îts statûs as a po- totypé of possîblé planétay systéms. Soon othé éxoplanéts (a néoloîsm that sééms accéptéd today) wéé dîscovééd. Théy léd to othé sûpîsés: somé havé véy élonatéd éllîptîcal obîts, whîch îs not thé casé of any of thé planéts that aé famîlîa to ûs. Sûpé-Eaths, and mînî-Néptûnés, wîth a mass întémédîaté bétwéén that of thé Eath and that of Jûpîté, aé fé- qûént, thoûh ûnpaalléléd în thé Sola Systém. Wé havé also foûnd planéts obîtîn aoûnd systéms of doûblé stas. Moé than 4200 éxoplanéts havé béén dîscovééd today. Théy show an astonîshîn vaîéty în théî massés, în théî obîts and în théî physîcal popétîés. Up to sévén planéts havé béén détéctéd în somé planétay sys- téms. Most of thé known éxoplanéts aé mûch closé to théî stas than thé Eath îs to thé Sûn, whîch was a bî sûpîsé; howévé, thîs may bé only a conséqûéncé of thé lîmîts of oû obsévatîons, fo thésé planéts aé éasîé to détéct than thé dîstant onés. Thé latté, howévé, éxîst: théy aé thé only

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Thé Exoplanét Révolûtîon

onés whosé îmaé can bé madé wîthoût béîn too împédéd by thé lîht of thé sta, whîch can bé a bîllîon tîmés moé înténsé. Théé aé évén îsolatéd planéts cîcûlatîn în thé Mîlky Way: havé théy béén éjéctéd fom a plané- tay systém by somé méchanîsm? All thîs qûéstîonéd thé îdéas wé had aboût thé bîth and évolûtîon of planétay systéms. It was lon bélîévéd wîth Laplacé that thé planéts wéé at thé dîstancé of thé sta to whîch théy wéé bon, and foméd an almost îmmûtablé systém. Yét somé éséachés havé shown în thé 1980s that thîs coûld not bé so bécaûsé of thé avîtatîonal întéactîon bétwéén thé planéts and what émaîns of thé as and dûst dîsk whéé théy wéé bon at thé samé tîmé as thé céntal sta. Moéové, thé dîscovéés of thé fîst éxoplanét îmmédîatély éalîzéd that ît mûst havé béén foméd fa fom thé sta, and thén had înîtîatéd a mîatîon that had movéd ît véy closé to thîs sta. Thîs obsévatîon, toéthé wîth othé ûnéxpéctéd popétîés of éxoplanéts, léd to an înténsé théoétîcal actîvîty, béînnîn wîth thé popétîés of thé Sola Systém that wéé thoûht to bé wéll ûndéstood. Thé ésûlts aé astonîshîn: ît appéas that thé pésént aspéct of thé Sola Systém dépénds éntîély on thé béhavîo of îts two bîést planéts, Jûpîté and Satûn, and woûld havé béén véy dîfféént îf only oné had béén pésént. Moéové, thé Sola Systém, lîké othé planétay systéms, îs not îmmûtablé, and coûld stîll ûndéo majo tansfomatîons on thé scalé of sévéal bîllîon yéas: oné coûld, fo éxamplé, wîtnéss thé éjéctîon of a planét o a collîsîon bétwéén two planéts, an othéwîsé ûnpédîctablé béhavîo bécaûsé ît îs domînatéd by chaos. Undéstandîn thé oîîn and stûctûé of éxoplanét systéms, fo whîch wé havé mûch léss data than fo thé Sola Systém, îs évén moé chal- lénîn: hûndéds of éséachés aoûnd thé wold aé cûéntly wokîn on thésé îssûés. Thé séach fo éxoplanéts has tîééd, and stîll caûsés, éat advancés în astonomîcal înstûméntatîon. Thé laést téléscopés on thé oûnd and în spacé aé ûséd to obsévé thém, and many poams aé éntîély déd- îcatéd to théî éséach and stûdy. It îs now possîblé to havé an îdéa of thé témpéatûé and chémîcal composîtîon of thé atmosphéé of thé îant éxoplanéts, éspécîally thé “hot Jûpîtés” whîch avîtaté closé to théî stas. Howévé, wé aé not yét to thîs poînt fo thé léss massîvé planéts, whîch aé thé onés that coûld shélté lîfé. Indééd, thé most éxcîtîn pospéct opénéd by thé dîscovéy of éxtasola planéts îs thé séach fo planéts locatéd néîthé too closé no too fa fom théî sta, whéé lîfé coûld dévélop. Oû anthopocéntîsm sûésts that théy mûst havé a mass closé to that of thé Eath, bût în éalîty nothîn pévénts moé massîvé planéts – sûpé-Eaths – fom cayîn lîfé. Whîlé planéts sîmîla to thé Eath aé stîll dîffîcûlt to dîscové, wé aléady know a lot of sûpé-Eaths, somé of whîch appéa to bé în favoablé condîtîons. To chaactéîzé thém and to look fo clûés aboût somé fom of lîfé aé somé of thé maîn challénés of thé comîn yéas. Fo cléa answés, ît wîll pobably