Measurements of Spin-Orbit Angles for Transiting Systems: Toward an Understanding of the Migration History of Exoplanets

143 Pages·2014·3.56 MB·English

by  Teruyuki Hirano (auth.)

Springer Theses
Recognizing Outstanding Ph.D. Research
Teruyuki Hirano
Measurements of
Spin-Orbit Angles
for Transiting
Systems
Toward an Understanding of the
Migration History of Exoplanets
Springer Theses
Recognizing Outstanding Ph.D. Research
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Teruyuki Hirano
Measurements of Spin-Orbit
Angles for Transiting
Systems
Toward an Understanding of the Migration
History of Exoplanets
Doctoral Thesis accepted by
the University of Tokyo, Tokyo, Japan
123
Author Supervisor
Dr. TeruyukiHirano Prof.Yasushi Suto
Department of Physics Department of Physics
The Universityof Tokyo The Universityof Tokyo
Tokyo Tokyo
Japan Japan
ISSN 2190-5053 ISSN 2190-5061 (electronic)
ISBN 978-4-431-54585-9 ISBN 978-4-431-54586-6 (eBook)
DOI 10.1007/978-4-431-54586-6
Springer TokyoHeidelberg New YorkDordrecht London
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(cid:2)SpringerJapan2014
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Parts of this thesis have been published in the following journal articles:
1.Hirano,T.,Narita,N.,Shporer,A.,Sato,B.,Aoki,W.,Tamura,M.:APossible
Tilted Orbit of the Super-Neptune HAT-P-11b. PASJ 63, 531–536 (2011)
2.Hirano,T.,Narita,N.,Sato,B.,Winn,J.N.,Aoki,W.,Tamura,M.,Taruya,A.,
Suto,Y.:FurtherObservationsoftheTiltedPlanetXO-3:ANewDetermination
of Spin-Orbit Misalignment, and Limits on Differential Rotation. PASJ 63,
L57–L61 (2011)
Supervisor’s Foreword
Thefirstdiscoveredexoplanet,Peg-51b,wasagasgiantorbitingaroundaSun-like
star with a 4.2-day period. This surprising discovery clearly suggested that the
architectureofexoplanetarysystemsiscompletelydifferentfromthatofoursolar
system. A couple of decades since the discovery, we have witnessed, and even
been fascinated by, the diversity of the architecture of more than 1,000 exoplan-
etary systems.
Oneoftheunsolvedproblemsistheoriginofthebroaddistributionoftheangle
between the stellar spin and the planetary orbital directions (hereafter, spin-orbit
angle). The spin-orbit angles of all the solar planets are fairly aligned, indicating
both angular momenta originated from the proto-planetary disk. This simple
picture,however,doesnotholdforexoplanetarysystems;theprojectedspin-orbit
angle k of about 70 transiting planetary systems has been measured so far, and
morethan40 %have|k|[p/8,andafewsystemsexhibitevenretrogradeorbits.
This thesis presents an important contribution to this fascinating subject. The
author starts with a brief history including the early contribution of our group at
The University of Tokyo and then discusses the three important results that he
obtainedduringhisgraduatecourse:(1)Constructingatheoreticalmodeltemplate
to determine the projected spin-orbit angle from the Rossiter–McLaughlin effect,
(2) Discovery of the planet–planet eclipse, and (3) Determining the stellar
obliquity from its photometric variation.
As described in the thesis, those results provide a fundamental contribution to
thetheoryoftheoriginandevolutionoftheexoplanetarysystemsthatisanactive
area of research in this field. I am confident that this thesis serves as a compre-
hensive guide for readers who plan to start working in the field.
Tokyo, May 2014 Prof. Yasushi Suto
vii
Acknowledgments
Iamverygratefultomysupervisor,YasushiSuto,forhispertinentandimportant
suggestions about transiting exoplanets as described in this thesis. Discussions
during coffee breaks with Atsushi Taruya were very fruitful and mathematically
strengthened my detailed analysis of the RM effect. I am also thankful to all the
members in the theoretical astrophysics group (UTAP), especially to my col-
leaguesYukaFujiiandToshiyaNamikawa,whosharedinvaluabletimeinUTAP.
IalsoappreciateKatsuhikoSato,Jun’ichiYokoyama,andNaokiYoshida,whoas
physicists gave me keen insights.
It is a great pleasure to express my deepest gratitude to Josh Winn. He kindly
accepted me and gave me a great opportunity to stay at MIT for one year and
always tried to find time to have discussions as my second supervisor. It should
alsobestressedthatitwashewhooriginallyintroducedmetothisexcitingfieldof
extrasolar planets. During my stay in Boston, Simon Albrecht and Roberto San-
chis-Ojeda were always kind to me, and I would like to express special thanks to
them here. Simon Albrecht kindly provided Figs. 2.8 and 2.9 in this thesis. In
additiontotheresearchcollaborations,goingoutforabeerwiththemwasalways
funandhelpedtoimprovemyEnglish.Withoutanydoubt,thetimethatIspentin
Boston was one of the most exciting and enduring memories in my entire life.
I gratefully acknowledge my collaborator, Norio Narita, who taught me the
observational skills, data reductions, and pleasures in studying transiting exo-
planetarysystems.ThediscussionswithBun’eiSato,YoichiTakeda,WakoAoki,
andMotohideTamura,werealwaysinvaluableforme.Ialsowishtogiveheartfelt
thanks to all the members in the Probe for Exoplanets around Cool Host stars
(PEaCH) group. I am very grateful for the support for my Subaru/HDS observa-
tionsbyAkitoTajitsu,asupportscientistfortheSubaru/HDS.Ialsoacknowledge
theverysignificantculturalroleandreverencethatthesummitofMaunaKeahas
always had within the indigenous Hawaiian community.
Finally,thisthesisisdedicatedtomyparentsandtomywife,Wakako.Without
their constant understanding and kind support, this thesis would not have been
completed.
ix
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Evolution History of Extrasolar Planetary Systems. . . . . . . . . . . . 5
2.1 Detection and Orbital Diversity of Exoplanets . . . . . . . . . . . . . 5
2.1.1 Radial Velocity Method. . . . . . . . . . . . . . . . . . . . . . . . 6
2.1.2 Transit Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1.3 Correlations of Planetary Parameters. . . . . . . . . . . . . . . 13
2.2 Planetary Migration Scenarios. . . . . . . . . . . . . . . . . . . . . . . . . 15
2.2.1 Disk Migration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.2.2 Planet-Planet Scattering. . . . . . . . . . . . . . . . . . . . . . . . 15
2.2.3 Kozai Migration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.3 Measurements of the Rossiter–McLaughlin Effect. . . . . . . . . . . 17
2.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.3.2 Observational Results . . . . . . . . . . . . . . . . . . . . . . . . . 19
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3 Improved Modeling of the Rossiter–McLaughlin Effect. . . . . . . . . 23
3.1 Modeling of the RM Effect for Transiting Exoplanets . . . . . . . . 23
3.2 Derivation of the New Analytic Formula for the RM Effect. . . . 25
3.2.1 Analytic Expression for the Iodine Cell Technique. . . . . 28
3.2.2 Analytic Expression for the Simultaneous
Reference Technique. . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.3 Validity of the Analytic Formula. . . . . . . . . . . . . . . . . . . . . . . 36
3.3.1 Comparison with Numerical Simulations
for the Iodine Cell Technique. . . . . . . . . . . . . . . . . . . . 36
3.3.2 Comparison with Numerical Simulations
for the Simultaneous Reference Technique. . . . . . . . . . . 42
3.3.3 Sensitivity of the Formula to Line Parameters . . . . . . . . 45
3.3.4 Comparison with the Published ‘‘Calibrations’’
for Keck/HIRES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
3.4 Impact of Differential Rotations of Stars . . . . . . . . . . . . . . . . . 51
3.5 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
xi
xii Contents
4 New Observations and Improved Analyses
of the Rossiter–McLaughlin Effect . . . . . . . . . . . . . . . . . . . . . . . . 59
4.1 HAT-P-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.1.1 Introduction of the HAT-P-11 System. . . . . . . . . . . . . . 59
4.1.2 Observations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
4.1.3 Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.1.4 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . 65
4.2 XO-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.2.1 Introduction of the XO-3 System . . . . . . . . . . . . . . . . . 67
4.2.2 Observations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.2.3 Analysis and Results. . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.2.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
4.3 KOI-94. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.3.1 Introduction of the KOI-94 System. . . . . . . . . . . . . . . . 75
4.3.2 Observations and Data Reduction . . . . . . . . . . . . . . . . . 76
4.3.3 Analysis and Results. . . . . . . . . . . . . . . . . . . . . . . . . . 76
4.3.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
4.4 Reanalysis of the Archived Data for Simultaneous
Reference Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
4.4.1 HD 189733 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
4.4.2 CoRoT-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
4.4.3 HAT-P-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
5 Toward the Measurements of Spin-Orbit Relations
for Small Planets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
5.2 Principle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
5.3 Observation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
5.4 Analyses and Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
5.4.1 Estimation of Rotational Periods. . . . . . . . . . . . . . . . . . 100
5.4.2 Estimation of Spectroscopic Parameters. . . . . . . . . . . . . 102
5.4.3 Evidence of Possible Spin-Orbit Misalignments . . . . . . . 105
5.5 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
5.5.1 Correlation Between Stellar Inclinations
and Other System Parameters. . . . . . . . . . . . . . . . . . . . 107
5.5.2 Comparison with Empirical Estimates for P . . . . . . . . . 111
s
5.5.3 Impact of Differential Rotation. . . . . . . . . . . . . . . . . . . 112
5.5.4 Comparison with the RM Measurement
for Kepler-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
5.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117