J/AJ/168/295 Radial velocities of HD 118203 (Zhang+, 2024)
A testbed for tidal migration: The 3D architecture of an eccentric hot Jupiter
HD 118203 b accompanied by a possibly aligned outer giant planet.
Zhang J., Huber D., Weiss L.M., Xuan J.W., Burt J.A., Dai F., Saunders N.,
Petigura E.A., Rubenzahl R.A., Winn J.N., Wang S.X., Van Zandt J.,
Brodheim M., Claytor Z.R., Crossfield I., Deich W., Fulton B.J.,
Gibson S.R., Halverson S., Hill G.M., Holden B., Householder A.,
Howard A.W., Isaacson H., Kaye S., Lanclos K., Laher R.R., Lubin J.,
Payne J., Roy A., Schwab C., Shaum A.P., Walawender J., Wishnow E.,
Yeh S.
<Astron. J., 168, 295 (2024)>
=2024AJ....168..295Z 2024AJ....168..295Z
ADC_Keywords: Exoplanets; Radial velocities; Spectra, optical
Keywords: Hot Jupiters ; Exoplanet dynamics ; Gaia ; Astrometry ;
Radial velocity ; Exoplanet migration
Abstract:
Characterizing outer companions to hot Jupiters plays a crucial role
in deciphering their origins. We present the discovery of a
long-period giant planet, HD 118203 c (mc=11.79-0.63+0.69^MJ,
ac=6.28-0.11+0.10AU) exterior to a close-in eccentric hot
Jupiter HD 118203 b (Pb=6.135d, mb=2.14±0.12MJ,
rb=1.14±0.029RJ, eb=0.31±0.007) based on 20yr radial
velocities (RVs). Using Rossiter-McLaughlin (RM) observations from the
Keck Planet Finder, we measured a low sky-projected spin-orbit angle
λb=-11.7°-10.0+7.6 for HD 118203 b and detected
stellar oscillations in the host star, confirming its evolved status.
Combining the RM observation with the stellar inclination measurement,
we constrained the true spin-orbit angle of HD 118203 b as
Ψb<33.5° (2σ), indicating the orbit normal of the hot
Jupiter nearly aligned with the stellar spin axis. Furthermore, by
combining RVs and Hipparcos-Gaia astrometric acceleration, we
constrained the line-of-sight mutual inclination between the hot
Jupiter and the outer planet to be 9.8°-9.3+16.2 at the
2σ level. HD 118203 is one of first hot Jupiter systems where
both the true spin-orbit angle of the hot Jupiter and the mutual
inclination between inner and outer planets have been determined. Our
results are consistent with a system-wide alignment, with low mutual
inclinations between the outer giant planet, the inner hot Jupiter,
and the host star. This alignment, along with the moderate
eccentricity of HD 118203 c, implies that the system may have
undergone coplanar high-eccentricity tidal migration. Under this
framework, our dynamical analysis suggests an initial semimajor axis
of 0.3-3.2AU for the proto-hot Jupiter.
Description:
We used 56 archival RVs of HD 118203 taken with the ELODIE
spectrograph (389.5-681.5nm), installed on the 1.93m reflector at
Observatoire de Haute-Provence in France, between 2004 May and 2006
June from da Silva+ (2006A&A...446..717D 2006A&A...446..717D) and Pepper+2020 (J/AJ/159/243).
Furthermore, we collected 26 RV data for HD 118203 from 2010-2024
using the High Resolution Echelle Spectrometer (HIRES; 0.3-1.0um) on
the Keck I 10m telescope at the W.M. Keck Observatory on Maunakea, Hawaii.
The Keck Planet Finder (KPF) is an echelle spectrometer on the Keck I
telescope at the W.M. Keck Observatory that covers the wavelength range
of 445-870nm with a resolving power of 98,000. The Rossiter-McLaughlin (RM)
observations (McLaughlin, 1924ApJ....60...22M 1924ApJ....60...22M;
Rossiter, 1924ApJ....60...15R 1924ApJ....60...15R) observations of HD 118203 b were
conducted during one transit on 2023 April 9 UT. A total of 76
exposures were obtained, each with an integration time of 180s and a
readout time of 60s.
Objects:
--------------------------------------------------------------
RA (2000) DE Designation(s) (Period)
--------------------------------------------------------------
13 34 02.53 +53 43 42.6 HD 118203 b = TOI-1271b (Period=6.135d)
--------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 65 158 HD 118203 radial velocities
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/ApJ/646/505 : Catalog of nearby exoplanets (Butler+, 2006)
J/ApJ/723/L223 : Radial velocities of HAT-P-11 (Winn+, 2010)
J/ApJ/757/18 : RVs for 16 hot Jupiter host stars (Albrecht+, 2012)
J/ApJ/780/159 : Rot.-mass-age relationship of old field stars (Epstein+, 2014)
J/ApJ/785/126 : HIRES radial velocity measurements (Knutson+, 2014)
J/ApJ/821/89 : 12yrs of RVs obs. of exoplanet systems (Bryan+, 2016)
J/ApJ/844/102 : KIC star plx from asteroseismology vs Gaia (Huber+, 2017)
J/AJ/153/21 : Abund. in the local region. II. F, G, & K dwarfs (Luck+, 2017)
J/ApJ/835/172 : Kepler asteroseismic LEGACY sample.I.Oscillations (Lund+, 2017)
J/A+A/619/L10 : pi Men radial velocity curves (Gandolfi+, 2018)
J/AJ/155/255 : RV and activity measurements of HAT-P-11 (Yee+, 2018)
J/A+A/623/A72 : Binarity of HIP stars from Gaia pm anomaly (Kervella+, 2019)
J/ApJS/241/12 : The Asteroseismic Target List (ATL) for TESS (Schofield+, 2019)
J/AJ/159/243 : Light curve of HD 118203 b from TESS (Pepper+, 2020)
J/AJ/159/280 : Gaia-Kepler stellar properties cat.I. KIC stars (Berger+, 2020)
J/A+A/642/A31 : pi Men radial velocity curves (Damasso+, 2020)
J/A+A/640/A73 : pi Men radial velocity curves (De Rosa+, 2020)
J/A+A/640/A32 : WASP-148 velocity curve (Hebrard+, 2020)
J/ApJS/254/42 : Hipparcos-Gaia (EDR3) Catalog of Accelerations (Brandt, 2021)
J/AJ/162/89 : HIRES radial velocity follow up for Kepler-129 (Zhang+, 2021)
J/ApJ/926/L8 : Spectroscopic and transit obs. of WASP-148 (Wang+, 2022)
J/AJ/165/164 : Tull RVels, rotation periods and Inclinations (Bowler+, 2023)
J/AJ/166/136 : HIRES/HARPS radial velocities for HAT-P-2 (de Beurs+, 2023)
J/AJ/167/175 : Radial velocity and photometry of TOI-677 (Hu+, 2024)
J/AJ/168/81 : TESS giants transiting giants. VI. Keck RVs (Saunders+, 2024)
J/AJ/167/89 : Architect. of S* Transit. Planets in Binaries.I. (Zhang+, 2024)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 14 F14.6 d BJD [2455370/2503902] Barycentric Julian Date of
observation
16- 24 F9.2 m/s RVel [-29640/172] Radial velocity
26- 30 F5.2 m/s e_RVel [0.6/28.4] Uncertainty in RVel (1)
32- 37 A6 --- Inst Instrument used to get the RVel (2)
39- 65 A27 --- Ref Reference for RVel
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Note (1): The RVel uncertainties do not include RVel jitter.
Note (2): Instruments as follows:
ELODIE = Spectrograph (389.5-681.5nm) on the 1.93m reflector at Observatoire
de Haute-Provence in France; 56 occurrences
HIRES = High Resolution Echelle Spectrometer (0.3-1.0um) on the Keck I
10m telescope at the W.M. Keck Observatory on Maunakea, Hawaii;
26 occurrences
KPF = Keck Planet Finder (445-870nm), an echelle spectrometer on the
Keck I 10m telescope at the W.M. Keck Observatory on Maunakea,
Hawaii; 76 occurrences
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History:
From electronic version of the journal
(End) Prepared by [AAS], Robin Leichtnam [CDS] 18-Sep-2025