J/AJ/157/245 High-precision radial velocities for HD 221416 (Huber+, 2019)
A hot Saturn orbiting an oscillating late subgiant discovered by TESS.
Huber D., Chaplin W.J., Chontos A., Kjeldsen H., Christensen-Dalsgaard J.,
Bedding T.R., Ball W., Brahm R., Espinoza N., Henning T., Jordan A.,
Sarkis P., Knudstrup E., Albrecht S., Grundahl F., Andersen M.F.,
Palle P.L., Crossfield I., Fulton B., Howard A.W., Isaacson H.T.,
Weiss L.M., Handberg R., Lund M.N., Serenelli A.M., Rorsted Mosumgaard J.,
Stokholm A., Bieryla A., Buchhave L.A., Latham D.W., Quinn S.N., Gaidos E.,
Hirano T., Ricker G.R., Vanderspek R.K., Seager S., Jenkins J.M., Winn J.N.,
Antia H.M., Appourchaux T., Basu S., Bell K.J., Benomar O., Bonanno A.,
Buzasi D.L., Campante T.L., Celik Orhan Z., Corsaro E., Cunha M.S.,
Davies G.R., Deheuvels S., Grunblatt S.K., Hasanzadeh A., Di Mauro M.P.,
Garcia R. A, Gaulme P., Girardi L., Guzik J.A., Hon M., Jiang C.,
Kallinger T., Kawaler S.D., Kuszlewicz J.S., Lebreton Y., Li T., Lucas M.,
Lundkvist M.S., Mann A.W., Mathis S., Mathur S., Mazumdar A., Metcalfe T.S.,
Miglio A., Monteiro M.J.P.F.G., Mosser B., Noll A., Nsamba B.,
Ong J.M.J., Ortel S., Pereira F., Ranadive P., Regulo C., Rodrigues T.S.,
Roxburgh I.W., Aguirre V.S., Smalley B., Schofield M., Sousa S.G.,
Stassun K.G., Stello D., Tayar J., White T.R., Verma K., Vrard M.,
Yildiz M., Baker D., Bazot M., Beichmann C., Bergmann C., Bugnet L.,
Cale B., Carlino R., Cartwright S.M., Christiansen J.L., Ciardi D.R.,
Creevey O., Dittmann J.A., Do Nascimento J.-D.Jr, Van Eylen V., Furesz G.,
Gagne J., Gao P., Gazeas K., Giddens F., Hall O.J., Hekker S., Ireland M.J.,
Latouf N., LeBrun D., Levine A.M., Matzko W., Natinsky E., Page E.,
Plavchan P., Mansouri-Samani M., McCauliff S., Mullally S.E., Orenstein B.,
Soto A.G., Paegert M., van Saders J.L., Schnaible C., Soderblom D.R.,
Szabo R., Tanner A., Tinney C.G., Teske J., Thomas A., Trampedach R.,
Wright D., Yuan T.T., Zohrabi F.
<Astron. J., 157, 245 (2019)>
=2019AJ....157..245H 2019AJ....157..245H (SIMBAD/NED BibCode)
ADC_Keywords: Stars, bright ; Stars, late-type ; Radial velocities ; Exoplanets
Keywords: asteroseismology - techniques: photometric -
planets and satellites: individual (HD 221416 b) -
stars: fundamental parameters -
planets and satellites: fundamental parameters
Abstract:
We present the discovery of HD 221416 b, the first transiting planet
identified by the Transiting Exoplanet Survey Satellite (TESS) for which
asteroseismology of the host star is possible. HD 221416 b (HIP 116158,
TOI-197) is a bright (V=8.2 mag), spectroscopically classified subgiant
that oscillates with an average frequency of about 430 µHz and displays
a clear signature of mixed modes. The oscillation amplitude confirms
that the redder TESS bandpass compared to Kepler has a small effect on
the oscillations, supporting the expected yield of thousands of solar-like
oscillators with TESS 2 minute cadence observations. Asteroseismic
modeling yields a robust determination of the host star radius
(R*=2.943±0.064 R☉), mass (M*=1.212±0.074 M☉), and
age (4.9±1.1 Gyr), and demonstrates that it has just started ascending
the red-giant branch. Combining asteroseismology with transit modeling
and radial-velocity observations, we show that the planet is a "hot Saturn"
(Rp=9.17±0.33 R⊕) with an orbital period of ∼14.3 days,
irradiance of F=343±24 F⊕, and moderate mass
(Mp=60.5±5.7 M⊕) and density (ρp=0.431±0.062 g/cm3).
The properties of HD 221416 b show that the host-star metallicity-planet
mass correlation found in sub-Saturns (4-8 R⊕) does not extend
to larger radii, indicating that planets in the transition between
sub-Saturns and Jupiters follow a relatively narrow range of densities.
With a density measured to ∼15%, HD 221416 b is one of the best
characterized Saturn-size planets to date, augmenting the small number
of known transiting planets around evolved stars and demonstrating the
power of TESS to characterize exoplanets and their host stars using
asteroseismology.
Description:
We obtained high-resolution spectra of HD 221416 using several facilities
within the TESS Follow-up Observation Program (TFOP), including HIRES
(Vogt et al. 1994SPIE.2198..362V 1994SPIE.2198..362V) on the 10 m telescope at Keck Observatory
(Maunakea, Hawai'i); the Hertzsprung SONG Telescope at Teide Observatory
(Tenerife; Grundahl et al. 2017ApJ...836..142G 2017ApJ...836..142G); HARPS (Mayor et al.
2003Msngr.114...20M 2003Msngr.114...20M), FEROS (Kaufer et al. 1999Msngr..95....8K 1999Msngr..95....8K), Coralie
(Queloz et al. 2001Msngr.105....1Q 2001Msngr.105....1Q), and FIDEOS (Vanzi et al.
2018MNRAS.477.5041V 2018MNRAS.477.5041V) on the MPG/ESO 3.6 m, 2.2 m, 1.2 m, and 1 m telescopes
at La Silla Observatory (Chile); Veloce (Gilbert et al. 2018SPIE10702E..0YG)
on the 3.9 m Anglo-Australian Telescope at Siding Spring Observatory
(Australia); TRES (Furesz 2008, PhD thesis Univ. Szeged) on the 1.5 m
Tillinghast reflector at the F. L. Whipple Observatory (Mt. Hopkins,
Arizona); and iSHELL (Rayner et al. 2012SPIE.8446E..2CR) on the NASA IRTF
Telescope (Maunakea, Hawai'i). All spectra used in this paper were obtained
between 2018 November 11 and December 30 and have a minimum spectral
resolution of R∼44000.
Objects:
-------------------------------------------------
RA (ICRS) DE Designation(s)
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23 32 08.07 -21 48 05.1 HD 221416 = TOI 197
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 37 107 High-precision radial velocities for TOI-197
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See also:
J/ApJ/809/77 : Transiting Exoplanet Survey Satellite (TESS) (Sullivan+, 2015)
J/AJ/156/102 : The TESS Input Catalog and Candidate Target List
(Stassun+, 2018)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 14 F14.6 d BJD Barycentric Julian Date
16- 22 F7.3 m/s RV [-36.267/23.433] Radial velocity
24- 29 F6.3 m/s e_RV [0.72/11.27] Uncertainty in RV (1)
31- 37 A7 --- Inst Instrument used
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Note (1): Error bars do not include contributions from stellar jitter and
measurements have not been corrected for zeropoint offsets.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 23-Aug-2019