J/AJ/159/241 The TESS-Keck Survey. I. HD332231 Radial Velocities (Dalba+, 2020)
The TESS-Keck Survey.
I. A Warm sub-Saturn-mass planet and a caution about stray light in TESS
cameras.
Dalba P.A., Gupta A.F., Rodriguez J.E., Dragomir D., Huang C.X., Kane S.R.,
Quinn S.N., Bieryla A., Esquerdo G.A., Fulton B.J., Scarsdale N.,
Batalha N.M., Beard C., Behmard A., Chontos A., Crossfield I.J.M.,
Dressing C.D., Giacalone S., Hill M.L., Hirsch L.A., Howard A.W., Huber D.,
Isaacson H., Kosiarek M., Lubin J., Mayo A.W., Mocnik T., Akana Murphy J.M.,
Petigura E.A., Robertson P., Rosenthal L.J., Roy A., Rubenzahl R.A., Van
Zandt J., Weiss L.M., Knudstrup E., Andersen M.F., Grundahl F., Yao X.,
Pepper J., Villanueva S., Ciardi D.R., Cloutier R., Jacobs T.L.,
Kristiansen M.H., LaCourse D.M., Lendl M., Osborn H.P., Palle E.,
Stassun K.G., Stevens D.J., Ricker G.R., Vanderspek R., Latham D.W.,
Seager S., Winn J.N., Jenkins J.M., Caldwell D.A., Daylan T., Fong W.,
Goeke R.F., Rose M.E., Rowden P., Schlieder J.E., Smith J.C., Vanderburg A.
<Astron. J., 159, 241 (2020)>
=2020AJ....159..241D 2020AJ....159..241D
ADC_Keywords: Exoplanets; Stars, F-type; Radial velocities; Spectra, optical
Keywords: Exoplanet astronomy ; Radial velocity ; Transit photometry ;
Exoplanet detection methods ; Exoplanets ; F dwarf stars ;
Spectroscopy ; Direct imaging
Abstract:
We report the detection of a Saturn-size exoplanet orbiting HD332231
(TOI1456) in light curves from the Transiting Exoplanet Survey
Satellite (TESS). HD332231 an F8 dwarf star with a V-band magnitude of
8.56 was observed by TESS in Sectors 14 and 15. We detect a
single-transit event in the Sector 15 presearch data conditioning
(PDC) light curve. We obtain spectroscopic follow up observations of
HD332231 with the Automated Planet Finder (APF), Keck I, and Spatial
Observations Network Group (SONG) telescopes. The orbital period we
infer from radial velocity (RV) observations leads to the discovery of
another transit in Sector 14 that was masked by PDC due to scattered
light contamination. A joint analysis of the transit and RV data
confirms the planetary nature of HD332231b, a Saturn-size
(0.867-0.025+0.027RJ), sub-Saturn-mass (0.244±0.021MJ)
exoplanet on a 18.71day circular orbit. The low surface gravity of
HD332231b and the relatively low stellar flux it receives make it a
compelling target for transmission spectroscopy. Also, the stellar
obliquity is likely measurable via the Rossiter-McLaughlin effect, an
exciting prospect given the 0.14au orbital separation of HD332231b.
The spectroscopic observations do not provide substantial evidence for
any additional planets in the HD332231 system, but continued RV
monitoring is needed to further characterize this system. We also
predict that the frequency and duration of masked data in the PDC
light curves for TESS Sectors 14-16 could hide transits of some
exoplanets with orbital periods between 10.5 and 17.5days.
Description:
We began monitoring the Radial Velocity (RV) variation of HD332231 in
2019-October to measure the companion's mass and further characterize
the system. The majority of the RV observations were acquired with the
2.4m Automated Planet Finder (APF) Telescope at Lick Observatory under
the TESS-Keck Survey (TKS) and another program dedicated to
single-transit follow-up (2019B-A006, PI:Dalba). We supplemented the
APF data set with additional observations from the 10m Keck I
telescope at the W.M. Keck Observatory.
Automated Planet Finder Telescope (APF)-Levy observed HD332231 using
the W decker, which has a width of 1" in the spectral dimension and 3"
in the spatial dimension. This slit provides a resolving power of
R∼114000 for a continuous spectrum between 3740 and 9700Å.
Keck-I is equipped with the High Resolution Echelle Spectrometer
(HIRES). We acquired 13 high-resolution (R∼60000) spectra of HD332231.
We also acquired a high-S/N spectral template using Keck-HIRES that
was used in the forward modeling procedure to determine the relative
Radial Velocities (RVs) of HD332231.
Additional RV measurements were collected using the robotic 1m
Hertzsprung Stellar Observations Network Group (SONG) telescope which
is equipped with a high-resolution echelle spectrograph. Thirteen
spectra of HD332231 were acquired (R∼90000) covering the wavelength
range 4400-6900Å. Each spectrum was obtained using an exposure time
of 2700s resulting in an S/N of ∼50.
Objects:
-------------------------------------------------------------------
RA (2000) DE Designation(s) (Period)
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20 26 57.92 +33 44 40.0 HD332231 = TYC 2689-70-1 (P=18.7120)
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 40 94 Radial Velocity Measurements of HD332231
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See also:
IV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)
J/ApJ/725/875 : Chromospheric activity for CPS stars (Isaacson+, 2010)
J/ApJ/719/890 : Keck radial velocities of GJ 876 (Rivera+, 2010)
J/AJ/142/19 : Speckle observations of KOI (Howell+, 2011)
J/other/Nat/486.375 : Stellar parameters of KOI stars (Buchhave+, 2012)
J/ApJ/772/L2 : Keck/HIRES radial velocities for HD97658 (Dragomir+,2013)
J/ApJ/805/175 : Keck and APF radial velocities of HD7924 (Fulton+, 2015)
J/ApJ/809/77 : Transiting Exoplanet Survey Satellite (Sullivan+, 2015)
J/ApJS/225/9 : Kepler TTVs. IX. Long-cadence data set (Holczer+, 2016)
J/A+A/587/A64 : Physical properties of giant exoplanets (Santerne+, 2016)
J/AJ/152/158 : Kepler transiting planet search (DR25) (Twicken+,2016)
J/ApJ/817/104 : Keck/HIRES radial velocity obs. of HD32963 (Rowan+, 2016)
J/ApJ/834/17 : Mass & rad. planets, moons, low mass stars (Chen+, 2017)
J/AJ/154/109 : California-Kepler Survey III. Planet radii (Fulton+,2017)
J/AJ/154/107 : California-Kepler Survey I. 1305 stars (Petigura+, 2017)
J/AJ/157/52 : RV observations in super-Earth systems (Bryan+, 2019)
J/AJ/157/245 : High-precision RV for HD 221416 (Huber+, 2019)
J/A+A/625/A16 : HD 2685 TESS photometry (Jones+, 2019)
J/AJ/157/191 : Light curve & RVs for TOI-172 (Rodriguez+, 2019)
J/AJ/158/136 : Keck & APF RVs for HD200964 (Rosenthal+, 2019)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.5 d BJD [1769/1918] Barycentric Julian Date at TBD;
BJD-2457000
12- 16 F5.1 m/s RV [-34.8/37.1] Radial Velocity
18- 21 F4.1 m/s e_RV [1.6/15] Uncertainty in RV
23- 27 F5.3 --- SHK [0.092/0.218]? Mount Wilson CaII H&K line
emission indicator (1)
29- 33 F5.3 --- e_SHK [0.001/0.002]? Uncertainty in SHK (1)
35- 40 A6 --- Tel Telescope Used (2)
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Note (1): Following Isaacson & Fischer (2010, J/ApJ/725/875). The SHK values
measured by APF-Levy and Keck-HIRES have a different zero-points.
Note (2): Telescope as follows:
APF = 2.4m Automated Planet Finder Telescope at Lick Observatory
Keck-1 = Keck-I/HIRES (High Resolution Echelle Spectrometer) at Keck
Observatory
SONG = Robotic 1m Hertzsprung Stellar Observations Network Group
(SONG) telescope.
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History:
From electronic version of the journal
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(End) Prepared by [AAS], Coralie Fix [CDS], 17-Jun-2020