J/AJ/166/32 Radial velocity follow up of HD 307842 (Hua+, 2023)
A Transiting Super-Earth in the Radius Valley and an Outer Planet Candidate
Around HD 307842.
Hua X., Wang S.X., Teske J.K., Gan T., Shporer A., Zhou G., Stassun K.G.,
Rabus M., Howell S.B., Ziegler C., Lissauer J.J., Winn J.N., Jenkins J.M.,
Ting E.B., Collins K.A., Mann A.W., Zhu W., Wang Su, Butler R.P.,
Crane J.D., Shectman S.A., Bouma L.G., Briceno C., Dragomir D., Fong W.,
Law N., Medina J.V., Quinn S.N., Ricker G.R., Schwarz R.P., Seager S.,
Sefako R., Stockdale C., Vanderspek R., Villasenor J.
<Astron. J., 166, 32 (2023)>
=2023AJ....166...32H 2023AJ....166...32H
ADC_Keywords: Exoplanets; Stars, G-type; Spectra, optical; Radial velocities
Keywords: Exoplanet astronomy ; Radial velocity ; Transit photometry ;
Super Earths
Abstract:
We report the confirmation of a TESS-discovered transiting super-Earth
planet orbiting a mid-G star, HD307842 (TOI-784). The planet has a
period of 2.8days, and the radial velocity (RV) measurements constrain
the mass to be 9.67-0.82+0.83M⊕. We also report the
discovery of an additional planet candidate on an outer orbit that is
most likely nontransiting. The possible periods of the planet
candidate are approximately 20-63days, with the corresponding RV
semiamplitudes expected to range from 3.2 to 5.4m/s and minimum masses
from 12.6 to 31.1 M⊕. The radius of the transiting planet
(planet b) is 1.93-0.09+0.11R⊕, which results in a mean
density of 7.4-1.2+1.4g/cm3 suggesting that TOI-784b is likely
to be a rocky planet though it has a comparable radius to a
sub-Neptune. We found TOI-784 b is located at the lower edge of the
so-called "radius valley" in the radius versus insolation plane, which
is consistent with the photoevaporation or core-powered mass-loss
prediction. The TESS data did not reveal any significant transit
signal of the planet candidate, and our analysis shows that the
orbital inclinations of planet b and the planet candidate are
88.60deg-0.86+0.84 and ≲88deg3-89deg2, respectively. More RV
observations are needed to determine the period and mass of the second
object, and search for additional planets in this system.
Description:
We collected a total of 35 RV data points using the Planet Finder
Spectrograph (PFS) on the 6.5m Magellan II Clay telescope at Las
Campanas Observatory in Chile. PFS is a high-resolution, optical
echelle spectrograph that covers a wavelength band of 391-734nm with a
resolving power of R∼130000 using the 0.3x2.5"slit.
We obtained three observations of TOI-784 via the CHIRON facility
between 2020 March and 2021 August to provide reconnaissance
spectroscopic vetting of the target. CHIRON is a fiber-fed
high-resolution echelle spectrograph at the SMARTS 1.5m telescope
located at Cerro Tololo Inter-American Observatory, Chile with a
spectral coverage of 410-870nm. TOI-784 was observed in the fiber
mode, with a spectral resolving power of R∼28000 and an exposure time
of 5 minutes.
We acquired TOI-784 spectra using LOC's Network of Robotic Echelle
Spectrographs (NRES). LCO-NRES consists of four high-resolution
optical echelle spectrographs (located in Chile, South Africa, Israel,
and USA) with a resolution of R∼53000 and a wavelength range spanning
380-860 nm. Each spectrograph is fed by two fibers: one fiber is
illuminated by the stellar light coming from a 1m telescope at the
respective site, and the second one is fed by a ThAr reference lamp.
Objects:
------------------------------------------------------------------------
RA (2000) DE Designation(s) (Period)
------------------------------------------------------------------------
10 37 21.88 -63 39 18.0 HD 307842 = 2MASS J10372190-6339181 (2.8d)
------------------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 38 58 Radial velocity measurements
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See also:
VI/39 : Model Atmospheres (Kurucz, 1979)
J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)
J/other/A+ARV/18.67 : Accurate masses and radii of normal stars (Torres+, 2010)
J/AJ/142/19 : Speckle observations of KOI (Howell+, 2011)
J/ApJS/197/8 : Kepler candidate multiple transiting planets (Lissauer+, 2011)
J/other/Nat/486.375 : Stellar parameters of KOI stars (Buchhave+, 2012)
J/ApJS/204/24 : Kepler planetary candidates. III. (Batalha+, 2013)
J/A+A/564/A125 : AGN Torus model comparison of AGN in the CDFS (Buchner+, 2014)
J/A+A/588/A38 : Light curves of spotted solar-type stars (Lehtinen+, 2016)
J/AJ/152/180 : Bolometric flux eclipsing binaries in Tycho-2 (Stassun+, 2016)
J/ApJ/825/19 : Mass-rad relationship for planets with Rp<4 (Wolfgang+, 2016)
J/AJ/154/109 : California-Kepler Survey. III. Planet radii (Fulton+, 2017)
J/AJ/153/136 : Planets & host stars with Gaia parallaxes (Stassun+, 2017)
J/A+A/612/A95 : K2-141 b radial velocity and light curve (Barragan+, 2018)
J/AJ/156/264 : California-Kepler Survey VII Planet radius gap (Fulton+, 2018)
J/AJ/156/254 : California-Kepler Survey. VI (Weiss+, 2018)
J/ApJ/875/29 : Spectroscopic analysis of the CKS sample. I. (Martinez+, 2019)
J/AJ/159/211 : Exoplanets parameters from Kepler and K2 (Cloutier+, 2020)
J/AJ/160/22 : TOI-1235 Radial velocities & opt spectros (Cloutier+, 2020)
J/AJ/159/19 : SOAR TESS survey. I. (Ziegler+, 2020)
J/ApJS/254/42 : Hipparcos-Gaia (EDR3) Catalog of Accelerations (Brandt, 2021)
J/ApJS/254/39 : Exoplanet candidates from TESS first 2yr obs (Guerrero+, 2021)
J/AJ/162/176 : The solar neighborhood. XLVIII. (Paredes+, 2021)
J/ApJS/256/33 : Magellan-TESS Survey. I. Midsurvey results (Teske+, 2021)
J/AJ/163/160 : Properties of 170 TOI hosts and companions (Behmard+, 2022)
J/AJ/163/101 : TESS-Keck survey. IX. RVel of HD1919139 (Lubin+, 2022)
J/other/Sci/377.1211 : RV and LC of 8 M dwarf stars with planets (Luque+, 2022)
J/AJ/163/179 : The California-Kepler Survey. X. (Petigura+, 2022)
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 16 F16.8 d BJD [2458909/2459664] Barycentric Julian Date
18- 25 F8.2 m/s RVel [-8.32/15786] Radial velocity
27- 31 F5.2 m/s e_RVel [0.6/27] Uncertainty in RVel
33- 38 A6 --- Inst Instrument (1)
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Note (1):Instruments as follows:
chiron = the CHIRON fiber-fed high-resolution echelle spectrograph at the
SMARTS 1.5m telescope located at Cerro Tololo Inter-American
Observatory, Chile.
nres1 = Network of Robotic Echelle Spectrographs (NRES) at Las Cumbres
Observatory in South African Astronomical Observatory,
South Africa.
nres2 = Network of Robotic Echelle Spectrographs (NRES) at Las Cumbres
Observatory in Cerro Tololo Interamerican Observatory, Chile.
pfs = Planet Finder Spectrograph on the 6.5m Magellan II Clay
telescope at Las Campanas Observatory in Chile.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 05-Feb-2024