J/AJ/165/88 Radial velocity follow up of TOI-561 b (Brinkman+, 2023)
TOI-561 b; A Low-density Ultra-short-period "Rocky" Planet around a Metal-poor
Star
Brinkman C.L., Weiss L.M., Dai F., Huber D., Kite E.S., Valencia D.,
Bean J.L., Beard C., Behmard A., Blunt S., Brady M., Fulton B.,
Giacalone S., Howard A.W., Isaacson H., Kasper D., Lubin J.,
MacDougall M., Akana Murphy J.M., Plotnykov M., Polanski A.S., Rice M.,
Seifahrt A., Stefansson G., Sturmer J.
<Astron. J., 165, 88 (2023)>
=2023AJ....165...88B 2023AJ....165...88B
ADC_Keywords: Exoplanets; Stars, metal-deficient; Spectra, optical;
Radial velocities
Keywords: Exoplanets ; Extrasolar rocky planets ; Super Earths ;
Exoplanet surface composition ; Exoplanet atmospheric composition
Abstract:
TOI-561 is a galactic thick-disk star hosting an ultra-short-period
(0.45-day-orbit) planet with a radius of 1.37R⊕, making it one
of the most metal-poor ([Fe/H]=-0.41) and oldest ({∼10Gyr) sites where
an Earth-sized planet has been found. We present new simultaneous
radial velocity (RVel) measurements from Gemini-N/MAROON-X and
Keck/HIRES, which we combined with literature RVels to derive a mass
of Mb=2.24±0.20M⊕. We also used two new sectors of TESS
photometry to improve the radius determination, finding
Rb=1.37±0.04R⊕ and confirming that TOI-561b is one of the
lowest-density super-Earths measured to date
(ρb=4.8±0.5g/cm3). This density is consistent with an
iron-poor rocky composition reflective of the host star's iron and
rock-building element abundances; however, it is also consistent with
a low-density planet with a volatile envelope. The equilibrium
temperature of the planet ({∼2300K) suggests that this envelope would
likely be composed of high mean molecular weight species, such as
water vapor, carbon dioxide, or silicate vapor, and is likely not
primordial. We also demonstrate that the composition determination is
sensitive to the choice of stellar parameters and that further
measurements are needed to determine whether TOI-561b is a bare rocky
planet, a rocky planet with an optically thin atmosphere, or a rare
example of a nonprimordial envelope on a planet with a radius smaller
than 1.5R⊕.
Description:
Our analysis incorporates 102 total radial velocities (RVels) from the
High Resolution Echelle Spectrograph (HIRES) on the W.M. Keck
Observatory 10m telescope Keck I on Maunakea, Hawaii.
Our analysis also incorporates 143 published RVels from the HARPS-N
spectrograph installed on the 3.6m Telescopio Nazionale Galileo (TNG)
at the Observatorio Roque de Los Muchachos in La Palma, Spain.
MAROON-X is a new, state-of-the-art fiber-fed spectrograph mounted on
the 8.1m Gemini North telescope on Maunakea, Hawaii. It operates in
the red-optical (500-920nm) with resolving power R∼85000 and uses
both red and blue arms to get two RVel measurements per exposure.
Objects:
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RA (2000) DE Designation(s) (Period)
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09 52 44.54 +06 12 58.9 TOI-561 = TIC 377064495 (P=0.4465690d)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 37 316 Radial velocities
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See also:
J/ApJS/210/20 : Small Kepler planets radial velocities (Marcy+, 2014)
J/ApJ/800/135 : HARPS-N radial velocities of KOI-69 (Dressing+, 2015)
J/ApJ/822/86 : False positive probabilities Q1-Q17 DR24 KOIs (Morton+, 2016)
J/AJ/154/109 : California-Kepler Survey. III. Planet radii (Fulton+, 2017)
J/ApJ/844/102 : KICstar parallaxes from asteroseismology vs Gaia (Huber+, 2017)
J/AJ/153/136 : Planets and host stars with Gaia parallaxes (Stassun+, 2017)
J/A+A/653/A41 : L 98-59 (TOI-175) ESPRESSO observations (Demangeon+, 2021)
J/AJ/161/56 : The TESS-Keck Survey. II. RVs of TOI-561 (Weiss+, 2021)
J/AJ/162/55 : 65 Transit-timing variation planets properties (Yee+, 2021)
J/MNRAS/511/4551 : TOI-561 CHEOPS light curves (Lacedelli+, 2022)
J/AJ/163/168 : Photometry and radial velocity of LTT 1445A (Winters+, 2022)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 11 F11.3 d BJD [2458599/2459650] Barycentric Julian Date
13- 18 F6.2 m/s RVel [-12.4/12.6] Radial velocity
20- 23 F4.2 m/s e_RVel [0.6/6] Uncertainty in RVel
25- 37 A13 --- Inst Spectrograph; HARPS, HIRES, or MAROON
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 02-Jun-2023