J/AJ/161/23 Radial velocity & light curve of low mass star TOI 540 (Ment+, 2021)
TOI 540 b: a planet smaller than Earth orbiting a nearby rapidly rotating low-
mass star.
Ment K., Irwin J., Charbonneau D., Winters J.G., Medina A., Cloutier R.,
Diaz M.R., Jenkins J.S., Ziegler C., Law N., Mann A.W., Ricker G.,
Vanderspek R., Latham D.W., Seager S., Winn J.N., Jenkins J.M., Goeke R.F.,
Levine A.M., Rojas-Ayala B., Rowden P., Ting E.B., Twicken J.D.
<Astron. J., 161, 23 (2021)>
=2021AJ....161...23M 2021AJ....161...23M
ADC_Keywords: Exoplanets; Stars, dwarfs; Spectra, optical; Photometry; Optical;
Radial velocities
Keywords: Transit photometry ; Exoplanets ; Extrasolar rocky planets ;
Stellar rotation
Abstract:
We present the discovery of TOI540b, a hot planet slightly smaller
than Earth orbiting the low-mass star 2MASSJ05051443-4756154. The
planet has an orbital period of P=1.239149 days(±170ms) and a
radius of r=0.903±0.052R⊕, and is likely terrestrial based
on the observed mass- radius distribution of small exoplanets at
similar insolations. The star is 14.008pc away and we estimate its
mass and radius to be M=0.159±0.014M☉ and
R=0.1895±0.0079R☉, respectively. The star is distinctive in
its very short rotational period of Prot=17.4264±0.0094hr and
correspondingly small Rossby number of 0.007 as well as its high
X-ray-to-bolometric luminosity ratio of LX/Lbol=0.0028 based on a
serendipitous XMM-Newton detection during a slew operation. This is
consistent with the X-ray emission being observed at a maximum value
of LX/Lbol∼10-3 as predicted for the most rapidly rotating M
dwarfs. TOI540b may be an alluring target to study atmospheric erosion
due to the strong stellar X-ray emission. It is also among the most
accessible targets for transmission and emission spectroscopy and
eclipse photometry with the James Webb Space Telescope, and may permit
Doppler tomography with high-resolution spectroscopy during transit.
This discovery is based on precise photometric data from the
Transiting Exoplanet Survey Satellite and ground-based follow-up
observations by the MEarth team.
Description:
We gathered four reconnaissance spectra of TOI 540 with the CHIRON
spectrograph mounted on the CTIO/Small and Moderate Aperture Research
Telescope System (SMARTS) 1.5m telescope at CTIO. The observations
were carried out between 2018 September and 2019 November in 3x20
minutes exposures per observation, employing the image slicer mode for
a resolution of R=80000.
In addition, we collected three spectra using the HARPS spectrograph
mounted on the ESO 3.6m telescope at La Silla. The HARPS spectrograph
has a measured spectral resolution of R=120000. The observations were
carried out in 2019 April (ESO HARPS Program 0103.C-0442, PI: Diaz)
with a 30 minute exposure time.
Transiting Exoplanets Survey Satellite (TESS) collected photometry of
TOI540 in observation sectors 4, 5, and 6, with the observations
spanning a nearly three-month period from 2018 October 19 to 2019
January 6.
Using the eight 40cm aperture telescopes of the MEarth-South telescope
array at the Cerro Tololo International Observatory (CTIO) in Chile,
we conducted follow-up observations of TOI540 to confirm the transits
of the terrestrial planet. The MEarth-South telescopes employ a custom
bandpass centered at the red end of the optical spectrum (similar to
TESS). We observed 10 transits of TOI540b between 2019 July 27 and
2019 December 8, using an exposure time of 40s per measurement.
Objects:
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RA (2000) DE Designation(s) (Period)
---------------------------------------------------------
05 05 14.43 -47 56 15.5 TOI 540 = TOI-540 P=1.239149d
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 34 7 RV data for TOI 540
fig1.dat 34 48493 TESS photometry of TOI 540 from Sectors 4-6
fig2.dat 33 20701 Follow-up photometry of TOI 540 from all 8 MEarth
telescopes by night
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/ApJ/757/112 : Stellar diameters. II. K and M-stars (Boyajian+, 2012)
J/ApJS/208/9 : Intrinsic colors and temperatures of PMS stars (Pecaut+, 2013)
J/AJ/148/119 : UCAC4 nearby star survey (Finch+, 2014)
J/ApJ/807/45 : Potentially habitable planets orbiting dwarfs (Dressing+,2015)
J/ApJ/800/135 : HARPS-N radial velocities of KOI-69 (Dressing+, 2015)
J/ApJ/804/64 : Empirical and model parameters of 183 M dwarfs (Mann+, 2015)
J/A+A/584/A72 : A transiting rocky planet at 6.5pc from Sun (Motalebi+, 2015)
J/AJ/152/141 : Solar neighborhood. XXXVII. RVs for M dwarfs (Benedict+, 2016)
J/A+A/588/A103 : Second ROSAT all-sky survey source catalog (Boller+, 2016)
J/ApJ/829/23 : Stellar flares from Q0-Q17 Kepler LCs (Davenport, 2016)
J/ApJ/821/93 : Rotation & Galactic kinematics of mid M dwarfs (Newton+, 2016)
J/AJ/154/109 : California-Kepler Survey. III. Planet radii (Fulton+, 2017)
J/A+A/618/A142 : Radial velocity for GJ 1132 (Bonfils+, 2018)
J/A+A/618/A20 : Limb-darkening for TESS, Kepler, Corot, MOST (Claret, 2018)
J/ApJ/856/23 : BANYAN. XI. The BANYAN Σ algorithm (Gagne+, 2018)
J/AJ/156/140 : 4 new eclipsing mid M-dwarf systems from MEarth (Irwin+, 2018)
J/AJ/156/217 : Stellar properties for M dwarfs in MEarth-South (Newton+,2018)
J/AJ/156/102 : TESS Input Catalog and Candidate Target List (Stassun+, 2018)
J/A+A/629/A111 : L 98-59 (TOI 175) HARPS observations (Cloutier+, 2019)
J/A+A/628/A39 : Radial velocities of GJ 357 (Luque+, 2019)
J/AJ/160/3 : Radial velocities M-dwarf LTT3780 with HARPS (Cloutier+, 2020)
J/AJ/159/211 : Exoplanets parameters from Kepler and K2 (Cloutier+, 2020)
J/AJ/160/22 : TOI-1235 Radial velocities & optical spectro. (Cloutier+,2020)
J/AJ/159/290 : RVs of 12 spectroscopic binaries M-dwarfs (Winters+, 2020)
J/AJ/159/19 : SOAR TESS survey. I. (Ziegler+, 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 F12.4 d BJD Barycentric Julian Date at TBD
14- 20 F7.4 km/s RVel [18.34/18.91] Barycentric Radial Velocity
22- 27 F6.4 km/s e_RVel [0.12/0.2] Uncertainty in RVel
29- 34 A6 --- Inst Instrument (1)
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Note (1): Instrument as follows:
chiron = CHIRON spectrograph at the CTIO/SMARTS 1.5-meter;
harps = HARPS spectrograph at the ESO 3.6-meter telescope at La Silla
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Byte-by-byte Description of file: fig1.dat
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Bytes Format Units Label Explanations
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1- 15 F15.7 d BJD Barycentric Julian Date
17- 25 F9.6 mag Flux Flux (magnitude difference)
27- 34 F8.6 mag e_Flux Uncertainty in Flux
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Byte-by-byte Description of file: fig2.dat
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Bytes Format Units Label Explanations
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1- 14 F14.6 d BJD Barycentric Julian Date
16- 24 F9.6 mag Flux Flux (magnitude difference)
26- 33 F8.6 mag e_Flux Uncertainty in Flux
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 26-Feb-2021