J/AJ/167/255 Transit time for planets in LHS 1678 System (Silverstein+, 2024)
Validation of a Third Planet in the LHS 1678 System.
Silverstein M.L., Barclay T., Schlieder J.E., Collins K.A., Schwarz R.P.,
Hord B.J., Rowe J.F., Kruse E., Astudillo-Defru N., Bonfils X.,
Caldwell D.A., Charbonneau D., Cloutier R., Collins K.I., Daylan T.,
Fong W., Jenkins J.M., Kunimoto M., McDermott S., Murgas F., Palle E.,
Ricker G.R., Seager S., Shporer A., Tey E., Vanderspek R., Winn J.N.
<Astron. J., 167, 255 (2024)>
=2024AJ....167..255S 2024AJ....167..255S
ADC_Keywords: Exoplanets; Stars, M-type; Optical
Keywords: Exoplanet systems ; Transit photometry ; Transit timing
variation method ; M dwarf stars
Abstract:
The nearby LHS-1678 (TOI-696) system contains two confirmed planets
and a wide-orbit, likely brown-dwarf companion, which orbit an M2
dwarf with a unique evolutionary history. The host star occupies a
narrow "gap" in the Hertzsprung-Russell diagram lower main sequence,
associated with the M-dwarf fully convective boundary and long-term
luminosity fluctuations. This system is one of only about a dozen
M-dwarf multiplanet systems to date that hosts an ultra-short-period
planet (USP). Here we validate and characterize a third planet in the
LHS-1678 system using TESS Cycle 1 and 3 data and a new ensemble of
ground-based light curves. LHS-1678d is a 0.98±0.07R⊕ planet
in a 4.97day orbit, with an insolation flux of
9.1-0.8+0.9S⊕. These properties place it near 4:3 mean
motion resonance with LHS-1678c and in company with LHS-1678c in the
Venus zone. LHS 1678 c and d are also twins in size and predicted
mass, making them a powerful duo for comparative exoplanet studies.
LHS-1678d joins its siblings as another compelling candidate for
atmospheric measurements with the JWST and mass measurements using
high-precision radial velocity techniques. Additionally, USP LHS-1678b
breaks the "peas-in-a-pod" trend in this system although additional
planets could fill in the "pod" beyond its orbit. LHS-1678's unique
combination of system properties and their relative rarity among the
ubiquity of compact multiplanet systems around M-dwarfs makes the
system a valuable benchmark for testing theories of planet formation
and evolution.
Description:
We employ the full TESS Cycle 1 and 3 data sets, a suite of 33
ground-based light curves from the Las Cumbres Observatory global
telescope (LCOGT) network and MEarth-South telescope array.
Objects:
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RA (2000) DE Designation(s) (Period planet d)
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04 32 42.63 -39 47 12.1 LHS 1678 = TOI-696 (P = 4.9652229)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 64 186 Exoplanet Transit Times
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See also:
J/ApJS/197/2 : Transit timing observations from Kepler. I. (Ford+, 2011)
J/ApJS/208/9 : Intrinsic colors & temperatures of PMS stars (Pecaut+, 2013)
J/ApJS/222/14 : Planetary candidates 1st yr K2 mission (Vanderburg+, 2016)
J/ApJ/834/17 : Mass & radius of planets, moons, low mass star (Chen+, 2017)
J/AJ/154/191 : Solar neighborhood. XLII. New nearby subdwarfs (Jao+, 2017)
J/AJ/155/180 : Catalog of cool dwarf targets for the TESS (Muirhead+, 2018)
J/AJ/156/102 : TESS Input Catalog & Candidate Target List (Stassun+, 2018)
J/AJ/155/48 : California-Kepler Survey. V. Masses and radii (Weiss+, 2018)
J/A+A/639/A77 : Proxima Cen RV, FWHM and fluxes (Suarez Mascareno+, 2020)
J/AJ/161/24 : TRICERATOPS predictions for 384 TOIs (Giacalone+, 2021)
J/ApJS/254/39 : Exoplanet candidates TESS first 2yr obs (Guerrero+, 2021)
J/MNRAS/512/2062 : 10 exoplanet systems transit timing (Basturk+, 2022)
J/other/Sci/377.1211 : RV and LC of 8 M dwarf stars with planets (Luque+, 2022)
J/AJ/166/63 : Mind the Gap. I. Ha activity for M-Dwarfs (Jao+, 2023)
J/AJ/165/265 : Properties of 363 M-dwarfs from TESS (Ment+, 2023)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 1 A1 --- Planet Planet identifier
3- 15 F13.8 d Transit [1411/2587] Transit time; BJD-2457000
17- 26 F10.8 d E_Transit [0.003/0.1] Upper 1-σ uncertainty
in Transit
28- 37 F10.8 d e_Transit [0.003/0.08] Lower 1-σ uncertainty
in Transit
39- 42 I4 --- Index [1/1361] Transit index (1)
44- 64 A21 --- Tel Telescope used; LCO, MEarth-S, or TESS
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Note (1): Index counts transits starting from first predicted transit and
increases with time. We report corresponding observed transits
only, so there are gaps in Index.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 14-Jun-2024