J/AJ/164/21 K2-139 G-band photometry with CHEOPS (Smith+, 2022)
A CHEOPS Search for Massive, Long-period Companions to the Warm Jupiter K2-139b.
Smith A.M.S., Csizmadia S.
<Astron. J., 164, 21-21 (2022)>
=2022AJ....164...21S 2022AJ....164...21S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, K-type; Exoplanets; Photometry, G band
Keywords: Extrasolar gaseous giant planets; Exoplanet astronomy; Exoplanets
Abstract:
K2-139b is a warm Jupiter with an orbital period of 28.4days, but only
three transits of this system have previously been observed-in the
long-cadence mode of K2-limiting the precision with which the orbital
period can be determined and future transits predicted. We report
photometric observations of four transits of K2-139b with ESA's
CHaracterising ExOPlanet Satellite (CHEOPS), conducted with the goal
of measuring the orbital obliquity via spot-crossing events. We
jointly fit these CHEOPS data alongside the three previously-published
transits from the K2 mission, considerably increasing the precision of
the ephemeris of K2-139b. The transit times for this system can now be
predicted for the next decade with a 1σ precision less than 10
minutes, compared to over one hour previously, allowing the efficient
scheduling of observations with Ariel. We detect no significant
deviation from a linear ephemeris, allowing us to exclude the presence
of a massive outer planet orbiting with a period less than 150 days,
or a brown dwarf with a period less than one year. We also determine
the scaled semimajor axis, the impact parameter, and the stellar limb
darkening with improved precision. This is driven by the shorter
cadence of the CHEOPS observations compared to that of K2, and
validates the subexposure technique used for analyzing long-cadence
photometry. Finally, we note that the stellar spot configuration has
changed from the epoch of the K2 observations; unlike the K2 transits,
we detect no evidence of spot-crossing events in the CHEOPS data.
Description:
CHaracterising ExOPlanet Satellite (CHEOPS) is a small (0.32m
diameter) telescope designed for high-precision monoband photometry of
individual exoplanetary systems. We observed two consecutive transits
in 2020 June and July, and a second pair of consecutive transits in
2021 June and July. Each "visit" consisted of seven consecutive orbits
of the CHEOPS satellite, or around 11.5hr. With a G-band magnitude of
11.5, K2-139 is a relatively faint target for CHEOPS, and therefore an
exposure time of 60s was used.
Objects:
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RA (2000) DE Designation(s) (Period)
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19 16 15.97 -17 54 38.4 K2-139 = K2-139 (P=28.38282d)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 37 1701 CHEOPS light curve of K2-139
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See also:
J/A+A/643/A94 : CHEOPS WASP-189 b transit light curve (Lendl+, 2020)
J/A+A/646/A157 : HD 108236 CHEOPS light curves (Bonfanti+, 2021)
J/A+A/653/A173 : CHEOPS 55 Cnc light curve (Morris+, 2021)
J/MNRAS/506/3810 : 7 transiting exoplanets CHEOPS light curves (Borsato+, 2021)
J/other/ExA/51.109 : Transit KELT-11b observed by CHEOPS (Benz+, 2021)
J/other/NatAs/5.775 : nu2 Lupi CHEOPS light curves (Delrez+, 2021)
J/other/RNAAS/5.13 : CHEOPS limb & gravity-darkening coefficient (Claret, 2021)
J/A+A/657/A52 : CHEOPS transit light curves of WASP-103 b (Barros+, 2022)
J/A+A/659/A74 : CHEOPS phase curve of WASP-189 b (Deline+, 2022)
J/A+A/659/L7 : AU Mic b and c transits with CHEOPS (Szabo+, 2022)
J/A+A/664/L15 : Quaoar stellar occultation observed by CHEOPS (Morgado+, 2022)
J/MNRAS/511/4551 : TOI-561 CHEOPS light curves (Lacedelli+, 2022)
J/MNRAS/514/77 : CHEOPS Early Science observations (Maxted+, 2022)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 F11.6 d BJD [9028/9398] Barycentric Julian Date at TDB;
BJD-2450000
13- 20 F8.6 --- Flux [0.97/1.02] Relative flux
22- 29 F8.6 --- e_Flux [0.0007/0.0009] Error on Flux
31- 37 F7.3 deg Roll [19.3/344] Spacecraft roll angle
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 21-Oct-2022