2019A&A...631A..90L


Query : 2019A&A...631A..90L

2019A&A...631A..90L - Astronomy and Astrophysics, volume 631A, 90-90 (2019/11-1)

Exoplanet characterisation in the longest known resonant chain: the K2-138 system seen by HARPS.

LOPEZ T.A., BARROS S.C.C., SANTERNE A., DELEUIL M., ADIBEKYAN V., ALMENARA J.-M., ARMSTRONG D.J., BRUGGER B., BARRADO D., BAYLISS D., BOISSE I., BONOMO A.S., BOUCHY F., BROWN D.J.A., CARLI E., DEMANGEON O., DUMUSQUE X., DIAZ R.F., FARIA J.P., FIGUEIRA P., FOXELL E., GILES H., HEBRARD G., HOJJATPANAH S., KIRK J., LILLO-BOX J., LOVIS C., MOUSIS O., DA NOBREGA H.J., NIELSEN L.D., NEAL J.J., OSBORN H.P., PEPE F., POLLACCO D., SANTOS N.C., SOUSA S.G., UDRY S., VIGAN A. and WHEATLEY P.J.

Abstract (from CDS):

The detection of low-mass transiting exoplanets in multiple systems brings new constraints to planetary formation and evolution processes and challenges the current planet formation theories. Nevertheless, only a mere fraction of the small planets detected by Kepler and K2 have precise mass measurements, which are mandatory to constrain their composition. We aim to characterise the planets that orbit the relatively bright star K2-138. This system is dynamically particular as it presents the longest chain known to date of planets close to the 3:2 resonance. We obtained 215 HARPS spectra from which we derived the radial-velocity variations of K2-138. Via a joint Bayesian analysis of both the K2 photometry and HARPS radial-velocities (RVs), we constrained the parameters of the six planets in orbit. The masses of the four inner planets, from b to e, are 3.1, 6.3, 7.9, and 13.0M with a precision of 34, 20, 18, and 15%, respectively. The bulk densities are 4.9, 2.8, 3.2, and 1.8g/cm3, ranging from Earth to Neptune-like values. For planets f and g, we report upper limits. Finally, we predict transit timing variations of the order two to six minutes from the masses derived. Given its peculiar dynamics, K2-138 is an ideal target for transit timing variation (TTV) measurements from space with the upcoming CHaracterizing ExOPlanet Satellite (CHEOPS) to study this highly-packed system and compare TTV and RV masses.

Abstract Copyright: © T. A. Lopez et al. 2019

Journal keyword(s): planets and satellites: detection - planets and satellites: fundamental parameters - stars: individual: K2-138 - techniques: radial velocities - techniques: photometric

VizieR on-line data: <Available at CDS (J/A+A/631/A90): tablea3.dat>

Simbad objects: 10

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Number of rows : 10
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 Kepler-10c Pl 19 02 43.0613892904 +50 14 28.701617339           ~ 115 1
2 Kepler-11f Pl 19 48 27.6228219845 +41 54 32.902654079           ~ 125 1
3 TRAPPIST-1 LM* 23 06 29.3684948589 -05 02 29.037301866     18.798 16.466 14.024 M7.5e 810 0
4 K2-138g Pl 23 15 47.7685349429 -10 50 58.897706806           ~ 6 0
5 K2-138d Pl 23 15 47.7685349429 -10 50 58.897706806           ~ 11 0
6 K2-138f Pl 23 15 47.7685349429 -10 50 58.897706806           ~ 12 0
7 K2-138b Pl 23 15 47.7685349429 -10 50 58.897706806           ~ 11 0
8 K2-138c Pl 23 15 47.7685349429 -10 50 58.897706806           ~ 10 0
9 K2-138e Pl 23 15 47.7685349429 -10 50 58.897706806           ~ 11 0
10 K2-138 * 23 15 47.7686067840 -10 50 58.895461284   13.01 12.21 12.12 11.40 ~ 36 0

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2023.01.27-22:15:27

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