2019A&A...624A..38D


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.13CEST01:44:59

2019A&A...624A..38D - Astronomy and Astrophysics, volume 624A, 38-38 (2019/4-1)

So close, so different: characterization of the K2-36 planetary system with HARPS-N.

DAMASSO M., ZENG L., MALAVOLTA L., MAYO A., SOZZETTI A., MORTIER A., BUCHHAVE L.A., VANDERBURG A., LOPEZ-MORALES M., BONOMO A.S., CAMERON A.C., COFFINET A., FIGUEIRA P., LATHAM D.W., MAYOR M., MOLINARI E., PEPE F., PHILLIPS D.F., PORETTI E., RICE K., UDRY S. and WATSON C.A.

Abstract (from CDS):


Context. K2-36 is a K dwarf orbited by two small (Rb=1.43±0.08R and Rc=3.2±0.3R), close-in (ab=0.022au and ac=0.054au) transiting planets discovered by the Kepler/K2 space observatory. They are representatives of two distinct families of small planets (Rp<4R) recently emerged from the analysis of Kepler data, with likely a different structure, composition and evolutionary pathways.
Aims. We revise the fundamental stellar parameters and the sizes of the planets, and provide the first measurement of their masses and bulk densities, which we use to infer their structure and composition.
Methods. We observed K2-36 with the HARPS-N spectrograph over ∼3.5yr, collecting 81 useful radial velocity measurements. The star is active, with evidence for increasing levels of magnetic activity during the observing time span. The radial velocity scatter is ∼17m/s due to the stellar activity contribution, which is much larger that the semi-amplitudes of the planetary signals. We tested different methods for mitigating the stellar activity contribution to the radial velocity time variations and measuring the planet masses with good precision.
Results. We find that K2-36 is likely a ∼1Gyr old system, and by treating the stellar activity through a Gaussian process regression, we measured the planet masses mb=3.9±1.1M and mc=7.8±2.3M. The derived planet bulk densities ρb=7.2–2.1+2.5g/cm3 and ρc=1.3–0.5+0.7g/cm3 point out that K2-36 b has a rocky, Earth-like composition, and K2-36 c is a low-density sub-Neptune.
Conclusions. Composed of two planets with similar orbital separations but different densities, K2-36 represents an optimal laboratory for testing the role of the atmospheric escape in driving the evolution of close-in, low-mass planets after ∼1Gyr from their formation. Due to their similarities, we performed a preliminary comparative analysis between the systems K2-36 and Kepler-36, which we deem worthy of a more detailed investigation.

Abstract Copyright: © ESO 2019

Journal keyword(s): stars: individual: K2-36 - planets and satellites: detection - planets and satellites: composition - techniques: radial velocities

VizieR on-line data: <Available at CDS (J/A+A/624/A38): tablea1.dat tablea2.dat>

Simbad objects: 21

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Number of rows : 21

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 K2-106b Pl 00 52 19.1416171671 +10 47 40.903737832           ~ 23 0
2 K2-78b Pl 03 48 54.0718595295 +13 29 00.723170374           ~ 4 0
3 NGTS-4b Pl 05 58 23.7549990436 -30 48 42.362982845           ~ 10 0
4 CoRoT-7b Pl 06 43 49.4690410679 -01 03 46.825797768           ~ 346 1
5 K2-36b Pl 11 17 47.7836955275 +03 51 59.007737897           ~ 5 0
6 K2-36 * 11 17 47.7836955275 +03 51 59.007737897   12.57 11.73 11.48   ~ 11 0
7 K2-36c Pl 11 17 47.7836955275 +03 51 59.007737897           ~ 4 0
8 BD-05 3504b Pl 12 27 29.5848289637 -06 43 18.766035130           ~ 13 0
9 K2-235b Pl 12 33 32.8440958980 -10 08 46.223886777           ~ 52 0
10 WASP-107 PM* 12 33 32.8440958980 -10 08 46.223886777   14.62 11.47     K6 14 0
11 NAME G 139-21b Pl 17 15 18.9337265994 +04 57 50.064695682           ~ 533 1
12 Kepler-36 Ro* 19 25 00.0430855076 +49 13 54.631289830   12.66 11.94     ~ 165 1
13 Kepler-36c Pl 19 25 00.0430855076 +49 13 54.631289830           ~ 88 1
14 Kepler-36b Pl 19 25 00.0430855076 +49 13 54.631289830           ~ 115 1
15 WASP-47e Pl 22 04 48.7262032385 -12 01 08.000987005           ~ 36 0
16 K2-112g Pl 23 06 29.3684052886 -05 02 29.031690445           ~ 97 0
17 K2-112e Pl 23 06 29.3684052886 -05 02 29.031690445           ~ 127 0
18 K2-112h Pl 23 06 29.3684052886 -05 02 29.031690445           ~ 63 0
19 K2-112d Pl 23 06 29.3684052886 -05 02 29.031690445           ~ 108 0
20 TRAPPIST-1 LM* 23 06 29.3684052886 -05 02 29.031690445     18.798 16.466 14.024 M7.5e 480 0
21 K2-112f Pl 23 06 29.3684052886 -05 02 29.031690445           ~ 105 0

    Equat.    Gal    SGal    Ecl

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2020.07.13-01:44:59

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