2018A&A...614A..16C


Query : 2018A&A...614A..16C

2018A&A...614A..16C - Astronomy and Astrophysics, volume 614A, 16-16 (2018/6-1)

Direct imaging of an ultracool substellar companion to the exoplanet host star HD 4113 A.

CHEETHAM A., SEGRANSAN D., PERETTI S., DELISLE J.-B., HAGELBERG J., BEUZIT J.-L., FORVEILLE T., MARMIER M., UDRY S. and WILDI F.

Abstract (from CDS):

Using high-contrast imaging with the SPHERE instrument at the Very Large Telescope (VLT), we report the first images of a cold brown dwarf companion to the exoplanet host star HD 4113A. The brown dwarf HD 4113C is part of a complex dynamical system consisting of a giant planet, a stellar host, and a known wide M-dwarf companion. Its separation of 535 ± 3 mas and H-band contrast of 13.35 ± 0.10 mag correspond to a projected separation of 22 AU and an isochronal mass estimate of 36 ± 5 MJ based on COND models. The companion shows strong methane absorption, and through fitting an atmosphere model, we estimate a surface gravity of logg = 5 and an effective temperature of ∼500-600 K. A comparison of its spectrum with observed T dwarfs indicates a late-T spectral type, with a T9 object providing the best match. By combining the observed astrometry from the imaging data with 27 years of radial velocities, we use orbital fitting to constrain its orbital and physical parameters, as well as update those of the planet HD 4113A b, discovered by previous radial velocity measurements. The data suggest a dynamical mass of 66–4+566^{+5}{–4}66–4+5MJ_ and moderate eccentricity of 0.44–0.07+0.080.44^{+0.08}_{-0.07}0.44-0.07+0.08 for the brown dwarf. This mass estimate appears to contradict the isochronal estimate and that of objects with similar temperatures, which may be caused by the newly detected object being an unresolved binary brown dwarf system or the presence of an additional object in the system. Through dynamical simulations, we show that the planet may undergo strong Lidov-Kozai cycles, raising the possibility that it formed on a quasi-circular orbit and gained its currently observed high eccentricity (e ∼ 0.9) through interactions with the brown dwarf. Follow-up observations combining radial velocities, direct imaging, and Gaia astrometry will be crucial to precisely constrain the dynamical mass of the brown dwarf and allow for an in-depth comparison with evolutionary and atmosphere models.

Abstract Copyright: © ESO 2018

Journal keyword(s): planets and satellites: detection - planet-star interactions - brown dwarfs

CDS comments: HD 4113D not in SIMBAD.

Simbad objects: 11

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Number of rows : 11
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 HD 4113C BD* 00 43 12.59 -37 58 57.4           T9 18 0
2 HD 4113 PM* 00 43 12.5955916128 -37 58 57.477720936   8.61 7.88     G5V 79 1
3 HD 4113b Pl 00 43 12.5956705785 -37 58 57.479407429           ~ 28 1
4 HD 19467B BD* 03 07 18.48 -13 45 43.3           T5.5+1 30 0
5 * 51 Eri b Pl 04 37 36.1323118067 -02 28 24.778826936           ~ 140 0
6 WISE J072227.27-054029.9 BD* 07 22 27.51096 -05 40 31.2096           T9 70 0
7 * e Vir PM* 13 16 46.5148594512 +09 25 26.960139646   5.81   4.8   G0V 529 1
8 * e Vir b Pl 13 16 46.5161591991 +09 25 26.967205938           ~ 96 1
9 WISE J165311.05+444422.8 BD* 16 53 11.05080 +44 44 22.8876           T8 10 0
10 * alf Lyr dS* 18 36 56.33635 +38 47 01.2802 0.03 0.03 0.03 0.07 0.10 A0Va 2590 0
11 HD 182488B BD* 19 23 34.0126 +33 13 19.078           T9 60 0

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2022.05.19-09:46:21

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