HAL will be down for maintenance from Friday, June 10 at 4pm through Monday, June 13 at 9am. More information
Skip to Main content Skip to Navigation
Journal articles

Spectral and atmospheric characterisation of a new benchmark brown dwarf HD 13724 B

Abstract : Context. HD 13724 is a nearby solar-type star at 43.48 ± 0.06 pc hosting a long-period low-mass brown dwarf detected with the CORALIE echelle spectrograph as part of the historical CORALIE radial-velocity search for extra-solar planets. The companion has a minimum mass of 26.77-2.2+4.4 MJup and an expected semi-major axis of ~240 mas making it a suitable target for further characterisation with high-contrast imaging, in particular to measure its inclination, mass, and spectrum and thus establish its substellar nature.
Aims: Using high-contrast imaging with the SPHERE instrument on the Very Large Telescope (VLT), we are able to directly image a brown dwarf companion to HD 13724 and obtain a low-resolution spectrum.
Methods: We combine the radial-velocity measurements of CORALIE and HARPS taken over two decades and high-contrast imaging from SPHERE to obtain a dynamical mass estimate. From the SPHERE data we obtain a low-resolution spectrum of the companion from Y to J band, as well as photometric measurements from IRDIS in the J, H, and K bands.
Results: Using high-contrast imaging with the SPHERE instrument at the VLT, we report the first images of a brown dwarf companion orbiting the host star HD 13724. It has an angular separation of 175.6 ± 4.5 mas and an H-band contrast of 10.61 ± 0.16 mag, and using the age estimate of the star to be ~1 Gyr gives an isochronal mass estimate of ~44 MJup. By combining radial-velocity and imaging data we also obtain a dynamical mass of 50.5-3.5+3.3 MJup. Through fitting an atmospheric model, we estimate a surface gravity of logg = 5.5 and an effective temperature of 1000 K. A comparison of its spectrum with observed T dwarfs estimates a spectral type of T4 or T4.5, with a T4 object providing the best fit.

Based on observations collected with SPHERE mounted on the VLT at Paranal Observatory (ESO, Chile) under programmes 0102.C-0236(A) (PI: Rickman) and 0104.C-0702(B) (PI: Rickman) as well as observations collected with the CORALIE spectrograph mounted on the 1.2 m Swiss telescope at La Silla Observatory and with the HARPS spectrograph on the ESO 3.6 m telescope at La Silla (ESO, Chile).

The radial-velocity measurements, reduced images and additional data products discussed in this paper are available on the DACE web platform at https://dace.unige.ch/

Complete list of metadata

https://hal-insu.archives-ouvertes.fr/insu-03667127
Contributor : Nathalie Pothier Connect in order to contact the contributor
Submitted on : Friday, May 13, 2022 - 11:11:48 AM
Last modification on : Sunday, May 15, 2022 - 3:34:02 AM

File

aa37524-20.pdf
Publisher files allowed on an open archive

Identifiers

Citation

E. L. Rickman, D. Ségransan, J. Hagelberg, J. -L. Beuzit, A. Cheetham, et al.. Spectral and atmospheric characterisation of a new benchmark brown dwarf HD 13724 B. Astronomy & Astrophysics, 2020, 635, ⟨10.1051/0004-6361/202037524⟩. ⟨insu-03667127⟩

Share

Metrics

Record views

0

Files downloads

0