Spectral and atmospheric characterisation of a new benchmark brown dwarf HD 13724 B
In: ISSN: 0004-6361, 2020
Online
academicJournal
Zugriff:
International audience ; 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 M Jup 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 M Jup . By combining radial-velocity and imaging data we also obtain a dynamical mass of 50.5 -3.5 +3.3 M Jup . 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 ...
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Spectral and atmospheric characterisation of a new benchmark brown dwarf HD 13724 B
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Autor/in / Beteiligte Person: | Rickman, E. L. ; Ségransan, D. ; Hagelberg, J. ; Beuzit, J. L. ; Cheetham, A. ; Delisle, J. B. ; Forveille, T. ; Udry, S. ; Laboratoire d'Astrophysique de Marseille (LAM) ; Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS) ; Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) ; Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ) ; Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France |
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Zeitschrift: | ISSN: 0004-6361, 2020 |
Veröffentlichung: | HAL CCSD ; EDP Sciences, 2020 |
Medientyp: | academicJournal |
DOI: | 10.1051/0004-6361/202037524 |
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