Orbital and spectral characterization of the benchmark T-type brown dwarf HD 19467B^★,★★

¹ STAR Institute, Université de Liège, Allée du Six Août 19c, 4000 Liège, Belgium
e-mail: almaire@uliege.be
² Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
³ INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
⁴ Department of Physics, University of Oxford, Oxford, UK
⁵ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, 92195 Meudon, France
⁶ INAF Catania Astrophysical Observatory, Via S. Sofia 78, 95123 Catania, Italy
⁷ CNRS, IPAG, Univ. Grenoble Alpes, 38000 Grenoble, France
⁸ INAF - Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807, Merate (Lc), Italy
⁹ Institute for Astronomy, The University of Edinburgh, Royal Observatory, Blackford Hill View, Edinburgh, EH9 3HJ, UK
¹⁰ Geneva Observatory, University of Geneva, Chemin des Maillettes 51, 1290 Versoix, Switzerland
¹¹ Unidad Mixta Internacional Franco-Chilena de Astronomía CNRS/INSU UMI 3386 and Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
¹² CRAL, UMR 5574, CNRS, Université Lyon 1, ENS Lyon, 9 av. Charles André, 69561 Saint-Genis-Laval Cedex, France
¹³ Aix-Marseille Université, CNRS, CNES, LAM, Marseille, France
¹⁴ Department of Astronomy, University of Michigan, 1085 S. University Ave, Ann Arbor, MI 48109-1107, USA
¹⁵ Dipartimento di Fisica e Astronomia “G. Galilei”, Università di Padova, Via Marzolo, 8, 35121 Padova, Italy
¹⁶ Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile
¹⁷ Núcleo Milenio Formación Planetaria - NPF, Universidad de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile
¹⁸ Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
¹⁹ Núcleo de Astronomía, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile
²⁰ Escuela de Ingeniería Industrial, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile
²¹ NOVA Optical Infrared Instrumentation Group, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands
²² DOTA, ONERA, Université Paris Saclay, 91123 Palaiseau, France

Received: 19 March 2020
Accepted: 16 May 2020

Abstract

Context. Detecting and characterizing substellar companions for which the luminosity, mass, and age can be determined independently is of utter importance to test and calibrate the evolutionary models due to uncertainties in their formation mechanisms. HD 19467 is a bright and nearby star hosting a cool brown dwarf companion detected with radial velocities and imaging, making it a valuable object for such studies.

Aims. We aim to further characterize the orbital, spectral, and physical properties of the HD 19467 system.

Methods. We present new high-contrast imaging data with the SPHERE and NaCo instruments. We also analyze archival data from the instruments HARPS, NaCo, HIRES, UVES, and ASAS. Furthermore, we use proper motion data of the star from HIPPARCOS and Gaia.

Results. We refined the properties of the host star and derived an age of 8.0^+2.0_−1.0 Gyr based on isochrones, gyrochronology, and chemical and kinematic arguments. This age estimate is slightly younger than previous age estimates of ~9–11 Gyr based on isochrones. No orbital curvature is seen in the current imaging, radial velocity, and astrometric data. From a joint fit of the data, we refined the orbital parameters for HD 19467B, including: a period of 398⁺⁹⁵₋₉₃ yr, an inclination of 129.8^+8.1_−5.1 deg, an eccentricity of 0.56 ± 0.09, a longitude of the ascending node of 134.8 ± 4.5 deg, and an argument of the periastron of 64.2^+5.5_−6.3 deg. We assess a dynamical mass of 74⁺¹²₋₉ M_J. The fit with atmospheric models of the spectrophotometric data of the companion indicates an atmosphere without clouds or with very thin clouds, an effective temperature of 1042⁺⁷⁷₋₇₁ K, and a high surface gravity of 5.34^+0.8_−0.9 dex. The comparison to model predictions of the bolometric luminosity and dynamical mass of HD 19467B, assuming our system age estimate, indicates a better agreement with the Burrows et al. (1997, ApJ, 491, 856) models; whereas, the other evolutionary models used tend to underestimate its cooling rate.