A new L5 brown dwarf member of the Hyades cluster with chromospheric activity

Abstract

Our aim is to identify brown dwarf members of the nearby Hyades open star cluster to determine the photometric and spectroscopic properties of brown dwarfs at moderately old ages and extend the knowledge of the substellar mass function of the cluster. We cross-matched the 2MASS and AllWISE public catalogues and measured proper motions to identify low-mass stars and brown dwarf candidates in an area of radius eight degrees around the central region of the Hyades cluster. We identified objects with photometry and proper motions consistent with cluster membership. For the faintest ($J$\,=\,17.2 mag) most promising astrometric and photometric low-mass candidate 2MASS\,J04183483$+$2131275\@, with a membership probability of 94.5\%, we obtained low-resolution (R\,=\,300--1000) and intermediate-resolution (R\,=\,2500) spectroscopy with the 10.4m Gran Telescopio Canarias. From the low-resolution spectra we determined a L5.0$\pm$0.5 spectral type, consistent with the available photometry. In the intermediate dispersion spectrum we detected H$\alpha$ in emission (marginally resolved with a full width half maximum of $\sim$2.8 Å) and determined a $\log ($L${}_{\mathrm{H}\alpha }$/L${}_{\mathrm{bol}})=-6.0$ dex. From H$\alpha$ we obtained a radial velocity of 38.0$\pm$2.9 km$\cdot$s${}^{-1}$, which combined with the proper motion leads to space velocities which are fully consistent with membership in the Hyades cluster.

References in corpus (20)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• The UKIDSS Galactic Plane Survey
• The Solar Neighborhood XVII: Parallax Results from the CTIOPI 0.9m Program -- Twenty New Members of the RECONS 10 Parsec Sample
• The WFCAM Science Archive
• The UKIRT Wide Field Camera ZYJHK Photometric System: Calibration from 2MASS
• Young L Dwarfs Identified in the Field: A Preliminary Low-Gravity, Optical Spectral Sequence from L0 to L5
• Meeting the Cool Neighbors. IX. The Luminosity Function of M7-L8 Ultracool Dwarfs in the Field
• Chromospheric Activity, Rotation, and Rotational Braking in M and L Dwarfs
• The Hawaii Infrared Parallax Program. II. Young Ultracool Field Dwarfs
• A Sample of Very Young Field L Dwarfs and Implications for the Brown Dwarf "Lithium Test" at Early Ages
• Activity and Kinematics of Ultracool Dwarfs Including An Amazing Flare Observation
• BOSS Ultracool Dwarfs I: Colors and Magnetic Activity of M and L dwarfs
• New brown dwarfs in Upper Sco using UKIDSS Galactic Cluster Survey science verification data
• Brown dwarfs and very low mass stars in the Hyades cluster : a dynamically evolved mass function
• Signatures of Cloud, Temperature, and Gravity From Spectra of the Closest Brown Dwarfs
• Trigonometric parallaxes of young field L dwarfs
• Spectroscopy of Hyades L dwarf candidates
• L dwarfs in the Hyades
• L and T dwarfs in the Hyades and Ursa Major moving groups

Cited by in corpus (7)

• A 3D view of the Hyades stellar and sub-stellar population
• Lithium depletion boundary, stellar associations, and Gaia
• Emission lines in the atmosphere of the irradiated brown dwarf WD0137-349B
• Results from The COPAINS Pilot Survey: four new brown dwarfs and a high companion detection rate for accelerating stars
• Detection of a giant white-light flare on an L2.5 dwarf with the Next Generation Transit Survey
• Radio Emission from a Nearby M dwarf Binary
• Substellar Hyades Candidates from the UKIRT Hemisphere Survey