Near-infrared spectroscopic characterisation of Gaia ultra-cool dwarf candidates; Spectral types and peculiarities

Abstract

Context: The local census of very low-mass stars and brown dwarfs is crucial to improving our understanding of the stellar-substellar transition and their formation history. These objects, known as ultra-cool dwarfs (UCDs), are essential targets for searches of potentially habitable planets. However, their detection poses a challenge because of their low luminosity. The Gaia survey has identified numerous new UCD candidates thanks to its large survey and precise astrometry. Aims: We aim to characterise 60 UCD candidates detected by Gaia in the solar neighbourhood with a spectroscopic follow-up to confirm that they are UCDs, as well as to identify peculiarities. Methods: We acquired the near-infrared (NIR) spectra of 60 objects using the SOFI spectrograph between 0.93 and 2.5 microns (R$\sim 600$). We identified their spectral types using a template-matching method. Their binarity is studied using astrometry and spectral features. Results: We confirm that 60 objects in the sample have ultra-cool dwarf spectral types close to those expected from astrometry. Their NIR spectra reveal that seven objects could host an unresolved coolest companion and seven UCDs share the same proper motions as other stars. The characterisation of these UCDs is part of a coordinated effort to improve our understanding of the Solar neighbourhood.

arXiv commentBased on observations made with the ESO New Technology Telescope at the La Silla Observatory under programme 106.214E.001 and 108.22G4.001. Accepted by A&A on the 30/01/2024

References in corpus (62)

• emcee: The MCMC Hammer
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• The Limiting Effects of Dust in Brown Dwarf Model Atmospheres
• Solar Chemical Abundances Determined with a CO5BOLD 3D Model Atmosphere
• Precipitating Condensation Clouds in Substellar Atmospheres
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• BANYAN. XI. The BANYAN $\Sigma$ multivariate Bayesian algorithm to identify members of young associations within 150 pc
• An Improved Spectroscopic Analysis of DA White Dwarfs from the Sloan Digital Sky Survey Data Release 4
• Characterization of M,L and T dwarfs in the Sloan Digital Sky Survey
• The First Hundred Brown Dwarfs Discovered by the Wide-field Infrared Survey Explorer (WISE)
• The 0.8-14.5 micron Spectra of Mid-L to Mid-T Dwarfs: Diagnostics of Effective Temperature, Grain Sedimentation, Gas Transport, and Surface Gravity
• Fundamental Parameters and Spectral Energy Distributions of Young and Field Age Objects with Masses Spanning the Stellar to Planetary Regime
• The Luminosity and Mass Functions of Low-Mass Stars in the Galactic Disk: II. The Field
• PESSTO : survey description and products from the first data release by the Public ESO Spectroscopic Survey of Transient Objects
• A Comprehensive Spectroscopic Analysis of DB White Dwarfs
• A Near-Infrared Spectroscopic Study of Young Field Ultracool Dwarfs
• Gaia Early Data Release 3: The Gaia Catalogue of Nearby Stars
• Atmospheric Parameters of Field L and T Dwarfs
• The NIRSPEC Brown Dwarf Spectroscopic Survey. I. Low-Resolution Near-Infrared Spectra
• On the Spectral Evolution of Hot White Dwarf Stars. I. A Detailed Model-Atmosphere Analysis of Hot White Dwarfs from SDSS DR12
• A new set of atmosphere and evolution models for cool T-Y brown dwarfs and giant exoplanets
• Discoveries from a Near-infrared Proper Motion Survey using Multi-epoch 2MASS Data
• 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
• Parallel Implementation of the PHOENIX Generalized Stellar Atmosphere Program
• The Effective Temperature Scale of M dwarfs
• Characterizing Young Brown Dwarfs using Low Resolution Near-IR Spectra
• The Spectroscopically Determined Substellar Mass Function of the Orion Nebula Cluster
• The Field Substellar Mass Function Based on the Full-sky 20-pc Census of 525 L, T, and Y Dwarfs
• The Sixth Data Release of the Radial Velocity Experiment (RAVE) -- I: Survey Description, Spectra and Radial Velocities
• The AllWISE Motion Survey and The Quest for Cold Subdwarfs
• Gaia Data Release 3. Astrometric binary star processing
• The 10 parsec sample in the Gaia era
• SpeX Spectroscopy of Unresolved Very Low Mass Binaries. II. Identification of Fourteen Candidate Binaries with Late-M/Early-L and T Dwarf Components
• An Empirical Measurement of the Initial-Final Mass Relation with Gaia White Dwarfs
• A New Generation of Cool White Dwarf Atmosphere Models. I. Theoretical Framework and Applications to DZ Stars
• The AllWISE Motion Survey, Part 2
• A new equation of state for dense hydrogen-helium mixtures II: taking into account hydrogen-helium interactions
• Meeting the Cool Neighbors VII: Spectroscopy of faint, red NLTT dwarfs
• Impact of a new H/He equation of state on the evolution of massive brown dwarfs. New determination of the hydrogen burning limit
• The ultracool-field dwarf luminosity-function and space density from the Canada-France Brown Dwarf Survey
• New ultra-cool and brown dwarf candidates in Gaia DR2
• Spectroscopic Detection of Carbon Monoxide in Two Late-type T Dwarfs
• Reaching the boundary between stellar kinematic groups and very wide binaries. The Washington Double Stars with the widest angular separations
• The Gaia Ultracool Dwarf Sample. I. Known L and T dwarfs and the first Gaia data release
• The Ultracool SpeXtroscopic Survey. I. Volume-Limited Spectroscopic Sample and Luminosity Function of M7$-$L5 Ultracool Dwarfs
• A 3D view of the Hyades stellar and sub-stellar population
• The Gaia Ultra-Cool Dwarf Sample -- II: Structure at the end of the main sequence
• The Fifth Catalogue of Nearby Stars (CNS5)
• A Brown Dwarf Census from the SIMP Survey
• Evolutionary models for ultracool dwarfs
• Hubble Space Telescope Imaging and Spectral Analysis of Two Brown Dwarf Binaries at the L Dwarf/T Dwarf Transition
• Chemical Properties of the Local Galactic Disk and Halo. I. Fundamental Properties of 1,544 Nearby, High Proper-Motion M dwarfs and subdwarfs
• Ultracool dwarfs in Gaia DR3
• Chemical Properties of the Local Disk and Halo. II. Abundances of 3745 M dwarfs and Subdwarfs from Improved Model Fitting of Low-Resolution Spectra
• Metallicity, temperature, and gravity scales of M subdwarfs
• New ultracool dwarf neighbours within 20pc from Gaia DR2
• Properties of ultra-cool dwarfs with Gaia. An assessment of the accuracy for the temperature determination
• $L$-band Spectra of Young Brown Dwarfs
• M Subdwarf Research III. Spectroscopic Diagnostics for Breaking Parameter Degeneracy