A new take on the low-mass brown dwarf companions on wide-orbits in Upper-Scorpius

Abstract

The Upper-Scorpius association (5-11 Myr) contains a unique population of low-mass (M<30 MJup) brown-dwarfs. The detailed relative characterization of their physical properties (mass, radius, temperature, composition, ongoing accretion) offers the opportunity to potentially explore their origin and their mechanisms of formation. We aim at characterizing the chemical and physical properties of three young, late-M brown-dwarfs claimed to be companions of the Upper-Scorpius stars USco161031.9-16191305, HIP77900, and HIP78530 using medium resolution spectroscopy at UV (R~3300), optical (R~5400), and near-infrared (R~4300) wavelengths. The spectra of six free-floating analogues from the same association are analyzed for comparison and to explore the potential physical differences between these substellar objects. We also aim at analyzing emission lines at UV and optical wavelengths to investigate the presence of ongoing accretion processes. The X-Shooter spectrograph at VLT was used to obtain the spectra of our targets over the 0.3-2.5 $\mu$m range simultaneously. Performing a forward modelling of the observed spectra with the ForMoSA code (Nested Sampling Bayesian inference method in using BT-SETTL15 models), we infer the Teff, log(g), and radius of our objects. Our results are compatible with physical parameters found for free floating analogues of the association and with evolutionary-model predictions. However the final accuracy on the Teff estimates is strongly limited by non-reproducibilities of the BT-SETTL15 models for late-M brown-dwarfs. We identified emission lines in the spectrum of several objects attributed to chromospheric activity except for USco1608-2315 for which they are indicative of active accretion. We confirm the x4 over-luminosity of USco161031.9-16191305B. It could be explained by the object activity and if the companion is an unresolved multiple system.

arXiv comment21 pages, 15 figures, 10 tables

References in corpus (129)

• Gaia Data Release 2. Summary of the contents and survey properties
• Interstellar Dust Grains
• Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
• Gaia Data Release 2: The astrometric solution
• A Survey of Stellar Families: Multiplicity of Solar-Type Stars
• Evolutionary models for cool brown dwarfs and extrasolar giant planets. The case of HD 20945
• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• A Non-Gray Theory of Extrasolar Giant Planets and Brown Dwarfs
• A Hipparcos census of the nearby OB associations
• X-shooter, the new wide band intermediate resolution spectrograph at the ESO Very Large Telescope
• The Limiting Effects of Dust in Brown Dwarf Model Atmospheres
• Models of Stars, Brown Dwarfs and Exoplanets
• Molecfit: A general tool for telluric absorption correction. I. Method and application to ESO instruments
• Automated data reduction workflows for astronomy
• An Analysis of the Shapes of Interstellar Extinction Curves. V. The IR-Through-UV Curve Morphology
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• Scattering by Interstellar Dust Grains: Optical and Ultraviolet
• An Infrared Spectroscopic Sequence of M, L and T Dwarfs
• A Census of the Young Cluster IC 348
• VOSA: Virtual Observatory SED Analyzer. An application to the Collinder 69 open cluster
• Very Low Mass Stars and Brown Dwarfs in Taurus-Auriga
• A Revised Age for Upper Scorpius and The Star-Formation History Among the F-Type Members of the Scorpius-Centaurus OB Association
• Extrasolar planet population synthesis I: Method, formation tracks and mass-distance distribution
• BANYAN. XI. The BANYAN $\Sigma$ multivariate Bayesian algorithm to identify members of young associations within 150 pc
• Molecfit: A general tool for telluric absorption correction II. Quantitative evaluation on ESO-VLT X-Shooter spectra
• X-Shooter spectroscopy of young stellar objects in Lupus: Accretion properties of class II and transitional objects
• Neglected Clouds in T and Y Dwarf Atmospheres
• Meeting the Cool New Neighbors V: A 2MASS-Selected Sample of Ultracool Dwarfs
• Scattering by Interstellar Dust Grains. II. X-Rays
• Accretion in Brown Dwarfs: an Infrared View
• X-Shooter spectroscopy of young stellar objects: IV -- Accretion in low-mass stars and sub-stellar objects in Lupus
• The Formation Mechanism of Brown Dwarfs
• UV excess measures of accretion onto young very low-mass stars and brown dwarfs
• Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
• Extrasolar planet population synthesis IV. Correlations with disk metallicity, mass and lifetime
• Further Defining Spectral Type "Y" and Exploring the Low-mass End of the Field Brown Dwarf Mass Function
• The properties of brown dwarfs and low-mass hydrogen-burning stars formed by disc fragmentation
• Fundamental Parameters and Spectral Energy Distributions of Young and Field Age Objects with Masses Spanning the Stellar to Planetary Regime
• The VAST Survey - III. The multiplicity of A-type stars within 75 pc
• From binaries to multiples II: hierarchical multiplicity of F and G dwarfs
• A Near-Infrared Spectroscopic Study of Young Field Ultracool Dwarfs
• The Palomar/MSU Nearby Star Spectroscopic Survey III: Chromospheric Activity, M-dwarf Ages and the Local Star Formation History
• Pulkovo Compilation of Radial Velocities for 35495 Hipparcos Stars in a Common System
• Atmospheric Parameters of Field L and T Dwarfs
• On the Correlation between the Magnetic Activity Levels, the Metallicities and the Radii of Low-Mass Stars
• Evidence for Mass-dependent Circumstellar Disk Evolution in the 5 Myr-old Upper Scorpius OB Association
• BANYAN. II. Very Low Mass and Substellar Candidate Members to Nearby, Young Kinematic Groups With Previously Known Signs of Youth
• Meeting the Cool Neighbors. IX. The Luminosity Function of M7-L8 Ultracool Dwarfs in the Field
• The "Mysterious" Origin of Brown Dwarfs
• Parallel Implementation of the PHOENIX Generalized Stellar Atmosphere Program
• The Disk Population of the Upper Scorpius Association
• Direct Imaging and Spectroscopy of a Planetary Mass Candidate Companion to a Young Solar Analog
• Characterizing Young Brown Dwarfs using Low Resolution Near-IR Spectra
• Mapping the Shores of the Brown Dwarf Desert I.: Upper Scorpius
• The Spectroscopically Determined Substellar Mass Function of the Orion Nebula Cluster
• Search for brown-dwarf companions of stars
• X-shooter spectroscopy of young stellar objects: I - Mass accretion rates of low-mass T Tauri stars in σOrionis
• A self-consistent cloud model for brown dwarfs and young giant exoplanets: comparison with photometric and spectroscopic observations
• A Disk Census for Young Brown Dwarfs
• Model atmospheres for massive gas giants with thick clouds: Application to the HR 8799 planets and predictions for future detections
• The Primordial Binary Population - I: A near-infrared adaptive optics search for close visual companions to A star members of Scorpius OB2
• Two Wide Planetary-Mass Companions to Solar-Type Stars in Upper Scorpius
• Magellan Adaptive Optics Imaging of PDS 70: Measuring the Mass Accretion Rate of a Young Giant Planet within a Gapped Disk
• X-Shooter spectroscopy of young stellar objects: II. Impact of chromospheric emission on accretion rate estimates
• Spectral and atmospheric characterization of 51 Eridani b using VLT/SPHERE
• A library of near-infrared integral field spectra of young M-L dwarfs
• Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. I. Stars with a Radiative Core
• The Directly Imaged Planet around the Young Solar Analog 1RXS J160929.1-210524: Confirmation of Common Proper Motion, Temperature and Mass
• Observed luminosity spread in young clusters and Fu Ori stars: a unified picture
• The effect of activity on stellar temperatures and radii
• Three Wide Planetary-Mass Companions to FW Tau, ROXs 12, and ROXs 42B
• The Young Planet-mass Object 2M1207b: a cool, cloudy, and methane-poor atmosphere
• Near-infrared cross-dispersed spectroscopy of brown dwarf candidates in the Upper Sco association
• A Survey for Low-mass Stars and Brown Dwarfs in the Upper-Scorpius OB Association
• Fundamental parameters and infrared excesses of Tycho-Gaia stars
• Characterization of exoplanets from their formation III: The statistics of planetary luminosities
• Accretion onto Planetary Mass Companions of Low-Mass Young Stars
• A Disk Around the Planetary-Mass Companion GSC 06214-00210 b: Clues About the Formation of Gas Giants on Wide Orbits
• Unusually Wide Binaries: Are They Wide or Unusual?
• An Empirical Correction for Activity Effects on the Temperatures, Radii, and Estimated Masses of Low-Mass Stars and Brown Dwarfs
• Discovery of a wide companion near the deuterium burning mass limit in the Upper Scorpius association
• New brown dwarfs in Upper Sco using UKIDSS Galactic Cluster Survey science verification data
• Age Determination in Upper Scorpius with Eclipsing Binaries
• Direct evidence of a sub-stellar companion around CT Cha
• Debris Disks in the Upper Scorpius OB Association
• Spatial Distributions of Young Stars
• Deuterium-burning in substellar objects
• Measuring tiny mass accretion rates onto young brown dwarfs
• Spectroscopic Confirmation of Young Planetary-Mass Companions on Wide Orbits
• Self-Consistent Magnetic Stellar Evolution Models of the Detached, Solar-Type Eclipsing Binary EF Aquarii
• The Formation and Evolution of Planetary Systems: Description of the Spitzer Legacy Science Database
• Discovery of a ~23 Mjup Brown Dwarf Orbiting ~700 AU from the Massive Star HIP 78530 in Upper Scorpius
• The GJ 504 system revisited. Combining interferometric, radial velocity, and high contrast imaging data
• Multiple Star Formation to the Bottom of the IMF
• Spectroscopy of Very Low Mass Stars and Brown Dwarfs in the Lambda Orionis Star Forming Region
• In-depth study of moderately young but extremely red, very dusty substellar companion HD206893B
• New Young Stars and Brown Dwarfs in the Upper Scorpius Association
• Multi-fibre optical spectroscopy of low-mass stars and brown dwarfs in Upper Sco
• X-Shooter study of accretion in $\rho$-Ophiucus: very low-mass stars and brown dwarfs
• Characterizing the Brown Dwarf Formation Channels from the Initial Mass Function and Binary-star Dynamics
• ALMA Measurements of Circumstellar Material in the GQ Lup System
• A Pan-STARRS + UKIDSS Search for Young, Wide Planetary-Mass Companions in Upper Scorpius
• Cloudless atmospheres for young low-gravity substellar objects
• New Brown Dwarf Disks in the TW Hydrae Association
• A WISE Survey of Circumstellar disks in the Upper Scorpius Association
• The optical+infrared L dwarf spectral sequence of young planetary-mass objects in the Upper Scorpius association
• OTS44: Disk and accretion at the planetary border
• Characterization of Low-mass, Wide-separation Substellar Companions to Stars in Upper Scorpius: Near-infrared Photometry and Spectroscopy
• Near-IR integral-field spectroscopy of the companion to GQ Lup
• A Correlation Between Circumstellar Disks and Rotation in the Upper Scorpius OB Association
• New constraints on the formation and settling of dust in the atmospheres of young M and L dwarfs
• An ALMA and MagAO Study of the Substellar Companion GQ Lup B
• A Keck LGS AO Search for Brown Dwarf and Planetary Mass Companions to Upper Scorpius Brown Dwarfs
• Millimeter Dust Emission in the GQ Lup System
• Accretion signatures in the X-shooter spectrum of the substellar companion to SR12
• BANYAN. VIII. New Low-Mass Stars and Brown Dwarfs with Candidate Circumstellar Disks
• An ALMA Constraint on the GSC 6214-210 B Circum-Substellar Accretion Disk Mass
• Three-dimensional structure of the Upper Scorpius association with the Gaia first data release
• Lithium in LP 944-20
• An Explanation of the Very Low Radio Flux of Young Planet-mass Companions
• An upper limit on the mass of the circumplanetary disk for DH Tau b
• An ALMA Survey for Disks Orbiting Low-Mass Stars in the TW Hya Association
• WEIRD: Wide-orbit Exoplanet search with InfraRed Direct imaging
• Physical parameters of late M-type members of Chamaleon I and TW Hydrae Association: Dust settling, age dispersion and activity
• Deep $z$-band observations of the coolest Y dwarf
• EPIC 203868608: A low-mass quadruple star system in the Upper Scorpius OB association
• Lithium in the Upper Centaurus Lupus and Lower Centaurus Crux Subgroups of Scorpius-Centaurus
• CFBDSIR 2149-0403: young isolated planetary-mass object or high-metallicity low-mass brown dwarf??
• Using binary statistics in Taurus-Auriga to distinguish between brown dwarf formation processes

Cited by in corpus (19)

• A medium-resolution spectrum of the exoplanet HIP 65426 b
• Assessing the C/O Ratio Formation Diagnostic: A Potential Trend with Companion Mass
• Strong H$\alpha$ emission and signs of accretion in a circumbinary planetary mass companion from MUSE
• Peering into the Young Planetary System AB Pic. Atmosphere, Orbit, Obliquity & Second Planetary Candidate
• X-SHYNE: X-shooter spectra of young exoplanet analogs. I. A medium-resolution 0.65-2.5$\mu \mathrm{m}$ one-shot spectrum of VHS\,1256-1257 b
• Emission line variability of young 10-30 Mjup companions : I. The case of GQ Lup b and GSC 06214-00210 b
• The search for disks or planetary objects around directly imaged companions: A candidate around DH Tau B
• Silicate clouds and a circumplanetary disk in the YSES-1 exoplanet system
• 2MASS J15491331-3539118: a new low-mass wide companion of the GQ Lup system
• A Mid-Infrared Study of Directly-Imaged Planetary-Mass Companions using Archival Spitzer/IRAC Images
• USco1621 B and USco1556 B: Two wide companions at the deuterium-burning mass limit in Upper Scorpius
• Multiples among B stars in the Scorpius-Centaurus association
• Multi-modal atmospheric characterization of $\beta$ Pictoris b: Adding high-resolution continuum spectra from GRAVITY
• X-SHYNE: X-Shooter spectra of young exoplanet analogs II. Presentation and analysis of the full library
• The planetary-mass-limit VLT/SINFONI library: Spectral extraction and atmospheric characterization via forward modeling
• Characterization of very wide companion candidates to young stars with planets and disks
• ExoplaNeT accRetion mOnitoring sPectroscopic surveY (ENTROPY) - II. Time series of Balmer line profiles of Delorme 1(AB)b
• Discovery of a brown dwarf with quasi-spherical mass-loss
• The mid-infrared spectrum of $\beta$ Pictoris b. First VLTI/MATISSE interferometric observations of an exoplanet