On the properties of discs around accreting brown dwarfs

Abstract

We present a grid of models of accreting brown dwarf systems with circumstellar discs. The calculations involve a self-consistent solution of both vertical hydrostatic and radiative equilibrium along with a sophisticated treatment of dust sublimation. We have simulated observations of the spectral energy distributions and several broadband photometric systems. Analysis of the disc structures and simulated observations reveal a natural dichotomy in accretion rates, with \logmdot $>-$9 and $\le -$9 classed as extreme and typical accretors respectively. Derivation of ages and masses from our simulated photometry using isochrones is demonstrated to be unreliable even for typical accretors. Although current brown dwarf disc candidate selection criteria have been shown to be largely reliable when applied to our model grid we suggest improved selection criteria in several colour indices. We show that as accretion rates increase brown dwarf disc systems are less likely to be correctly identified. This suggests that, within our grid, systems with higher accretion rates would be preferentially lost during brown dwarf target selection. We suggest that observations used to assert a $\dot{M}\propto M_{\ast }^2$ relationship may contain an intrinsic selection bias.

13 figures, 2 tables, 2 appendices and 25 pages. Accepted for publication in MNRAS

References in corpus (18)

• The Herschel-SPIRE instrument and its in-flight performance
• Spitzer Observations of NGC 1333: A Study of Structure and Evolution in a Nearby Embedded Cluster
• Accretion in the Rho-Oph pre-main sequence stars
• Demographics of Transition Objects
• On the formation of H-alpha line emission around classical T Tauri stars
• Rotation and accretion of very low mass objects in the SigmaOri cluster
• Fitting the young main-sequence; distances, ages and age spreads
• Young, Low-Mass Brown Dwarfs with Mid-Infrared Excesses
• The Rise and Fall of Debris Disks: MIPS Observations of h and chi Persei and the Evolution of Mid-IR Emission from Planet Formation
• Measuring tiny mass accretion rates onto young brown dwarfs
• Empirical isochrones and relative ages for young stars, and the radiative-convective gap
• Disks around Brown Dwarfs in the Sigma Orionis Cluster
• Magnetocentrifugally Driven Flows from Young Stars and Disks. VI. Accretion with a Multipole Stellar Field
• The $\dot{M}-M$ relationship in pre-main sequence stars
• Spitzer Spectroscopy of Circumstellar Disks in the 5 Myr Old Upper Scorpius OB Association
• Structural and compositional properties of brown dwarf disks: the case of 2MASS J04442713+2512164
• The transition disc frequency in M stars
• Accretion in rho-Ophiuchi brown dwarfs: infrared hydrogen line ratios

Cited by in corpus (10)

• Pre-main-sequence isochrones -- II. Revising star and planet formation timescales
• Spectroscopic Confirmation of Young Planetary-Mass Companions on Wide Orbits
• Multi-fibre optical spectroscopy of low-mass stars and brown dwarfs in Upper Sco
• Strong Biases in Estimating the Time Dependence of Mass Accretion Rates in Young Stars
• No evidence for intense, cold accretion onto YSOs from measurements of Li in T-Tauri stars
• A Significant Population of Candidate New Members of the Rho Ophiuchi Cluster
• Bayesian fitting of Taurus brown dwarf spectral energy distributions
• Constraints on the height of the inner disk rim in pre-main-sequence stars
• Fast Photometric Variability of Very Low Mass Stars in IC 348: Detection of Superflare in an M-dwarf
• Dynamic Photometric Variability in Three Young Brown Dwarfs in Taurus: Detection of Optical Flares with TESS data