The First Proto-Brown Dwarf Binary Candidate Identified through Dynamics of Jets

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
Tien-Hao Hsieh ◽  
Shih-Ping Lai ◽  
Arnaud Belloche ◽  
Friedrich Wyrowski
Keyword(s):  
Binary System ◽  
Orbital Motion ◽  
Brown Dwarf ◽  
Low Mass Stars ◽  
Core Mass ◽  
Substellar Objects ◽  
Current Mass ◽  
Low Mass ◽  
Dynamical Features ◽  
First Time

AbstractThe formation mechanism of brown dwarfs (BDs) is one of the long-standing problems in star formation because the typical Jeans mass in molecular clouds is too large to form these substellar objects. To answer this question, it is crucial to study a BD at the embedded phase (proto-brown dwarf). IRAS16253 is classified as a Very Low Luminosity Object (VeLLO, Lint < 0.1L⊙), which is considered as a proto-brown dwarf candidate. We use the IRAM 30m, APEX telescopes and the SMA to probe the molecular jet/outflow driven by IRAS 16253 in CO (2–1), (6–5), and (7–6) and study its dynamical features and physical properties. We detect a wiggling pattern in the position-velocity diagrams of the jets. Assuming that this pattern is due to the orbital motion of a binary system, we obtain the current mass of the binary is ~0.026 M⊙. Together with the low parent core mass, IRAS16253 will likely form one or two proto-BD in the future. This is the first time that the current mass of a proto-BD binary system is identified through the dynamics of the jets. Since IRAS16253 is located in an isolated environment, we suggest that BDs can form through fragmentation and collapse like low mass stars.

scholarly journals Very Low Mass Stars and Brown Dwarf Candidates in Orion OB1a and OB1b

2003 ◽  
Vol 211 ◽  
pp. 119-122
Author(s):  
Frederick M. Walter ◽  
William H. Sherry ◽  
Scott J. Wolk
Keyword(s):  
Ir Spectroscopy ◽  
Main Sequence ◽  
Brown Dwarf ◽  
Low Mass Stars ◽  
Space Density ◽  
Near Ir ◽  
Substellar Objects ◽  
Low Mass ◽  
M Stars

VRI images within the belt of Orion and the Ori OB1a association reveal a pre-main sequence locus extending to below our completeness limit of about V=21. We report here on followup JHK imaging and optical and near–IR spectroscopy of the faintest and reddest of the PMS candidates. We find that they are unreddened mid-to-late M “stars” which fall on a few million year isochrone. Masses are largely substellar, reaching as low as about 0.02 M⊙ (20 Jovian masses). The space density of the substellar objects is high.

scholarly journals A Search for Lithium in Brown Dwarf Candidates

1993 ◽  
Vol 137 ◽  
pp. 171-173
Author(s):  
Rafael Rebolo ◽  
Eduardo L. Martin ◽  
Antonio Magazzu
Keyword(s):  
High Resolution ◽  
Resonance Line ◽  
Brown Dwarfs ◽  
Brown Dwarf ◽  
Low Mass Stars ◽  
Substellar Objects ◽  
Low Mass

AbstractWe are conducting a search for lithium in very low mass objects with the aim of discriminating between stellar and substellar objects. Lithium is expected to be preserved in brown dwarfs with M/M⊙ ≤0.06, while it is known to be efficiently destroyed in low mass stars. In this paper we present high resolution observations in the region of the λ 6708 Li I resonance line of 5 very low mass dwarfs. In none of them lithium is detected, implying a Li destruction in their atmospheres of about four orders of magnitude. Our results suggest that these objects are probably very low mass stars rather than brown dwarfs.

scholarly journals Direct-imaging discovery of a 12–14 Jupiter-mass object orbiting a young binary system of very low-mass stars

2013 ◽  
Vol 553 ◽  
pp. L5 ◽  
Author(s):  
P. Delorme ◽  
J. Gagné ◽  
J. H. Girard ◽  
A. M. Lagrange ◽  
G. Chauvin ◽  
...  
Keyword(s):  
Binary System ◽  
Direct Imaging ◽  
Low Mass Stars ◽  
Low Mass

scholarly journals VLT/SPHERE astrometric confirmation and orbital analysis of the brown dwarf companion HR 2562 B

2018 ◽  
Vol 615 ◽  
pp. A177 ◽  
Author(s):  
A.-L. Maire ◽  
L. Rodet ◽  
C. Lazzoni ◽  
A. Boccaletti ◽  
W. Brandner ◽  
...  
Keyword(s):  
Orbital Motion ◽  
Orbital Plane ◽  
Real Data ◽  
Far Infrared ◽  
Brown Dwarf ◽  
Orbital Parameters ◽  
System A ◽  
Low Mass ◽  
Debris Disk ◽  
Orbital Periods

Context. A low-mass brown dwarf has recently been imaged around HR 2562 (HD 50571), a star hosting a debris disk resolved in the far infrared. Interestingly, the companion location is compatible with an orbit coplanar with the disk and interior to the debris belt. This feature makes the system a valuable laboratory to analyze the formation of substellar companions in a circumstellar disk and potential disk-companion dynamical interactions. Aims. We aim to further characterize the orbital motion of HR 2562 B and its interactions with the host star debris disk. Methods. We performed a monitoring of the system over ~10 months in 2016 and 2017 with the VLT/SPHERE exoplanet imager. Results. We confirm that the companion is comoving with the star and detect for the first time an orbital motion at high significance, with a current orbital motion projected in the plane of the sky of 25 mas (~0.85 au) per year. No orbital curvature is seen in the measurements. An orbital fit of the SPHERE and literature astrometry of the companion without priors on the orbital plane clearly indicates that its orbit is (quasi-)coplanar with the disk. To further constrain the other orbital parameters, we used empirical laws for a companion chaotic zone validated by N-body simulations to test the orbital solutions that are compatible with the estimated disk cavity size. Non-zero eccentricities (>0.15) are allowed for orbital periods shorter than 100 yr, while only moderate eccentricities up to ~0.3 for orbital periods longer than 200 yr are compatible with the disk observations. A comparison of synthetic Herschel images to the real data does not allow us to constrain the upper eccentricity of the companion.

scholarly journals X-Ray Detection of Brown Dwarfs with Chandra

2003 ◽  
Vol 211 ◽  
pp. 447-450 ◽  
Author(s):  
Scott J. Wolk
Keyword(s):  
Brown Dwarfs ◽  
Stellar Clusters ◽  
Brown Dwarf ◽  
Low Mass Stars ◽  
X Ray ◽  
Low Mass ◽  
Vast Range

I review recent observations of brown dwarfs by the Chandra X-ray Observatory. These observations fall in 2 categories, young stellar clusters which contain brown dwarfs and brown dwarf candidates and directed pointings at brown dwarfs and very low mass stars. Surprisingly, there are already over 60 published detections of brown dwarfs by Chandra. A review of the X–ray characteristics shows these objects are subject to flaring and their temperatures and luminosities have a vast range which is related to age.

scholarly journals Detection of Nine M8.0–L0.5 Binaries: The Very Low Mass Binary Population and Its Implications for Brown Dwarf Formation Theories

2003 ◽  
Vol 211 ◽  
pp. 249-256
Author(s):  
Laird M. Close ◽  
Nick Siegler ◽  
Melanie Freed
Keyword(s):  
Wave Front ◽  
Adaptive Optics ◽  
Major Axis ◽  
Broad Peak ◽  
Brown Dwarf ◽  
Semi Major Axis ◽  
Highly Sensitive ◽  
Low Mass ◽  
First Time

Use of the highly sensitive Hōkūpa'a/Gemini curvature wave-front sensor has allowed for the first time direct adaptive optics (AO) guiding on very low mass (VLM) stars with SpT=M8.0–L0.5. A survey of 39 such objects detected 9 VLM binaries (7 of which were discovered for the first time to be binaries). Most of these systems (55%) are tight (separation < 5 AU) and have similar masses (ΔKs < 0.8 mag; 0.85 < q < 1.0). However, 2 systems (LHS 2397a, and 2M2331016-040618) have large ΔKs > 2.38 mag and consist of a VLM star orbited by a much cooler L6.5–L8.5 brown dwarf companion. Based on our initial flux limited (Ks < 12 mag) survey of 39 M8.0–L0.5 stars (mainly from the sample of Gizis et al. 2000) we find a binary fraction in the range 19±7% for M8.0–L0.5 binaries with separations > 2.6 AU. This is slightly less than the 32 ± 9% measured for more massive (M0–M4) stars over the same separation range (Fischer & Marcy 1992). It appears M8.0–L0.5 binaries (as well as L and T dwarf binaries) have a much smaller semi-major axis distribution peak (~ 4 AU) compared to more massive M and G stars which have a broad peak at larger ~ 30 AU separations. We also find no VLM binaries (Mtot < 0.18M⊙) with separations > 20 AU. We find that a velocity “kick” of ~ 3 km/s can reproduce the observed cut-off in the semi-major axis distribution at ˜ 20 AU. This kick may have been from the VLM system being ejected from its formation mini-cluster.

scholarly journals On producers of cosmic organic compounds: exploring the boron abundance in lithium-rich K giant stars

2017 ◽  
Vol 13 (S332) ◽  
pp. 237-241 ◽  
Author(s):  
N. A. Drake ◽  
R. de la Reza ◽  
V. V. Smith ◽  
K. Cunha
Keyword(s):  
Organic Compounds ◽  
Organic Material ◽  
Emission Lines ◽  
Low Mass Stars ◽  
Strong Emission ◽  
Giant Stars ◽  
First Approximation ◽  
Low Mass ◽  
Stellar Interiors ◽  
First Time

AbstractThe element boron belongs, together with lithium and beryllium, to a known trio of important elements for the study of evolutionary processes in low mass stars. Because B is the least fragile of this trio to be destroyed in the stellar interiors, it can be used to test if the Li enrichment is of planetary origin. Here, for the first time, boron lines are examined in the UV for four giants with different degrees of large Li enrichment by means of observations with the Hubble telescope. Two main results are found in our study. One is that to first approximation B abundances appear not to be in excess, invalidating the planet engulfment mechanism. The second one is that the two stars with very large Li abundances present emission lines indicating that quite strong active chromospheres are acting in these very Li-rich giants. These new results obtained from the UV complement our recent studies in the mid-IR (de la Rezaet al.2015) where strong emission-line features of organic material were found in the spectra of some Li-rich stars.

scholarly journals Brown Dwarf Model Atmospheres Based on Multi-Dimensional Radiation Hydrodynamics

2009 ◽  
Vol 5 (H15) ◽  
pp. 756-756 ◽  
Author(s):  
France Allard ◽  
Bernd Freytag
Keyword(s):  
Cloud Model ◽  
Molecular Transport ◽  
Brown Dwarfs ◽  
Model Atmosphere ◽  
Magnetic Activity ◽  
Cloud Formation ◽  
Brown Dwarf ◽  
Low Mass Stars ◽  
The Status ◽  
Low Mass

AbstractThe atmospheres of Brown Dwarfs (BDs) are the site of molecular opacities and cloud formation, and control their cooling rate, radius and brightness evolution. Brown dwarfs evolve from stellar-like properties (magnetic activity, spots, flares, mass loss) to planet-like properties (electron degeneracy of the interior, cloud formation, dynamical molecular transport) while retaining, due to their fully convective interior, larger rotational velocities (≤ 30 km/s i.e. P < 4 hrs versus 11 hrs for Jupiter). Model atmospheres treating all this complexity are therefore essential to understand the evolution properties, and to interpret the observations of these objects. While the pure gas-phase based NextGen model atmospheres (Allard et al. 1997, Hauschildt et al. 1999) have allowed the understanding of the several populations of Very Low Mass Stars (VLMs), the AMES-Dusty models (Allard et al. 2001) based on equilibrium chemistry have reproduced some near-IR photometric properties of M and L-type brown dwarfs, and played a key role in the determination of the mass of brown dwarfs and Planetary Mass Objects (PMOs) in the eld and in young stellar clusters. In this paper, we present a new model atmosphere grid for VLMs, BDs, PMOs named BT-Settl, which includes a cloud model and dynamical molecular transport based on mixing information from 2D Radiation Hydrodynamic (RHD) simulations (Freytag et al. 2009). We also present the status of our 3D RHD simulations including rotation (Coriolis forces) of a cube on the surface of a brown dwarf. The BT-Settl model atmosphere grid will be available shortly via the Phoenix web simulator (http://phoenix.ens-lyon.fr/simulator/).

scholarly journals Astrometry in the Service of Planet Formation Studies: Disk Lifetimes in Nearby Star Forming Regions and a Planet Candidate around a Mature Brown Dwarf

2013 ◽  
Vol 8 (S299) ◽  
pp. 230-231
Author(s):  
Alycia J. Weinberger ◽  
Alan P. Boss ◽  
Guillem Anglada-Escudé
Keyword(s):  
Planet Formation ◽  
Circumstellar Disks ◽  
Giant Planets ◽  
Brown Dwarf ◽  
Low Mass Stars ◽  
Nearby Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Low Mass ◽  
Stellar Associations

AbstractWe present preliminary astrometric results aimed at understanding the lifetime of circumstellar disks and potential for planet formation. We have obtained parallaxes to stars in the TW Hydrae, Upper Scorpius, and Chamaeleon I stellar associations. These enable new estimates for the ages of the stars. We are also performing the Carnegie Astrometric Planet Search of nearby low mass stars for gas giant planets on wide orbits. We have our first candidate around a mature brown dwarf.

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