scholarly journals Two close binaries across the hydrogen-burning limit in the Praesepe open cluster

2020 ◽  
Vol 498 (3) ◽  
pp. 3964-3974
Author(s):  
N Lodieu ◽  
C del Burgo ◽  
E Manjavacas ◽  
M R Zapatero Osorio ◽  
C Alvarez ◽  
...  
Keyword(s):  
Binary System ◽  
Adaptive Optics ◽  
Near Infrared ◽  
Open Cluster ◽  
Flux Ratio ◽  
Close Binaries ◽  
Mass Star ◽  
Evolutionary Models ◽  
Stellar Cluster ◽  
Low Mass

ABSTRACT We present Keck I/OSIRIS and Keck II/NIRC2 adaptive optics imaging of two member candidates of the Praesepe stellar cluster (d  =  186.18 ± 0.11 pc; 590–790 Myr), UGCS J08451066+2148171 (L1.5 ± 0.5) and UGCS J08301935+2003293 (no spectroscopic classification). We resolved UGCS J08451066+2148171 into a binary system in the near-infrared, with a K-band wavelength flux ratio of 0.89 ± 0.04 and a projected separation of 60.3 ± 1.3 mas (11.2 ± 0.7 au; 1σ). We also resolved UGCS J08301935+2003293 into a binary system with a flux ratio of 0.46 ± 0.03 and a separation of 62.5 ± 0.9 mas. Assuming zero eccentricity, we estimate minimum orbital periods of ∼100 yr for both systems. According to theoretical evolutionary models, we derive masses in the range of 0.074–0.078 and 0.072–0.076 M⊙ for the primary and secondary of UGCS J08451066+2148171 for an age of 700 ± 100 Myr. In the case of UGCS J08301935+2003293, the primary is a low-mass star at the stellar/substellar boundary (0.070–0.078 M⊙), while the companion candidate might be a brown dwarf (0.051–0.065 M⊙). These are the first two binaries composed of L dwarfs in Praesepe. They are benchmark systems to derive the location of the substellar limit at the age and metallicity of Praesepe, determine the age of the cluster based on the lithium depletion boundary test, derive dynamical masses, and improve low-mass stellar and substellar evolutionary models at a well-known age and metallicity.

scholarly journals Discovery of a Tight Brown Dwarf Companion to the Low Mass Star LHS 2397a

2003 ◽  
Vol 211 ◽  
pp. 261-264 ◽  
Author(s):  
Melanie Freed ◽  
Laird M. Close ◽  
Nick Siegler
Keyword(s):  
Adaptive Optics ◽  
Spectral Type ◽  
Proper Motion ◽  
Near Infrared ◽  
Mass Star ◽  
Infrared Photometry ◽  
Brown Dwarf ◽  
Dynamical Mass ◽  
Low Mass ◽  
Adaptive Optics System

Using the adaptive optics system, Hōkūpa'a, at Gemini-North, we have directly imaged a companion around the UKIRT faint standard M8 star, LHS 2397a (FS 129) at a separation of 2.96 AU. Near-Infrared photometry obtained on the companion has shown it to be an L7.5 brown dwarf and confirmed the spectral type of the primary to be an M8. We also derive a substellar mass of the companion of 0.068M⊙, although masses in the range (0.061 – 0.069) are possible, and the primary mass as 0.090M⊙ (0.089 – 0.094). Reanalysis of archival imaging from HST has confirmed the secondary as a common proper motion object. This binary represents the first clear example of a brown dwarf companion within 4 AU of a low mass star, and should be the first L7.5 to have a dynamical mass. As part of a larger survey of M8-M9 stars, this object may indicate that there is no “brown dwarf desert” around low mass primaries.

scholarly journals Near-Infrared Adaptive Optics Spectroscopy of Binary Brown Dwarfs HD 130948B and HD 130948C

2003 ◽  
Vol 211 ◽  
pp. 269-270
Author(s):  
M Goto ◽  
A.T. Tokunaga ◽  
M. Cushing ◽  
D. Potter ◽  
N. Kobayashi ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Binary System ◽  
Adaptive Optics ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Brown Dwarfs ◽  
Brown Dwarf ◽  
Low Mass ◽  
The Individual

We present near-infrared spectroscopy of low-mass companions in the HD 130948 system (Goto et al. 2002a). Adaptive optics on the Subaru Telescope allowed for spectroscopy of the individual components of the 0″.13 binary system. Based on a direct comparison with a series of template spectra, we determined the spectral types of HD 130948B and C to be L4 ± 1. We find they are most likely a binary brown dwarf system.

scholarly journals Subaru AO Coronagraphic and Direct Imaging of YSOs

2004 ◽  
Vol 221 ◽  
pp. 313-319
Author(s):  
Motohide Tamura ◽  
Misato Fukagawa ◽  
Masahiko Hayashi ◽  
Keyword(s):  
Star Formation ◽  
Adaptive Optics ◽  
Near Infrared ◽  
Circumstellar Disk ◽  
Be Stars ◽  
Direct Imaging ◽  
Low Mass Stars ◽  
Stellar Cluster ◽  
Be Star ◽  
Low Mass

A cold near-infrared stellar coronagraph combined with adaptive optics (CIAO) is introduced. As an open-use instrument on the Subaru 8.2-m telescope, it has been used for several star formation studies with high spatial resolutions (from natural seeing of about 0.6 arcsec down to 0.07 arcsec with adaptive optics). A brief explanation is described of the instrument as well as its current main project of systematic surveys of disks and young companions around T Tauri stars and Herbig Ae/Be stars. In particular, observations of HL Tau are presented in some details. Our images of HL Tau show several new circumstellar features including the presence of a red H - K color region of ∼150 AU, probably corresponding to the small circumstellar disk. The observations of a high density stellar cluster of MWC 137 are also reported. It appears to be a cluster of very low-mass stars around Herbig Be star or a cluster of B stars around a super giant.

Deep Near-Infrared Surveys and Young Brown Dwarf Populations in Star-Forming Regions

2003 ◽  
Vol 211 ◽  
pp. 87-90
Author(s):  
M. Tamura ◽  
T. Naoi ◽  
Y. Oasa ◽  
Y. Nakajima ◽  
C. Nagashima ◽  
...  
Keyword(s):  
High Resolution ◽  
Adaptive Optics ◽  
Near Infrared ◽  
Brown Dwarf ◽  
Ir Camera ◽  
Star Forming ◽  
Star Forming Regions ◽  
New Instrument ◽  
Infrared Surveys ◽  
Low Mass

We are currently conducting three kinds of IR surveys of star forming regions (SFRs) in order to seek for very low-mass young stellar populations. First is a deep JHKs-bands (simultaneous) survey with the SIRIUS camera on the IRSF 1.4m or the UH 2.2m telescopes. Second is a very deep JHKs survey with the CISCO IR camera on the Subaru 8.2m telescope. Third is a high resolution companion search around nearby YSOs with the CIAO adaptive optics coronagraph IR camera on the Subaru. In this contribution, we describe our SIRIUS camera and present preliminary results of the ongoing surveys with this new instrument.

A Search for Brown Dwarfs in the Alpha Persei Cluster

2003 ◽  
Vol 211 ◽  
pp. 179-180
Author(s):  
Nicolas Lodieu ◽  
Mark McCaughrean ◽  
Jérôme Bouvier ◽  
David Barrado y Navascués ◽  
John R. Stauffer
Keyword(s):  
Near Infrared ◽  
Open Cluster ◽  
Brown Dwarfs ◽  
Wide Field ◽  
Brown Dwarf ◽  
Young Open Cluster ◽  
Low Mass ◽  
Alpha Persei ◽  
Calar Alto ◽  
Infrared Survey

We present preliminary results from a deep near-infrared survey of a ~ 1 square degree area in the young open cluster Alpha Persei using the wide-field Omega-Prime camera on the Calar Alto 3.5m telescope, yielding a list of new low-mass cluster members, including brown dwarf candidates.

scholarly journals KIC 1571511B: a benchmark low-mass star in an eclipsing binary system in the Kepler field★

2012 ◽  
Vol 423 (1) ◽  
pp. L1-L5 ◽  
Author(s):  
A. Ofir ◽  
D. Gandolfi ◽  
Lars Buchhave ◽  
C. H. S. Lacy ◽  
A. P. Hatzes ◽  
...  
Keyword(s):  
Binary System ◽  
Mass Star ◽  
Eclipsing Binary ◽  
Low Mass

scholarly journals Mass-Luminosity Relations of Very Low Mass Stars

2003 ◽  
Vol 211 ◽  
pp. 413-416 ◽  
Author(s):  
D. Ségransan ◽  
X. Delfosse ◽  
T. Forveille ◽  
J.L. Beuzit ◽  
C. Perrier ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Main Sequence ◽  
Near Infrared ◽  
Radial Velocities ◽  
Low Mass Stars ◽  
Multiple Stars ◽  
Low Mass

We present new accurate masses at the bottom of the main sequence as well as an improved empirical mass-luminosity relation for very low mass stars in the visible and near infrared. Masses were obtained by combining very accurate radial velocities and adaptive optics images of multiple stars obtained at different orbital phases.

scholarly journals CS Cha B: A disc-obscured M-type star mimicking a polarised planetary companion

2020 ◽  
Vol 640 ◽  
pp. L12
Author(s):  
S. Y. Haffert ◽  
R. G. van Holstein ◽  
C. Ginski ◽  
J. Brinchmann ◽  
I. A. G. Snellen ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Near Infrared ◽  
Type Star ◽  
Atmospheric Models ◽  
Planetary Mass ◽  
Medium Resolution ◽  
Low Mass ◽  
Integral Field Spectrograph ◽  
Integral Field

Context. Direct imaging provides a steady flow of newly discovered giant planets and brown dwarf companions. These multi-object systems can provide information about the formation of low-mass companions in wide orbits and/or help us to speculate about possible migration scenarios. Accurate classification of companions is crucial for testing formation pathways. Aims. In this work we further characterise the recently discovered candidate for a planetary-mass companion CS Cha b and determine if it is still accreting. Methods. MUSE is a four-laser-adaptive-optics-assisted medium-resolution integral-field spectrograph in the optical part of the spectrum. We observed the CS Cha system to obtain the first spectrum of CS Cha b. The companion is characterised by modelling both the spectrum from 6300 Å to 9300 Å and the photometry using archival data from the visible to the near-infrared (NIR). Results. We find evidence of accretion and outflow signatures in Hα and OI emission. The atmospheric models with the highest likelihood indicate an effective temperature of 3450 ± 50 K with a log g of 3.6 ± 0.5 dex. Based on evolutionary models, we find that the majority of the object is obscured. We determine the mass of the faint companion with several methods to be between 0.07 M⊙ and 0.71 M⊙ with an accretion rate of Ṁ = 4 × 10−11±0.4 M⊙ yr−1. Conclusions. Our results show that CS Cha B is most likely a mid-M-type star that is obscured by a highly inclined disc, which has led to its previous classification using broadband NIR photometry as a planetary-mass companion. This shows that it is important and necessary to observe over a broad spectral range to constrain the nature of faint companions.

The innermost regions of massive protostars traced by masers, high-resolution radio continuum, and near-infrared imaging

2017 ◽  
Vol 13 (S336) ◽  
pp. 289-290
Author(s):  
Fabrizio Massi ◽  
Luca Moscadelli ◽  
Carmelo Arcidiacono ◽  
Francesca Bacciotti
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
High Spatial Resolution ◽  
Radio Continuum ◽  
High Mass ◽  
Mass Star ◽  
Near Infrared Imaging ◽  
Stellar Objects ◽  
First Results ◽  
Low Mass

AbstractWhether high-mass stars (M > 7M⊙) emerge from a scaled-up version of the low-mass star formation scenario, i. e. through disk-mediated accretion, is still debated. We present the first results of an observational programme aimed to map the innermost regions of high-mass stellar objects by combining together high-spatial resolution maser and radio continuum observations, and near-infrared imaging.

scholarly journals 2MASS J10274572+0629104: the very short period young M6 dwarf binary system identified in K2 data

2019 ◽  
Vol 486 (3) ◽  
pp. 4144-4148
Author(s):  
R R Paudel ◽  
J E Gizis ◽  
A J Burgasser ◽  
C Hsu
Keyword(s):  
Infrared Spectroscopy ◽  
Binary System ◽  
Light Curve ◽  
Near Infrared ◽  
Rotation Periods ◽  
Beat Pattern ◽  
Short Period ◽  
Low Mass ◽  
Periodic Signals ◽  
Gaia Dr2

ABSTRACT We report the identification of a very low mass new binary system 2MASS J10274572+0629104, based on Kepler K2 photometry and Gaia DR2 astrometry. It is located at a distance of 90.0 ± 2.9 pc. The K2 light curve is consistent with a beat pattern of two periodic signals, and using Lomb–Scargle periodogram, we find two rotation periods of 0.2114 ± 0.0002 and 0.2199 ± 0.0003 d. We conclude that these rotation periods arise from two stars with similar spectral types of M6, and have nearly equal luminosity. It is the first ultracool binary system to be identified based on beat patterns in the light curve. Near-infrared spectroscopy yields RV = −9.8 ± 0.6 km s−1, v sin i = 21.5 ± 1.1 km s−1, Teff = 3110 ± 40 K, and log g = 5.2 ± 0.2. The motions are consistent with a young age, as are the rotation periods, but the source does not appear to be part of any known moving group. Furthermore, we detected three strong white light flares in the K2 light curve, with estimated total (UV/optical/IR) energies of 2.6 × 1033, 5.0 × 1033, and 3.5 × 1033 erg, respectively.

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