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Variability is a common characteristic of pre-main-sequence stars (PMS). Near-IR variability surveys of young stellar objects (YSOs) can probe stellar and circumstellar environments and provide information about the dynamics of the on going…

Astrophysics · Physics 2009-06-23 Catarina Alves de Oliveira , Mark Casali

We present an analysis of near-infrared time-series photometry in J, H, and K bands for about 100 epochs of a 1 square degree region of the Lynds 1003/1004 dark cloud in the Cygnus OB7 region. Augmented by data from the Wide-field Infrared…

Solar and Stellar Astrophysics · Physics 2015-06-16 Scott J. Wolk , Thomas S. Rice , Colin A. Aspin

We report the serendipitous discovery of an elliptical shell of CO associated with the faint stellar object SSTc2d J163134.1-24006 as part of the "Ophiuchus Disk Survey Employing ALMA" (ODISEA), a project aiming to study the entire…

We have refined the census of stars and brown dwarfs in the Upper Sco association (~10 Myr, ~145 pc) by 1) updating the selection of candidate members from our previous survey to include the high-precision astrometry from the second data…

Solar and Stellar Astrophysics · Physics 2020-07-08 K. L. Luhman , T. L. Esplin

We obtained deep $UBVRI$ H$\alpha$ photometric data of the field situated to the west of the main Carina nebula and centered on WR~22. Medium-resolution optical spectroscopy of a subsample of X-ray selected objects along with archival data…

Solar and Stellar Astrophysics · Physics 2016-08-11 Brajesh Kumar , Saurabh Sharma , Jean Manfroid , Eric Gosset , Gregor Rauw , Yaël Nazé , Ram Kesh Yadav

We present a volume-limited multiplicity survey with magnitude cutoff (K =< 10.5 mag) of 158 young stellar objects located within or in the vicinity of the Rho Ophiuchi Dark Cloud. With exception of eleven already well observed objects, all…

Astrophysics · Physics 2009-11-11 Thorsten Ratzka , Rainer Koehler , Christoph Leinert

The Upper-Scorpius association is the OB association nearest to the Sun (145 pc). Its young age (5 Myr) makes it an ideal place to search for low-mass stars and brown dwarfs, as these objects should be relatively bright. We have performed a…

Astrophysics · Physics 2009-10-31 David R. Ardila , Eduardo L. Martin , Gibor Basri

We present the results of an optical photometry and high-resolution spectroscopy campaign for a modest sample of X-ray selected stars in the Chamaeleon and Rho Ophiuchus star forming regions. With R~50000 optical spectra, we establish…

Solar and Stellar Astrophysics · Physics 2016-03-03 David James , Alicia Aarnio , Alexander Richert , Phillip Cargile , Nuno Santo , Claudio Melo , Jerome Bouvier

We analyse multi-wavelength observations of 32 young star clusters and associations in M33 with known oxygen abundance (8 < 12 + log(O/H) < 8.7), using ultraviolet (UV), optical, mid-infrared (MIR), CO (1-0) and 21-cm line (HI)…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 M. Grossi , E. Corbelli , C. Giovanardi , L. Magrini

Spitzer Space Telescope spectra of the low mass young stellar object (YSO) IRS 46 (L_bol ~ 0.6 L_sun) in Ophiuchus reveal strong vibration-rotation absorption bands of gaseous C2H2, HCN, and CO2. This is the only source out of a sample of…

We have carried out a survey of optically-selected dark clouds using the bolometer array SCUBA on the James Clerk Maxwell Telescope, at 850 microns wavelength. The survey covers a total of 0.5 square degrees and is unbiased with reference…

Astrophysics · Physics 2009-11-07 Anja E. Visser , John S. Richer , Claire J. Chandler

We conducted an infrared search for faint companions around 351 young stellar objects in the rho Ophiucus molecular cloud and the Serpens molecular cloud. Nine objects in the Spitzer/IRAC archival images were identified as young stellar…

Solar and Stellar Astrophysics · Physics 2015-05-28 Chiaki Shirono , Yoichi Itoh , Yumiko Oasa

We investigate the mass function in the substellar domain down to a few Jupiter masses in the young sigma Orionis open cluster (3+/-2 Ma, d = 360^+70_-60 pc). We have performed a deep IJ-band search, covering an area of 790 arcmin^2 close…

We present the substellar mass function of star-forming clusters ($\simeq$0.1 Myr old) in a low-metallicity environment ($\simeq$$-$0.7 dex). We performed deep JWST/NIRCam and MIRI imaging of two star-forming clusters in Digel Cloud 2, a…

Astrophysics of Galaxies · Physics 2024-08-29 Chikako Yasui , Natsuko Izumi , Masao Saito , Ryan M. Lau , Naoto Kobayashi , Michael E. Ressler

Recent surveys have identified sub-stellar objects down to planetary masses in nearby star-forming regions. Reliable determination of the disk frequency in young brown dwarfs is of paramount importance to understanding their origin. Here we…

Astrophysics · Physics 2016-08-30 Ray Jayawardhana , David R. Ardila , Beate Stelzer , Karl E. Haisch

This paper describes a high-resolution, infrared spectroscopic survey of young, low-mass stars designed to identify and characterize pre-main-sequence spectroscopic binaries. This is the first large infrared radial velocity survey of very…

Astrophysics · Physics 2008-11-26 L. Prato

We present maps of 14.4 deg^2 of the Ophiuchus dark clouds observed by the Spitzer Space Telescope Multiband Imaging Photometer for Spitzer (MIPS). These high quality maps depict both numerous point sources as well as extended dust emission…

We report on initial results from a Spitzer program to search for very low-mass brown dwarfs in Ophiuchus. This program is an extension of an earlier study by Allers et al. which had resulted in an extraordinary success rate, 18 confirmed…

Solar and Stellar Astrophysics · Physics 2015-05-19 Paul M. Harvey , Daniel T. Jaffe , Katelyn Allers , Michael Liu

We present the results of near-infrared imaging and low-resolution near- infrared spectroscopy of low mass objects in the NGC 1333 molecular cloud. A JHK survey of an 11.4' x 11.7' area of the northern cluster was conducted to a sensitivity…

We combine results from imaging searches for substellar objects in the sigma Orionis cluster and follow-up photometric and spectroscopic observations to derive a census of the brown dwarf population in a region of 847 arcmin^2. We identify…