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Brown dwarfs are failed stars with very low mass (13 to 75 $M_J$), and an effective temperature lower than 2500 K. Thus, they play a key role in understanding the gap in the mass function between stars and planets. However, due to their…

With the prevalence of wide-field, time-domain photometric sky surveys, the number of eclipsing white dwarf systems being discovered is increasing dramatically. An efficient method to follow these up will be key to determining any…

Mid-infrared data, including Spitzer warm-IRAC [3.6] and [4.5] photometry, is critical for understanding the cold population of brown dwarfs now being found, objects which have more in common with planets than stars. As effective…

We present a spectroscopic catalog of 67082 M dwarfs from the LAMOST pilot survey. For each spectrum of the catalog, spectral subtype, radial velocity, equivalent width of H${\alpha}$, a number of prominent molecular band indices and the…

M dwarfs are the dominating type of stars in the solar neighbourhood. They serve as excellent tracers for the study of the distribution and properties of the nearby interstellar dust. In this work, we aim to obtain high accuracy reddening…

Solar and Stellar Astrophysics · Physics 2022-06-22 Han Shen , Bingqiu Chen , Helong Guo , Haibo Yuan , Weixiang Sun , Jing Li

To understand the parameter degeneracy of M subdwarf spectra at low resolution, we assemble a large number of spectral features in the wavelength range of 0.6-2.5 {\mu}m with band strength quantified by narrowband indices. Based on the…

Solar and Stellar Astrophysics · Physics 2023-01-18 Shuo Zhang , Hua-Wei Zhang , Georges Comte , Derek Homeier , Rui Wang , Neda Hejazi , Yin-Bi Li , A-Li Luo

Stellar oscillations appear all across the Hertzsprung-Russell diagram. Recent theoretical studies support their existence also in the atmospheres of M dwarfs. These studies predict for them short periodicities ranging from 20~min to 3~h.…

We report on an ongoing project to investigate activity in the M dwarf stellar population observed by the Pan-STARRS 1 Medium Deep Survey (PS1-MDS). Using a custom-built pipeline, we refine an initial sample of $\approx$ 4 million sources…

An extensive sample of M, L and T dwarfs identified in the Sloan Digital Sky Survey (SDSS) has been compiled. The sample of 718 dwarfs includes 677 new objects (629 M dwarfs, 48 L dwarfs) together with 41 that have been previously…

Astrophysics · Physics 2019-08-15 S. L. Hawley , K. R. Covey , G. R. Knapp , D. A. Golimowski , X. Fan

Recent monitoring programs of ultra cool field M and L dwarfs (low mass stars or brown dwarfs) have uncovered low amplitude photometric I-band variations which may be associated with an inhomogeneous distribution of photospheric…

Astrophysics · Physics 2009-11-07 C. A. L. Bailer-Jones , M. Lamm

We present spectrograph design details and initial radial velocity results from the PRL optical fiber-fed high-resolution cross-dispersed echelle spectrograph (PARAS), which has recently been commissioned at the Mt Abu 1.2 m telescope, in…

We present results from commissioning observations of the mid-IR instrument, MIRAC-5, on the 6.5-m MMT telescope. MIRAC-5 is a novel ground-based instrument that utilizes a state-of-the-art GeoSnap (2 - 13 microns) HgCdTe detector with…

[Abridged] We present a search for fast optical transients (~0.5 hr-1 day) using repeated observations of the Pan-STARRS1 Medium-Deep Survey (PS1/MDS) fields. Our search takes advantage of the consecutive g/r-band observations (16.5 min in…

We empirically determine effective temperatures and bolometric luminosities for a large sample of nearby M dwarfs, for which high accuracy optical and infrared photometry is available. We introduce a new technique which exploits the flux…

Astrophysics · Physics 2009-11-13 L. Casagrande , C. Flynn , M. Bessell

We conducted a search for brown dwarf candidates in a James Webb Space Telescope deep field around A2744 to investigate the space density of these objects at kiloparsec distances. Our methodology employed an initial selection based on…

Solar and Stellar Astrophysics · Physics 2026-02-17 D. H. Li , Z. H. Zhang , H. H. Peng , M. C. Galvez-Ortiz , S. Y. Zhou , H. R. A. Jones

We test state-of-the-art model atmospheres for young very low-mass stars and brown dwarfs in the infrared, by comparing the predicted synthetic photometry over 1.2-24 {\mu}m to the observed photometry of M-type spectral templates in…

Solar and Stellar Astrophysics · Physics 2015-05-27 Jonathan Tottle , Subhanjoy Mohanty

We present a systematic study of the physical properties of late-M dwarfs based on high-quality dynamical mass measurements and near-infrared (NIR) spectra. We use astrometry from Keck NGS and LGS AO imaging to determine orbits for late-M…

Solar and Stellar Astrophysics · Physics 2015-05-19 Trent Dupuy , Michael Liu , Brendan Bowler , Michael Cushing , Christiane Helling , Soeren Witte , Peter Hauschildt

Brown dwarfs provide a unique opportunity to study atmospheres and their physical and chemical processes with high precision, especially in temperature ranges relevant to exoplanets. In this study, we performed high-resolution ($R \sim…

M dwarfs are important targets in the search for Earth-like exoplanets due to their small masses and low luminosities. Several ongoing and upcoming space missions are targeting M dwarfs for this reason, and the ESA PLATO mission is one of…

JWST is opening many avenues for exploration. For cold brown dwarfs and exoplanets, JWST has opened the door to the mid-infrared wavelength region, where such objects emit significant energy. For the first time, astronomers have access to…

Solar and Stellar Astrophysics · Physics 2025-01-07 S. K. Leggett , Pascal Tremblin