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The re-emergence of the 0.99 $\mu$m FeH feature in brown dwarfs of early- to mid-T spectral type has been suggested as evidence for cloud disruption where flux from deep, hot regions below the Fe cloud deck can emerge. The same mechanism…

Solar and Stellar Astrophysics · Physics 2015-10-28 Esther Buenzli , Mark. S. Marley , Dániel Apai , Didier Saumon , Beth A. Biller , Ian J. M. Crossfield , Jacqueline Radigan

We report the discovery of a linear relationship between the root-mean-square (rms) variability amplitude and the mean flux in the accreting white dwarf binary system MV Lyrae. Our lightcurve, obtained with the Kepler satellite, spans 633…

Solar and Stellar Astrophysics · Physics 2015-06-03 S. Scaringi , E. Kording , P. Uttley , C. Knigge , P. J. Groot , M. Still

White dwarfs are often found in binary systems with orbital periods ranging from tens of minutes to hours in which they can accrete gas from their companion stars. In about 15% of these binaries, the magnetic field of the white dwarf is…

Solar and Stellar Astrophysics · Physics 2017-12-15 S. Scaringi , T. J. Macarone , C. D'Angelo , C. Knigge , P. J. Groot

We present the results from a five-year campaign to gather multi-epoch, high-resolution spectra of a volume-complete sample of 413 M dwarfs with masses 10-30% that of the Sun that lie within 15 parsecs. We report weighted mean systemic…

Understanding the processes of planet formation and accretion in young systems is essential to unraveling the initial conditions of planetary systems. The PDS 70 system, which hosts two directly imaged protoplanets, provides a unique…

Observations of rotational modulations of brown dwarfs and giant exoplanets allow the characterization of condensate cloud properties. As of now rotational spectral modulations have only been seen in three L-type brown dwarfs. We report…

EX Lupi, a low-mass young stellar object, went into an accretion-driven outburst in March of 2022. The outburst caused a sudden phase change of ~ 112$^{\circ}$ $\pm$ 5$^{\circ}$ in periodically oscillating multiband lightcurves. Our high…

Radial velocity measurements are presented for 85 late M- and L-type very low mass stars and brown dwarfs obtained with the Magellan Echellette (MagE) spectrograph. Targets primarily have distances within 20 pc of the Sun, with more distant…

By comparing near-infrared spectra with atmosphere models, we infer the effective temperature, surface gravity, projected rotational velocity, and radial velocity for 21 very-low-mass stars and brown dwarfs. The unique sample consists of…

Solar and Stellar Astrophysics · Physics 2014-11-20 Emily L. Rice , T. Barman , Ian S. McLean , L. Prato , J. Davy Kirkpatrick

In the poster presented in Cool Star 15, we analyzed the effect of disk accretion on the evolution of very low mass pre-main sequence stars and young brown dwarfs and the resulting uncertainties on the determination of masses and ages. We…

Astrophysics · Physics 2009-11-13 Jose Gallardo , Isabelle Baraffe , Gilles Chabrier

We present here optical I-band photometric variability study down to $\simeq$ 19 mag of a young ($\sim$2-3 Myr) star-forming region IC 348 in the Perseus molecular cloud. We aim to explore the fast rotation (in the time-scales of hours) in…

Solar and Stellar Astrophysics · Physics 2020-11-25 Samrat Ghosh , Soumen Mondal , Somnath Dutta , Ramkrishna Das , Santosh Joshi , Sneh Lata , Dhrimadri Khata , Alik Panja

We present multiple epochs of near-IR spectroscopy for a sample of 25 young stars, including T Tauri, Herbig Ae/Be, and FU Ori objects. Using the FSPEC instrument on the Bok 90-inch telescope, we obtained K-band spectra of the BrGamma…

Solar and Stellar Astrophysics · Physics 2015-06-23 J. A. Eisner , G. H. Rieke , M. J. Rieke , K. M. Flaherty , Jordan M. Stone , T. J. Arnold , S. R. Cortes , E. Cox , C. Hawkins , A. Cole , S. Zajac , A. L. Rudolph

We report the discovery of two new magnetic cataclysmic variables with brown dwarf companions and long orbital periods ($P_{\rm orb}=95\pm1$ and $104\pm2$ min). This discovery increases the sample of candidate magnetic period bouncers with…

The VISTA Variables in the Via Lactea (VVV) survey obtained near-infrared photometry toward the Galactic bulge and the southern disc plane for a decade (2010 - 2019). We designed a modified Lomb-Scargle method to search for large-amplitude…

We explore the rotation and activity of very low mass (VLM) objects by means of a photometric variability study. Our targets in the vicinity of Epsilon Ori belong to the OriOB1b population in the Orion star-forming complex. In this region…

Astrophysics · Physics 2009-11-10 Alexander Scholz , Jochen Eisloeffel

We performed R-band time series observations of the young, metal rich open cluster NGC 2301 for 12 nights in Feb. 2004. B images were also obtained and color magnitude diagrams, having limits of R=19.5 and B=21.5, were produced. Only asmall…

We report $I$-band photometric observations of the radio-detected M9.5 dwarf BRI 0021-0214, obtained with the Galway Ultra Fast Imager (GUFI) on the 1.8m Vatican Advanced Technology Telescope VATT at Mt. Graham International Observatory,…

Solar and Stellar Astrophysics · Physics 2022-11-03 S. Dulaimi , A. Golden , R. P. Boyle , R. F. Butler

We apply an eclipse mapping technique using `genetically modified fire-flies' to the eclipse light curves of HU Aqr and EP Dra. The technique makes as few assumptions as possible about the location of accretion stream material, allowing the…

Astrophysics · Physics 2009-11-10 C. M. Bridge , Pasi Hakala , Mark Cropper , Gavin Ramsay

Measurements of accretion rates onto planetary mass objects may distinguish between different planet formation mechanisms, which predict different accretion histories. In this Letter, we use \HST/WFC3 UVIS optical photometry to measure…

Solar and Stellar Astrophysics · Physics 2015-06-18 Yifan Zhou , Gregory J. Herczeg , Adam L. Kraus , Stanimir Metchev , Kelle Cruz

The central engines of disc-accreting stellar-mass black holes appear to be scaled down versions of the supermassive black holes that power active galactic nuclei. However, if the physics of accretion is universal, it should also be…

High Energy Astrophysical Phenomena · Physics 2015-10-12 S. Scaringi , T. J. Maccarone , E. Koerding , C. Knigge , S. Vaughan , T. R. Marsh , E. Aranzana , V. Dhillon , S. C. C. Barros
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