2MASS 1315−2649: A High Proper-Motion L Dwarf with Strong Hα Emission

Hall, Patrick B.

doi:10.1086/345549

Cited by 25 publications

(16 citation statements)

References 13 publications

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“…These are heavily blended with airglow lines known for the UVES instrument (Hanuschik 2003). The EW for H α of 24.1 Å seems to imply that the brown dwarf is in a rather quiescent state since Hall (2002) found EW of 121 Å and of 25 Å half a year later. …”

Section: A2 Ad Leo Yz CMI Prox Cen and Lhs 292mentioning

confidence: 89%

PHOENIX model chromospheres of mid- to late-type M dwarfs

Fuhrmeister¹,

Schmitt²,

Hauschildt³

2005

A&A

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Abstract. We present semi-empirical model chromospheres computed with the atmosphere code PHOENIX. The models are designed to fit the observed spectra of five mid-to late-type M dwarfs. Next to hydrogen lines from the Balmer series we used various metal lines, e.g. from Fe , for the comparison between data and models. Our computations show that an NLTE treatment of C, N, O impacts on the hydrogen line formation, while NLTE treatment of less abundant metals such as nickel influences the lines of the considered species itself. For our coolest models we investigated also the influence of dust on the chromospheres and found that dust increases the emission line flux. Moreover we present an (electronically published) emission line list for the spectral range of 3100 to 3900 and 4700 to 6800 Å for a set of 21 M dwarfs and brown dwarfs. The line list includes the detection of the Na  D lines in emission for a L3 dwarf.

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Section: A2 Ad Leo Yz CMI Prox Cen and Lhs 292mentioning

confidence: 89%

PHOENIX model chromospheres of mid- to late-type M dwarfs

Fuhrmeister¹,

Schmitt²,

Hauschildt³

2005

A&A

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“…Flares on brown dwarfs appear to be less frequent than on M dwarfs, but have been seen in both X-ray and radio (Berger et al 2001). Optical spectra have shown variable Hα emission in L dwarfs (Hall 2002;Liebert et al 2003;Reiners & Basri 2008) that may be the result of flares. LSST's new observations of such a large number of brown dwarfs over dozens of epochs will provide much-needed empirical determinations of flare rates.…”

Section: Variability Of Vlm Stars and Brown Dwarfsmentioning

confidence: 99%

LSST Science Book, Version 2.0

Abell¹,

Burke²,

Hamuy³

et al. 2009

552

653

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Prepared by the LSST Science Collaborations, with contributions from the LSST Project. PrefaceMajor advances in our understanding of the Universe over the history of astronomy have often arisen from dramatic improvements in our ability to observe the sky to greater depth, in previously unexplored wavebands, with higher precision, or with improved spatial, spectral, or temporal resolution. Aided by rapid progress in information technology, current sky surveys are again changing the way we view and study the Universe, and the next-generation instruments, and the surveys that will be made with them, will maintain this revolutionary progress. Substantial progress in the important scientific problems of the next decade (determining the nature of dark energy and dark matter, studying the evolution of galaxies and the structure of our own Milky Way, opening up the time domain to discover faint variable objects, and mapping both the inner and outer Solar System) all require wide-field repeated deep imaging of the sky in optical bands.The wide-fast-deep science requirement leads to a single wide-field telescope and camera which can repeatedly survey the sky with deep short exposures. The Large Synoptic Survey Telescope (LSST), a dedicated telecope with an effective aperture of 6.7 meters and a field of view of 9.6 deg 2 , will make major contributions to all these scientific areas and more. It will carry out a survey of 20,000 deg 2 of the sky in six broad photometric bands, imaging each region of sky roughly 2000 times (1000 pairs of back-to-back 15-sec exposures) over a ten-year survey lifetime.The LSST project will deliver fully calibrated survey data to the United States scientific community and the public with no proprietary period. Near real-time alerts for transients will also be provided worldwide. A goal is worldwide participation in all data products. The survey will enable comprehensive exploration of the Solar System beyond the Kuiper Belt, new understanding of the structure of our Galaxy and that of the Local Group, and vast opportunities in cosmology and galaxy evolution using data for billions of distant galaxies. Since many of these science programs will involve the use of the world's largest non-proprietary database, a key goal is maximizing the usability of the data. Experience with previous surveys is that often their most exciting scientific results were unanticipated at the time that the survey was designed; we fully expect this to be the case for the LSST as well.The purpose of this Science Book is to examine and document in detail science goals, opportunities, and capabilities that will be provided by the LSST. The book addresses key questions that will be confronted by the LSST survey, and it poses new questions to be addressed by future study. It contains previously available material (including a number of White Papers submitted to the ASTRO2010 Decadal Survey) as well as new results from a year-long campaign of study and evaluation. This book does not attempt to be complete; there are many ...

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“…The limited observations of 2M1022+58 suggest similarities between the two objects, as H emission in PC 0025 also varies by an order of magnitude. Hall (2002) suggested that the L3 dwarf 2MASSI J1315309À 264951 (hereafter 2M1315À26) shows similar strong, variable activity. It has been observed twice with an H EW of $120 8 [log (F H /F bol ) ¼ À4], and two other epochs of spectroscopy show H EWs of 97 and 25 8.…”

Section: Strong H Emission From the L1 Dwarf 2mass J10224821+5825453mentioning

confidence: 99%

Activity and Kinematics of Ultracool Dwarfs, Including an Amazing Flare Observation

et al. 2007

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We present the activity and kinematics of a representative volume-limited (20 pc) sample of 152 late-M and L dwarfs (M7YL8) photometrically selected from the Two Micron All Sky Survey (2MASS). Using new proper-motion measurements and spectrophotometric distance estimates, we calculate tangential velocities. The sample has a mean tangential velocity of hV tan i ¼ 31:5 km s À1 , a velocity dispersion of tan ¼ 20:7 km s À1 , and a maximum tangential velocity of V tan ¼ 138:8 km s À1 . These kinematic results are in excellent agreement with previous studies of ultracool dwarfs in the local solar neighborhood. H emission, an indicator of chromospheric activity, was detected in 63 of 81 late-M dwarfs and in 16 of 69 L dwarfs examined. We find a lack of correlation between activity strength, measured by log (F H /F bol ), and V tan , although velocity distributions suggest that the active dwarfs in our sample are slightly younger than the inactive dwarfs. Consistent with previous studies of activity in ultracool dwarfs, we find that the fraction of H-emitting objects per spectral type peaks at spectral type M7 and declines through mid-L dwarfs. Activity strength is similarly correlated with spectral type for types later than M7. Eleven dwarfs out of 150 show evidence of variability, ranging from small fluctuations to large flare events. We estimate a flare cycle of $5% for late-M dwarfs and $2% for L dwarfs. Observations of strong, variable activity on the L1 dwarf 2MASS J10224821+5825453 and an amazing flare event on the M7 dwarf 2MASS J1028404À143843 are discussed.

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2MASS 1315−2649: A High Proper-Motion L Dwarf with Strong Hα Emission

Cited by 25 publications

References 13 publications

PHOENIX model chromospheres of mid- to late-type M dwarfs

PHOENIX model chromospheres of mid- to late-type M dwarfs

LSST Science Book, Version 2.0

Activity and Kinematics of Ultracool Dwarfs, Including an Amazing Flare Observation

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