Adam Burgasser | University of California, San Diego (original) (raw)

Papers by Adam Burgasser

Abstract We present FIRE spectroscopic observations of the ultracool (T 520 K) brown dwarf, UGPS ... more Abstract We present FIRE spectroscopic observations of the ultracool (T 520 K) brown dwarf, UGPS 0722-05, obtained during instrument commissioning on the 6.5 m Baade Magellan Telescope at Las Campanas Observatory. At a distance of 4.1 pc, this cool brown dwarf is well-suited for detailed followup, and represents a keystone at the transition between the lowest-mass brown dwarfs and exoplanets.

Abstract The 2MASS survey allows large numbers of the new class of L dwarfs to be identified. Spe... more Abstract The 2MASS survey allows large numbers of the new class of L dwarfs to be identified. Spectroscopic studies show that most of these objects are brown dwarfs. We propose to use K-band infrared spectroscopy to determine spectral types for over 100 L dwarfs. This will place the field L dwarf substellar luminosity function on a firm statistical basis, and allow modelling of the substellar mass function.

Abstract The major goal of the NIRSPEC Brown Dwarf Spectroscopic Survey (BDSS-McLean et al. 2000,... more Abstract The major goal of the NIRSPEC Brown Dwarf Spectroscopic Survey (BDSS-McLean et al. 2000, ApJ, 533, L45) is to obtain a complete sample of low resolution (R 2000) spectra spanning the M, L, and T dwarf sub-classes in order to extend spectral classification schemes to near-infrared wavebands and to investigate the spectral signatures of temperature, gravity, and composition by comparison to theoretical models.

Abstract All of the young star-forming regions are distant (d> 120 pc), making it difficult to re... more Abstract All of the young star-forming regions are distant (d> 120 pc), making it difficult to resolve structure on the scale of disks (10-100 AU) and jets (? AU). Furthermore, examining these structures around low-mass objects is especially prohibitive since these objects are intrinsically faint. However, recent identification of the nearby, young (10; Myr) TW Hydrae Association (TWA) has ameliorated this situation. With only 24 systems, the TWA offers unique case studies at a critical time in disk evolution and planet-building processes.

Abstract While Spitzer has already contributed significantly to the study of winds and weather on... more Abstract While Spitzer has already contributed significantly to the study of winds and weather on highly irradiated extrasolar planets, the atmospheres of free-floating brown dwarfs probe weather in an entirely different physical regime, where global atmospheric flows arise primarily from a combination of rapid rotation and internal convection, without external forcing.

Abstract: The Folded-port InfraRed Echellette (FIRE) has recently been commissioned on the Magell... more Abstract: The Folded-port InfraRed Echellette (FIRE) has recently been commissioned on the Magellan 6.5 m Baade Telescope. This single object, near-infrared spectrometer simultaneously covers the 0.85-2.45 micron window in both cross-dispersed (R~ 6000) or prism-dispersed (R~ 250-350) modes. FIRE's compact configuration, high transmission optics and high quantum efficiency detector provides considerable sensitivity in the near-infrared, making it an ideal instrument for studies of cool stars and brown dwarfs.

Abstract We have used multi-epoch Spitzer/IRAC images to search for substellar companions to seve... more Abstract We have used multi-epoch Spitzer/IRAC images to search for substellar companions to several hundred nearby stars based on their common proper motions. Through this work, we have identified a very promising candidate that could be the coldest and faintest known brown dwarf by a fairly large margin, and thus may inhabit a new spectral class (tentatively dubbed the Y class).

Abstract Over the last 3 to 4 years there has been increasing evidence, both theoretical and obse... more Abstract Over the last 3 to 4 years there has been increasing evidence, both theoretical and observational, that the fraction of wide, low-mass companions to spectroscopic binary systems is considerably higher than for single objects. Not only does the fraction of stellar companions increase but also that of substellar companions. We propose a survey to find benchmark brown dwarfs by taking advantage of the high fraction of wide, low-mass companions to tight spectroscopic binaries.

Abstract We propose to use HST/NICMOS to image a sample of 27 of the nearest {< 20 pc} and lowest... more Abstract We propose to use HST/NICMOS to image a sample of 27 of the nearest {< 20 pc} and lowest luminosity T-type brown dwarfs in order to identify and characterize new very low mass binary systems. Only 3 late-type T dwarf binaries have been found to date, despite that fact that these systems are critical benchmarks for evolutionary and atmospheric models at the lowest masses. They are also the most likely systems to harbor Y dwarf companions, an as yet unpopulated putative class of very cold {T< 600 K} brown dwarfs.

Abstract We present the discovery of a candidate brown dwarf member to the TW Hydrae Association,... more Abstract We present the discovery of a candidate brown dwarf member to the TW Hydrae Association, an 8 Myr old co-moving group. This object is only the fourth candidate brown dwarf in the association, joining TWA 5B, 2MASS 1207-3932AB, and 2MASS 1139-3159. Its near-infrared spectrum is remarkably similar to that of 2MASS 1139-3159, with low-gravity features showing an overall red color compared to field late-type M dwarfs, a triangular-shaped H-band, and a very weak FeH-band at 0.99 microns.

Abstract The Transiting Exoplanet Survey Satellite (TESS) is a low cost, SMEX-class planet finder... more Abstract The Transiting Exoplanet Survey Satellite (TESS) is a low cost, SMEX-class planet finder. In a two year all-sky survey, TESS will observe more than two million bright, nearby stars, searching for temporary drops in brightness that are caused by planetary transits, which occur when a planet's orbit carries it directly in front of its parent star. Such transits not only provide the means of identifying the planet, but also provide knowledge of the planet's diameter, mass density, surface gravity, temperature, and other key properties.

1. Science. 2001 Feb 23;291(5508):1487-8. What is a planet? McCaughrean M, Reid N, Tinney C, Kirk... more 1. Science. 2001 Feb 23;291(5508):1487-8. What is a planet? McCaughrean M, Reid N, Tinney C, Kirkpatrick D, Hillenbrand L, Burgasser A, Gizis J, Hawley S. PMID: 11234073 [PubMed]. Publication Types: Letter.

Abstract Using multi-epoch 2MASS data, we have conducted a very large area (~ 6000 square degrees... more Abstract Using multi-epoch 2MASS data, we have conducted a very large area (~ 6000 square degrees) near-infrared proper motion survey. The goal of this survey is to search for nearby, optically faint/invisible sources that would have been missed by previous optical motion surveys. Earlier near-infrared searches for nearby stars have relied solely on photometric criteria that are heavily biased toward solar-age, solar-metallicity stars and brown dwarfs.

Abstract Brown dwarf spectra are rich in diagnostics of temperature, gravity and metallicity. How... more Abstract Brown dwarf spectra are rich in diagnostics of temperature, gravity and metallicity. However, in the coldest sources, these parameters can be entangled with competing effects for a few major absorbers. We have identified three late-type T dwarfs that exhibit spectroscopic and kinematic indications of being either old, metal poor or both.