Results 11 to 20 of about 2,970 (266)
Clouds, Brightening and Multiplicity Across the L Dwarf∕T Dwarf Transition [PDF]
AIP Conference Proceedings, 2009 The transition between the two lowest-luminosity spectral classes of brown dwarfs--the L dwarfs and T dwarfs--is traversed by nearly all brown dwarfs as they cool over time. Yet distinct features of this transition, such as the "J-band bump" and an unusually high rate of multiplicity, remain outstanding problems, although evidence points to condensate ...
Adam J. Burgasser, Eric Stempels
openaire +2 more sources
First T dwarfs in the VISTA Hemisphere Survey [PDF]
Astronomy & Astrophysics, 2012 The aim of the project is to improve our current knowledge of the density of T dwarfs and the shape of the substellar initial mass function by identifying a magnitude-limited sample of T dwarfs in the full southern sky. We present the results of a photometric search aimed at discovering cool brown dwarfs in the Southern sky imaged at infrared ...
Lodieu, N +23 more
openaire +7 more sources
Methane and the Spectra of T Dwarfs [PDF]
Symposium - International Astronomical Union, 2003 We have updated our PHOENIX model atmospheres and theoretical spectra for ultracool dwarfs with new opacity data for methane based on line strength predictions with the STDS software. By extending the line list to rotational levels of J = 40 we can significantly improve the shape of the near-IR absorption features of CH4, and in addition find an ...
Homeier, Derek +2 more
openaire +2 more sources
The Classification of T Dwarfs [PDF]
, 2001 We discuss methods for classifying T dwarfs based on spectral morphological features and indices. T dwarfs are brown dwarfs which exhibit methane absorption bands at 1.6 and 2.2 $μm$. Spectra at red optical (6300--10100 Å) and near-infrared (1--2.5 $μm$) wavelengths are presented, and differences between objects are noted and discussed.
Burgasser, A. J. +2 more
openaire +3 more sources
Modeling Brown Dwarfs, L Dwarfs, and T Dwarfs [PDF]
Symposium - International Astronomical Union, 2003 In this contribution, I review a subset of our recent efforts in spectral and opacity modeling aimed at guiding the study of brown dwarfs, L dwarfs, and T dwarfs. I discuss theoretical calculations of the alkali line profiles, newly generated CrH opacities, new evidence for refractory rainout in T dwarfs from optical spectral measurements, and the ...
openaire +2 more sources
The 2MASS Wide-Field T Dwarf Search. III. Seven New T Dwarfs and Other Cool Dwarf Discoveries [PDF]
The Astronomical Journal, 2004 27 pages incl. 9 figures and 8 tables, accepted for publication AJ, May 2004; note that findercharts are provided separately as jpg ...
Burgasser, Adam J. +5 more
openaire +2 more sources
Binaries and the L Dwarf/T Dwarf Transition [PDF]
The Astrophysical Journal, 2007 51 pages, 14 figures; accepted for publication in ...
openaire +2 more sources
T Dwarf Photometric Variability [PDF]
Symposium - International Astronomical Union, 2003 We report on a J and H photometric variability survey of 10 T dwarfs. Four brown dwarfs in the sample show significant J band variability at the 99% confidence level or higher. The amplitude of variation ranges from 2 to 17%. Our data show evidence of variability for late as well as early T dwarfs.
Etienne Artigau +2 more
openaire +1 more source
Exploring the Extremes: Characterizing a New Population of Old and Cold Brown Dwarfs
The Astronomical Journal, 2023 Mapping out the populations of thick disk and halo brown dwarfs is important for understanding the metallicity dependence of low-temperature atmospheres and the substellar mass function.
Aaron M. Meisner +5 more
doaj +1 more source
The Astrophysical Journal Letters, 2023 Cold, substellar objects such as brown dwarfs have long been recognized as contaminants in color-selected samples of active galactic nuclei (AGNs). In particular, their near- to mid-infrared colors (1–5 μ m) can closely resemble the V-shaped ( f _λ ...
Danial Langeroodi, Jens Hjorth
doaj +1 more source