Results 31 to 40 of about 86,337 (303)

Parallaxes of L and T dwarfs [PDF]

Proceedings of the International Astronomical Union, 2004
We discuss a new program to measure the parallaxes of a number of L and T dwarfs, objects that bridge the gap between M dwarfs and planets. This pilot project tests the feasibility of using large telescopes with infrared detectors to determine parallaxes at the level of milli-arcseconds (mas). First results show that we are able to achieve the required
R. L. Smart, C. A. L. Bailer-Jones, H. R. A. Jones   +2 more
openaire   +1 more source

A Cross-Match of 2MASS and SDSS: Newly-Found L and T Dwarfs and an Estimate of the Space Densitfy of T Dwarfs [PDF]

, 2007
We report new L and T dwarfs found in a cross-match of the SDSS Data Release 1 and 2MASS. Our simultaneous search of the two databases effectively allows us to relax the criteria for object detection in either survey and to explore the combined databases
Berriman B., Borysow A., Collinge M. J., Dagny Looper, G. Bruce Berriman, Gelino C. R., J. Davy Kirkpatrick, Mainzer A. K., Perryman M. A. C., Stanimir A. Metchev   +9 more
core   +2 more sources

The First Y Dwarf Data from JWST Show that Dynamic and Diabatic Processes Regulate Cold Brown Dwarf Atmospheres

The Astrophysical Journal, 2023
The James Webb Space Telescope (JWST) is now observing Y dwarfs, the coldest known brown dwarfs, with effective temperatures T _eff ≲ 475 K. The first published observations provide important information: not only is the atmospheric chemistry out of ...
S. K. Leggett, Pascal Tremblin
doaj   +1 more source

Preliminary Parallaxes of 40 L and T Dwarfs from the U.S. Naval Observatory Infrared Astrometry Program [PDF]

, 2003
We present preliminary trigonometric parallaxes and proper motions for 22 L dwarfs and 18 T dwarfs measured using the ASTROCAM infrared imager. Relative to absolute parallax corrections are made by employing 2MASS and/or SDSS photometry for reference ...
A. A. Henden, A. J. Burgasser, B. Canzian, C. B. Luginbuhl, D. A. Golimowski, D. P. Schneider, Delfosse X., F. J. Vrba, G. R. Knapp, H. H. Guetter, J. A. Munn, J. Brinkmann, J. Davy Kirkpatrick, Luginbuhl C. B., S. K. Leggett, T. R. Geballe, Vrba F. J., X. Fan   +17 more
core   +3 more sources

WIYN Open Cluster Study 89. M48 (NGC 2548) 2: Lithium Abundances in the 420 Myr Open Cluster M48 from Giants through K Dwarfs

The Astrophysical Journal, 2023
We consider WIYN/Hydra spectra of 329 photometric candidate members of the 420 Myr old open cluster M48 and report lithium detections or upper limits for 234 members and likely members.
Qinghui Sun, Constantine P. Deliyannis, Aaron Steinhauer, Barbara J. Anthony-Twarog, Bruce A. Twarog   +4 more
doaj   +1 more source

Hubble Space Telescope NICMOS Observations of T Dwarfs: Brown Dwarf Multiplicity and New Probes of the L/T Transition [PDF]

, 2006
We present the results of a Hubble Space Telescope NICMOS imaging survey of 22 T-type field brown dwarfs. Five are resolved as binary systems with angular separations of 0"05-0"35, and companionship is established on the basis of component F110W-F170M ...
Adam Burrows, Adam J. Burgasser, Burgasser A. J., Delfosse X., Duquennoy A., I. Neill Reid, J. Davy Kirkpatrick, James Liebert, Kelle L. Cruz, Maxted P. F. L., Michael E. Brown, Potter D., Sandy K. Leggett, Tsuji T.   +13 more
core   +4 more sources

ULAS J141623.94+134836.3: A BLUE T DWARF COMPANION TO A BLUE L DWARF [PDF]

The Astronomical Journal, 2010
We confirm the substellar nature of ULAS J141623.94+134836.3, a common proper motion companion to the blue L dwarf SDSS J141624.08+134826.7 identified by Burningham et al. and Scholz. Low-resolution 0.8-2.4 micron spectroscopy obtained with IRTF/SpeX shows strong H2O and CH4 absorption bands, consistent with a T7.5 spectral type, and we see possible ...
Burgasser, Adam J., Looper, Dagny L., Rayner, John T.   +2 more
openaire   +4 more sources

Optical properties of metal-poor T dwarf candidates

Astronomy & Astrophysics, 2023
Context. Metal-poor brown dwarfs are poorly understood because they are extremely faint and rare. Only a few candidates have been identified as T-type subdwarfs in infrared surveys and their optical properties remain unconstrained. Aims. We aim to improve the knowledge of the optical properties of T subdwarf candidates to break the degeneracy between ...
J.-Y. Zhang, N. Lodieu, E. L. Martín
openaire   +2 more sources

Uniform Atmospheric Retrieval Analysis of Ultracool Dwarfs. II. Properties of 11 T dwarfs [PDF]

The Astrophysical Journal, 2017
Abstract Brown dwarf spectra are rich in information revealing of the chemical and physical processes operating in their atmospheres. We apply a recently developed atmospheric retrieval tool to an ensemble of late-T dwarf (600–800 K) near-infrared (1–2.5 μm) spectra.
Michael R. Line, Mark S. Marley, Michael C. Liu, Ben Burningham, Caroline V. Morley, Natalie R. Hinkel, Johanna Teske, Jonathan J. Fortney, Richard Freedman, Roxana Lupu   +9 more
openaire   +2 more sources

Spectroscopic Detection of Carbon Monoxide in Two Late-type T Dwarfs [PDF]

, 2008
M band spectra of two late-type T dwarfs, 2MASS J09373487+2931409, and Gliese 570D, confirm evidence from photometry that photospheric CO is present at abundance levels far in excess of those predicted from chemical equilibrium. These new and unambiguous
Bishop, Burgasser, Burgasser, Burgasser, Burgasser, Burgasser, Burrows, Cushing, D. A. Golimowski, D. Saumon, Fegley, Freedman, Geballe, Geballe, Golimowski, Griffith, Houck, Hubeny, K. S. Noll, Kirkpatrick, Knapp, Leggett, Leggett, Lodders, M. S. Marley, Moses, Noll, Noll, Oppenheimer, Patten, Perryman, S. K. Leggett, Saumon, Saumon, Saumon, Saumon, Saumon, Stephens, T. R. Geballe, Thorén, Valenti, Vrba, Zapatero Osorio   +42 more
core   +2 more sources