Bibcode
Leggett, Sandy; Roellig, Thomas; Cushing, Michael; Houck, James; Jameson, Richard; Kirkpatrick, Davy; Lodieu, Nicolas; Lucas, Phil; Mainzer, Amanda; Marley, Mark; Pinfield, David; Saumon, Didier; Sloan, Greg; van Cleve, Jeff; Warren, Steve; Wilson, John
Referencia bibliográfica
Spitzer Proposal ID #40419
Advertised on:
5
2007
Número de citas
0
Número de citas referidas
0
Descripción
We request 13.9 hours of IRS GTO time to observe two recently discovered
very low-mass T dwarfs, the early-T HN PegB and the very late-T ULAS
J0034. As inferred from models, the two T dwarfs have similar masses of
around 20 MJupiter, and similar gravities, but very different effective
temperatures of Teff ~1100 K and 650 K for HN PegB and ULAS J0034,
respectively. The warmer T dwarf is of special interest as models
currently cannot reproduce the flux distributions of the early-T dwarfs.
HN PegB is the only early-T dwarf that is observable with the IRS that
is also a companion to a main sequence star, so that age and metallicity
can be constrained. The cooler T dwarf is of special interest as it is
the coolest T dwarf currently known. The IRS data will allow us to
complete the spectral energy distributions of these key brown dwarfs,
for which near-infrared and IRAC data are already available. This will
in turn enable a better determination of the fundamental parameters
Teff, gravity and metallicity, as well as allow a study of the clearing
of the cloud decks in the early-T dwarf, and of the chemical mixing due
to vertical transport in the atmosphere of the late-T dwarf.
Constraining these parameters and processes will allow refinement of the
mass and age determinations for these important dwarfs.