The Spectral Character of Giant Planets and Brown Dwarfs

TL;DR

This paper discusses the spectral characteristics of giant planets and brown dwarfs, highlighting recent discoveries, theoretical modeling advancements, and upcoming observational efforts across multiple telescopes and instruments.

Contribution

The authors present upgraded non-gray spectral and color models for giant planets and brown dwarfs, covering a wide temperature and mass range, supporting ongoing and future observational searches.

Findings

Detection of over 20 giant planets and brown dwarfs since 1995.

First direct detection of a brown dwarf with methane features, Gl229 B.

Development of comprehensive spectral models for substellar objects.

Abstract

Since October of 1995, employing Doppler spectroscopy astronomers have discovered as many as 20 giant planets and brown dwarfs, including companions to $\tau$ Boo, 51 Peg, $\upsilon$ And, 55 Cnc, $\rho$ CrB, 70 Vir, 16 Cyg B, and 47 UMa. These discoveries have excited the planetary science community, astronomers, and the public at large. Within hours of the announcement of the planet 51 Peg b, the first direct detection of an unimpeachable brown dwarf, Gl229 B, was also announced. Gl229 B is a watershed since it has methane spectral features and a surface temperature below 1000 Kelvin, characteristics unique to objects with substellar masses. During the last two years, building upon our previous experience in the modeling of brown dwarfs and M stars, we published theoretical studies of the evolution and spectra of extrasolar giant planets. We have recently upgraded our capabilities and now generate non-gray spectral and color models of both giant planets and brown dwarfs. This theory will soon encompass objects whose effective temperatures range from 100 K to 4000 K and whose masses span three orders of magnitude. The evolutionary, spectral, and color calculations upon which we have embarked are in direct support of the searches now being planned in earnest with the HST (WFPC2, NICMOS), the IRTF, the MMT 6.5-meter upgrade, the LBT, Keck's I and II, ISO, UKIRT, NGST, the VLT, COROT, DENIS, 2MASS, and SIRTF.