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Extrasolar Planets and Brown Dwarfs James Liebert Steward Observatory University of Arizona Tucson, AZ McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop Extrasolar Planets: Planets found around other stars usually similar to our Sun and Brown dwarfs: entities between the size (mass) of many Jupiters and low mass stars Definition of a star: a gravitationally-bound sphere of gas massive enough to fuse hydrogen into helium, thereby providing the energy to shine In units of the mass of the Sun 2 x 1033 gm = 2 x 1030 kg = 1M Jupiter is very close to 0.001 M Jovian planets defined to be up to 13 MJ (0.013 M) Brown dwarfs 0.013 - 0.075 M Hydrogen fusion requires a mass of 0.075M (75MJ) McDonald Observatory workshop Brown is not a color McDonald Observatory workshop QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture. McDonald Observatory workshop QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture. McDonald Observatory workshop QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture. McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop Binary stars: Each orbits the common center of mass QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop McDonald Observatory workshop LHS 4033 Most Massive Well Measured White Dwarf 1.31-1.335M 10,900 K 0.0037R Dahn, Bergeron, Liebert, Harris, Canzian, Leggett, And Boudreault 2004 ApJ, 605, 400 McDonald Observatory workshop McDonald Observatory workshop J. Davy Kirkpatrick -- Annual Reviews of Astronomy and Astrophysics McDonald Observatory workshop J. Davy Kirkpatrick -- “Inventor” of the L Dwarf Classification System McDonald Observatory workshop Adam Burgasser: Definer of T Dwarfs and National Collegiate Diving Champion (U. California, San Diego) McDonald Observatory workshop Modelling a T6.5 emission Dwarf Infrared Spectrum (Liebert and Burgasser 2007 ApJ,655,522) McDonald Observatory workshop McDonald Observatory workshop Dispersion in infrared colors At a given spectral type Variable dust layers in L ‘s Open circles: subdwarfs (lower [Fe/H]) also higher gravity Open triangles: young and low gravity McDonald Observatory workshop Temperatures from Luminosities (via trig parallaxes) and Radii Teff ~ (L / 4πR2)1/4 1/4 R = constant ~ Rjup Declining Teff as brown dwarf cools with time Small temperature change from L6 -- T5 means Rapid evolution through these Spectral types Infrared types not as cleanly Monotonic with Teff as are Optical types McDonald Observatory workshop At this time.. the latest T8 dwarfs are believed to be about Teff ~ 700-750 K The synthetic spectra from Burrows models shown here suggest what cooler objects discovered by deeper surveys will look like Kirkpatrick (2006 PPl V review) suggests 3 possible qualitative changes in the spectra that might trigger A new spectral type Y McDonald Observatory workshop McDonald Observatory workshop The J Band Bump at early-mid T types: CO > CH4 (and H2) Absorption switches from J to K band More flux gets out at J Band despite Lower Teff Open circles: apparently Single stars Filled circles inside a circle: Resolved binaries McDonald Observatory workshop McDonald Observatory workshop