Brown Dwarf Science with VLST John Gizis Physics

Brown Dwarf Science with VLST John Gizis Physics and Astronomy " " " Outline: The Big Questions Where we are and how VLST would help. . .

Brown Dwarf Science with VLST Formation Atmospheres

Brown Dwarf Science with VLST Formation IMF Binarity Disks Atmospheres

Brown Dwarf Science with VLST Formation IMF Binarity Disks Atmospheres Evolution Beyond T dwarfs Activity

Brown Dwarf Science with VLST " " Burrows et al. 1993, 1997 Brown dwarfs below ~0. 074 MM fail to achieve stable nuclear burning. Cool and fade steadily

Brown Dwarf Science with VLST " " Burrows et al. 1993, 1997 Brown dwarfs below ~0. 074 MM fail to achieve stable nuclear burning. Cool and fade steadily

Brown Dwarf Science with VLST " " " Burrows et al. 2003 Brown dwarfs below ~0. 074 MM fail to achieve stable nuclear burning. Cool and fade steadily Planets vs. brown dwarfs

Brown Dwarf Science with VLST " " Vrba et al. 2004 2 MASS and SDSS find objects Sequence to T 8 or ~800 K.

" " " L dwarf sequence Disappearance of molecules as grains form. Cloud deck ~1600 K Kirkpatrick et al. 1999

" " " T dwarf sequence Classification in near -IR. Cloud deck ~1600 K below photosphere. Burgasser et al. 2003

" " T dwarf sequence Classification in near -IR. Burgasser et al. 2002

" " " Burrows et al. 2003 On beyond T with VLST? Not really. . . Want large sky area and mid-infrared. Spitzer, JWST WISE

" " Burrows et al. 2003 But followup will require large telescopes. . . We will have many cool, very-lowmass brown dwarfs by any VLST launch date

" " Burrows et al. 2003 But followup will require large telescopes. . . We will have many cool, very-lowmass brown dwarfs by any VLST launch date

Images " " Separations 2 -10 AU " P 2 = a 3/MT " Current periods are ~30 years. " " Gizis et al. 2003 20% of L and T dwarfs are resolved by HST We can expect that a VLST could find the binaries at 0. 1 AU -- <1 yr period. These could include very-low-mass companions.

" " Gizis et al. 2003 For 5 MJ field brown dwarfs, a separation of 5 AU will have a period >100 years. Need a VLST both to get enough photons and to resolve them (at one micron). A VLST would get to separations of. 1 AU and periods < 1 yr. Also need VLST to resolve open cluster and Taurus brown dwarfs.

" " Gizis et al. 2003 For 5 MJ field brown dwarfs, a separation of 5 AU will have a period >100 years. Need a VLST both to get enough photons and to resolve them (at one micron). A VLST would get to separations of. 1 AU and periods < 1 yr. Also need VLST to resolve open cluster and Taurus brown dwarfs.

" " Gizis et al. 2003 For 5 MJ field brown dwarfs, a separation of 5 AU will have a period >100 years. Need a VLST both to get enough photons and to resolve them (at one micron). A VLST would get to separations of. 1 AU and periods < 1 yr. Also need VLST to resolve open cluster and Taurus brown dwarfs.

" " Burrows et al. 1997 Open cluster T dwarfs Star-formking regions: Probe to lowest masses.

" " UKIRT Open cluster T dwarfs Star-formking regions: Probe to lowest masses.

Low Metallicity/Halo " " " Imaging at ~1 micron should detect brown dwarfs in globular clusters. Need to reach T~800 K to be interesting. Resolution and field of view.

Low Metallicity/Halo " Field Halo Brown Dwarfs " 2 M 0532+8346 " An L subdwarf Burgasser et al. 2003

Spectra " Beyond T dwarfs Liebert et al. 2002

Activity " " " Gizis et al. 2000 found that activity declines sharply after M 6. But, flares are common. Burgasser et al. 2003 find some Ha at 10 -18 erg/sec/cm 2 Liebert et al. 2002

Activity " " " Gizis et al. 2000 found that activity declines sharply after M 6. But, flares are common. Burgasser et al. 2003 find some Ha at 10 -18 erg/sec/cm 2 Liebert et al. 2002

Hawley & Johns-Krull 2003 Activity " " " HST/STIS can detect M 8/M 9 dwarfs Need VLST for Le/Te dwarfs. Also, for cluster late -M dwarfs.

Formation " " Gizis 2002; r Oph BD from Luhman What about accreting brown dwarfs/planets Detection of emission lines in T dwarfs in star-forming regions.

Resolution? " " Gizis 2002; r Oph BD from Luhman Field brown dwarfs have v sin i ~ 5 -80 km/s Width of emission lines HDO: 1% variations? Lithium in distant clusters

" " " Hurt Weather? Variability at I band is few percent. Can we show that it is due to clouds? Hotspots? Sunspots?

Summary " " " Hurt Very Large Space Telescope Needed for followup of expected discoveries. Needed for more distant L/T dwarfs