Presentation is loading. Please wait.

Presentation is loading. Please wait.

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

Similar presentations


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

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

2 Brown Dwarf Science with VLST Formation Atmospheres

3 Brown Dwarf Science with VLST Formation IMF Binarity Disks Atmospheres

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

5 Brown Dwarf Science with VLST  Brown dwarfs below ~0.074M M fail to achieve stable nuclear burning. " Cool and fade steadily Burrows et al. 1993, 1997

6 Brown Dwarf Science with VLST  Brown dwarfs below ~0.074M M fail to achieve stable nuclear burning. " Cool and fade steadily Burrows et al. 1993, 1997

7 Brown Dwarf Science with VLST  Brown dwarfs below ~0.074M M fail to achieve stable nuclear burning. " Cool and fade steadily " Planets vs. brown dwarfs Burrows et al. 2003

8 Brown Dwarf Science with VLST " 2MASS and SDSS find objects " Sequence to T8 or ~800K. Vrba et al. 2004

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

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

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

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

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

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

15 Images " 20% of L and T dwarfs are resolved by HST " Separations 2-10AU " P 2 = a 3 /M T " Current periods are ~30 years. " 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

16 " For 5 M J 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 < 1yr. " Also need VLST to resolve open cluster and Taurus brown dwarfs. Gizis et al. 2003

17 " For 5 M J 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 < 1yr. " Also need VLST to resolve open cluster and Taurus brown dwarfs. Gizis et al. 2003

18 " For 5 M J 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 < 1yr. " Also need VLST to resolve open cluster and Taurus brown dwarfs. " Resolution Gizis et al. 2003

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

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

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

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

23 Spectra " Beyond T dwarfs Liebert et al. 2002

24 Activity " Gizis et al found that activity declines sharply after M6. " But, flares are common.  Burgasser et al find some H  at erg/sec/cm2 Liebert et al. 2002

25 Activity " Gizis et al found that activity declines sharply after M6. " But, flares are common.  Burgasser et al find some H  at erg/sec/cm 2 Liebert et al. 2002

26 Activity " HST/STIS can detect M8/M9 dwarfs " Need VLST for Le/Te dwarfs. " Also, for cluster late-M dwarfs. Hawley & Johns-Krull 2003

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

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

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

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


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

Similar presentations


Ads by Google