Eduardo Martin CSIC-INTA Centro de Astrobiologia (CAB), Madrid /℗≤? ULTRACOOL DWARF (UCD=VERY LATE-M, L, T, Y) = VERY LOW-MASS STARS + BROWN DWARF + YOUNG GIANT PLANETS
SUBSTELLAR MASS OBJECT = BROWN DWARF + GIANT PLANET UCDs: Definition Ultracool dwarfs: Dwarfs with spectral type later than M7 (Teff<2600K). Dust grain condensation in atmospheres (Fe, Al2O3, MgSiO3). M. Cushing et al. 2003 ApJ 582, 1066 NIR spectral sequence for UCDs Brown dwarf: Degenerate e- plasma Limited nuclear fusion
Hayashi & Nakano 1963, Kumar 1963, Chabrier & Baraffe 2000 Martín et al. 1997,1999; Kirkpatrick et al. 1999,2000; Burgasser et al. 2002 Exoplanet search sensitivity critically depends on age
UScoCTIO 108b (V. Béjar et al. 2008 ApJ, 673, L185)
2MASS search for red objects (J-Ks>1) around 500 candidates members of USco
Discovery image: J-band 2MASS
Colour composite image: IJK’ (WHT,TNG) ρ ~ 4.6” (670UA) θ = 177° Discovery image: I-band IAC80 The Upper Scorpius association
• Distance ~ 145pc • Age ~ 5 Myr
Spectroscopy of UScoCTIO 108 A & B UScoCTIO 108 B: • : M9.5-L3 • Low gravity features • Activity •Teff = 2150 ± 300 K
UScoCTIO 108 A: • : M7 • Low gravity features • Li is totally preserved • Signatures of an accretion disks Teff= 2700 ± 100 K Physical parameters of UScoCTIO 108 AB
60 ± 20 M UScoCTIO 108 A: -1.95 ± 0.15 Jup UScoCTIO 108 B: -3.14 ± 0.20 14+2-8 Mjup q≈0.2 B. Riaz et al. 2013 A&A, 559, 109 NIR variability & PM B.P. Bowler et al. 2014 ApJ, in press 2M1207b compared with BDs and PMOs in the Pleiades
Deeper H2O bands in low-g UCD spectra
Zapatero-Osorio, Martin et al 2014 ApJ Lett. in prep.
HST/WFPC2-PC imaging of 134 late-M and L dwarfs (H. Bouy et al. 2003, AJ, 126, 1526)