Spectroscopy of ultra-cool dwarfs Brown dwarfs come of age. Fuerteventura. May 20-24, 2013 Víctor J. S. Béjar (IAC)

Ultra-cool definition L, T and Y spectral types Substellarity: Li Test Low gravity ultra-cool dwarfs Low metallicity ultra-cool sub-dwarfs Extrasolar planets and L,T dwarfs Final remarks Outline

Ultra-cool dwarf definition Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Kirkpatrick et al. 1997

Early discoveries of ultra-cool dwarfs Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Up to 1995, 20 dwarfs (≥M7) were known Kirkpatrick et al. 1995

Early discoveries of L dwarfs Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets 1988: Becklin & Zuckerman found GD165 B (>=M10) 1993 fist spectrum of GD165B was obtained (Kirkpatrick et al. 1993) 1997: several L dwarfs were discovered (Kirpatrick et al. 1997, Delfosse et al. 1997, Ruiz et al. 1997) Kirkpatrick et al Ruiz et al Delfosse et al Becklin & Zuckerman 1988

Spectral type definition: L dwarfs Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets In 1997 Kirkpatrick proposed a new spectral types and suggest “H”, “L”, “T” or “Y” letters Martín et al was the first to proposed “L” spectral type. Kirkpatrick et al Martín et al. 1997

Spectral classification of L dwarfs Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Kirkpatrick et al Martín et al Two classification of L dwarfs appear: one base on standards (Kirkpatrick et al. 1999) and other based on pseudo continuum (Martín et al. 1999)

Early discoveries of T dwarfs Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Burgasser et al Nakajima et al : Nakajima et al. found Gl229B 1995 fist nIR spectrum of Gl229B was obtained (Oppenheimer et al. 1995) : several field T dwarfs were discovered by Sloan and 2MASS (Strauss et al. 1999, Cuby et al. 1999, Burgasser et al. 1999, 2000, Leggett et al. 2000) Oppernheimer et al Gl570D

Spectral classification of T dwarfs Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Geballe et al. 2002Burgasser et al Two classification of T dwarfs appear: one base on standards (Burgasser et al. 2002) and other based on fluxes ratio (Geballe et al. 2002). Unified scheme in Burgasser et al. 2005

Discovery of Y dwarfs Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Luhman et al Two companions (>T10) found by Luhman et al and Liu et al Several Y dwarfs discovered by WISE satellite (Cushing et al.2011, Kirkpatrick et al. 2012, Tinney et al. 2012) Liu et al Cushing et al. 2011

Spectral characteristics of Y dwarfs Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Cushing et al Very red optical/near-infrared to mid-infrared colors (Kirkpatrick et al. 2011) Narrower flux in J, H-band Possible bluer Y-J and redder J-K color Kirkpatrick et al. 2012

Are all L and T dwarfs brown dwarfs? (Kirkpatrick et al. 2005) Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets

A substellarity test: the Li test Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Substellar objects M<0.060 Msol don’t destroy Li: Li+ p   2 4 He (Chabrier & Baraffe 2000) )

The Li test Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Originally proposed by Rebolo 1991, developed in several papers (Magazz ù et al. 1991, 93, Rebolo et al. 1992, Mart í n et al. 1994, Pavlenko et al ) Detected in PPL15, Teide1 y Calar3 (Basri et al. 1996, Rebolo et al. 1996). Rebolo et al Rebolo 1991

The Li test Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Objects with Li and ages > 120 Myr or Teff M5.5-6) are substellar Is UX Tau C the first Li brown dwarf? Basri 2000 Magazz ù et al. 1991, Pavlenko et al UX Tau C (M6)

The Li test in T dwarfs Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Kirkpatrick et al argue that Li disappear at Teff<1500K, but Pavlenko et al indicate that line should be present in Teff~1000K Li is not detected in  Indi B (MBa~74M Jup, MBb~47M Jup, Cardoso et al. 2010) Li in the T0-T0.5 WISE B (Luhman 16B)? -> YES (see Burgasser’s talk) King et al Luhman et al Li

Young ultra-cool dwarfs Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets 1995: Discovery of the M8.5 Teide 1 (Rebolo et al. 1995) Discovery of first young L dwarfs: Roque25 (Martín et al. 1998), G196-3B (Rebolo et al. 1998) First ultra-cool M dwarfs in regions <10Myr:  Oph (Luhman et al. 1997) First L dwarfs in regions <10Myr: IPMOs (Lucas & Roche 2000, Zapatero Osorio et al. 2000) T dwarfs in clusters?: SOri70 (Zapatero Osorio et al 2002), CFBDSIR (Delorme et al. 2012, see his talk), Pleiades (Casewell et al. 2011)

Low gravity and youth features (optical) Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Strong H  emission line in late M dwarfs Alcaline lines are weaker in low-gravity objects (Martín et al. 1996, but also Steele & Jameson 1995) TiO and VO are more intense in low-gravity L dwarfs: different classification in opt and IR B é jar et al Zapatero Osorio et al (see Zapatero Osorio’s talk) Mart í n et al. 1999

Low gravity features (near-IR) Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Alcaline lines are also weaker Triangular shape of H-band Steeper slope of K-band (see poster by Canty) Lucas et al Mc Govern et al Bihain et al. 2010

Low gravity field dwarfs Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Kirkpatrick et al found a peculiar L dwarf. Several of them presented in Cruz et al (Kirkpatrick et al. 2006) Zapatero Osorio et al LL

Ultra-cool Sub-dwarfs Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets First classification of ultra-cool subdwarfs by Gizis 1997: sdM and esdM New classification proposed by Lepine et al. 2007: sdM, esdM, usdM First low-metallicity L-type objects (Burgasser et al. 2003, Lepine et al. 2003) Peculiar blue near-infrared colors and more intense CaH, TiO (see M. Espinoza’s talk) Burgasser et al Gizis 1997

Isolated UCDs vs. wide companions Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets SED of isolated substellar objects is similar to wide companions Chauvin et al Chauvin et al. 2005

Exoplanets vs. UCDs Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets SED of isolated substellar objects is similar to exoplanets SOri70 & HD189733b Zapatero Osorio et al. 2002; Swain et al HD189733b (Swain et al. 2008)

Solar System vs. UCDs Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Burgasser et al WHAT IS THE SPECTRAL TYPE OF JUPIER? Is Jupiter a Y-dwarf?

In the last 25 years, >1000 UCDs have been discovered New L, T and Y spectral types have been defined Not all of them are brown dwarfs, but some of them are very low mass stars and planetary mass objects Gravity (age) and metallicity play a role Exoplanets and substellar comunity should work together Final remarks