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Spectroscopy of ultra-cool dwarfs

Spectroscopy of ultra-cool dwarfs. Brown dwarfs come of age. Fuerteventura. May 20-24, 2013. Víctor J. S. Béjar (IAC). Outline. Ultra-cool definition L, T and Y spectral types Substellarity: Li Test Low gravity ultra-cool dwarfs Low metallicity ultra-cool sub-dwarfs

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Spectroscopy of ultra-cool dwarfs

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

  2. Outline • 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

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

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

  5. Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Early discoveries of L dwarfs • 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) Becklin & Zuckerman 1988 Kirkpatrick et al. 1997 Ruiz et al. 1997 Delfosse et al. 1997

  6. Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Spectral type definition: L dwarfs • In 1997 Kirkpatrick proposed a new spectral types and suggest “H”, “L”, “T” or “Y” letters • Martín et al. 1997 was the first to proposed “L” spectral type. Kirkpatrick et al. 1998 Martín et al. 1997

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

  8. Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Early discoveries of T dwarfs • 1995: Nakajima et al. found Gl229B • 1995 fist nIR spectrum of Gl229B was obtained (Oppenheimer et al. 1995) • 1999-2000: 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) Nakajimaet al. 1995 Gl570D Oppernheimeret al. 1995 Burgasser et al. 2000

  9. Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Spectral classification of T dwarfs • 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 Burgasseret al. 2002 Geballe et al. 2002

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

  11. Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Spectral characteristics of Y dwarfs • 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 Cushinget al. 2011

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

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

  14. Introduction L,T,Y SpTLi test low-g UCD low-metal UCsD exoplanets The Li test • Originally proposed by Rebolo 1991, developed in several papers (Magazzù et al. 1991, 93, Rebolo et al. 1992, Martín et al. 1994, Pavlenko et al. 1995) • Detected in PPL15, Teide1 y Calar3 (Basri et al. 1996, Rebolo et al. 1996). Rebolo 1991 Rebolo et al. 1996

  15. Introduction L,T,Y SpTLi test low-g UCD low-metal UCsD exoplanets The Li test • Objects with Li and ages > 120 Myr or Teff<2800K (>M5.5-6) are substellar • Is UX Tau C the first Li brown dwarf? UX Tau C (M6) Magazzù et al. 1991, Pavlenko et al. 1995 Basri 2000

  16. Introduction L,T,Y SpTLi test low-g UCD low-metal UCsD exoplanets The Li test in T dwarfs • Kirkpatrick et al. 2000 argue that Li disappear at Teff<1500K, but Pavlenko et al. 2000 indicate that line should be present in Teff~1000K • Li is not detected in  Indi B (MBa~74MJup, MBb~47MJup, Cardoso et al. 2010) • Li in the T0-T0.5 WISE 1049-5319 B (Luhman 16B)? -> YES (see Burgasser’s talk) Li Luhman et al. 2013 King et al. 2010

  17. Introduction L,T,Y SpT Li testlow-g UCD low-metal UCsD exoplanets Young ultra-cool dwarfs • 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), CFBDSIR2149-0403 (Delorme et al. 2012, see his talk), Pleiades (Casewell et al. 2011)

  18. Introduction L,T,Y SpT Li testlow-g UCD low-metal UCsD exoplanets Low gravity and youth features (optical) • 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 Martín et al. 1999 Béjar et al. 1999 Zapatero Osorio et al. 2013 (see Zapatero Osorio’s talk)

  19. Introduction L,T,Y SpT Li testlow-g UCD low-metal UCsD exoplanets Low gravity features (near-IR) • Alcaline lines are also weaker • Triangular shape of H-band • Steeper slope of K-band (see poster by Canty) Mc Govern et al. 2004 Lucas et al. 2001 Bihain et al. 2010

  20. Introduction L,T,Y SpT Li testlow-g UCD low-metal UCsD exoplanets Low gravity field dwarfs • Kirkpatrick et al. 2006 found a peculiar L dwarf. Several of them presented in Cruz et al. 2009 L L Zapatero Osorio et al. 2013 (Kirkpatrick et al. 2006)

  21. Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Ultra-cool Sub-dwarfs • 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) Burgasseret al. 2003 Gizis 1997

  22. Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Isolated UCDs vs. wide companions • SED of isolated substellar objects is similar to wide companions Chauvinet al. 2004 Chauvinet al. 2005

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

  24. Introduction L,T,Y SpT Li test low-g UCD low-metal UCsD exoplanets Solar System vs. UCDs • WHAT IS THE SPECTRAL TYPE OF JUPIER? • Is Jupiter a Y-dwarf? Burgasser et al. 2009

  25. Final remarks • 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

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