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M. R. Zapatero Osorio (LAEFF-INTA, Spain) B. L. Lane (MIT, USA) Ya. Pavlenko (MAO, Ukraine)

Dynamical masses of the binary brown dwarf GJ 569B using high-resolution NIR spectra. M. R. Zapatero Osorio (LAEFF-INTA, Spain) B. L. Lane (MIT, USA) Ya. Pavlenko (MAO, Ukraine) E. L. Martín (IAC, Spain) M. Britton, S. R. Kulkarni (Caltech, USA). La Gomera, June 2004.

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M. R. Zapatero Osorio (LAEFF-INTA, Spain) B. L. Lane (MIT, USA) Ya. Pavlenko (MAO, Ukraine)

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  1. Dynamical masses of the binary brown dwarf GJ 569B using high-resolution NIR spectra M. R. Zapatero Osorio (LAEFF-INTA, Spain) B. L. Lane (MIT, USA) Ya. Pavlenko (MAO, Ukraine) E. L. Martín (IAC, Spain) M. Britton, S. R. Kulkarni (Caltech, USA) La Gomera, June 2004

  2. GJ 569: a tertiary system B A GJ 569B is a proper motion companion located at 50 AU from GJ 569A. Forrest et al. (1988) Keck AO images. GJ 569B is resolved into two objects of spectral types M8.5V and M9V, separated by 0.9 AU, and total mass of 0.125 Msol. Martín et al. (2000); Lane et al. (2001) Keck AO NIRSPEC low –res spectra. Teff ~ 2450, 2300 K. Lane et al. (2001)

  3. GJ 569B: the binary companion Astrometric results: Period = 876.0 ± 9.2 days e = 0.32 ± 0.01 a = 0.90 ± 0.01 AU i = 34 ± 2 deg w = 257 ± 2 deg W = 321 ± 2 deg Epoch (MJD) = 51822 ± 3 days Total mass =0.125 ± 0.005 Msol Lane et al. (2001)

  4. GJ 569Ba and Bb: Keck AO NIRSPEC hi-res spectra GJ 569Ba GJ 569Bb 28 June 2001; J-band 2D spectrum Four observing dates between 2001 May and 2001 September.

  5. GJ 569Ba and Bb: Keck AO NIRSPEC hi-res spectra GJ 569Ba GJ 569Bb

  6. GJ 569Ba and Bb: velocities The expected velocity curve, based solely on the astrometric result, is plotted as a red line. The observed relative velocities and the curve are in very good agreement.

  7. GJ 569Ba and Bb: velocities GJ 569Ba The best fit to the unweighted velocity data yields: M (GJ 569Ba) = 0.068 ± 0.011 Msol M (GJ 569Bb) = 0.057 ± 0.011 Msol GJ 569Bb is the first brown dwarf confirmed dynamically, i.e., without any theoretical assumption. GJ 569Bb Zapatero Osorio et al. (2004)

  8. GJ 569: the age of the system The galactic UVW velocities of GJ 569A are within 1s the values of a known star cluster moving group, which has an estimated age of 300-800 Myr. Additionally, the star GJ 569A exhibits many of the attributes of young stars (120-1000 Myr). GJ 569A Chereul et al. (1999)

  9. GJ 569Ba and Bb and evolutionary models Ba Ba Bb Bb Models nicely reproduce the substellar mass-luminosity relation of the binary if the system is about 300 Myr.

  10. Dependence of KI lines on Teff and gravity Teff = 2400 K log g = 4.5 From synthetic computations, the KI lines are remarkably sensitive to both Teff and gravity. (See also observed spectra of Gorlova et al. 2003; McGovern et al. 2004).

  11. GJ 569Ba and Bb: Keck AO NIRSPEC hi-res spectra Model atmospheres fitting yields: log g = 4.5-5.0 [cm s-2] Teff = 2400-2500 K vrot sin i ~ 30 km s-1 KI KI

  12. Increasing list of nearby ultra-cool binaries … 0.146 Msol Bouy et al. (2004) Table from Close et al. (2003) Eps Indi B 2.6 T1/T6 0.047 0.028 15(McCaughrean et al. 2004)

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