1. Una búsqueda de compañeros de estrellas Luyten con el Observatorio Virtual A search for companions to Luyten stars with the Virtual Observatory
José A. Caballero1
F. Xavier Miret2
Joan Genebriera3
Tófol Tobal2
Jordi Cairol2
David Montes1
1: Dpto. de Astrofísica, Universidad Complutense de Madrd
2: Observatori Astrònomic del Garraf, Barcelona
3: Observatorio de Tacande, La Palma

2. Albus 1
(Caballero & Solano 2007, ApJ, 665, L151)
Serendipitous discovery of a very bright white dwarf candidate...
...that is actually one of the brightest He-B subdwarfs
(Vennes, Kawka & Smith 2007, ApJ, 668, L59;
A. Ulla et al. in prep.)

3. Koenigstuhl 1 AB
(Caballero 2007a, A&A, 462, L61)
The (second) widest ultracool binary: a challenge for very low-mass formation ejection scenarios!
Seven astrometric epochs since until :
r = 77.76(7) arcsec
d = 23(2) pc
r = 1800(170) AU
MA = 0.103(6) Msol
MB = 0.079(4) Msol

4. Koenigstuhl 2 AB
(Caballero 2007d, ApJ, 667, 520)
A new very low-mass star in a wide binary: the third widest system with MA + MB < 0.4 Msol (in a draw)
Primary: LP
(Luyten 1979)
Secondary: 2M (M8.0V; Cruz et al. 2003)
r = 450(40) AU
MA = 0.26(4) Msol
MB = 0.086(4) Msol

5. Koenigstuhl 3 ABC The widest system containing an L dwarf component
(Caballero 2007d, ApJ, 667, 520)
The widest system containing an L dwarf component
Frequency of wide multiples with late-type (>M5) components: 5.0 ± 1.8 %
Primary: HD
(F8.0V; Hipparcos)
Secondary: 2M AB (M8.0V+L3.0V; Gizis et al. 2000, 2003)
r = 7.530(7) arcmin !
r = 11900(300) AU
MA = 1.02(7) Msol
MBC = Msol
And Koenigstuhl 4 AB is coming!
(Caballero, in prep.)

6. The Garraf survey:
an Aladin-based search for common-, high-proper motion pairs
The New Luyten Two Tenths (NLTT) catalogue (Luyten 1979), m > 0.2 arcsec a-1
Improved astrometry in Salim & Gould (2003): stars
Selection: proper motions between 0.5 and 1.0 arcsec a-1
Still 1947 stars!
Using Aladin instead of SuperCOSMOS Science Archive
Still a lot of work one person...

7. Help #1:
Xavier, Tófol and Xavier at the Observatori Astrònomic del Garraf
OAG (1976): a non-proffesional centre dedicated to the study of visual double stars
OAG revised the Comellas’ and catalogues and coordinated most of non-proffesional observations of doubles in Spain from 1990 to 2003
OAG is one the main measurement providers of the USNO Washington Double Stars catalogue (104)

8. The Garraf survey: Methodology
Data loading and cross-matching: USNO-B1+2MASS
Proper-motion diagram and candidate selection
Recovery of known pairs with incorrect USNO-B1 proper motions with the “proper motion filter”
One-by-one inspection of all selected binary candidates (SIMBAD, CCDM, Tycho-2...)

9. The Garraf survey: Current status
~160 common-m candidate companions studied to date
86 rejected systems with bad USNO-B1 astrometry
8 pairs with different USNO-B1 proper motions
20 physical systems with both star components in Hipparcos
29 physical systems with only one star component in Hipparcos
19 physical systems with no components in Hipparcos
Half a dozen new serendipitously-discovered physical systems

10. Help #2: The Tacande astro-photometric follow-up
A battery of “small” telescopes in La Palma: 40, 20, 15, 12, 9 cm
40 cm Cassegrain Relay, F6/5, with a CCD ST8XE

11. Garraf 1AB: An example of serendipitous discovery...
A: G , M4.5e, X-ray, variable, age ~ 300 Ma (Daemgen et al. 2007)
B: G , M5.5?
Known binary in Giclas et al. (1971)

12. Garraf 1AB: Age? r = 46.0 ± 0.3 arcsec  = 347.34 ± 0.16 deg
A bright, young, very wide, low-mass binary in the solar neighbourhood
Multi-epoch relative astrometry:
1952 Jul 17 POSSI Red
1988 Jun 13 POSSII Blue
1992 Aug 31 POSSII Red
1993 Jun 13 POSSII Infrared
1998 Jun 01 2MASS
2001 Aug 26 CMC14
2008 Mar 07 Tacande
Age?
r = 46.0 ± 0.3 arcsec
 = ± 0.16 deg
d = pc
r = AU
MA = Msol
MB = Msol

13. Help #3:
Optical imaging and low-resolution spectroscopy of Garraf 1AB with CAFOS / 2.2 m by David Montes
M4.5e + M5.0:e. Accurate BVRI magnitudes. New astrometric epoch (2008 Apr 30)

14. Conclusions A search for companions to Luyten stars with the Virtual Observatory What will be a trained investigator be able do with SDSS + UKIDSS + LSST + GAIA...?