Looking for the siblings of the Sun Borja Anguiano & RAVE collaboration

Outline Where was the Sun born ? What we can learn from the chemical homogeneity of the open clusters ?...And from the kinematics/orbits of the “menbers of the family” ? Have they already lost their memories ? And the ages ? A few ideas to look for a needle in a haystack...

The Sun in the Galaxy: The travel of our lives ! The Sun is 4.57 ± 0.05 Gyr old (Wasserburg 1995) and it’s situated 8.5 kpc from the center of the Galaxy (IAU 1985) a) Large radial gradient of metallicity in our Galaxy b) The initial dispersion in metallicity of stars born at a common time and a common R is small [Fe/H] = +0.05dex dex((R i - R o) /kpc) dex(t/10^9 years) The Sun was born in the inner parts of the Galaxy (Ri ~ 6.6 ± 0.9 kpc). Wielen et al. (1996).

Stars like the Sun are born in clusters (Lada et al. 1993) How was the star cluster of the Sun ? -Edgeworth-Kuiper belt: nearby encounter with a star in the early history of the solar system (Malhotra 2008) -Well-organized planetary system: the parental cluster cannot be very dense. -Presence of radioactive-isotopes in primitive meteorites, the Sun was polluted by a SN of star about solar masses within a distance of pc (Looney et al. 2006). - Star cluster where the Sun was born: M ~ solar masses and radius of 1-3 pc. (Zwart 2009)

Where are these stars today ? Dissolution time of a star cluster t ~ 2.3 Myr M^0.6 (Lamers et al. 2005) -The cluster is long gone and the star are spread over the Galaxy- The Sun has been orbiting the GC around 27 times: Galactic jungle -spiral arms, giant molecular clouds, radial mixing, diffusion of stellar orbits...See work of Bland-Hawthorn, Krumholz & Freeman (2009), Zwart (2009) What can RAVE do for theses stars ?

From the chemical abundances: Chemical information remains preserved in an open cluster (De Silva, Freeman, Asplund et al. 2007, Sestito et al. 2007)

From the kinematics: The orbital velocity is much higher than the velocity dispersion of the stars in the parental cluster, therefore the members are not very far from the orbit of the Sun but they could be at different locations along this orbit. Can we use the preservation of the phase space and the angular momentun to find the solar siblings ? Helmi et al. 1999

Strategy: From RAVE (C. Boeche’s abundances): S/N > 80 [Fe/H] ± 0.2 dex [Si/H] ± 0.2 dex [Mg/H] ± 0.3 dex [Ti/H] ± 0.3 dex [Al/H] ± 0.2 dex 689 stars were selected (first estimate of stellar parameters, accurate RV, proper motions, distances) Accurate individual abundances and ages are needed !!!

Follow-up observations Work in progrees: Spectral range, site, telescope, instrument, strategy to get the abundances and ages...etc. Conclusion Identify the family of the Sun could allow us to understand better the dinamical processes in the Galaxy, the evaporation of open clusters and our place in the Milky Way.