Transcript Looking for the siblings of the Sun

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 - 0.09dex((Ri Ro)/kpc) - 0.048dex(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).
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
15-25 solar masses within a distance of 0.02-1.6 pc
(Looney et al. 2006).
- Star cluster where the Sun was born: M ~ 500-3000
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 GalaxyThe 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)
The orbital velocity is
From the kinematics:
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
Helmi et al. this
1999 orbit.
Can we use the preservation of the phase space
and the angular momentun to find the solar siblings
?
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.