INVESTIGADORES
GRANADA Anahi
artículos
Título:
Populations of rotating stars. III. SYCLIST, the new Geneva population synthesis code
Autor/es:
GEORGY, CYRIL; GRANADA, ANAHÍ; EKSTROM, SYLVIA; MEYNET, GEORGES; ANDERSON, RICHARD I.; WYTTENBACH, AURELIEN; EGGENBERGER, PATRICK; MAEDER, ANDRE
Revista:
ASTRONOMY AND ASTROPHYSICS
Editorial:
EDP SCIENCES S A
Referencias:
Lugar: Paris; Año: 2014 vol. 566 p. 1 - 15
ISSN:
0004-6361
Resumen:
Context. Constraints on stellar models can be obtained from observations
of stellar populations, provided the population results from a well
defined star formation history. Aims: We present a new tool for
building synthetic colour-magnitude diagrams of coeval stellar
populations. We study, from a theoretical point of view, the impact of
axial rotation of stars on various observed properties of single-aged
stellar populations: magnitude at the turnoff, photometric properties of
evolved stars, surface velocities, surface abundances, and the impact of
rotation on the age determination of clusters by an isochrone fitting.
One application to the cluster NGC 663 is performed. Methods:
Stellar models for different initial masses, metallicities, and zero-age
main sequence (ZAMS) rotational velocities are used for building
interpolated stellar tracks, isochrones, and synthetic clusters for
various ages and metallicities. The synthetic populations account for
the effects of the initial distribution of the rotational velocities on
the ZAMS, the impact of the inclination angle and the effects of gravity
and limb darkening, unresolved binaries, and photometric errors.
Interpolated tracks, isochrones, and synthetic clusters can be computed
through a public web interface. Results: For clusters with a
metallicity in the range [0.002, 0.014] and an age between 30 Myr and 1
Gyr, the fraction of fast rotators on the main sequence (MS) band is the
largest just below the turnoff. This remains true for two different
published distributions of the rotational velocities on the ZAMS. This
is a natural consequence of the increase in the MS lifetime due to
rotation. The fraction of fast rotators one magnitude below the turnoff
also increases with the age of the cluster between 30 Myr and 1 Gyr. The
most nitrogen-rich stars are found just below the turnoff. There is an
increase in the fraction of enriched stars when the metallicity
decreases. We show that the use of isochrones computed from rotating
stellar models with an initial rotation that is representative of the
average initial rotation of the stars in clusters provides a reasonable
estimate of the age, even though stars in a real cluster did not start
their evolution with an identical initial rotation.