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http://inaoe.repositorioinstitucional.mx/jspui/handle/1009/1917| STELLAR LIFETIME AND ULTRAVIOLET PROPERTIES OF THE OLD METAL-RICH GALACTIC OPEN CLUSTER NGC 6791: A PATHWAY TO UNDERSTAND THE ULTRAVIOLET UPTURN OF ELLIPTICAL GALAXIES∗ | |
| Emanuele Bertone | |
| Acceso Abierto | |
| Atribución-NoComercial-SinDerivadas | |
| Galaxies: elliptical and lenticular, cD Galaxies: evolution Open clusters and associations: individual (NGC 6791) Stars: evolution Ultraviolet: galaxies | |
| The evolutionary properties of the old metal-rich Galactic open cluster NGC 6791 are assessed based on deep UB photometry and Two Micron All Sky Survey JK data. For the 4739 stars in the cluster, bolometric luminosity and effective temperature have been derived from theoretical (U − B) and (J − K) color fitting. The derived H-R diagram has been matched with the Uvblue grid of synthetic stellar spectra to obtain the integrated spectral energy distribution (SED) of the system, together with a full set of UV (Fanelli) and optical (Lick) narrowband indices. The total bolometric magnitude of NGC 6791 is M ᵇ°ˡ₆₇₉₁= −6.29, with a color (B − V ) ₆₇₉₁= 0.97. The cluster appears to be a fairly good proxy of standard elliptical galaxies, although with significantly bluer infrared colors, a shallower 4000Å Balmer break, and a lower Mg2 index. The confirmed presence of a dozen hot stars along their extreme horizontal-branch evolution leads the cluster SED to consistently match the properties of the most active UV-upturn galaxies, with 1.7% ± 0.4% of the total bolometric luminosity emitted shortward of 2500 Å. The cluster helium abundance results in Y₆₇₉₁ = 0.30 ± 0.04, while the post-main-sequence (PMS) implied stellar lifetime from star number counts fairly agrees with the theoretical expectations from both the Padova and Basti stellar tracks. A PMS fuel consumption of 0.43 ± 0.01Mꙩ is found for NGC 6791 stars, in close agreement with the estimated mass of cluster He-rich white dwarfs. Such a tight figure may lead one to suspect that a fraction of the cluster stellar population does not actually reach the minimum mass required to effectively ignite He in the stellar core. | |
| The Astrophysical Journal | |
| 10-04-2012 | |
| Artículo | |
| Inglés | |
| Estudiantes Investigadores Público en general | |
| Buzzoni, Alberto, et al., (2012), STELLAR LIFETIME AND ULTRAVIOLET PROPERTIES OF THE OLD METAL-RICH GALACTIC OPEN CLUSTER NGC 6791: A PATHWAY TO UNDERSTAND THE ULTRAVIOLET UPTURN OF ELLIPTICAL GALAXIES∗, The Astrophysical Journal, Vol. 749(35):1-13 | |
| ASTRONOMÍA Y ASTROFÍSICA | |
| Versión aceptada | |
| acceptedVersion - Versión aceptada | |
| Aparece en las colecciones: | Artículos de Astrofísica |
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