Instituto de Astrofísica de Canarias • IAC
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- https://twitter.com/IAC_Astrofisica
- https://www.facebook.com/InstitutodeAstrofisicadeCanarias
- https://www.instagram.com/iac_astrofisica/
- https://www.linkedin.com/company/instituto-de-astrof-sica-de-canarias
- https://www.flickr.com/photos/institutodeastrofisicadecanarias/
- http://www.youtube.com/user/IACvideos
- http://vimeo.com/astrofisicaiac
- https://www.dailymotion.com/-IAC-
- https://www.iac.es/es/blog/vialactea
Bibcode
Bono, G.; Iannicola, G.; Braga, V. F.; Ferraro, I.; Stetson, P. B.; Magurno, D.; Matsunaga, N.; Beaton, R. L.; Buonanno, R.; Chaboyer, B.; Dall’Ora, M.; Fabrizio, M.; Fiorentino, G.; Freedman, W. L.; Gilligan, C. K.; Madore, B. F.; Marconi, M.; Marengo, M.; Marinoni, S.; Marrese, P. M.; Martinez-Vazquez, C. E.; Mateo, M.; Monelli, M.; Neeley, J. R.; Nonino, M.; Sneden, C.; Thevenin, F.; Valenti, E.; Walker, A. R.
Referencia bibliográfica
The Astrophysical Journal, Volume 870, Issue 2, article id. 115, 21 pp. (2019).
Fecha de publicación:
1
2019
Número de autores
29
Número de autores del IAC
1
Número de citas
31
Número de citas referidas
28
Descripción
We developed a new approach to provide accurate estimates of the metalcontent, reddening, and true distance modulus of RR Lyrae stars (RRLs).The method is based on hom*ogeneous optical (BVI) and near-infrared (JHK)mean magnitudes and on predictedperiod–luminosity–metallicity relations (IJHK) and absolutemean magnitude–metallicity relations (BV). We obtained solutionsfor three different RRL samples in ω Cen: first overtone (RRc,90), fundamental (RRab, 80), and global (RRc+RRab) in which the periodof first overtones were fundamentalized. The metallicity distributionshows a well defined peak at [Fe/H]∼‑1.98 and a standarddeviation of σ = 0.54 dex. The spread is, as expected, metal-poor([Fe/H] ≤ ‑2.3) objects. The current metallicity distributionis ∼0.3 dex more metal-poor than similar estimates for RRLsavailable in the literature. The difference vanishes if the truedistance modulus we estimated is offset by ‑0.06/‑0.07 magin true distance modulus. We also found a cluster true distance modulusof μ = 13.720 ± 0.002 ± 0.030 mag, where the formererror is the error on the mean and the latter is the standard deviation.Moreover, we found a cluster reddening of E(B ‑ V) = 0.132± 0.002 ± 0.028 mag and spatial variations of the order ofa few arcmin across the body of the cluster. Both the true distancemodulus and the reddening are slightly larger than similar estimatesavailable in the literature, but the difference is within 1σ. Themetallicity dependence of distance diagnostics agrees with theory andobservations, but firm constraints require accurate and hom*ogeneousspectroscopic measurements.
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