Issue |
A&A
Volume 560, December 2013
|
|
---|---|---|
Article Number | A22 | |
Number of page(s) | 8 | |
Section | Galactic structure, stellar clusters and populations | |
DOI | https://doi.org/10.1051/0004-6361/201322670 | |
Published online | 29 November 2013 |
Anchors for the cosmic distance scale: the Cepheids U Sagittarii, CF Cassiopeiae, and CEab Cassiopeiae
1 Saint Mary’s University, Halifax, Nova Scotia, Canada
2 Mount Saint Vincent University, Halifax, Nova Scotia, Canada
3 European Southern Observatory, Av. Alonso de Cordova, 3107, 19001 Casilla, Santiago, Chile
4 Instituto de Astronomía, Universidad Católica del Norte, Av. Angamos 0610, 1270709 Antofagasta, Chile
5 Departamento de Astronomia, Universidade Federal do Rio Grande do Sul, Av. Bento Gonalves 9500, 91501-970 Porto Alegre, RS, Brazil
6 Sternberg Astronomical Institute, Moscow M. V. Lomonosov State University, 119992 Moscow, Russia
7 Isaac Newton Institute of Chile, Moscow Branch, Universitetskij Pr. 13, 119992 Moscow, Russia
8 Dominion Astrophysical Observatory, Victoria, British Columbia, Canada
9 Departamento de Astronomía, Universidad de Concepción, 160 Casilla, Concepción, Chile
10 Departamento de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Av. Gran Bretaña 1111, 5030 Casilla, Valparaíso, Chile
11 Astronomical Observatory, Odessa National University, Odessa, Ukraine
12 Isaac Newton Institute of Chile, Odessa Branch, T. G. Shevkenko Park, 65014 Odessa, Ukraine
13 Las Campanas Observatory, Carnegie Institution of Washington, Colina el Pino, 601 Casilla, La Serena, Chile
Received: 14 September 2013
Accepted: 2 November 2013
New and existing X-ray, UBVJHKsW(1 − 4), and spectroscopic observations were analyzed to constrain fundamental parameters for M 25, NGC 7790, and dust along their sight-lines. The star clusters are of particular importance because they host the classical Cepheids U Sgr, CF Cas, and the visual binary Cepheids CEa and CEb Cas. Precise results from the multiband analysis, in tandem with a comprehensive determination of the Cepheids’ period evolution (dP/dt) from ~140 years of observations, helped to resolve concerns raised regarding the clusters and their key Cepheid constituents. Specifically, the distances derived for members of M 25 and NGC 7790 are 630 ± 25 pc and 3.40 ± 0.15 kpc, respectively.
Key words: stars: variables: Cepheids / Hertzsprung-Russell and C-M diagrams
© ESO, 2013
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