Anchors for the cosmic distance scale: the Cepheids U Sagittarii, CF Cassiopeiae, and CEab Cassiopeiae
Abstract
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.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- December 2013
- DOI:
- arXiv:
- arXiv:1311.0865
- Bibcode:
- 2013A&A...560A..22M
- Keywords:
-
- stars: variables: Cepheids;
- Hertzsprung-Russell and C-M diagrams;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- To appear in Astronomy and Astrophysics
