MASSIVE STAR MULTIPLICITY: THE CEPHEID W Sgr
- Smithsonian Astrophysical Observatory, MS 4, 60 Garden Street, Cambridge, MA 02138 (United States)
- Science Programs, Computer Sciences Corporation, Space Telescope Science Institute, 3700 San Martin Dr., Baltimore MD 21218 (United States)
- Space Telescope Science Institute/CSC, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
We have obtained spectra of the W Sgr system with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope (HST). The spectra resolve the system into a distant companion B which is the hottest star in the system and the spectroscopic binary (A = Aa + Ab). A and B are separated by 0.''16. We have extracted the spectra of both of these. We see no flux in the Aa + Ab spectrum which cannot be accounted for by the Cepheid, and put an upper limit on the spectral type and mass of the companion Ab of F5 V and {<=}1.4 M {sub sun}. Using the orbit from HST fine guidance sensor measurements from Benedict et al., this results in an upper limit to the mass of the Cepheid of {<=}5.4 M {sub sun}. We also discuss two possible distant companions. Based on the photometry from the Two Micron All Sky Survey Point Source Catalog, they are not physical companions of the W Sgr system.
- OSTI ID:
- 21269275
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 137, Issue 3; Other Information: DOI: 10.1088/0004-6256/137/3/3700; Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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