Ultraviolet Imaging of the Globular Cluster 47 Tucanae

Robert W. O'Connell; Ben Dorman; Ronak Y. Shah; Robert T. Rood; Wayne B. Landsman; Ralph C. Bohlin; Susan G. Neff; Morton S. Roberts; Andrew M. Smith; Theodore P. Stecher

doi:10.1086/118619

arXiv · astro-ph/9704042

Ultraviolet Imaging of the Globular Cluster 47 Tucanae

Robert W. O'Connell·Ben Dorman·Ronak Y. Shah·Robert T. Rood·Wayne B. Landsman·Ralph C. Bohlin·Susan G. Neff·Morton S. Roberts·Andrew M. Smith·Theodore P. Stecher

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Abstract

We have used the Ultraviolet Imaging Telescope to obtain deep far-UV (1620 Angstrom), 40' diameter images of the prototypical metal-rich globular cluster 47 Tucanae. We find a population of about 20 hot (Teff > 9000 K) objects near or above the predicted UV luminosity of the hot horizontal branch (HB) and lying within two half-light radii of the cluster center. We believe these are normal hot HB or post-HB objects rather than interacting binaries or blue stragglers. IUE spectra of two are consistent with post-HB phases. These observations, and recent HST photometry of two other metal-rich clusters, demonstrate that populations with rich, cool HB's can nonetheless produce hot HB and post-HB stars. The cluster center also contains an unusual diffuse far-UV source which is more extended than its V-band light. It is possible that this is associated with an intracluster medium, for which there was earlier infrared and X-ray evidence, and is produced by C IV emission or scattered light from grains.

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BibTeX RIS

Robert W. O'Connell, Ben Dorman, Ronak Y. Shah, Robert T. Rood, Wayne B. Landsman, Ralph C. Bohlin, Susan G. Neff, Morton S. Roberts, Andrew M. Smith, Theodore P. Stecher. 1997-04-03. Ultraviolet Imaging of the Globular Cluster 47 Tucanae. https://doi.org/10.1086/118619

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