UV-Visible Observations of Hot Stars in Young Magellanic Cloud Star Clusters
Abstract
We propose to use WFPC2 to image 4 young populous star clusters in the Magellanic Clouds {NGC 330 in the SMC, NGC 1818, 2004, and 2100 in the LMC} using the far-UV F160BW filter and the visible F555W filter. The resulting F160BW- F555W colors will allow accurate temperature determinations for both main sequence and blue supergiant stars in these clusters. These observations will then be compared with the predictions of standard and non-standard evolutionary codes to improve constraints on the evolution of mbox 10 to mbox20Msun stars. In particular, these HST observations will help resolve the following differences between optical ground-based color-magnitude diagrams and current evolutionary theory:, o the observed and predicted temperatures of the main sequence turnoff apparently differ by several thousand degrees, while the luminosities differ by up to 1 mag in V;, o the luminosity of the red giants and the main sequence turnoff are not consistent with the predictions of standard models;, o the observed ratios of red and blue supergiants are much greater than expected on the basis of standard models., The HST is essential for this project since only it provides both the far -UV sensitivity needed for excellent temperature discrimination and the high spatial resolution needed for photometry in these crowded cluster fields.
- Publication:
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HST Proposal
- Pub Date:
- July 1996
- Bibcode:
- 1996hst..prop.6425B