Ultraviolet Imagery of NGC 6752: A Test of Extreme Horizontal Branch Models

Details Ultraviolet Imagery of NGC 6752: A Test of Extreme Horizontal Branch Models Ultraviolet Imagery of NGC 6752: A Test of Extreme Horizontal Branch Models

1996-09-18

arxiv.org/abs/astro-ph/9609127v1

Astronomy and Astrophysics

Astrophysics

14 pages, AASTeX, includes 4 EPS figures ApJ Letters accepted

Scientific paper

10.1086/310368

We present a 1620 A image of the nearby globular cluster NGC 6752 obtained with the Ultraviolet Imaging Telescope (UIT) during the Astro-2 mission of the Space Shuttle Endeavour in 1995 March. An ultraviolet-visible color-magnitude diagram (CMD) is derived for 216 stars matched with the visible photometry of Buonanno et al. (1986). This CMD provides a nearly complete census of the hot horizontal branch (HB) population with good temperature and luminosity discrimination for comparison with theoretical tracks. The observed data show good agreement with the theoretical zero-age horizontal branch (ZAHB) of Sweigart (1996) for an assumed reddening of E(B-V) = 0.05 and a distance modulus of 13.05. The observed HB luminosity width is in excellent agreement with the theoretical models and supports the single star scenario for the origin of extreme horizontal branch (EHB) stars. However, only four stars can be identified as post-EHB stars, whereas almost three times this many are expected from the HB number counts. If this effect is not a statistical anomaly, then some non-canonical effect may be decreasing the post-EHB lifetime. The recent non-canonical models of Sweigart (1996), which have helium-enriched envelopes due to mixing along the red giant branch, cannot explain the deficit of post-EHB stars, but might be better able to explain their luminosity distribution.

Affiliated with

Also associated with

No associations

Rating

Ultraviolet Imagery of NGC 6752: A Test of Extreme Horizontal Branch Models does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Ultraviolet Imagery of NGC 6752: A Test of Extreme Horizontal Branch Models, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ultraviolet Imagery of NGC 6752: A Test of Extreme Horizontal Branch Models will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-177605