A Superwind from Early Post-Red Giant Stars?

Abstract

We suggest that the gap observed at 20,000 K in the horizontal branches of several Galactic globular clusters is caused by a small amount of extra mass loss which occurs when stars start to "peel off" the red giant branch (RGB), i.e., when their effective temperature starts to increase, even though they may still be on the RGB. We show that the envelope structure of RGB stars which start to peel off is similar to that of late asymptotic giant branch stars known to have a super-wind phase. An analogous super-wind in the RGB peel-off stars could easily lead to the observed gap in the distribution of the hottest HB stars.

9 pages; Accepted by ApJ Letters; Available also at http://www.astro.puc.cl/~mcatelan/

References in corpus (1)

• Horizontal-Branch Models and the Second-Parameter Effect. III. The Impact of Mass Loss on the Red Giant Branch, and the Case of M5 and Palomar 4/Eridanus

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• Particle-physics constraints from the globular cluster M5: Neutrino Dipole Moments
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• The lack of close binaries among hot horizontal branch stars in NGC6752
• Modelling Chromospheric Line Profiles in NGC2808: Evidence of Mass Loss from RGB Stars
• Long period variables in the globular cluster 47 Tuc: radial velocity variations
• The MODEST questions: challenges and future directions in stellar cluster research