2009MNRAS.393.1016D -
Mon. Not. R. Astron. Soc., 393, 1016-1033 (2009/March-1)
Red giant stellar collisions in the Galactic centre.
DALE J.E., DAVIES M.B., CHURCH R.P. and FREITAG M.
Abstract (from CDS):
We show that collisions with stellar-mass black holes can partially explain the absence of bright giant stars in the Galactic Centre, first noted by Genzel et al. We show that the missing objects are low-mass giants and asymptotic giant branch stars in the range 1-3M☉. Using detailed stellar evolution calculations, we find that to prevent these objects from evolving to become visible in the depleted K bands, we require that they suffer collisions on the red giant branch, and we calculate the fractional envelope mass losses required. Using a combination of smoothed particle hydrodynamic calculations, restricted three-body analysis and Monte Carlo simulations, we compute the expected collision rates between giants and black holes, and between giants and main-sequence stars in the Galactic Centre. We show that collisions can plausibly explain the missing giants in the 10.5 < K < 12 band. However, depleting the brighter (K < 10.5) objects out to the required radius would require a large population of black hole impactors which would in turn deplete the 10.5 < K < 12 giants in a region much larger than is observed. We conclude that collisions with stellar-mass black holes cannot account for the depletion of the very brightest giants, and we use our results to place limits on the population of stellar-mass black holes in the Galactic Centre.
Abstract Copyright:
© 2009 The Authors. Journal compilation © 2009 RAS
Journal keyword(s):
stars: late-type - Galaxy: centre
Simbad objects:
4
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