Astronomy and Astrophysics – Astronomy
Scientific paper
Jul 2007
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007dda....38.0504d&link_type=abstract
American Astronomical Society, DDA meeting #38, #5.04
Astronomy and Astrophysics
Astronomy
Scientific paper
We report on the discovery of a surprising observed correlation between the slope of the low-mass stellar global mass function (GMF) of globular clusters (GCs) and their central concentration parameter c=log(rt/rc), i.e., the logarithmic ratio of tidal and core radii. This result is based on the analysis of a sample of 20 Galactic GCs with solid GMF measurements from deep HST or VLT data. All the high-concentration clusters in the sample have a steep GMF, most likely reflecting their initial mass function. Conversely, low-concentration clusters tend to have a flatter GMF, implying that they have lost many stars via evaporation or tidal stripping. No GCs are found with a flat GMF and high central concentration. This finding appears counterintuitive, since the same two-body relaxation mechanism that causes stars to evaporate and the cluster to eventually dissolve should also lead to higher central density and possibly core collapse. Therefore, more concentrated clusters should have lost proportionately more stars and have a shallower GMF than low-concentration clusters, contrary to what is observed. It is possible that severely depleted GCs have also undergone core collapse and have already recovered a normal radial density profile. It is, however, more likely that GCs with a flat GMF have a much denser and smaller core than that suggested by their surface brightness profile and may well be undergoing collapse at present. In either case, we may have so far seriously underestimated the number of post-core collapse clusters, and many may be lurking in the Milky Way.
de Marchi Guido
Paresce Francesco
Pulone Luigi
No associations
LandOfFree
Why haven't Loose Globular Clusters collapsed yet 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 Why haven't Loose Globular Clusters collapsed yet, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Why haven't Loose Globular Clusters collapsed yet will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1662601