HST Observations of the Main Sequence of M4

Details HST Observations of the Main Sequence of M4 HST Observations of the Main Sequence of M4

2004-01-21

arxiv.org/abs/astro-ph/0401440v1

Astronomy and Astrophysics

Astrophysics

37 pages, 14 figures, submitted to AJ

Scientific paper

This paper presents new results from a photometric study of the main-sequence stars in M4, the closest globular cluster to the sun. Multi-field, multi-epoch observations at approximately 1, 2, and 6 core-radii were obtained with the WFPC2 camera on the HST. The multi-epoch observations allowed us to clean the data on the basis of proper motion. In all the fields the cluster main sequence can be traced to at least V = 27.0 but there remains a trail of stars to the limit of the data near V = 30 in the deepest outer field. There is no evidence that we have reached the end of the hydrogen burning main sequence in any of our fields, however, there is some indication that very few stars remain to be detected in the deepest data. The scatter about the cluster main sequence yields a surprisingly small and variable binary fraction; f_b = 2% in the inner parts of the cluster falling to the 1% range outside. For the currently visible main sequence stars, the cluster mass function is very flat (alpha =0.1) in the outer field and flattens further in the inner fields suggesting well developed mass segregation. The observed variation in the mass function is broadly consistent with isotropic, multi-mass Michie-King models. Because we have a large sample of white dwarfs in the outer field we are able to show that the cluster IMF above 0.8Msun was considerably steeper than the present day mass function for low mass stars. Two appendicies are included in this contribution; a detailed discussion of the techniques used to reduce the data and a direct comparison between the cluster stars and those belonging to the inner spheroid of the Galaxy yielding a Galactocentric distance of 7.5+/-0.6 kpc.

Affiliated with

Also associated with

No associations

Rating

HST Observations of the Main Sequence of M4 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 HST Observations of the Main Sequence of M4, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and HST Observations of the Main Sequence of M4 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-384397