On the velocity dispersion in the core of the globular cluster M15

Computer Science – Numerical Analysis

Scientific paper

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

18

Celestial Mechanics, Computerized Simulation, Cross Correlation, Error Analysis, Globular Clusters, Numerical Analysis, Velocity Distribution, Astronomical Observatories, Charge Coupled Devices, Hubble Space Telescope, Spectrographs

Scientific paper

A projected velocity dispersion sigmap of 0 = 14.0 km/s is derived from an integrated light spectrum obtained at the European Southern Observatory (ESO) at La Silla, Chile, over a central 6 sec x 6 sec area in the core of the globular cluster M15. Extensive numerical simulations of velocity dispersion determinations from integrated light spectra show that all the velocity dispersions obtained from integrated light measurements over small central areas suffer from large statistical errors due to the small numbers of bright stars present in the integration area. These simulations, over our area of integration of 6 sec x 6 sec, give sigmap = 15(+6/-4) km/s as the most probable values for the central velocity dispersion and its statistical error. The observational result differs from the challenging high central velocity dispersion sigmap of 0 = 25 km/s derived by Peterson, Seitzer, & Cudworth (1989) are consistent with ours. In a similar way, all the above velocity dispersion values obtained from integrated light measurements are consistent with the velocity dispersion sigmap = 14.2 +/- 1.9 km/s obtained by Peterson et al. (1989) from the radial velocities of 27 stars within 20 sec of the center. Given the large statistical errors on the integrated light measurements, there is no significant observational evidence that the central value of the velocity dispersion is much larger than about 15 km/s. All observed values are consistent with the predictions from various theoretical dynamical models of M15: sigmap of 0 = 12-17 km/s from Illingworth & King (1977), sigma p of 0 = 13-15 km/s from Phinney & Sigurdsson (1991) and Phinney (1993), and sigmap of 0 = 14 km/s from Grabhorn et al. (1992). Although it cannot be ruled out, the presence of a massive black hole or some nonthermal dynamics in the core of M15 is not required by the present observations.

No associations

LandOfFree

Say what you really think

Search LandOfFree.com for scientists and scientific papers. Rate them and share your experience with other people.

Rating

On the velocity dispersion in the core of the globular cluster M15 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 On the velocity dispersion in the core of the globular cluster M15, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On the velocity dispersion in the core of the globular cluster M15 will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFWR-SCP-O-884847

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.