Monthly Archives: May 2007

Newly discovered bright and remote clusters in M31

Extragalactic globular clusters :: preprint

[0705.4037] An updated survey of globular clusters in M31. II Newly discovered bright and remote clusters:

An updated survey of globular clusters in M31. II Newly discovered bright and remote clusters Authors: S. Galleti, M. Bellazzini, L. Federici, A. Buzzoni, F. Fusi Pecci (Submitted on 28 May 2007) Abstract: We present the first results of a large spectroscopic survey of candidate globular clusters located in the extreme outskirts of the nearby M31 galaxy. We obtained low resolution spectra of 48 targets selected from the XSC of 2MASS, as in Galleti et al. (2005). The observed candidates have been robustly classified according to their radial velocity and by verifying their extended/point-source nature from ground-based optical images. Among the 48 observed candidates clusters we found 5 genuine remote globular clusters…

Distances of GCs Ter5, Liller 1, UKS and Terzan 4 with NICMOS…

Bulge globular clusters :: preprint

Distances of the bulge globular clusters Terzan 5, Liller 1, UKS 1 and Terzan 4 based on HST NICMOS photometry

Authors: S. Ortolani, B. Barbuy, E. Bica, M. Zoccali, A. Renzini

Abstract: A large number of pulsars and X-rays sources are detected in globular clusters. To understand the structure and content of these clusters, accurate distances are required. We derive the distances of Terzan 5, Liller 1 and UKS 1 using as a reference a recent distance determination of NGC 6528, based on HST/NICMOS and NTT/SOFI infrared photometry. The distance of the metal-poor cluster Terzan 4 was derived from a comparison with M92 in NICMOS bands…

URL: http://babbage.sissa.it/abs/0705.4030

Hubble finds multiple stellar “baby booms” in a globular cluster

Hubble finds multiple stellar “baby booms” in a globular cluster:

Analysis of Hubble observations of the massive globular cluster NGC 2808 provides evidence that it has three generations of stars that formed early in the cluster’s life. This is a major upset for conventional theories as astronomers have long thought that globular star clusters had a single “baby boom” of stars early in their lives and then settled down into a long, quiet middle age.

NGC 2808

NGC 2808 :: Credits: European Space Agency, NASA, G. Piotto (University of Padua, Italy) and A. Sarajedini (University of Florida, USA). Acknowledgement: Davide de Martin (ESA/Hubble)