Two high-velocity stars shot out from the core of the globular cluster 47 Tucanae

Abstract

view Abstract Citations (52) References (34) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Two High-Velocity Stars Shot Out from the Core of the Globular Cluster 47 Tucanae Meylan, G. ; Dubath, P. ; Mayor, M. Abstract The discovery of two high-velocity stars in the core of the globular cluster 47 Tucanae is reported. Located respectively at about 3 and 38 arcsec from the center, they have radial velocities relative to the cluster equal to -36.7 and +32.4 km/s, corresponding to 4.0 and 3.6 times the velocity dispersion in the core, which is equal to 9.1 km/s. These velocities are of the order of, or larger than, the central escape velocity estimates. The long time baseline between repeated observations and the constancy of the radial velocity values indicate that neither of these two stars is a binary or a pulsating star. They have positions on the red giant branch and asymptotic giant branch in the color-magnitude diagram which favor their membership. The main mechanism for explaining these two interlopers is the ejection out of the core by stellar encounters between a single star and a binary, or between two binary stars. The large stellar radii involved (about 40 and 100 solar radii) imply large impact parameters. Publication: The Astrophysical Journal Pub Date: December 1991 DOI: 10.1086/170816 Bibcode: 1991ApJ...383..587M Keywords: Asymptotic Giant Branch Stars; Globular Clusters; Radial Velocity; Red Giant Stars; Stellar Motions; Binary Stars; Color-Magnitude Diagram; Stellar Cores; Stellar Spectrophotometry; Astrophysics; CLUSTERS: GLOBULAR; STARS: HIGH-VELOCITY; STARS: STELLAR DYNAMICS full text sources ADS | data products SIMBAD (5)