Absolute proper motions of globular clusters
The absolute proper motions for a total of 92 globular clusters of the Milky Way (60% of all clusters included in the catalogue published by Harris) are inferred from the UCAC2 proper motions of their likely member stars. The median formal error of the cluster proper motions is equal to 0.8ÂmarcsecÂyear–1 in both right ascension and declination, whereas the proper-motion errors of individual clusters range from 0.2 to 3ÂmarcsecÂyear–1. Tests performed demonstrate the overall validity of the cluster motions; the resulting transverse velocities remain, on the average, virtually constant out to a heliocentric distance of 15Âkpc and the full space velocity of most of the clusters relative to the Galactic centre remains, on the average, unchanged near 190ÂkmÂs–1 out to a Galactocentric distance of about 20Âkpc, in agreement with the overall isothermal structure of the Galactic halo.
Document Type: Research Article
Affiliations: Sternberg Astronomical Institute, Universitetskij Prospekt 13, Moscow, 119992, Russia
Publication date: 2006-04-01