... 2004 September 18 . M55: Globular Star Cluster . ... Explanation: The fifty-fifth entry in Charles Messier's catalog, M55 is a large and lovely globular cluster of around 100,000 stars. ... Globular star clusters like M55 roam the halo of our Milky Way Galaxy as gravitationally bound populations of stars known to be much older than stellar groups found in the galactic disk. Astronomers who make detailed studies of globular cluster stars can accurately measure the cluster ages and distances. ...

... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. September 17, 1999 . M3: Half A Million Stars . ... Explanation: This immense ball of half a million stars older than the sun lies 30,000 light-years above the plane of our Galaxy. Cataloged as M 3 (and NGC 5272), it is one of about 250 globular star clusters which roam our galactic halo . ... About APOD > . ... NASA Technical Rep.: ...

Supernova 1999cl in M88 . This page is devoted to information on Supernova 1999cl in M88 Basic information on this SN, including the last reported brightness, on this Supernova can be found on the main supernova page. Information on the original web pages for many of these images can be found on the Supernova links web page. ... M1 Supernova Search has a 1999cl page . ... Pedro Re' Animated gif image . ... DAX Observatory . ... vsnet-obs 21040 ] (fwd) Observation of Supernova 1999cl in M88 . ...

... At present, he is a Leading researcher at the Department of Non-Stationary Stars and Stellar Spectroscopy, heading the group of the General Catalogue of Variable Stars, and a Leading researcher at the Department of Variable Stars and Galactic Astronomy of the Sternberg Astronomical Institute, heading the group of Variable Stars. ... P.P. Parenago, B.V. Kukarkin, P.N. Kholopov leaded the team of variable star catalogue compilers at Astronomical Council/INASAN and at Sternberg Institute through years....

ABSOLUTE PROPER MOTIONS OF 331 OPEN CLUSTERS . ... The proper motions of stars in the fields of 331 open clusters were taken from Four-Million Star Catalog (4M-catalog) of positions and proper motions (Volchkov et al. ... The absolute proper motions for 21 young open clusters have been derived by comparison of precise relative proper motions of individual stars and their corresponding absolute proper motions. ... Sign of proper motions in RA . ... 0.0001 arcsec/yr . ... rms error in RA proper motion . ...

... The distance scales of the objects are matched both by comparing the first derivatives of the angular velocity determined separately from radial velocities and proper motions and by the statistical-parallax method. ... Good agreement between the inferred 0 and our calculations based on space velocities suggests that the Lindblad relation holds throughout the entire sample volume. ... Brandt and Blitz (1993) published the distances and radial velocities for a total of 206 H II-regions. ... Astron. ...