... 2000 October 22 . Wild Duck Open Cluster M11 . ... Explanation: Many stars like our Sun were formed in open clusters . The above open cluster, M11 , contains thousands of stars and is just over three thousand light years distant. ... Open clusters , also called galactic clusters, contain fewer and younger stars than globular clusters . Also unlike globular clusters, open clusters are generally confined to the plane of our Galaxy . ... About APOD | ...

... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. December 18, 1999 . Irregular Galaxy Sextans A . ... Their newly formed, bright, blue star clusters found along beautiful, symmetric spiral arms are guaranteed to attract attention. But small irregular galaxies form stars too , like this lovely, gumdrop-shaped galaxy, Sextans A . ... About APOD > . ...

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 . ...

... After the 2nd World War, the Executive Committee of the International Astronomical Union (IAU) made two groups in Moscow responsible for catalogues of variable stars. ... Presently, the variable-star catalogue groups still exist within the Sternberg Astronomical Institute and the Institute of Astronomy of Russian Academy of Sciences . ... Elena Kazarovets (variable stars in open clusters, Peremennye Zvezdy journal, GCVS) . ... Nataliya N. Kireeva (variable stars, globular clusters, GCVS) . ...

... Here is a brief outline of the current theory of the events in the early history of the solar system: . A cloud of interstellar gas and/or dust (the "solar nebula") is disturbed and collapses under its own gravity. ... The gas cools off enough for the metal, rock and (far enough from the forming star) ice to condense out into tiny particles. (i.e. some of the gas turns back into dust). ... Once the larger of these particles get big enough to have a nontrivial gravity, their growth accelerates. ...