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|Astrophysical parameters of Galactic open clusters|
We present a catalogue of astrophysical data for 520 Galactic openclusters. These are the clusters for which at least three most probablemembers (18 on average) could be identified in the ASCC-2.5, a catalogueof stars based on the Tycho-2 observations from the Hipparcos mission.We applied homogeneous methods and algorithms to determine angular sizesof cluster cores and coronae, heliocentric distances, mean propermotions, mean radial velocities, and ages. For the first time we derivedistances for 200 clusters, radial velocities for 94 clusters, and agesof 196 clusters. This homogeneous new parameter set is compared withearlier determinations, where we find, in particular, that the angularsizes were systematically underestimated in the literature.
|New infrared star clusters in the southern Milky Way with 2MASS|
We carried out a 2MASS J, H and Ks survey of infrared starclusters in the Milky Way sector 230deg< l <350deg. This zone was the least studied in the literature,previously including only 12 infrared clusters or stellar groups with|b|< 10deg, according to the recent catalogue by Bica etal. (2003). We concentrated efforts on embedded clusters, which arethose expected in the areas of known radio and optical nebulae. Thepresent study provides 179 new infrared clusters and stellar groups,which are interesting targets for detailed future infrared studies. Thesample of catalogued infrared clusters and stellar groups in the Galaxyis now increased by 63%.
|Thackeray's globules in IC 2944|
We have studied the complex of small globules discovered by A.D.Thackeray in the southern HII region IC 2944. They are located preciselyon the line-of-sight to the luminous OB stars in the region, and thusappear as shadows against the bright HII region. Thanks to thisgeometry, exceptionally fine details can be discerned on CCD images,which show that the globules are generally sharp-edged and highlystructured, and that the complex contains a multitude of fragments inall sizes down to the resolution element of about one arcsec (1800 AU).CO millimeter observations reveal that the largest globule consists oftwo kinematically separate entities, with masses of about 11 and 4M_sun. Very large velocity differences exist between the variousglobules, suggesting that the globules comprise a highly dynamic systemperhaps one million years old. We believe that the globules are theremnants of an elephant-trunk observed from behind, originating as aRayleigh-Taylor instability in an expanding neutral shell powered by thehot HII region. The globule complex is now in an advanced stage ofdisintegration. We have found no evidence for star formation in any ofthe globules. Based on observations collected at the European SouthernObservatory, La Silla, Chile
|Star-forming loops in the IRAS sky images|
Loops containing diffuse and discrete emission are a feature of the IRASsky images. Some of these loops are limb-brightened shells resultingfrom supernovae or stellar winds acting on the interstellar medium.Secondary star formation appears to have occurred at the surface ofthese shells. A significant proportion of the early-type stars in thesolar neighborhood appear to have formed in stellar loops.
|The O-type ionizing cluster in IC 2944|
Observational data on IC 2944 are compiled and analyzed. It is shownthat, contrary to some recent discussions (Ardeberg and Maurice, 1980;Perry and Landolt, 1986), the O stars in the field of the H II region IC2944 constitute a significant physical cluster.
|Multicolor photometry of the presumed stellar aggregate IC 2944|
Based on the results of a multicolor photometric study of IC 2944,several lines of evidence indicate that the aggregate is an apparentstellar concentration due to the superposition of early-type field starsalong the line of sight. The distance interval covered by the early-typestars is void of interstellar dust; the reddening over the region, whichexhibits a decided longitude effect, is caused by foreground material.Individual observations are tabulated for the photometric variables,together with the heliocentric JD times of midobservation. Theintermediate helium star CPD -62 deg 2124 does not exhibit photometricvariations but the amount of data is limited.
|Catalogue of Eclipsing and Spectroscopic Binary Stars in the Regions of Open Clusters|
|Uniform survey of clusters in the southern Milky Way.|
Abstract image available at:http://adsabs.harvard.edu/abs/1975AJ.....80...11V
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