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HD 252812


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Distribution of early type stars and dusty matter in the direction of the star cluster NGC 2175
The distribution of 120 O-B9-A2 stars and of the interstellar dust inthe direction of the star clusters NGC 2175 and NGC 2175s (the complexS252) is studied in terms of V, (B-V), and (U-B) data. Ten star groups(associations) are found at distances of 410, 720, 1000, 1500, 2200,3100, 4000, 5200, 7000, and 8100 pc. Three of these, at distances of410, 720, and 1000 pc, are type B associations. The remaining seven areOB associations. They are designated as Gem B 0.41, Gem B 0.72, Gem B1.0, Gem OB 1.5, Gem OB 2.2, Gem OB 3.1, Gem OB 4.0, Gem OB 5.2, Gem OB7.0, and Gem OB 8.1. The V absorption (AV) for stars No.2, 18, 20, 23,24, 26, 40, 41, 47, 69, 87, 88, 90, 95, 100 and 109 is estimated to be2m.78,4m.72, 2m.69, 3m.33, 2m.61, 2m.86, 4m.67, 6m.21, 3m.14, 3m.92,2m.69, 3m.04, 5m.95, 5m.95, 3m.20 and 5m.66, respectively. For most ofthese stars the absorption lies between 0m.5 and 2m.5. This largeabsorption may be caused by circumstellar absorption. The dust in theassociations Gem B 0.41 and Gem B 0.72 is distributed nonuniformly.There is no dust in the space between the associations. Essentiallythere is no dust inside those groups (associations) which lie atdistances greater than 1 kpc.

UBV beta Database for Case-Hamburg Northern and Southern Luminous Stars
A database of photoelectric UBV beta photometry for stars listed in theCase-Hamburg northern and southern Milky Way luminous stars surveys hasbeen compiled from the original research literature. Consisting of over16,000 observations of some 7300 stars from over 500 sources, thisdatabase constitutes the most complete compilation of such photometryavailable for intrinsically luminous stars around the Galactic plane.Over 5000 stars listed in the Case-Hamburg surveys still lackfundamental photometric data.

UBVRI photometry and polarimetry of the stars in S252 (NGC 2175). II. Interpretation.
Photoelectric UBVRI photometry and polarimetry and photographic UBVRphotometry have been used to study the stellar cluster NGC2175associated with the Hii region-molecular cloud complex Sharpless252. Thecolour excess E_B-V_ of stars in NGC2175 ranges from the foregroundcolour excess of 0.4mag up to 1.7mag. The distance modulus of S252obtained by fitting ZAMS to the colour-magnitude diagrams of NGC2175 is11.7+/-0.3mag (2.2+/-0.3kpc). The lower part of the colour-magnitudediagrams of the main cluster contains stars still contracting towardsZAMS indicating an age of the order of one million years for thecluster. The age of a small subcluster to the east of the Hii region isa few million years. High stellar polarizations up to 12% have beenobserved. The average wavelength of the maximum polarization in S252 is0.53+/-0.01μm and the polarization efficiency is near the empiricalmaximum value 3A_v_. The polarization field in S252 is regular butcannot be explained by a single magnetic field direction.

UBVRI photometry and polarimetry of the stars in S 252 (NGC 2175). I. The observations.
Photoelectric UBVRI photometry and polarimetry and photographic UBVRphotometry of stars in the direction of the galactic H II regionSharpless 252 are reported

NGC 2175 - The cluster age and the nature of the nebulosity surrounding S 252a
The galactic cluster NGC 2175 has been proposed as an extraordinarilyyoung stellar association. New photometric and spectroscopic data do notsupport this suggestion. There do not appear to be any pre-main-sequenceB stars present in the cluster. We have derived an age for the clusterof 2 million years. The physical nature of an optical nebulosityassociated with the B star S 252a was investigated. It is concluded thatthe object is primarily a reflection nebula due to a dense neutralcloud. This cloud is surrounded by a thin, high density, low excitationionized zone. An evolutionary model for the cloud is proposed.

A study of the I GEM association.
Not Available

Mesures d'étoiles doubles obtenues au télescope de Marseille. Mouvements Observés sur quelques couples
Not Available

Studies of bright diffuse galactic nebulae with special regard to their spatial distribution.
Not Available

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Pozíciós és asztrometriai adatok

Csillagkép:Orion
Rektaszcenzió:06h10m52.72s
Deklináció:+20°36'32.7"
Vizuális fényesség:10.478
RA sajátmozgás:-204.1
Dec sajátmozgás:-130.9
B-T magnitude:10.846
V-T magnitude:10.509

Katalógusok és elnevezések:
Megfelelő nevek   (Edit)
HD 1989HD 252812
TYCHO-2 2000TYC 1322-1497-1
USNO-A2.0USNO-A2 1050-03149521

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