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Limited diversity of the interstellar extinction law
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| An interesting nebular object in LDN 288
In this paper the results of multiwavelength investigation of an unusualnebular object SNO 85 are presented. In 2MASS images this object lookslike a star with a jet. In DSS2 R image the end of the jet is connectedwith an interesting symmetric structure, consisting of arcs and loops.Such a structure is seen also in the opposite direction from the centralstar; it favors the existence of two opposite jets, which repeat therotation and precession movements of the central star. The results of12CO observations of the dark nebula LDN 288, connected withSNO 85, are also given. From these observations the following resultswere obtained: SNO 85 is situated in a dense condensation and theneighbor B type star GSC 0625400181 is surrounded by a hollow cavity.The velocity of the dark cloud is ˜2.5 km/s and its distance isestimated as (380 990) pc. The object SNO 85 itself is associated withan IRAS point source IRAS 17547-1832, the infrared colors of this sourceare typical for a non-evolved source embedded in the dense dark cloud.This region is perhaps a star formation one because there is alsoanother star with a straight jet in the vicinity of B type star GSC0625400181.
| New Estimates of the Solar-Neighborhood Massive Star Birthrate and the Galactic Supernova Rate
The birthrate of stars of masses >=10 Msolar is estimatedfrom a sample of just over 400 O3-B2 dwarfs within 1.5 kpc of the Sunand the result extrapolated to estimate the Galactic supernova ratecontributed by such stars. The solar-neighborhood Galactic-plane massivestar birthrate is estimated at ~176 stars kpc-3Myr-1. On the basis of a model in which the Galactic stellardensity distribution comprises a ``disk+central hole'' like that of thedust infrared emission (as proposed by Drimmel and Spergel), theGalactic supernova rate is estimated at probably not less than ~1 normore than ~2 per century and the number of O3-B2 dwarfs within the solarcircle at ~200,000.
| Catalog of Galactic OB Stars
An all-sky catalog of Galactic OB stars has been created by extendingthe Case-Hamburg Galactic plane luminous-stars surveys to include 5500additional objects drawn from the literature. This work brings the totalnumber of known or reasonably suspected OB stars to over 16,000.Companion databases of UBVβ photometry and MK classifications forthese objects include nearly 30,000 and 20,000 entries, respectively.
| 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.
| An Einstein Observatory SAO-based catalog of B-type stars
About 4000 X-ray images obtained with the Einstein Observatory are usedto measure the 0.16-4.0 keV emission from 1545 B-type SAO stars fallingin the about 10 percent of the sky surveyed with the IPC. Seventy-fourdetected X-ray sources with B-type stars are identified, and it isestimated that no more than 15 can be misidentified. Upper limits to theX-ray emission of the remaining stars are presented. In addition tosummarizing the X-ray measurements and giving other relevant opticaldata, the present extensive catalog discusses the reduction process andanalyzes selection effects associated with both SAO catalog completenessand IPC target selection procedures. It is concluded that X-rayemission, at the level of Lx not less than 10 exp 30 ergs/s, is quitecommon in B stars of early spectral types (B0-B3), regardless ofluminosity class, but that emission, at the same level, becomes lesscommon, or nonexistent, in later B-type stars.
| Walraven photometry of nearby southern OB associations
Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars inthe regions of five nearby southern OB associations: Scorpio Centaurus(Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2.Derived V and (B - V) in the Johnson system are included.
| The interstellar 217 NM band - A third catalogue of equivalent widths
A catalog of equivalent widths of the 217 nm interstellar absorptionband as well as other parameters characterizing the extinction curve inthe ultraviolet has been compiled for 790 O and B stars. A relativelytight correlation between the equivalent width of the 217 nm band andE(B-V) indicates that the absorber of this band is connected with thepopulation of larger interstellar grains responsible for the visualextinction. The parameter characterizing the amount of extinction in thefar UV is only weakly correlated with E(B-V), a result in accord withthe assumption that a second population of very small grains causes therapid increase of the far-UV extinction.
| Spectral classification and photometry of southern B stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1961MNRAS.122..239F&db_key=AST
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| Takýmyýldýz: | Kalkan |
| Sað Açýklýk: | 18h28m20.13s |
| Yükselim: | -09°35'05.3" |
| Görünürdeki Parlaklýk: | 10.532 |
| özdevim Sað Açýklýk: | 0.7 |
| özdevim Yükselim: | -2.9 |
| B-T magnitude: | 11.116 |
| V-T magnitude: | 10.581 |
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