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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.
| First CCD measurements in the {DELTA}a system for detecting CP2 stars.
This is the first time that CCD-photometry in the three filter {DELTA}asystem (Maitzen, 1976A&A....52..223M) was carried out after twodecades of classical photoelectric photometry. The aim is to extend thesuccessful search for chemically peculiar stars to more and distant openclusters as well as far galactic fields. In this paper we presentCCD-photometry for a sample of 25 field stars with publishedspectroscopic peculiarity types. 22 of them show discordance betweentheir Michigan catalogue types (non-peculiar) and the Bidelman &MacConnell (1973AJ.....78..678B; BC) peculiarity assignments. Eightstars are peculiar in {DELTA}a (five of them also in the Geneva index{DELTA}(V1-G)) thus supporting BC, mainly among their Silicon stardiscoveries. Considering cases where Silicon line enhancements wereinterpreted as peculiar instead as indicator of higher luminosity by BC,and the perfect detection of the three unambiguous peculiar stars, inaddition to the achievement of an accuracy of 0.003mags, we arejustified to conclude that the performance of our CCD-{DELTA}aphotometry perfectly matches the requirements of the conventionalphotometric technique and thus opens the way to observations of fainterstars.
| Uvbyβ photometry of all stars earlier than G0 and brighter than m_pg_~10.3mag in Selected Area 194
Four-colour and Hβ photometry is introduced for 594 stars earlierthan G0 in the Kapteyn's Selected Area 194. The results give V, b-y,m_1_, c_1_, and β on the standard systems, with overall rms errorsfor one observation of one star of 0.009mag, 0.004mag, 0.006mag,0.009mag, and 0.009mag, respectively. The data cover an area of about5deg x 5deg and is intended for an investigation of the distribution ofthe interstellar medium toward the northern part of the SouthernCoalsack and its surroundings. A comparison to earlier results obtainedby other authors has shown that the c_1_ indices obtained for the latetype stars were underestimated, in average, by 0.020mag. Since suchdifference may account for an error of little more than 10% in theestimated stellar distances, a correction was applied to the c_1_ indexof these stars.
| A spectral survey of the southern Milky Way 1 : general description and catalogue 1 (l=306 -318 degrees).
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974A&AS...16..445S&db_key=AST
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | קנטאור |
| התרוממות ימנית: | 13h15m39.83s |
| סירוב: | -62°03'35.7" |
| גודל גלוי: | 9.103 |
| תנועה נכונה: | -21.4 |
| תנועה נכונה: | -5.6 |
| B-T magnitude: | 9.217 |
| V-T magnitude: | 9.113 |
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