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מאמרים קשורים
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.
| The Henry Draper Extension Charts: A catalogue of accurate positions, proper motions, magnitudes and spectral types of 86933 stars
The Henry Draper Extension Charts (HDEC), published in the form offinding charts, provide spectral classification for some 87000 starsmostly between 10th and 11th magnitude. This data, being highlyvaluable, as yet was practically unusable for modern computer-basedastronomy. An earlier pilot project (Roeser et al. 1991) demonstrated apossibility to convert this into a star catalogue, using measurements ofcartesian coordinates of stars on the charts and positions of theAstrographic Catalogue (AC) for subsequent identification. We presenthere a final HDEC catalogue comprising accurate positions, propermotions, magnitudes and spectral classes for 86933 stars of the HenryDraper Extension Charts.
| A study of SCO 0B1 and NGC 6231. II - A new analysis
A new analysis of the Sco 0B1 association, and the two open clusters NGC6231 and Tr 24 was undertaken, making use of the extensive amount ofpublished data for this region of the southern sky. The averageinterstellar reddening, due mostly to foreground particulate matter, isE(b - y) = 0.326 mag or E(B - V) = 0.44 mag, with a pronouncednorth-to-south variation across the association. The distance moduli ofthe three aggregates are indistinguishable from one another; their meandistance from the sun is 2.0 kpc. A logarithmic age of 6.9 +/- 0.2 yearswas derived for the systems. Photometric criteria were used to assigndifferent degrees of membership to the B-type stars. Potential variablestar candidates were noted. Contrary to previous suggestions, NGC 6231retains its role as the nucleus of Sco 0B1 and, finally, the physicalreality of Tr 24 itself is questioned and briefly discussed.
| Further photometry and spectroscopy in the young cluster region TR 24/Sco OB 1
Further photometric and spectroscopic observations in the Tr 24/Sco OB 1area are presented. The new data support our earlier suggestion that Tr24 and Sco OB1 form one stellar aggregate. A high percentage (greater 70percent) of suspected pre-main sequence stars from photometry showspectral evidence for young age and/or variability. It seems now firmlyestablished that a subclustering containing 29 stars is a spatialrelated, coevally born concentration of pre-main sequence stars. Largediscrepancies in recent distance determinations of Sco OB 1 are pointedout and discussed. No real reconciliation is found, but it is suggestedthat the stars traditionally assigned to Sco OB 1 may in fact be apartial overlap of two associations.
| VBLUW photometry of the association SCO OB1 (containing the open cluster NGC 6231) - A discussion on the evolutionary status of the hypergiant Zeta(1) SCO (B1Ia+)
Attention is given to VBLUW photometry obtained for nearly 190 stars inSco OB1, of which almost 60 appear to be foreground objects.Temperature, surface gravity, and individual reddenings have beenobtained. It appears that the reddening is not uniformly distributedacross the association. Virtually all reddening is due to dust in thelocal spiral arm, up to a distance of almost 700 pc from the sun. Akinematical age of about one million years, as determined by Braes(1967), is in reasonable agreement with the average evolutionary age ofabout 3.6 + or - 0.6 years for the 12 brightest stars.
| UBV photometry of TR 24 and its relation to SCO OB1
In an area of 1.3 x 0.3 deg centered on Tr 24 UBV photometry down toabout 14m has been obtained. From color-magnitude and color-colordiagrams a distance of 2300 pc, a foreground reddening of Av = 1.10m anda cluster with an age of less than 10 to the 7th yr is derived. Tr 24and Sco OB1 form one large cluster containing many pre-main sequencestars. The existence of a small (8 x 3 pc) subgroup is pointed out whichcontains more than 20 stars and could be a T Tau-association embedded inTr 24.
| Determination of proper motions in the region of the association Scorpius OB1
Not Available
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משמש של הקבוצה הבאה
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | עקרב |
| התרוממות ימנית: | 16h56m24.71s |
| סירוב: | -40°33'13.5" |
| גודל גלוי: | 10.072 |
| תנועה נכונה: | 0.8 |
| תנועה נכונה: | -2 |
| B-T magnitude: | 10.11 |
| V-T magnitude: | 10.076 |
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