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And in the Darkness Bind Them: Equatorial Rings, B[e] Supergiants, and the Waists of Bipolar Nebulae
We report the discovery of two new circumstellar ring nebulae in thewestern Carina Nebula, and we discuss their significance in stellarevolution. The brighter of the two new objects, SBW 1, resembles alidless staring eye and encircles a B1.5 Iab supergiant. Although seenin Carina, its luminosity class and radial velocity imply a largerdistance of ~7 kpc in the far Carina arm. At that distance its size andshape are nearly identical to the equatorial ring around SN 1987A, butSBW 1's low N abundance indicates that the ring was excreted without itsstar passing through a red supergiant phase. The fainter object, SBW 2,is a more distorted ring, is N-rich, and is peculiar in that its centralstar seems to be invisible. We discuss the implications of these two newnebulae in context with other circumstellar rings such as those aroundSN 1987A, Sher 25, HD 168625, RY Scuti, WeBo 1, SuWt 2, and others. Thering bearers fall into two groups: Five rings surround hot supergiants,and it is striking that all except for the one known binary are carboncopies of the ring around SN 1987A. We propose a link between these Bsupergiant rings and B[e] supergiants, where the large spatiallyresolved rings derive from the same material that would have given riseto emission lines during the earlier B[e] phase, when it was much closerto the star. The remaining four rings surround evolved intermediate-massstars; all members of this ring fellowship are close binaries, hintingthat binary interactions govern the forging of such rings. Two-thirds ofour sample are found in or near giant H II regions. We estimate thatthere may be several thousand more dark rings in the Galaxy, but we arescarcely aware of their existence-either because they are onlyilluminated in precious few circumstances or because of selectioneffects. For intermediate-mass stars, these rings might be thepreexisting equatorial density enhancements invoked to bind the waistsof bipolar nebulae.Based in part on observations made at the Clay Telescope of the MagellanObservatory, a joint facility of the Carnegie Observatories, HarvardUniversity, the Massachusetts Institute of Technology, the University ofArizona, and the University of Michigan.
| Observations of OB-stars at the former Leiden Southern Station
About 700 stars, mostly OB-stars, were observed by the author at theformer Leiden Southern Station at Hartebeespoortdam, South Africa, inthe observing seasons 1965, 1968, 1969, 1974, 1977, 1978. Observationswere made in the five channels of the Walraven photometric system. Dueto weathering of the telescope mirror the W channel gave no reliableresults for the faintest stars (m = 11 mag); in these cases the U-Wcolour index is not given. The change in sensitivity in the V channel,supposedly having occurred in 1968, was not recognised. Table~5 is onlyavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/369/527
| Five-colour photometry of OB-stars in the Southern Hemisphere
Observations of OB-stars, made in 1959 and 1960 at the Leiden SouthernStation near Hartebeespoortdam, South Africa, with the VBLUW photometerattached to the 90 cm light-collector, are given in this paper. They arecompared with photometry obtained by \cite[Graham (1968),]{gra68}\cite[Walraven & Walraven (1977),]{wal77} \cite[Lub & Pel(1977)]{lub77} and \cite[Van Genderen et al. (1984).]{gen84} Formulaefor the transformation of the present observations to those of\cite[Walraven & Walraven (1977)]{wal77} and \cite[Lub & Pel(1977)]{lub77} are given. Table 4 is only available in electronic format the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) orvia http://cdsweb.u-strasbg.fr/Abstract.html
| 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.
| A spectroscopic database for Stephenson-Sanduleak Southern Luminous Stars
A database of published spectral classifications for objects in theStepenson-Sanduleak Luminous Stars in the Southern Milky Way catalog hasbeen compiled from the literature. A total of 6182 classifications for2562 stars from 139 sources are incorporated.
| The local system of early type stars - Spatial extent and kinematics
Published uvby and H-beta photometric data and proper motions arecompiled and analyzed to characterize the structure and kinematics ofthe bright early-type O-A0 stars in the solar vicinity, with a focus onthe Gould belt. The selection and calibration techniques are explained,and the data are presented in extensive tables and graphs and discussedin detail. The Gould belt stars of age less than 20 Myr are shown togive belt inclination 19 deg to the Galactic plane and node-lineorientation in the direction of Galactic rotation, while the symmetricaldistribution about the Galactic plane and kinematic properties (purecircular differential rotation) of the belt stars over 60 Myr oldresemble those of fainter nonbelt stars of all ages. The unresolveddiscrepancy between the expansion observed in the youngest nearby starsand the predictions of simple models of expansion from a point isattributed to the inhomogeneous distribution of interstellar matter.
| UBV photometry for southern OB stars
New UBV photometry of 1227 OB stars in the southern Milky Way ispresented. For 1113 of these stars, MK spectral types have been reportedpreviously in a comprehensive survey to B = 10.0 mag.
| Four-colour and H-beta photometry for early type stars in three southern galactic regions
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980A&AS...41...85L&db_key=AST
| On the 4430 A interstellar band - A visual classification
A system of visual classification of the strength of the interstellarband 4430 A has been developed, based on spectra taken at spectralclassification dispersion. The intensity of the band was divided into 8main classes, defined by a group of selected standard stars. The systemwas applied to 1,111 southern OB stars contained in the catalog ofspectral types by Garrison, Hiltner, and Schild (1977). The mean errorin the classification was estimated to be plus or minus 1 class.Equivalent widths were measured for 100 stars; an excellent correlationwith the visual estimations was obtained. A calibration between thesetwo parameters is given.
| MK spectral classifications for southern OB stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977ApJS...35..111G&db_key=AST
| O stars and supergiants south of declination -53 0.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976AJ.....81..116H&db_key=AST
| Spectroscopic and photometric observations of luminous stars in the Cen-Nor (l=305-340 degrees) section of the Milky Way.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975A&AS...19..243H&db_key=AST
| 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
| Studies of the Milky Way from Centaurus to Norma. III. OB stars.
Not Available
| Photo-electric colours of southern early-type stars
Not Available
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Osservazione e dati astrometrici
| Costellazione: | Centauro |
| Ascensione retta: | 13h55m52.32s |
| Declinazione: | -59°22'16.5" |
| Magnitudine apparente: | 7.855 |
| Distanza: | 500 parsec |
| Moto proprio RA: | -2.9 |
| Moto proprio Dec: | -2.2 |
| B-T magnitude: | 7.999 |
| V-T magnitude: | 7.867 |
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