Masses and luminosities of O- and B-type stars and red supergiants
Massive stars are of interest as progenitors of supernovae, i.e.neutron stars and black holes, which can be sources of gravitationalwaves. Recent population synthesis models can predict neutron star andgravitational wave observations but deal with a fixed supernova rate oran assumed initial mass function for the population of massive stars. Here we investigate those massive stars, which are supernovaprogenitors, i.e. with O- and early B-type stars, and also allsupergiants within 3 kpc. We restrict our sample to those massive starsdetected both in 2MASS and observed by Hipparcos, i.e. only those starswith parallax and precise photometry. To determine the luminositieswe calculated the extinctions from published multi-colour photometry,spectral types, luminosity class, all corrected for multiplicity andrecently revised Hipparcos distances. We use luminosities andtemperatures to estimate the masses and ages of these stars usingdifferent models from different authors. Having estimated theluminosities of all our stars within 3 kpc, in particular for all O- andearly B-type stars, we have determined the median and mean luminositiesfor all spectral types for luminosity classes I, III, and V. Ourluminosity values for supergiants deviate from earlier results: Previouswork generally overestimates distances and luminosities compared to ourdata, this is likely due to Hipparcos parallaxes (generally moreaccurate and larger than previous ground-based data) and the fact thatmany massive stars have recently been resolved into multiples of lowermasses and luminosities. From luminosities and effective temperatureswe derived masses and ages using mass tracks and isochrones fromdifferent authors. From masses and ages we estimated lifetimes andderived a lower limit for the supernova rate of ?20 events/Myraveraged over the next 10 Myr within 600 pc from the sun. These data arethen used to search for areas in the sky with higher likelihood for asupernova or gravitational wave event (like OB associations).
|
Inaccuracies in the spectral classification of stars from the Tycho-2 Spectral Type Catalogue
We compare the spectroscopic and trigonometric parallaxes of commonstars from the Tycho-2 Spectral Type and Hipparcos Catalogues. Thiscomparison has revealed that the distance estimations for theoverwhelming majority of stars by both methods yield very similarresults. However, there is a small fraction of stars for which thedistance estimates differ significantly. It is these stars that are thesubject of our study. We have been able to find the causes of thesedifferences.
|
Evidence for Chimney Breakout in the Galactic Supershell GSH 242-03+37
We present new high-resolution neutral hydrogen (H I) images of theGalactic supershell GSH 242-03+37. These data were obtained with theParkes Radiotelescope as part of the Galactic All-Sky Survey (GASS). GSH242-03+37 is one of the largest and most energetic H I supershells inthe Galaxy, with a radius of 565+/-65 pc and an expansion energy of3×1053 ergs. Our images reveal a complicated shell withmultiple chimney structures on both sides of the Galactic plane. Thesechimneys appear capped by narrow filaments about 1.6 kpc above and belowthe Galactic midplane, confirming structures predicted in simulations ofexpanding supershells. The structure of GSH 242-03+37 is extremelysimilar to the only other Galactic supershell known to have blown out ofboth sides of the plane, GSH 277+00+36. We compare the GASS H I datawith X-ray and Hα images, finding no strong correlations.
|
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.
|
The distribution of bright OB stars in the Canis Major-Puppis-Vela region of the Milky Way
The picture of the young stellar groups in the Canis Major-Puppis-Vela(215 deg
|
Strömgren and Hβ photometry of O and B type stars in star-forming regions. I. Canis Major - Puppis - Vela
Strömgren and Hβ photometry of OB-stars generally brighterthan 9.5 mag in the Canis Major - Puppis - Vela region of Milky Way isreported. The observations are based on the Milky Way luminous-star (LS)identifications and are designed to create a complete, magnitude-limitedsample of LS for this field. We present new uvby photometry for 127 LSand Hβ photometry for 25 of them. These observations are part of anongoing effort to improve the completeness of the existing uvbybetadata-base for the bright OB-type stars in the Milky Way, with the aim toinvestigate the structure of selected star-forming regions. Based ondata from the Strömgren Automatic Telescope of the CopenhagenAstronomical Observatory, La Silla. Tables 3 and 4 are only available inelectronic form at the CDS via anonymous ftp to 130.79.128.5 or viahttp://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.
|
The warped distribution of young stars in the southern Milky Way
From a sample presented by Reed containing OB stars with a heliocentricdistance greater than 5kpc, we have selected those stars with agalactocentric azimuth between 240 deg and 275 deg, i.e. in the regionof the maximum warp in the southern hemisphere. Only nine stars havethese characteristics, but they permit a first, unambiguous detection ofthe southern stellar warp in the Milky Way. This seems to be as large asthe gaseous warp, and does not present evidence of twisting of the lineof nodes. Flaring of the stellar distribution with respect to thecentroid of the HI warp is also noticeable.
|
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.
|
Distant (r greater than 5 kpc) OB stars in the galaxy
Distances and reddenings have been computed from UBV Beta photometry for1042 stars in the Stephenson and Sanduleak (1971) Catalog of LuminousStars in the Southern Milky Way ('LS' Catalog). The local spiral featureis likely a continuous feature toward Puppis at l approximately equals240 deg, and the Carina feature apparently extends to a distance of some10 kpc from the Sun. Detailed information is presented for 73 LS starsthat appear to be at least 5 kpc from the Sun. Of these, three (LS 1329,2419, and 2598) are close to 1.5 kpc below the galactic plane, and one,LS 607, may be ideally suited as a distant rotation-curve point.Radial-velocity and spectroscopic data would be valuable for theseobjects.
|
Ultraviolet observations in Puppis with the space telescope 'GLAZAR'
The results of observations of 159 stars at 1640 A in Puppis made withthe space telescope 'Glazar' are presented. It is shown that theobserved stars are members of different groups of stars situated atdistances of about 120, 370, 700, 1250, 2400, and 4000 pc. The last twogroups belong to the Pup OB1 and Pup OB2 stellar associations. There isrelatively little absorption in the observed region. The absorbingmatter is mainly concentrated in small clouds. It is suggested thatthree stars - CP - 27 deg 4197, HD 60479, and HD 61672 - are embedded ina dust envelope and that the star HD 60057 has a hot subdwarf companion.Forty-four of the observed stars are new OB or early A-type stars,spectral types of which were not known.
|
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.
|
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.
|
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.
|
The OB stars in the vicinity of the long period Cepheid VZ Puppis
UVB, beta photoelectric photometry of catalogued OB stars surrounding VZPuppis reveals only a few stars at the Cepheid's distance of 5.6 kpc.Good evidence is found, however, for the existence of an OB associationat 4 kpc in agreement with other young spiral tracers in and below theplane. A comparison of the distribution of these tracers with that of HI confirms that the Schmidt model rotation curve is not valid below theplane and suggests that there are distinct kinematic groups among thePopulation I objects in this direction.
|
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
|
A Finding List of High-Luminosity Stars. II.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1951ApJ...114..482M&db_key=AST
|
