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New runaway OB stars with HIPPARCOS
A Monte Carlo method for detection of runaway OB stars fromobservational data is proposed. 61 runaway OB star candidates have beendetected by an analysis of Hipparcos proper motions. The peculiartangential and total transverse velocities have been determined forthese stars. A list of the detected runaway star candidates ispresented. The evidence of a discrepancy between photometric andparallactic distances of runaway OB star candidates is presented.
| High-resolution observations of interstellar NaI and CaII towards the southern opening of the `Local Interstellar Chimney': probing the disc-halo connection
We present high-resolution (R= 400 000) observations of interstellarCaII and NaI absorption lines towards seven stars in the direction ofthe southern opening of the recently identified Local InterstellarChimney. These lines of sight probe the lower Galactic halo (0.3<~|z|<~ 2.5 kpc), without the complication of sampling denseforeground interstellar material. In addition to components withvelocities expected from Galactic rotation, these stars also exhibitcomponents with negative local standard of rest velocities, which arecontrary to the sense of Galactic rotation for the sightlines observed.After a discussion of possible origins for these peculiar velocities, weconclude that at least some of them result from gas falling towards theGalactic plane from distances of |z|>~ 300 pc. The narrow linewidthsare generally inconsistent with temperatures as high as the ~6000 Kgenerally assumed for the so-called Lockman layer. Rather, the picturethat emerges is one of a scattered, generally infalling, population ofhigh-|z| diffuse clouds, seemingly not very different from thoseencountered in the local interstellar medium. Overall, we argue that ourresults are most consistent with a `Galactic fountain' model.
| Red and infrared colours of B stars and the reddening law in the Galaxy
The red and infrared intrinsic colours of B stars are derived fromphotometric observations through the UBV(RI)_CJHK and Hβ filters of257 early-type stars. Those stars for which the UBV and Hβmeasurements match the published spectral class, and which show no othersigns of peculiarity, are used to determine the intrinsic photometriccolours of B stars in the red and infrared. From these intrinsic coloursthe interstellar reddening relationships for the red and infraredcolours are evaluated, and the results are compared with previousestimates of these quantities. The values of R, E(B-V) and the distanceare then determined for the individual stars. R is confirmed to be closeto 3.1 in most cases, but was found to be much larger in somedirections. The relationship between R and the location of a star in theGalaxy is investigated. Usually the abnormally reddened stars seemed tobe associated with known regions of star formation. The paper alsoidentifies seven likely variable stars and a number of stars withpossible dust shells.
| The galactic reddening law - The evidence from uvby-beta photometry of B stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985A&A...142..189T&db_key=AST
| Four-colour and H beta photometry of southern B stars at high galactic latitudes
Four-color and H beta photometry has been obtained for 105 early-type HDstars with galactic latitudes less than -45 deg. They are mostly late Bstars of luminosity class V to III. Two new Am stars and several Ap orBp stars are detected photometrically. Absolute magnitudes aredetermined from the photometry and from MK types where available. Theinterstellar reddening of many of the more distant stars is very small,suggesting either the existence of undetected peculiar stars in thesample or that there are areas of effectively zero reddening at highsouthern galactic latitudes.
| Faint blue stars in the region near the South Galactic Pole.
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