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A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun
Traditionally, runaway stars are O- and B-type stars with large peculiarvelocities. We would like to extend this definition to young stars (upto ?50 Myr) of any spectral type and to identify those present in theHipparcos catalogue by applying different selection criteria, such aspeculiar space velocities or peculiar one-dimensional velocities.Runaway stars are important for studying the evolution of multiple starsystems or star clusters, as well as for identifying the origins ofneutron stars. We compile the distances, proper motions, spectral types,luminosity classes, V magnitudes and B-V colours, and we utilizeevolutionary models from different authors to obtain star ages. We studya sample of 7663 young Hipparcos stars within 3 kpc from the Sun. Theradial velocities are obtained from the literature. We investigate thedistributions of the peculiar spatial velocity and the peculiar radialvelocity as well as the peculiar tangential velocity and itsone-dimensional components and we obtain runaway star probabilities foreach star in the sample. In addition, we look for stars that aresituated outside any OB association or OB cluster and the Galactic planeas well as stars for which the velocity vector points away from themedian velocity vector of neighbouring stars or the surrounding local OBassociation/cluster (although the absolute velocity might be small). Wefind a total of 2547 runaway star candidates (with a contamination ofnormal Population I stars of 20 per cent at most). Thus, aftersubtracting these 20 per cent, the runaway frequency among young starsis about 27 per cent. We compile a catalogue of runaway stars, which isavailable via VizieR.
| 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).
| 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.
| A Spectroscopic Reconnaissance of Ultraviolet-bright Stars
We have carried out spectroscopic observations and made preliminaryclassifications of 62 UV-bright stars identified by H. H. Lanning onplates taken by A. Sandage. The goal was to search for ``interesting''objects, such as emission-line stars, hot subdwarfs, and high-gravitystars. Our targets were grouped into two samples, a bright(mB<13) sample of 35 stars observed with the Kitt Peak 2.1m telescope and a faint (13
| Catalogue of H-alpha emission stars in the Northern Milky Way
The ``Catalogue of Stars in the Northern Milky Way Having H-alpha inEmission" appears in Abhandlungen aus der Hamburger Sternwarte, Band XIin the year 1997. It contains 4174 stars, range {32degr <= l() II< 214degr , -10degr < b() II < +10degr } having the Hαline in emission. HBH stars and stars of further 99 lists taken from theliterature till the end of 1994 were included in the catalogue. We givethe cross-identification of stars from all lists used. The catalogue isalso available in the Centre de Données, Strasbourg ftp130.79.128.5 or http://cdsweb.u-strasbg.fr and at the HamburgObservatory via internet.
| 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.
| Catalogue of stars in the Northern Milky Way having H-alpha in emission.
The catalogue contains 4174 stars in the Northern Milky Way, range32° ? lII< 214°, -10° < bII< +10°, having the H? line in emission. The HBH list (mainlist, Schmidt camera Hamburg-Bergedorf, red plates taken in the years1964-70) contains 1979 objects partly identical with those in otherlists of H? emission-line stars given in the literature up till1994. Non-stellar objects (e.g. H II regions, planetary nebulae) havenot been included in this catalogue except for those objects containingcentral stars which have the H? line in emission, and also forsome doubtful cases. In Part 1 the authors give the equatorial (2000.0)and galactic coordinates, the brightness and the spectrum (if existingin the literature), the membership of HBH, the estimation of continuumand H?-line intensity, the reference to the finding chart in Part2 and the cross-identification of 100 lists mostly of H? emissionline stars. In Part 2 the authors present the finding charts for morethan half of the objects; they have the "normal" orientation and mainlysize 7 arcmin square. At the end they give elementary statistics of thepresent data showing also gaps in the material.
| A finding list of faint UV-bright stars in the galactic plane, 2
Fifty-three UV-bright stars have been found on three two-color 48-in.Schmidt plates centered on the galactic plane. The sources detectedrange in U-B color from near U- B = 0 to U - B = -1.5, and in magnitudefrom mB approximately = 10 to approximately 21. Some of themore interesting sources are discussed, and finding charts are includedfor all sources listed. Additionally, follow-up spectroscopic andpostitional information is provided for several objects first listed inPaper I of this series. One new cataclysmic variable discovered duringthe course of this portion of the survey has been published previouslyand is discussed herein.
| A Catalogue of Be-Stars
Not Available
| Die galaktischen Emissions-B-Sterne : (Spectralklassifikation, Photometrie, Entwicklung und Verteilung in der Milchstraszenebene)
Not Available
| Catalogue of stellar spectra classified in the Morgan-Keenan system
Not Available
| Luminous Stars in the Northern Milky Way
Not Available
| Photometric, Polarization, and Spectrographic Observations of O and B Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1956ApJS....2..389H&db_key=AST
| Studies in Galactic STRUCTURE.II.LUMINOSITY Classification for 1270 Blue Giant Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1955ApJS....2...41M&db_key=AST
| Interstellar Polarization of 405 Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1954ApJ...120..454H&db_key=AST
| A Finding List of O and B Stars of High Luminosity.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1951ApJ...113..141N&db_key=AST
| Second Supplement to the Mount Wilson Catalogue and Bibliography of Stars of Classes B and a whose Spectra have Bright Hydrogen Lines.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1949ApJ...110..387M&db_key=AST
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Osservazione e dati astrometrici
| Costellazione: | Cigno |
| Ascensione retta: | 20h29m20.18s |
| Declinazione: | +46°39'59.1" |
| Magnitudine apparente: | 10.13 |
| Moto proprio RA: | -3.7 |
| Moto proprio Dec: | -4.5 |
| B-T magnitude: | 10.42 |
| V-T magnitude: | 10.154 |
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