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Two-colour photometry for 9473 components of close Hipparcos double and multiple stars
Using observations obtained with the Tycho instrument of the ESAHipparcos satellite, a two-colour photometry is produced for componentsof more than 7 000 Hipparcos double and multiple stars with angularseparations 0.1 to 2.5 arcsec. We publish 9473 components of 5173systems with separations above 0.3 arcsec. The majority of them did nothave Tycho photometry in the Hipparcos catalogue. The magnitudes arederived in the Tycho B_T and V_T passbands, similar to the Johnsonpassbands. Photometrically resolved components of the binaries withstatistically significant trigonometric parallaxes can be put on an HRdiagram, the majority of them for the first time. Based on observationsmade with the ESA Hipparcos satellite.
| Kinematic signatures of violent formation of galactic OB associations from HIPPARCOS measurements
Proper motions measured by Hipparcos confirm the large anomalousvelocities of the OB associations located around the Cygnus Superbubble(Cygnus OB1, OB3, OB7, and OB9), and reveal a clearly organizedexpanding pattern in Canis Major OB1. At the distances of theseassociations, the organized velocity patterns imply LSR velocities of upto ~ 60 km s(-1) for the associations in Cygnus, and about ~ 15 km s(-1)in Canis Major OB1. The magnitude and spatial arrangement of theexpanding motions suggests that very energetic phenomena are responsiblefor the formation of the present OB associations. This is independentlysupported by observations of the associated interstellar medium carriedout in other wavelengths. The gravitational instability scenarioproposed by Comeron & Torra 1994 (ApJ 423, 652) to account for theformation of the stars in the Cygnus Superbubble region is reviewed inthe light of the new kinematic data. It is found that the energeticrequirements set by the highest velocities on the OB associationpowering the Superbubble, Cygnus OB2, are too large by orders ofmagnitude. However, the scenario can still account for the formation ofmost of the stars if, as can be reasonably expected, the stars with thehighest measured velocities are actually runaways from Cygnus OB2itself. As for Canis Major OB1, we consider their formation in asupernova remnant, as suggested by Herbst & Assousa 1977 (ApJ, 217,473). The detection of a new runaway star, HIC 35707 (=HD 57682), whosemotion is directed away from the derived center of expansion, supportsthis scenario and provides an independent age for the supernova remnant,assuming that the runaway star was the binary companion of thesupernova. Based on a number of arguments, however, we find it unlikelythat the stars are a direct consequence of instabilities in theexpanding shell. We propose instead that their formation was triggeredin preexisting clouds, accelerated and compressed by the supernovaexplosion.
| Derivation of the Galactic rotation curve using space velocities
We present rotation curves of the Galaxy based on the space-velocitiesof 197 OB stars and 144 classical cepheids, respectively, which rangeover a galactocentric distance interval of about 6 to 12kpc. Nosignificant differences between these rotation curves and rotationcurves based solely on radial velocities assuming circular rotation arefound. We derive an angular velocity of the LSR of{OMEGA}_0_=5.5+/-0.4mas/a (OB stars) and {OMEGA}_0_=5.4+/-0.5mas/a(cepheids), which is in agreement with the IAU 1985 value of{OMEGA}_0_=5.5mas/a. If we correct for probable rotations of the FK5system, the corresponding angular velocities are {OMEGA}_0_=6.0mas/a (OBstars) and {OMEGA}_0_=6.2mas/a (cepheids). These values agree betterwith the value of {OMEGA}_0_=6.4mas/a derived from the VLA measurementof the proper motion of SgrA^*^.
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| Infrared emission of Canis Major OB1/R1 star forming region
Using IRAS data, the infrared emission character of the star-formingregion CMa OB1/R1 complex was studied in detail and compared with theoptical, CO, and radio continuum observations. The results show that theemission from this complex consists of a diffuse emission and severaldiscrete sources. The infrared diffuse emission can be explained by twoO stars, but the extended H II region may be the combined result of aremnant of an old H II region and those two O stars, which are still onthe main sequence. Most of the discrete sources correspond to theemission or reflection nebulae, but a few have no optical counterparts.The latter may be excited by early-type stars just arriving at the mainsequence and still embedded in dense dust cloud.
| The Infrared Emission from the Star Forming Region Canis-Majoris / OB1 / r1 Complex
Not Available
| Radio continuum observations of the Canis Major R1 region
Observations of the CMa R1 region in the radio continuum at 10 GHz weremade using the 45-m radio telescope at the Nobeyama Radio Observatory.The beam size was 2.7 arcmin in HPBW. An area of 2 x 3 deg containingthree H II regions (S292, S296, and S297) was scanned, and a calibratedmap was obtained. This area has rather uniform foreground extinction andcontains no hidden compact H II region. The emission ring (S296) shows athermal spectrum, confirming the ionization balance between OB stars andionized gases in the CMa OB1 region. A new small radio source is alsofound on the northwest side of the map.
| Exciting stars and the distances of the diffuse nebulae
Not Available
| Visual multiples. VII - MK classifications
Classifications are given for 865 components of visual multiples; theyshow no systematic differences from the MK system, and the random errorsare one subclass in type and two-thirds of a luminosity class. It isfound that at least 1% of the F-type IV and V stars are weak-lined, 32%of the A4-F1 IV and V stars are Am, and 5% of the A0-A3 IV and V starsare early-type Am. Attention is called to the large fraction (55%) ofthe A3-A9 III-V stars that are of luminosity classes III or IV, unlikethe percentage (16%) at neighboring types.
| Canis Major OB1, Canis Major R1, NGC 2353, and W Canis Majoris.
Abstract image available at:http://adsabs.harvard.edu/abs/1978PASP...90..436E
| Observational evidence for supernova-induced star formation - Canis Major R1
Observational evidence is presented which indicates that star formationin the young association CMa R1 was initiated by a supernova explosion(probably of Type II) that occurred about half a million years ago.Palomar Sky Survey prints, neutral-hydrogen maps, and radial-velocitydata are examined which show that the CMa R1 association is located onthe outer edge of a ring of optical and radio emission, that anexpanding neutral-hydrogen shell is coincident with the optical feature,and that HD 54662 is a runaway star in the CMa OB1 association and maybe associated with the event that produced the observed supernovaremnant. The optical and radio features are interpreted as a supernovaremnant with an age of about 500,000 years and an initial outburstenergy of the order of 5 by 10 to the 50th power ergs, which isexpanding into an initially nonuniform medium characterized by aninitial atomic-hydrogen density of approximately 1 per cu cm in thedirection toward CMa R1 and less than half that value in the directiontoward the sun.
| A study of the stellar association Canis Major OB 1.
Abstract image available at:http://adsabs.harvard.edu/abs/1974A&A....37..229C
| Investigation of a Milky Way field in Canis Major
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974AJ.....79.1022C&db_key=AST
| Spectroscopic observations of stars in HII regions.
Not Available
| On the kinematical and spatial coincidence of optical and radio spiral arms in our galaxy.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973A&A....24..393M&db_key=AST
| A Test for Relative Motions of Gas and Young Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972PASP...84..273M&db_key=AST
| Observations of stars in HII regions : spectral classification and UBVphotometry.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971AJ.....76..260C&db_key=AST
| A Catalogue of H II Regions.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1959ApJS....4..257S&db_key=AST
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| קבוצת-כוכבים: | כלב גדול |
| התרוממות ימנית: | 07h06m56.44s |
| סירוב: | -11°19'38.5" |
| גודל גלוי: | 7.666 |
| מרחק: | 10000000 פארסק |
| תנועה נכונה: | -0.4 |
| תנועה נכונה: | -0.6 |
| B-T magnitude: | 7.598 |
| V-T magnitude: | 7.661 |
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