The total-to-selective extinction ratio determined from near IR photometry of OB stars
The paper presents an extensive list of the total to selectiveextinction ratios R calculated from the infrared magnitudes of 597 O andB stars using the extrapolation method. The IR magnitudes of these starswere taken from the literature. The IR colour excesses are determinedwith the aid of "artificial standards" - Wegner (1994). The individualand mean values of total to selective extinction ratios R differ in mostcases from the average value R=3.10 +/-0.05 - Wegner (1993) in differentOB associations. The relation between total to selective extinctionratios R determined in this paper and those calculated using the "methodof variable extinction" and the Cardelli et al. (1989) formulae isdiscussed. The R values presented in this paper can be used to determineindividual absolute magnitudes of reddened OB stars with knowntrigonometric parallaxes.
|
Classification and properties of UV extinction curves
The catalog of Savage et al. (\cite{ref27}) reporting colour excesses of1415 stars from ANS photometry offers the opportunity to deeplyinvestigate the characteristics of UV extinction curves which differfrom the standard extinction of the diffuse interstellar medium. To thisaim we have selected a sample of 252 curves, which have been comparedwith the relations derived by Cardelli et al. (\cite{ref4}; CCM in thefollowing) for a variety of R_V values in the range 2.4-5 and have beenclassified as normal if they fit at least one of the CCM curves oranomalous otherwise. We find that normal curves with small R_V are justas numerous as those with large R_V. The anomalous objects are arrangedinto two groups according to the strength of the bump at 0.217 mu . Fora given value of c_2 this increases along the sequence: type Aanomalous, normals and type B anomalous, suggesting that this sequenceshould correspond to an increase of the amount of small grains along thesightline. Considerations concerning the environmental characteristicsindicate that the anomalous behaviour is not necessarily tied to theexistence of dense gas clouds along the line of sight.
|
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.
|
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.
|
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.
|
UBVRI photometry and polarimetry of the stars in S252 (NGC 2175). II. Interpretation.
Photoelectric UBVRI photometry and polarimetry and photographic UBVRphotometry have been used to study the stellar cluster NGC2175associated with the Hii region-molecular cloud complex Sharpless252. Thecolour excess E_B-V_ of stars in NGC2175 ranges from the foregroundcolour excess of 0.4mag up to 1.7mag. The distance modulus of S252obtained by fitting ZAMS to the colour-magnitude diagrams of NGC2175 is11.7+/-0.3mag (2.2+/-0.3kpc). The lower part of the colour-magnitudediagrams of the main cluster contains stars still contracting towardsZAMS indicating an age of the order of one million years for thecluster. The age of a small subcluster to the east of the Hii region isa few million years. High stellar polarizations up to 12% have beenobserved. The average wavelength of the maximum polarization in S252 is0.53+/-0.01μm and the polarization efficiency is near the empiricalmaximum value 3A_v_. The polarization field in S252 is regular butcannot be explained by a single magnetic field direction.
|
UBVRI photometry and polarimetry of the stars in S 252 (NGC 2175). I. The observations.
Photoelectric UBVRI photometry and polarimetry and photographic UBVRphotometry of stars in the direction of the galactic H II regionSharpless 252 are reported
|
Extinction law survey based on UV ANS photometry
The paper presents an extensive survey of interstellar extinction curvesderived from the ANS photometric measurements of early type starsbelonging to our Galaxy. This survey is more extensive and deeper thanany other one, based on spectral data. The UV color excesses aredetermined with the aid of 'artificial standards', a new techniqueproposed by the authors which allows the special check of Sp/L match ofa target and the selected standard. The results indicate that extinctionlaw changes from place to place.
|
Observations in regions of Cassiopeia, Gemini, and Monoceros with the Glazar space telescope
Observations at 1640 A of regions in Cassiopeia, Gemini, and Monocerosmade with the Glazar space telescope are presented; 7, 11, 13, and 35early-type stars brighter than about 9 mag were detected in the observedregions. The distribution of dust matter in the corresponding regions isstudied. It is determined that companions of HD 4442, 4797, and BD + 62deg 2225 are subdwarfs of sdB - sdO types; the hot companion of HD220102 may be of the type from B8 Ib-II to sdB. It is shown that HD 5233and 261490 are probably embedded in dense circumstellar envelopes.
|
Empirical temperature calibrations for early-type stars
Three temperature calibrations of suitable photometric quantities havebeen derived for O and B stars. A sample of 120 stars with reliableT(eff.) determinations has been used for establishing each calibration.The different calibrations have been critically discussed and compared.Temperature determinations for 1009 program stars have been obtainedwith an accuracy of the order of 10 percent.
|
Hot components and circumstellar grains in M supergiant syncretic binaries
Ultraviolet and infrared spectra were obtained in order to study grainsin cool star and hot star syncretic type binaries. Grains are found inonly about half of the syncretic systems. The results suggest thatgrains have not formed in many syncretic systems because of ultravioletradiation from the hot star. Circumstellar extinction could not beunambiguously detected in those systems with grains.
|
The interstellar 217 NM band - A third catalogue of equivalent widths
A catalog of equivalent widths of the 217 nm interstellar absorptionband as well as other parameters characterizing the extinction curve inthe ultraviolet has been compiled for 790 O and B stars. A relativelytight correlation between the equivalent width of the 217 nm band andE(B-V) indicates that the absorber of this band is connected with thepopulation of larger interstellar grains responsible for the visualextinction. The parameter characterizing the amount of extinction in thefar UV is only weakly correlated with E(B-V), a result in accord withthe assumption that a second population of very small grains causes therapid increase of the far-UV extinction.
|
The variation of interstellar extinction in the ultraviolet
One hundred and fifty-four reddened stars that are apparently normal inthe visible were selected from the S2/68 Ultraviolet Sky Survey. Theultraviolet data for 92 of these cannot be explained in terms of a fixedinterstellar extinction law. Between 1400 and 2740 A, the extinctioncurve for each star can be well represented by two parts; astraight-line scattering component and a Lorentzian 2200 A absorptionfeature. Independent variations are found in both parts and these cannotbe explained by photometric or spectral classification errors. Bothparts vary smoothly, implying that there is no fixed extinction law, andone star in three is found to depart from the mean law by more than 1mag at either 1500 or 2200 A. The two variations allow not only all 154stars to be explained but also anomalous stars reported by otherauthors. These are not special but merely situated towards the limits ofthe variations. A variation in the relative proportions of graphite andsilicate grains goes some way towards explaining the observations. Theprofile of the 2200 A feature is determined, the symmetrical shape isconfirmed, and the profile fits a Lorentzian very closely.
|
Observations of interstellar diffuse absorption band at 4430 A
Observations of the interstellar diffuse absorption band at 4430 A for800 O and B stars in Neckel's (1967) catalog are being carried out, and482 spectra obtained up to September 1983 have been reduced. It isconfirmed that the strength of the interstellar diffuse absorption bandat 4430 A does not simply relate to the abundance of interstellar grainson the line of sight. The relation between the color excess E(B-V) andthe equivalent width of the band to the direction of l = 130-140 deg andb = -5 to +5 deg shows that some parameter(s) other than E(B-V) is (are)needed to understand the cause of this band.
|
Catalog of O-B stars observed with Tokyo Meridian Circle
A catalog of the O-B stars, selected from 'Blaauw-Parenago' list andRubin's catalog, has been compiled on the FK4 system by the observationsmade with Gautier 8-inch Meridian Circle at the Tokyo AstronomicalObservatory during the period, 1971 to 1979. It contains 1059 stars andwas compiled for the future establishment of high precision propermotions of O-B stars.
|
A catalog of ultraviolet interstellar extinction excesses for 1415 stars
Ultraviolet interstellar extinction excesses are presented for 1415stars with spectral types B7 and earlier. The excesses with respect to Vare derived from Astronomical Netherlands Satellite (ANS) 5-channel UVphotometry at central wavelengths of approximately 1550, 1800, 2500, and3300 A. A measure of the excess extinction in the 2200-A extinction bumpis also given. The data are valuable for investigating the systematicsof peculiar interstellar extinction and for studying the character of UVinterstellar extinction in the general direction of stars for which theextinction-curve shape is unknown.
|
Infrared photometry of early-type stars. I
K (2.2-micron) magnitudes are given for reddened early-type stars in thegalactic anticenter region between galactic longitudes of 160 and 230deg, in conjunction with ultraviolet photometry from the TD1 satellite.A value of 3.12 + or - 0.05 for the extinction ratio R is derived forthe general field and for the Mon OB2 region. The strength of theinterstellar absorption feature at 2200 A is calibrated in terms oftotal visual extinction. Many of the emission-line stars show infraredexcess, and there are indications that in some of these the 2200-Aabsorption is depleted.
|
Correlations of the band at 2175 A with other interstellar features
Using published spectrophotometric and filter-photometric data from theOAO-2 and TD-1A satellites, equivalent widths of the ultraviolet 2175-Aband are determined for 194 stars. This list of data is used to studycorrelations between the 2175-A band and the diffuse 4430-A, 5780-A, and5797-A bands as well as the hydrogen column density and the equivalentwidth of the sodium D2 line.
|
The correlation between the ultraviolet lambda 2200 feature and the diffuse lambda 4430 band.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975MNRAS.173..237N&db_key=AST
|
Studies of ultraviolet interstellar extinction with the sky-survey telescope of the TD-1 satellite. I - Results for three galactic regions
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975A&A....44..195N&db_key=AST
|
On the velocity dependence of the interstellar NA I/Ca II ratio.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974ApJ...192...51S&db_key=AST
|
Wavelength dependence of polarization. XXVI. The wavelength of maximum polarization as a characteristic parameter of interstellar grains.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974AJ.....79..581C&db_key=AST
|
Wavelength dependence of polarization. XXV. Rotation of the position angle by the interstellar medium.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974AJ.....79..565C&db_key=AST
|
Optical interstellar lines in dark clouds.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973ApJ...186..149C&db_key=AST
|
Some Spectroscopic Characteristics of the OB Stars: an Investigation of the Space Distribution of Certain OB Stars and the Reference Frame of the Classification
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971ApJS...23..257W&db_key=AST
|
Catalog of Indidual Radial Velocities, 0h-12h, Measured by Astronomers of the Mount Wilson Observatory
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJS...19..387A&db_key=AST
|
Étoiles doubles nouvelles (4^éme série) découvertes à Nice avec la lunette de 50 centimètres
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970A&AS....1..105C&db_key=AST
|
Spiral arms
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1967MNRAS.137..337D&db_key=AST
|
Catalogue d'etoiles O et B.
Not Available
|
Photoelectric 4430 A observations of 506 O, B and A stars.
Not Available
|
INHABITED SKY
