Young Stars in the Camelopardalis Dust and Molecular Clouds. I. The Cam OB1 Association
The distribution of dust and molecular clouds in the direction ofGalactic longitudes 132--158° and latitudes ± 12\degr\ isinvestigated. The maps of dust distribution in the area were plottedfrom the following surveys: the star counts in the DSS I database byDobashi et al. (2005), the survey of the average infrared color excessesby Froebrich et al. (2007) and the thermal dust emission survey at 100μ m by Schlegel et al. (1998). The distribution of molecular cloudswas taken from the whole sky CO survey by Dame et al. (2001). All thesesurveys show very similar cloud patterns in the area. Using the radialvelocities of CO, the distances to separate clouds are estimated. Arevised list of the Cam OB1 association members contains 43 stars andthe open cluster NGC 1502. 18 young irregular variable and Hαemission stars are identified in the area. All this proves that the starforming process in the Camelopardalis clouds is still in progress.
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Toward an adequate method to isolate spectroscopic families of diffuse interstellar bands
We divide some of the observed diffuse interstellar bands (DIBs) intofamilies that appear to have the spectral structure of single species.Three different methods are applied to separate such families, exploringthe best approach for future investigations of this type. Starting witha statistical treatment of the data, we found that statistical methodsby themselves give insufficient results. Two other methods of dataanalysis (`averaging equivalent widths' and `investigating the figureswith arranged spectrograms') were found to be more useful as tools forfinding the spectroscopic families of DIBs. On the basis of thesemethods, we suggest some candidates as `relatives' of 5780- and5797-Å bands.
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Interstellar extinction law near the Galactic equator along the Camelopardalis, Perseus and Cassiopeia border
The interstellar reddening law is investigated along the Galacticequator near the Cam, Per and Cas border. We used seven-color photometryof O-B5 stars in the Vilnius photometric system in the optical range,photometry of the ANS orbiting observatory in the ultraviolet range andbroad-band color indices V- K in the infrared. In the optical range(345-660 nm) the interstellar reddening law is found to be nearlynormal. In the ultraviolet wavelengths shorter than the 330 nm ANSpassband, the extinction is found to be slightly larger than theaverage. Some stars, for example HD 24432, exhibit much strongerultraviolet extinction which is well seen already in the 345 nm passbandof the Vilnius system. However, such stars are rare. The ratio R =A_V/EB-V is found to be 2.9, i.e., it is slightly smallerthan the normal. This is confirmed by the study of the wavelength ofmaximum polarization of reddened stars in the area. Both the ultravioletanomaly and the smaller R value are in good agreement with the Cardelliet al. (\cite{carcm88}) prediction. We conclude that in the investigatedarea it is safe to use normal ratios of color excesses to calculatereddening-free Q-parameters for the classification of stars fromphotometric data in the optical spectral range.
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Far-ultraviolet extinction and diffuse interstellar bands
We relate the equivalent widths of the major diffuse interstellar bands(DIBs) near 5797 and 5780Å with different colour excesses,normalized by E(B-V), which characterize the growth of interstellarextinction in different wavelength ranges. It is demonstrated that thetwo DIBs correlate best with different parts of the extinction curve,and the ratio of these diffuse bands is best correlated with thefar-ultraviolet (UV) rise. A number of peculiar lines of sight are alsofound, indicating that the carriers of some DIBs and the far-UVextinction can be separated in certain environments, e.g. towards thePer OB2 association.
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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.
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Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS
Radial velocities have been determined for a sample of 2930 B2-F5 stars,95% observed by the Hipparcos satellite in the north hemisphere and 80%without reliable radial velocity up to now. Observations were obtainedat the Observatoire de Haute Provence with a dispersion of 80Ä,mm(-1) with the aim of studying stellar and galactic dynamics.Radial velocities have been measured by correlation with templates ofthe same spectral class. The mean obtained precision is 3.0 km s(-1)with three observations. A new MK spectral classification is estimatedfor all stars. Based on observations made at the Haute ProvenceObservatory, France and on data from The Hipparcos Catalogue, ESA.Tables 4, 5 and 6 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr or viahttp://cdsweb.u-strasbg.fr/Abstract.htm
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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.
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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.
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CH(+) in the interstellar medium
This paper describes observations of interstellar CH(+) along the linesof sight to O and B stars with E(B-V)s up to +1.13. Along some lines ofsight with strong detections of CH(+), we find distinct radial velocityshifts between the CH(+) lines and other neutral species, such as Ca Iand CH. The shifts are small but are predicted by shock models of CH(+)formation in which the shock is inclined with respect to the observer.We have also found no column densities exceeding approximately1013.8/sq cm. When these data are examined along with theother CH(+) data collected from the literature, the previously seentendency of CH(+) column density to increase with E(B-V) does notcontinue beyond reddenings of about +0.6. These findings offer supportto the shock model of CH(+) formation for at least some lines of sight.
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The interstellar (C-12)N/(C-13)N ratio toward Zeta Persei
High-resolution, high signal-to-noise observations of interstellar CNtoward Zeta Per are performed to determine the C-12/C-13 isotope ratioin this line of sight. Observations of (C-12)N/(C-13)N in severaldiffuse clouds are performed to assess whether CN suffers fromisotope-selective effects. Values are obtained which are higher than thevalue toward Zeta Oph determined by Crane and Hegyi (1988) and lowerthan the results toward the more reddened stars HD 21483 obtained byMeyer et al. (1989) and Palazzi et al. (1990). Theory and observationsindicate the existence of a spatial C-12/C-13 gradient which decreasestoward the Galactic center at an approximate rate of 12 percent/kpc atthe distance of the solar radius. It is argued that since a gradient ofthis character cannot explain the CN results, isotope-selective effectsprovide a more likely explanation for the large range in (C-12)N/(C-13)Nratios.
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Absolute magnitudes of B emission line stars - Correlation between the luminosity excess and the effective temperature
A new determination of the visual absolute magnitude of Be stars iscarried out. For this, a new calibration of visual absolute magnitudesof B stars of luminosity classes, V, IV, and III is first obtained froma sample of 215 stars. The absolute luminosity excess in the visual isdetermined for a sample of 49 Be stars. It is found that this excess iscorrelated with the effective temperature of the underlying stars. Awell defined correlation between this excess and the emission in thefirst two Balmer lines is established. From these results, using asimple model of circumstellar envelope, it is inferred that the zones ofthe circumstellar envelope contributing to the emission in the continuumand in the lines have to be rather small. It is also deduced that theemission measure of the envelope is correlated with the temperature ofthe central star and that the irregular photometric variations of Bestars are an envelope-opacity phenomenon.
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Groups of stars with common motion in the Galaxy - Groups of B stars of luminosity classes I and II and their comparison with groups of long-period Cepheids and open clusters
In a sample of 93 stars of luminosity classes I and II, ten groups withcommon motion in space are isolated. The reality of five groups isestablished by numerical experiment. A comparison is made with groups oflong-period Cepheids and open clusters. Regularities in the distributionof groups of different objects in space are found. The reality of therotation of a star aggregate consisting of three Cepheid groups isestablished.
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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.
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Predicting peculiar interstellar extinction from gaseous abundances
Molecular and atomic abundances are examined for 19 lines of sightthrough dense clouds, each with a peculiar selective extinction curve.The interstellar clouds appear to fall into two distinct categories:CN-rich, with relatively small amounts of neutral iron, or CN-poor, withlarge amounts of neutral iron. Lines of sight having a CN/(Fe I)abundance ratio about two or greater, are found to have a shallow 2175 Afeature relative to the underlying extinction, while the strength ofbump is 3.60 + or - 0.36 for the other dense clouds in the presentstudy. The difference is the strength of the extinction bump betweenthese two ensembles is 1.03 + or - 0.23. Several atomic abundances areexamined as potential indicators of peculiar extinction. The Mn I upperlimits in the present study support that Mn is being preferentiallydepleted. Fe I is underabundant relative to K I by 0.7 (dex) in thelarge (CN)/(Fe I) compared to the small (CN)/(Fe I) lines of sight.
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A search for interstellar and circumstellar C60
It has recently been suggested that the diffuse interstellar bands maybe formed by ionized polyhedral carbon molecules such as C60(+). Whilespecific laboratory measurements of absorption bands of this molecularion have not been made, a feature due to the neutral molecule C60 hasbeen discovered at 3860A. Examination of spectra of several reddenedstars, as well as one star known to have circumstellar carbonaceousdust, shows no sign of the feature, leading to upper limits of the orderof 10 to the 14th/sq cm for the column density of C60. These limits arenot yet sensitive enough to violate the expectations of crudepredictions.
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Probing the possibility of a C-12/C-13 abundance gradient from observations of interstellar CH+
High SNR observations of interstellar CH+ have been performed of thereddened, early-type stars HD 24432m, HD 183143, and HD 157038 in aneffort to probe the existence of a C-12/C-13 abundance gradient in theGalaxy. The isotope ratios appear to be a true reflection of the isotoperatios in the gas. The measurement results are in good agreement withthe local ISM value of 43 + or - 4. Thus, the ISM appears hommogeneouswithin 1.7 kpc of the sun. The interstellar material in the observedregion of the Galaxy has suffered a significant amount of chemicalevolution in the past 4.5 billion years. This finding is in disagreementwith most of the results derived from radio observations of othermolecular species.
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Probing the Possibility of A 12C/13C Abundance Gradient from Observations of Interstellar CH
Not Available
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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.
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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.
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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.
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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.
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New UBVRI photometry for 900 supergiants
A description is presented of the results obtained in connection with asystematic program of supergiant photometry on the Johnson UBVRI system.During the eight years after the start of the program, almost 1000 starshave been observed, about 400 three or more times each. The originalselection of stars used the spectral type catalog of Jaschek et al.(1964) to choose supergiants. Since observations were possible from bothChile and Canada, no declination limits were imposed, and no particularselection criteria were imposed other than to eliminate carbon stars.These are so red as to require enormous extrapolations of thetransformation equations.
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Peculiar ultraviolet interstellar extinction
In connection with investigations of the physical characteristics ofinterstellar dust, a study of objects with peculiar extinction mightprovide new insights about the composition, size distribution,formation, and destruction of the particulate matter. Meyer and Savage(1981) have found that the dust toward many stars exhibits peculiar UVextinction. The present investigation is concerned with InternationalUltraviolet Explorer (IUE) spectrophotometric measurements for a sampleof stars judged by Meyer and Savage to have highly anomalous UVextinction as inferred from the broad-band Astronomical NetherlandsSatellite (ANS) data. The reported IUE measurements provide theopportunity to determine if the ANS photometry measurements of Meyer andSavage are anomalous because of peculiar extinction.
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A survey of interstellar neutral potassium. I - Abundances and physical conditions in clouds toward 188 early-type stars
Observations of interstellar absorption in the resonance doublet 7664,7698 A of neutral potassium toward 188 early-type stars at a spectralresolution of 8 km/s are reported. The 7664 A line is successfullyseparated from nearly coincident telluric O2 absorption for all but afew of the 165 stars for which K I absorption is detected, makingpossible an abundance analysis by the doublet ratio method. Therelationships between the potassium abundances and other atomicabundances, the abundance of molecular hydrogen, and interstellarreddening are investigated.
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IUE observations of lines of sight with peculiar ultraviolet extinction
Low resolution IUE data were used to derive UV extinction curves for agroup of stars known to have peculiar extinction parameters from ANSdata. The resulting curves have a wide range of appearances. Althoughthe ratio E(BUMP)/E(B-V) differs by a factor of three in the extremecases, the wavelength of maximum absorption does not appear to change.No evidence for new fine structure in UV extinction was found. Thestructure near 62 micrometers in the existing mean extinction curvesappears to be the result of luminosity mismatch errors. The newextinction curves have shapes that separate into two distinct classes;those associated with clear field extinction and those associated withextinction in dense nebular environments. The range of variation in thecurves is so large, the common practice of ironing out the bump canproduce enormous errors in the resultant UV energy distributions whenE(B-V) 0.3.
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Ultraviolet interstellar extinction toward 1367 stars observed by ANS
Five-band UV photometry is used to investigate the character ofinterstellar extinction toward 1367 stars of spectral type B3 andearlier, with observations producing a galactic average of 5.11, 4.78,6.52, 4.10 and 1.95 at 1550, 1800, 2200, 2500, and 3300 A, respectively.Differences in the strengths of the UV extinction features of thesestars appear to be independent, since objects with either strong or weak2200 A extinction can have strong, normal or weak far-UV extinction.Further investigation reveals that some of the deviant stars areembedded in localized regions whose average extinction curves divergedramatically from the galactic mean. The anomalous extinction of theseregions attests to localized inhomogeneities in the UV characteristicsof interstellar dust. Because the evaluation of UV extinction toward aparticular star would be more accurate if based on the average curve ofthe region immediately surrounding that star rather than that of theentire Galaxy, it is recommended that the galactic average presented beused with caution to correct astronomical data of individual objects.
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Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978ApJS...38..309H&db_key=AST
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Observations in linearly polarized light of the intensity of the diffuse lam 6180 absorption band in 56 southern O, B and A stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978A&A....70..195G&db_key=AST
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A comparison of optical and radio wavelength observations of CH in the diffuse interstellar medium
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978ApJ...224..125L&db_key=AST
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Observations of interstellar CH and a study of its chemistry and excitation
Abstract image available at:http://adsabs.harvard.edu/abs/1975ApJ...197..123Z
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INHABITED SKY
