The association of IRAS sources and 12CO emission in the outer Galaxy
We have revisited the question of the association of CO emission withIRAS sources in the outer Galaxy using data from the FCRAO Outer GalaxySurvey (OGS). The availability of a large-scale high-resolution COsurvey allows us to approach the question of IRAS-CO associations from anew direction - namely we examined all of the IRAS sources within theOGS region for associated molecular material. By investigating theassociation of molecular material with random lines of sight in the OGSregion we were able to construct a quantitative means to judge thelikelihood that any given IRAS-CO association is valid and todisentangle multiple emission components along the line of sight. Thepaper presents a list of all of the IRAS-CO associations in the OGSregion. We show that, within the OGS region, there is a significantincrease ( ~ 22%) in the number of probable star forming regions overprevious targeted CO surveys towards IRAS sources. As a demonstration ofthe utility of the IRAS-CO association table we present the results ofthree brief studies on candidate zone-of-avoidance galaxies with IRAScounterparts, far outer Galaxy CO clouds, and very bright CO clouds withno associated IRAS sources. We find that ~ 25% of such candidate ZOAGsare Galactic objects. We have discovered two new far outer Galaxystar-forming regions, and have discovered six bright molecular cloudsthat we believe are ideal targets for the investigation of the earlieststages of sequential star formation around HII regions. Finally, thispaper provides readers with the necessary data to compare othercatalogued data sets with the OGS data.Tables 1, 2 and A1 are only available in electronic form at the CDS viaanonymous ftp to\ cdsarc.u-strasbg.fr (130.79.128.5) or via\http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/399/1083
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High-Resolution Spectroscopy of the Yellow Hypergiant ρ Cassiopeiae from 1993 through the Outburst of 2000-2001
We present an overview of the spectral variability of the peculiarF-type hypergiant ρ Cas, obtained from our long-term monitoringcampaigns over the past 8.5 yr with four spectrographs in the northernhemisphere. Between 2000 June and September an exceptional variabilityphase occurred when the V brightness dimmed by about a full magnitude.The star recovered from this deep minimum by 2001 April. It is the thirdoutburst of ρ Cas on record in the last century. We observe TiOabsorption bands in high-resolution near-IR spectra obtained with theUtrecht Echelle Spectrograph during the summer of 2000. TiO formation inthe outer atmosphere occurred before the deep brightness minimum.Atmospheric models reveal that the effective temperature decreases by atleast 3000 K, and the TiO shell is driven supersonically withM~=5.4×10-2 Msolar yr-1. Strongepisodic mass loss and TiO have also been observed during the outburstsof 1945-1947 and 1985-1986. A detailed analysis of the exceptionaloutburst spectra is provided, by comparing with high-resolution opticalspectra of the early M-type supergiants μ Cep (Ia) and Betelgeuse(Iab). During the outburst, central emission appears above the localcontinuum level in the split Na D lines. A prominent optical emissionline spectrum appears in variability phases of fast wind expansion. Theradial velocity curves of Hα and of photospheric metal absorptionlines signal a very extended and velocity-stratified dynamic atmosphere.The outburst spectra indicate the formation of a low-temperature,optically thick circumstellar gas shell of 3×10-2Msolar during 200 days, caused by dynamic instability of theupper atmosphere of this pulsating massive supergiant near the Eddingtonluminosity limit. We observe that the mass-loss rate during the outburstis of the same order of magnitude as has been proposed for the outburstsof η Carinae. We present calculations that correctly predict theoutburst timescale, whereby the shell ejection is driven by the releaseof hydrogen ionization recombination energy.
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The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
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Radio continuum emission from stars: a catalogue update.
An updated version of my catalogue of radio stars is presented. Somestatistics and availability are discussed.
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The metallicity and luminosity of RV Tauri variables from medium-resolution spectra
Results are reported from spectroscopic observations of members of theRV Tauri class of pulsating variable stars at moderate resolution, andfrom photometric observations of these stars with the B and V filters ofthe Johnson UBV system and the first four filters of the Wingeight-color narrowband near-IR system. Of the 22 variables observed, TiOabsorption was detected in eight, and 10 variables displayedhydrogen-line emission at some phase. Spectral classifications wereassigned relative to the MK process. Color excesses were determined forthose variables for which spectroscopic and photometric data wereobtained within a few days of each other. The spectra obtained at aresolution of 2.5 A were fitted with synthetic spectra to determine thestellar atmospheric parameters. The range in metallicity among thevariables was found to be quite extensive, -0.3 to -0.7, and may reflecta mixture of stellar populations or masses.
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Photoelectric photometry of G-M stars in the Vilnius system
Not Available
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The visually brightest early-type supergiants in the spiral galaxies NGC 2403, M81, and M101
Moderate-resolution spectroscopy of the candidate brightest blue starsin the nearby spirals NGC 2403, M81, and M101 reveals that many are notsingle stars, but compact H II regions, clusters, and multiple systems.This is an additional and serious limitation on their use as distanceindicators. The derivation of the luminosities of the confirmed singleblue supergiants is discussed, and, combining these results withprevious work on the brightest red supergiants, a brief discussion andcomparison of the evolution of their most massive stars are given. Theproperties of the brightest blue and red stars in NGC 2403 and M81 arebasically in agreement with the pattern of massive-star evolutionobserved in Local Group galaxies. The distance to M101 is stillcontroversial, but at the larger distance modulus, the luminosities ofits brightest early and late-type supergiants place them beyond theEddington limit for their initial mass and temperature.
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Nineteen new spectroscopic binaries and the rate of binary stars among F-M supergiants
Nineteen spectroscopic binaries (SBs) have been discovered in radialvelocity measurements made with the CORAVEL spectrophotometer on 181northern F-M supergiants. The rate of detected SBs among northern F-Msupergiants is 21 percent, without any dependence on spectral orluminosity class. The study of the binary F-M supergiants with knownorbital elements indicates that all the systems with a period smallerthan the critical value P(circ) have a nearly circular orbit. The valueof P(circ) depends on the luminosity class, being 400-600 d for class Iband 2000-7000 d for class Ia. This circularization of the orbits may bedue to the transfer of angular momentum during the phase of binary massexchange.
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Kinematic properties of supergiants in the Perseus spiral arm
Analysis of the space motions of supergiants in the Perseus arm regionindicates that the stellar peculiar-velocity field has a large-scalenonuniformity probably resulting both from the presence of sizablegroups of young stars and from systematic motions in the arm aspredicted by density-wave theory. Proper motions are tabulated for 78stars.
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List of 333 variable, microvariable or suspected variable stars detected in the Geneva photometry
A list is presented of 333 stars, excluded from the GCVS and itssupplements, whose probability of variability ranges from high tocertain. The standard deviations observed in the V magnitude togetherwith the known spectral types, however, only allow speculation as to thetype of variable in question pending supplementary observations whichreveal the individual characteristics of these stars.
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H-alpha emission in F-K high luminosity stars
The presence and variability of H-alpha emission in very luminous F-Ksupergiants is investigated, and the lower limit of MV whereH-alpha begins to appear in emission is determined. Basic information onthe sample of eight stars is presented, including the spectral type,MV, H-alpha activity, and the shape of the H-alpha profile.The emission is variable in intensity and shape for all the stars. Thevery luminous supergiant HD 217476, which is both a radio star and abinary, shows particularly great variability.
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A search for radio emission from late-type supergiant stars
Radio continuum observations at 10.5 GHz have been made of 29high-luminosity F0-K5 supergiant stars. Two sources were detected (atthe 3-sigma confidence level) in this survey. One corresponds to theunusual spectrum-variable star HR 8752=HD 217476 (G0 Ia). The other islocated approximately one arc minute southwest of the star HD 18391 (G0Ia), with a positional error box containing no obvious opticalcandidate(s).
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Infrared photometry of high-luminosity supergiants earlier than M and the interstellar extinction law
Photometric measurements from 2.3 to 23 microns are reported for someluminous F, G, and K supergiants. The infrared excesses observed do notappear to be representative of the class. At about 4.9 microns, andabsorption feature with a depth of 0.4 mag appears abruptly in thesupergiants near spectral type G5. This feature is possibly due toabsorption by the fundamental vibration band of either CO or CN. Thecolor-excess method yields a reddening curve which gives a value for theratio of total to selective extinction of about 3.40.
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The space distribution and kinematics of supergiants
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970AJ.....75..602H&db_key=AST
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UBV photometry of 550 F, G and K type stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1966MNRAS.133..475A&db_key=AST
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Hα Photometry of late-type stars I. F, G and K-type stars north of the equator
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1964MNRAS.128..435P&db_key=AST
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Überriesen FO-K7 Ia-II in Assoziationen und OB-Sterngruppen. II. Mitteilung von: Leuchtkraft, Alter und Eigenfarben galaktischer Überriesen. Mit 1 Textabbildung
Not Available
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Überriesen FO-K7 Ia-II in galaktischen Sterhaufen. I. Mittelung von: Leuchtkraft, Alter und Eigenfarben galaktischer Überriesen. Mit 3 Textabbildungen
Not Available
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Photoelectric measurements of the λ4200 A CN band and the G band in G8-K5 spectra
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1960MNRAS.120..287G&db_key=AST
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Spectral Classification of Stars Noted on Case Objective-Prism Plates. I
Not Available
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A Finding List of F Stars of High Luminosity.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1952ApJ...115..475N&db_key=AST
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INHABITED SKY
