Colour excesses of F-G supergiants and Cepheids from Geneva photometry.
A reddening scale for F-G supergiants and Cepheids is presented.Supergiants with low reddenings or in clusters form the basis of thecalibration. In this sense, it is entirely empirical. The data have beenobtained in the Geneva photometric system. Comparisons with otherreddening scales show no disagreement. The only problem is with Fernie'sscale for Cepheids (1990), where a systematic trend exists. Its originis not clear. It is suggested to extend the number of supergiants withindependently obtained colour excesses in order to test the existence ofa possible luminosity dependence of the calibration. A period-colourrelation for Cepheids is deduced, on the basis of the present reddeningcorrections. It gives strong support for V473 Lyr being a secondovertone pulsator.
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Ca II H and K Filter Photometry on the UVBY System. II. The Catalog of Observations
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....109.2828T&db_key=AST
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Stromgren and H beta photometry of OB associations and open clusters. I - ARA OB1
Stromgren and H beta photometry of 38 stars in the field of Ara OB1 ispresented. The excesses, the absolute magnitudes and the temperatures ofthe stars have been obtained. The masses and the ages are alsoestimated, based on the models of Maeder and Meynet. Two differentgroups have been distinguished by their space locations at V0 - MV =10.23 and 12.01 mag (assuming a normal extinction law). The more distantgroup is younger and more massive. The magnitude and the excess of theWR star MR62 point to its probable membership of this group. There aregood reasons to suspect a value of the total-to-selective absorptionratio that is greater than the normal 3.2, which leads to a significantreduction of the true distance moduli.
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Photometry of F-K type bright giants and supergiants. I - Intermediate band and H-Beta observations
Over 1500 observations of 560 bright giants and supergiants of types F-Kare presented and compared to the observations by Gray and Olsen (1991).The present results include intermediate-band which is slightlydifferent from the Stromgren data by Gray and Olsen due to a differentwidth for the v filter. A systematic difference in m(1) - M(1) withdecreasing temperature is noted in the two H-Beta data sets, and thecorrelations are defined.
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A new discussion on the M(v) - W(O I 7774 A) relationship for F-G stars in the light of high-resolution data
High-resolution CCD data and a large group of F-G stars of fundamentallydetermined distances are used here to investigate the intrinsic natureof the M(v) - W(O I) relation and the effect of other atmosphericparameters on this relation. The M(v) - W(O I) relation is not linear inthe absolute magnitude range -10 to +21. Introduction of the (b - y)0color index to represent stellar temperature leads to a calibration ofthe M(v) - W(O I) - (b-y)0 relationship in the above M(v) range, whichcan serve as a valuable tool to determine M(v) for F-G field stars. Nosystematic effect of the turbulent velocity on the calibration is found.
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Photometry of F-K type bright giant and supergiants. II - Calibration on indices in terms of luminosity reddening and abundance of F-type stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1991AJ....102.1826E&db_key=AST
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Near infrared spectra of RV Tauri stars
Medium resolution spectrograms of the near infrared spectral region in asample of RV Tauri stars with spectral types F and early G have beencompared with those of a sample of population I objects. It is shownthat the equivalent widths of Ca II infrared triplet and Paschen linesallow to separate RV Tauri stars from population I supergiants.Moreover, the possibility of using the O I triplet at 7774 A as a toolfor testing the period-luminosity relation for RV Tauri stars isdiscussed.
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The calibration of the Stromgren photometric system for A, F and early G supergiants. I - The observational data
An empirical calibration of the Stromgren uvby-beta photometric systemfor the A, F, and early G supergiants is being derived. This paperexplains the observational program and the photometric reductiontechniques used and presents a catalog of new Stromgren photometry forover 600 A, F, and G supergiants.
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Walraven photometry of nearby southern OB associations
Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars inthe regions of five nearby southern OB associations: Scorpio Centaurus(Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2.Derived V and (B - V) in the Johnson system are included.
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Colour excesses and absolute magnitudes for non-Cepheid F-G supergiants from uvbybeta photometry
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1990A&A...239..205A&db_key=AST
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A photometric determination of the metal content for F-G type supergiants in the Large Magellanic Cloud
A VBLUW photometric analysis is used to derive the metal content of some100 F- and G type supergiants in the LMC. Using the empirical locus ofPel in the V-B/B-L diagram in conjunction with the relative dependenceof theoretical colors on the metal abundance, a metal deficiency of1.4-1.6 is found for the LMC stars in comparison with those in the solarneighborhood. With an average UBV system foreground reddening of E(B-V)= 0.05 for the LMC, these stars have a metal content of 0.66 + 0.11,-0.03 of the solar abundance. Agreement is found with the result ofprevious studies. Application to the derivation of the reddenings ofmost of the galactic supergiants is noted.
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Interstellar NaI absorption towards the stellar association ARA OB1
Observations have been made of the interstellar D-line absorption of NaI towards a loose grouping of OB stars (containing the association AraOB1 and probably the H-alpha emission regions RCW 107 and 108) centeredat 1 = 337.5 deg and b = - 0.5 deg. The individual absorption spectracontain several velocity components which show well-defined groupings at- 37, -18 and 0 km/s. The corresponding median optical depths are 2, 7and 6. The evidence indicates that both the -37 and -18 km/s Na I cloudsare located in the Carina-Sagittarius spiral arm. Several H II regionsare located at similar longitudes, but most are close to zero latitudeand are more distant than the arm. The association contains the galacticcluster NGC 61993. The results suggest that the turbulence seenoptically towards this cluster has been caused by the interactionbetween two cloud groups moving towards each other at velocities of 10to 15 km/s.
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Radial velocities of southern stars obtained with the photoelectric scanner CORAVEL. III - 790 late-type bright stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985A&AS...59...15A&db_key=AST
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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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Finding list and spectral classifications for southern luminous stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976AJ.....81..225M&db_key=AST
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Five-channel photometry of cepheids and supergiants in the southern Milky Way.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976A&AS...24..413P&db_key=AST
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Wavelength dependence of interstellar polarization and ratio of total to selective extinction
A multichannel polarimeter-photometer which uses dichroic filters toseparate the (UBVR) spectral regions is described. The instrument wasused with a 24-inch rotatable tube telescope for polarimetricobservation of nearby stars. Polarization data for 364 nearby stars aretabulated, together with the wavelength dependence of linear andinterstellar polarization.
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Classification of Some Bright F-Type Stars with Unusual Spectra
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973PASP...85..328M&db_key=AST
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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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H-alpha emission objects in two selected regions of the southern Milky Way (Cen & Nor).
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970A&A.....8..123V&db_key=AST
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Regional Variations in the Wavelength Dependence of Interstellar Polarization
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969ApJ...158..441S&db_key=AST
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Infrared Surveys of the Southern Milky way. I. Suspected Supergiant Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969ApJ...156L..37A&db_key=AST
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An association of O and B stars in Ara
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1963MNRAS.125..105W&db_key=AST
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INHABITED SKY
