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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Ultraviolet and optical studies of binaries with luminous cool primaries and hot companions. IV - Further IUE detections
We have obtained IUE spectra for 31 middle and late-type giant andsupergiant stars whose TD-1 fluxes or ground-based spectra indicate thepresence of a hot component, or whose radial velocities indicate anunseen component. Stellar components earlier than type F1 were detectedin 22 cases. While 20 of the hot secondaries are seen weakly in opticalspectra, two are UV discoveries: HD 58134 and HD 183864. The hotcompanions are classified accurately by temperature class from theirfar-UV spectra. The interstellar extinction of each system and therelative luminosities of the components are derived from the UV andoptical fluxes, using a new grid of UV intrinsic colors for hot dwarfs.We find that many giant stars apparently have companions which are toohot and hence too luminous for consistency with the primary's spectralclassification.
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Luminosities of yellow supergiants from near-infrared spectra - Calibration through Magellanic Cloud stars
The possibility of using medium resolution spectrograms in the nearinfrared region to determine luminosities of A-G supergiants has beenexplored. A sample of 49 of these stars has been observed in the twoMagellanic Clouds, and using the intensities of the O I 7774 triplet andan index (CP), which is a combination of the Ca II triplet and Paschenlines intensities, a preliminary luminosity calibration, based on LMCstars, has been obtained. Such a calibration predicts reliableluminosities for Galactic supergiants, and offers the advantage of beingcompletely reddening independent. The reddening free CP index combinedwith BVRI color indices has also been used to estimate the interstellarreddenings of Magellanic Cloud stars.
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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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The sun among the stars. V - A second search for solar spectral analogs: The Hyades' distance
A five-part search for a match of the solar spectrum throughout the sky,down to the limit of the Bright Star Catalog, is completed by 20A-resolution comparisons of G-type star photoelectric violet spectrawith those of Jupiter satellites and the blue sky. It is confirmed thatsolar analogs are rare. The strengths, relative to the sun, of theabsorption features at 3850 and 3740 A are measured quantitatively forall 164 stars observed. Their dependence on B-V and U-V leads to thesame solar colors previously derived from the solar analogs alone, withB-V equals 0.66 and U-B equals 0.20. Giants and subgiants are excludedfrom consideration, and stellar metal content dependence was closelyobserved. The sun is found to fit the mass-luminosity relation of theHyades within 0.16 m, independent of the assumed helium abundance, ifevolutionary and metal abundance effects are taken into account.
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O stars and supergiants south of declination -53 0.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976AJ.....81..116H&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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Study of the F-type 1 MK spectral types.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975AJ.....80..637M&db_key=AST
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Radial velocities of southern OB stars and supergiants
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969MNRAS.143....1B&db_key=AST
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Five-colour observations of 24 classical Cepheids
Not Available
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INHABITED SKY
