A New Approach to the Study of Stellar Populations in Early-Type Galaxies: K-Band Spectral Indices and an Application to the Fornax Cluster
The strong spectral features near 2.2 ?m in early-type galaxiesremain relatively unexplored. Yet, they open a tightly focused window onthe coolest giant stars in these galaxies-a window that can be used toexplore both age and metallicity effects. Here, new measurements ofK-band spectral features are presented for 11 early-type galaxies in thenearby Fornax galaxy cluster. Based on these measurements, the followingconclusions have been reached: (1) in galaxies with no signatures of ayoung stellar component, the K-band Na I index is highly correlated withboth the optical metallicity indicator [MgFe]' and the central velocitydispersion ? (2) in the same galaxies, the K-band Fe featuressaturate in galaxies with ?>150 km s-1, while Na I(and [MgFe]') continues to increase; (3) [Si/Fe] (and possibly [Na/Fe])is larger in all observed Fornax galaxies than in Galactic open clusterswith near-solar metallicity; (4) in various near-IR diagnostic diagrams,galaxies with signatures of a young stellar component (strong H?,weak [MgFe]') are clearly separated from galaxies with purely oldstellar populations; furthermore, this separation is consistent with thepresence of an increased number of M-giant stars (most likely to bethermally pulsating AGB stars); (5) the near-IR Na I versus ? or versus ? diagrams discussed here seem as efficientfor detecting putatively young stellar components in early-type galaxiesas the more commonly used age/metallicity diagnostic plots using opticalindices (e.g., H? vs. [MgFe]'). The combination of these spectralindices near 2.2 ?m with high spatial resolution spectroscopy fromground-based or space-based observatories promises to provide newinsights into the nature of stellar populations in the central regionsof distant early-type galaxies.Based on new observations performed at the European SouthernObservatory, Cerro Paranal, Chile; ESO program 68.B-0674A and70.B-0669A, as well as archival data from ESO program 076.B-0457A andthe SINFONI Science Verification data set.
|
Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
|
New Estimates of the Solar-Neighborhood Massive Star Birthrate and the Galactic Supernova Rate
The birthrate of stars of masses >=10 Msolar is estimatedfrom a sample of just over 400 O3-B2 dwarfs within 1.5 kpc of the Sunand the result extrapolated to estimate the Galactic supernova ratecontributed by such stars. The solar-neighborhood Galactic-plane massivestar birthrate is estimated at ~176 stars kpc-3Myr-1. On the basis of a model in which the Galactic stellardensity distribution comprises a ``disk+central hole'' like that of thedust infrared emission (as proposed by Drimmel and Spergel), theGalactic supernova rate is estimated at probably not less than ~1 normore than ~2 per century and the number of O3-B2 dwarfs within the solarcircle at ~200,000.
|
Catalog of Galactic OB Stars
An all-sky catalog of Galactic OB stars has been created by extendingthe Case-Hamburg Galactic plane luminous-stars surveys to include 5500additional objects drawn from the literature. This work brings the totalnumber of known or reasonably suspected OB stars to over 16,000.Companion databases of UBVβ photometry and MK classifications forthese objects include nearly 30,000 and 20,000 entries, respectively.
|
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.
|
Uvby-beta observations of 528 type B stars with V between the 8th and 9th magnitude
The paper presents uvby-beta measurements of 528 type B stars selectedfrom the SAO Catalog on the basis of two criteria: the spectral types inthe range B3-B5 and mV between the 8th and the 9th magnitude. Reddeningindependent (c1) values are estimated from the spectral classificationand compared to the observed values. No systematic trend with observed(b-y), H-beta, or spectral type appears to be present, but the range of(c1) residuals is surprisingly large. A rather large part of the starshas small beta values, smaller than for the BIa supergiants. Only twoare classified as O stars and most of them have the suffix e, ne, ornne. Most beta values for the O type stars are slightly above the upperlimit of 2.585 m.
|
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.
|
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.
|
H-beta photometry of southern early-type stars
H-beta photoelectric photometry is presented for 209 southern hemisphereearly-type stars from the HD catalog with galactic latitudes /b/ greaterthan 6 deg. Four-color photometry exists for all these stars and MKtypes for most of them. Absolute magnitudes have been estimated for allbut the emission-line stars and distances from the sun and the galacticplane determined.
|
Four colour photometry of southern early-type stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978MNRAS.182..629K&db_key=AST
|
Photometry and spectral classification of early-type stars away from the galactic plane.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970MNRAS.150...23H&db_key=AST
|
INHABITED SKY
