|Spatially resolved PAH emission in the inner disks of Herbig Ae/Be stars|
We present adaptive-optics high-angular resolution (~0.1 arcsec)spectroscopic observations in the 3 μm region of eight well-knownHerbig Ae/Be stars with circumstellar disks. We detected the aromaticemission feature at 3.3 μm for four out of six of our objects withflared disks (HD 169142, HD 97048, HD 100453, HD 100546), someadditional features at 3.4 and 3.46 μm, and strong diamond featuresat 3.43 and 3.53 μm in two of our flared objects (HD 100546 and HD97048 respectively). We also detected hydrogen recombination line at3.74 μm in practically all the objects. The emission in thepolycyclic aromatic hydrocarbon (PAHs) feature at 3.3 μm and in theadditional carbon dust features in the 3.4-3.5 μm region is, for thefirst time, spatially resolved in all the sources where the features aredetected. The full-width at half-maximum sizes that we derive aretypical of emission arising in a circumstellar disk. On the other hand,the continuum emission remains unresolved, with the exception of HD97048 where it is marginally resolved. We compared the observed spatialdistribution of the 3.3 μm PAH feature and the adjacent continuum tothe predictions of a disk model that includes transiently heated smallgrains and PAHs, in addition to large grains in thermal equilibrium(Habart et al. 2004a). The model predicts that, as observed, the 3.3μm PAH emission feature is significantly broader than that of theadjacent continuum and also that about 50% of its integrated intensitycomes from a radius R< 30 AU. We find that the predicted brightnessprofiles reproduce the observed ones very well. This proves beyond doubtthat the energetic 3.3 μm PAH emission feature takes its origin inthe inner disk regions.
|New periodic variables from the Hipparcos epoch photometry|
Two selection statistics are used to extract new candidate periodicvariables from the epoch photometry of the Hipparcos catalogue. Theprimary selection criterion is a signal-to-noise ratio. The dependenceof this statistic on the number of observations is calibrated usingabout 30000 randomly permuted Hipparcos data sets. A significance levelof 0.1 per cent is used to extract a first batch of candidate variables.The second criterion requires that the optimal frequency be unaffectedif the data are de-trended by low-order polynomials. We find 2675 newcandidate periodic variables, of which the majority (2082) are from theHipparcos`unsolved' variables. Potential problems with theinterpretation of the data (e.g. aliasing) are discussed.
|The Pulkovo Spectrophotometric Catalog of Bright Stars in the Range from 320 TO 1080 NM|
A spectrophotometric catalog is presented, combining results of numerousobservations made by Pulkovo astronomers at different observing sites.The catalog consists of three parts: the first contains the data for 602stars in the spectral range of 320--735 nm with a resolution of 5 nm,the second one contains 285 stars in the spectral range of 500--1080 nmwith a resolution of 10 nm and the third one contains 278 stars combinedfrom the preceding catalogs in the spectral range of 320--1080 nm with aresolution of 10 nm. The data are presented in absolute energy unitsW/m(2) m, with a step of 2.5 nm and with an accuracy not lower than1.5--2.0%.
|The ROSAT all-sky survey catalogue of optically bright OB-type stars.|
For the detailed statistical analysis of the X-ray emission of hot starswe selected all stars of spectral type O and B listed in the Yale BrightStar Catalogue and searched for them in the ROSAT All-Sky Survey. Inthis paper we describe the selection and preparation of the data andpresent a compilation of the derived X-ray data for a complete sample ofbright OB stars.
|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.
|The determination of T_eff_ of B, A and F main sequence stars from the continuum between 3200 A and 3600 A.|
A method of determination of the effective temperature of B, A and Fmain sequence stars is proposed, using the slope of the continuumbetween 3200A and 3600A. The effective temperature calibration is basedon a sample of stars with energy distributions known from UV to the red.We have determined the Balmer jump and the effective temperatures for235 main sequence stars. The temperatures found have been compared withthose derived by Underhill et al. (1979), Kontizas & Theodossiou(1980), Theodossiou (1985), Morossi & Malagnini (1985). Thecomparison showed good agreement for most of the stars in common. On theother hand, the temperatures derived from the reddening-free colourfactor QUV, from the colour index (m1965-V) and from (B-V), given inGulati et al. (1989), are systematically lower than our temperatures,however the differences are within one-sigma error.
|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.
|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.
|Spectral classification from the ultraviolet line features of S2/68 spectra. V - Supplement series|
The paper presents the ultraviolet classification of more than 450 B-Aand F spectra obtained with the sky survey telescope mounted on the TD1satellite. Concerning abnormal objects, attention is given to the Bestars, the binary stars, the helium weak stars, and the lambda Booobjects. With regard to Be stars, it is concluded that the 1930 Awavelength feature is linked to the existence of either shell structuresor Fe II emission lines in the visual spectral range. In addition, it issuggested that stellar spectra at wavelengths of 1410, 1610-20 and 2400A are equivalent to the He-weak group in the classical range.
|On the anomaly of the far UV extinction in the 30 Doradus region|
Area-integrated ultraviolet observations made with the NetherlandsAstronomical Satellite (ANS) of about 800 fields in a 0.7 square degreeregion around the giant H II region 30 Doradus in the Large MagellanicCloud are discussed. The five-channel ANS photometric system is shown tobe information-redundant in the present application: the LMCobservations can be discussed in terms of only two parameters, i.e., theextrapolated visual brightness and a temperature parameter (color). Acolor-brightness diagram for about 600 fields with good qualitymeasurements is given, and it is concluded that most of the spread incolor is caused by differential extinction. By various independentmethods it is found that the 2200 A-feature is deficient by a factor ofthree, on a logarithmic scale, relative to the average galacticextinction law.
|Is star formation bimodal ? II. The nearest early-type stars.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977PASP...89..187E&db_key=AST
|The spatial distribution of young stars in VELA (l=250 to 284).|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977A&AS...27..343D&db_key=AST
|Photometric standards for the southern hemisphere. II|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972AJ.....77..733B&db_key=AST
|New kinematical data for bright southern OB-stars|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972A&AS....5..129L&db_key=AST
|Four-color and H-beta photometry for bright B-type stars in the southern hemisphere.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971AJ.....76..621C&db_key=AST
|Four Southern Photoelectric Sequences|
|MK Spectral Types for Bright Southern OB Stars|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969ApJ...157..313H&db_key=AST
|The Scorpio-Centaurus Association, III. Radial velocities of 70 additional stars|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1962MNRAS.124..189B&db_key=AST