- ID:
- ivo://CDS.VizieR/J/A+A/434/1125
- Title:
- B-type Supergiants in the SMC
- Short Name:
- J/A+A/434/1125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution UCLES/AAT spectra are presented for nine B-type supergiants in the SMC, chosen on the basis that they may show varying amounts of nuclear-synthetically processed material mixed to their surface. These spectra have been analysed using a new grid of approximately 12000 non-LTE line blanketed TLUSTY model atmospheres to estimate atmospheric parameters and chemical composition.
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- ID:
- ivo://CDS.VizieR/J/AJ/155/190
- Title:
- Carina Nebula hot stars: stellar parameters and RVs
- Short Name:
- J/AJ/155/190
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Carina Nebula is an active star-forming region in the southern sky that is of particular interest due to the presence of a large number of massive stars in a wide array of evolutionary stages. Here, we present the results of the spectroscopic analysis of 82 B-type stars and 33 O-type stars that were observed in 2013 and 2014. For 82 B-type stars without line blending, we fit model spectra from the Tlusty BSTAR2006 grid to the observed profiles of H{gamma} and He {lambda}{lambda}4026, 4388, and 4471 to measure the effective temperatures, surface gravities, and projected rotational velocities. We also measure the masses, ages, radii, bolometric luminosities, and distances of these stars. From the radial velocities measured in our sample, we find 31 single lined spectroscopic binary candidates. We find a high dispersion of radial velocities among our sample stars, and we argue that the Carina Nebula stellar population has not yet relaxed and become virialized.
- ID:
- ivo://CDS.VizieR/III/243
- Title:
- Catalogue of neutral He lines of B-stars
- Short Name:
- III/243
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue of equivalent widths (EW) for neutral helium lines presented is based on numerous photographic spectral observations of B-stars made during 1978-1986 with the 6m telescope of Special Astrophysical Observatory of Russian Academy of Sciences. Original results of spectroscopy of B-stars inside the galactic open clusters and stellar associations were published by Klochkova and Panchuk in 1986PAZh...12..928K and 1987PAZh...13...56K. To make easier the procedure of EW reduction, several A- and O-stars were included in the Catalogue. All sequent steps of EW reduction were described in Klochkova and Panchuk (1987SoSAO..54....5K, Neutral Helium Lines in the Spectra of B-Stars - Part One - Catalogue). Due to profiles of HeI lines are essentially distinguished in spectra both of supergiants and normal stars, the procedure of EW reduction were made separately for these types of stars. After reduction to the common system of the published data and of observational data obtained by authors a homogeneous catalogue of equivalent widths EW for eight neutral helium lines (HeI, {lambda} 4009, 4026, 4121, 4144, 4387, 4471, 4713{AA}) for 524 stars is compiled. The catalogue is added by the mean values of EW for H{gamma} and H{delta} lines being also reduced to the common system of equivalent widths. The work is supported by the Russian Fondation for Basic Research (project 05-07-90087).
- ID:
- ivo://CDS.VizieR/J/PAZh/38/776
- Title:
- Complete sample of OB stars within 350pc
- Short Name:
- J/PAZh/38/776
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The sample of 37485 suspected OB stars selected by Gontcharov (2008AstL...34....7G) from the Tycho-2 catalogue has been cleaned of the stars that are not of spectral types OV-A0V. For this purpose, the apparent magnitude VT from Tycho-2, the absolute magnitude MVT calibrated as a function of the dereddened color index (BT-VT)0, the interstellar extinction AVT calculated from the 3D analytical model by Gontcharov (2009AstL...35..780G) as a function of the Galactic coordinates, and the photometric distance Rph calculated as a function of VT, M_VT_, and A_VT_ have been reconciled in an iterative process. The 20514 stars that passed the iterations have (BT-VT)_0_<0 and M_VT_>-5 and are considered as a sample of OV-A0V stars complete within 350 pc of the Sun. Based on the theoretical relation between the dereddened color and age of the stars, the derived sample has been divided into three subsamples: (BT-VT)_0_< -0.2, -0.2<(BT-VT)_0_< -0.1, and -0.1<(BT-VT)_0_<0, younger than 100, 100-200, and 200-400 Myr, respectively. The spatial distribution of all 20514 stars and the kinematics analyzed for more than 1500 stars with radial velocities from the PCRV and RAVE catalogues are different for the subsamples, showing smooth rotations, shears, and deformations of the layer of gas producing stars with the formation of the Gould Belt, the Great Tunnel, the Local Bubble, and other structures within the last 200 Myr. The detected temporal variations of the velocity dispersions, solar motion components, Ogorodnikov-Milne model parameters, and Oort constants are significant, agree with the results of other authors, and show that it is meaningless to calculate the kinematic parameters for samples of stars with uncertain ages or with a wide range of ages.
- ID:
- ivo://CDS.VizieR/J/A+A/444/941
- Title:
- Effective temperature of B stars
- Short Name:
- J/A+A/444/941
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We establish an empirical effective temperature calibration of main sequence, luminosity class V to III B-type stars for the Delta a photometric system which was originally developed to detect magnetic chemically peculiar objects of the upper main sequence (early B-type to early F-type) at 5200A. However, this system provides the index g1-y which shows an excellent correlation with B-V as well as b-y and can be used as an indicator of the effective temperature. This is supplemented by a very accurate color-magnitude diagram, y or V versus g1-y, which can be used, for example, to determine the reddening, distance and age of an open cluster. This makes the Delta a photometric system an excellent tool to investigate the HR diagram in more detail. Using the reddening-free parameters and already established calibrations within the Stromgren uvbybeta, Geneva 7-color and Johnson UBV systems, a polynomial fit of third degree for the averaged effective temperatures to the individual (g1-y)0 values was derived. For this purpose, data from the literature as well as new observations were taken resulting in 225 suitable bright normal B-type objects. The statistical mean of the error for this sample is 238K which is sufficient to investigate the HRD of distant galactic open clusters as well as extragalactic aggregates in the future.
- ID:
- ivo://CDS.VizieR/J/A+A/501/297
- Title:
- Effective temperatures of B Supergiants
- Short Name:
- J/A+A/501/297
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Effective temperatures of early-type supergiants are important to test stellar atmosphere- and internal structure-models of massive and intermediate mass objects at different evolutionary phases. However, these Teff values are more or less discrepant depending on the method used to determine them. We aim to obtain a new calibration of the Teff parameter for early-type supergiants as a function of observational quantities that are: a) highly sensitive to the ionization balance in the photosphere and its gas pressure; b) independent of the interstellar extinction; c) as much as possible model-independent.
- ID:
- ivo://CDS.VizieR/J/ApJ/850/194
- Title:
- Equivalent widths of 8 DIBs for 186 O & B stars
- Short Name:
- J/ApJ/850/194
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the behavior of eight diffuse interstellar bands (DIBs) in different interstellar environments, as characterized by the fraction of hydrogen in molecular form (f_H2_), with comparisons to the corresponding behavior of various known atomic and molecular species. The equivalent widths of the five "normal" DIBs ({lambda}{lambda}5780.5, 5797.1, 6196.0, 6283.8, and 6613.6), normalized to E_B-V_, show a "lambda-shaped" behavior: they increase at low f_H2_, peak at f_H2_~0.3, and then decrease. The similarly normalized column densities of Ca, Ca+, Ti+, and CH+ also decline for f_H2_>0.3. In contrast, the normalized column densities of Na, K, CH, CN, and CO increase monotonically with fH2, and the trends exhibited by the three C_2_ DIBs ({lambda}{lambda}4726.8, 4963.9, and 4984.8) lie between those two general behaviors. These trends with f_H2_ are accompanied by cosmic scatter, the dispersion at any given f_H2_ being significantly larger than the individual errors of measurement. The lambda-shaped trends suggest the balance between creation and destruction of the DIB carriers differs dramatically between diffuse atomic and diffuse molecular clouds; additional processes aside from ionization and shielding are needed to explain those observed trends. Except for several special cases, the highest W{lambda}(5780)/W{lambda}(5797) ratios, characterizing the so-called "sigma-zeta effect," occur only at f_H2_<0.2. We propose a sequence of DIBs based on trends in their pair-wise strength ratios with increasing f_H2_. In order of increasing environmental density, we find the {lambda}6283.8 and {lambda}5780.5 DIBs, the {lambda}6196.0 DIB, the {lambda}6613.6 DIB, the {lambda}5797.1 DIB, and the C_2_ DIBs.
- ID:
- ivo://CDS.VizieR/J/ApJS/186/175
- Title:
- Far-UV spectroscopic atlas of B stars
- Short Name:
- J/ApJS/186/175
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have constructed a detailed spectral atlas covering the wavelength region 930-1225{AA} for 10 sharp-lined B0-B9 stars near the main sequence. Most of the spectra we assembled are from the archives of the Far Ultraviolet Spectroscopic Explorer satellite, but for nine stars, wavelength coverage above 1188{AA} was taken from high-resolution International Ultraviolet Explorer or echelle Hubble Space Telescope/Space Telescope Imaging Spectrograph spectra. To represent the tenth star at type B0.2V, we used the Copernicus atlas of tau Sco. We made extensive line identifications in the region 949-1225{AA} of all atomic features having published oscillator strengths at types B0, B2, and B8. These are provided as a supplementary data product-hence the term detailed atlas. Our list of found features totals 2288, 1612, and 2469 lines, respectively. We were able to identify 92%, 98%, and 98% of these features with known atomic transitions with varying degrees of certainty in these spectra. The remaining lines do not have published oscillator strengths. Photospheric lines account for 94%, 87%, and 91%, respectively, of all our identifications, with the remainder being due to interstellar (usually molecular H2) lines. We also discuss the numbers of lines with respect to the distributions of various ions for these three most studied spectral subtypes. A table is also given of 162 least blended lines that can be used as possible diagnostics of physical conditions in B star atmospheres.
- ID:
- ivo://CDS.VizieR/J/A+A/506/471
- Title:
- Frequency analysis of CoRoT B stars
- Short Name:
- J/A+A/506/471
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We search for new variable B-type pulsators in the CoRoT data assembled primarily for planet detection, as part of CoRoT's Additional Programme. We aim to explore the properties of newly discovered B-type pulsators from the uninterrupted CoRoT spacebased photometry and to compare them with those of known members of the beta Cep and slowly pulsating B star (SPB) classes. We developed automated data analysis tools which include algorithms for jump correction, light curve detrending, frequency detection, frequency combination search and frequency and period spacing search. Besides numerous new classical slowly pulsating B stars, we find evidence for a new class of low-amplitude B-type pulsators between the SPB and delta Sct instability strips, with a very broad range of frequencies and low amplitudes, as well as several slowly pulsating B stars with residual excess power at frequencies typically a factor three above their expected g-mode frequencies. The frequency data we obtained for numerous new B-type pulsators represent an appropriate starting point for further theoretical analyses of these stars, once their effective temperature, gravity, rotation velocity and abundances will be derived spectroscopically in the framework of an ongoing FLAMES survey at VLT.
- ID:
- ivo://CDS.VizieR/J/ApJ/873/91
- Title:
- Interferometric obs. of B-type stars with CHARA
- Short Name:
- J/ApJ/873/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present interferometric observations of 25 spectral type-B stars that were made with the Precision Astronomical Visible Observations and the CLassic Interferometry with Multiple Baselines beam combiners at the Center for High Angular Resolution Astronomy Array (CHARA). The observations provide the angular sizes of these stars with an average error of 6%. The stars range in size from 1.09mas for {beta} Tau down to 0.20mas for 32 Ori. We collected ultraviolet to infrared spectrophotometry and derived temperatures, angular diameters, and reddening estimates that best fit the spectra, as well as solutions with the angular size fixed by the interferometric measurements. There is generally good agreement between the observed and spectral fit angular diameters, indicating that the fluxes predicted from model atmospheres are reliable. On the other hand, the temperatures derived from angular diameters and fluxes tend to be larger (by ~4%) than those from published results based on analysis of the line spectrum. This discrepancy may in part be attributed to unexplored atmospheric parameters or the existence of unknown companions. The physical radii of the stars are calculated from the angular diameters and Gaia DR2 parallaxes, and the target stars are placed in the Hertzsprung-Russell diagram for comparison with evolutionary tracks.
