- ID:
- ivo://CDS.VizieR/J/A+A/557/A1
- Title:
- Bright B-type variables in Scorpius
- Short Name:
- J/A+A/557/A1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The first two of a total of six nano-satellites that will constitute the BRITE-Constellation space photometry mission have recently been launched successfully. In preparation for this project, we carried out time-resolved colour photometry in a field that is an excellent candidate for BRITE measurements from space. We acquired 117h of Stromgren uvy data during 19 nights. Our targets comprised the {beta} Cephei stars {kappa} and {lambda} Sco, the eclipsing binary {mu}^1^ Sco, and the variable super/hypergiant {zeta}^1^ Sco. For {kappa} Sco, a photometric mode identification in combination with results from the spectroscopic literature suggests a dominant (l,m)=(1,-1) {beta} Cephei-type pulsation mode of the primary star. The longer period of the star may be a rotational variation or a g-mode pulsation. For {lambda} Sco, we recover the known dominant {beta} Cephei pulsation, a longer-period variation, and observed part of an eclipse. Lack of ultraviolet data precludes mode identification for this star. We noticed that the spectroscopic orbital ephemeris of the closer pair in this triple system is inconsistent with eclipse timings and propose a refined value for the orbital period of the closer pair of 5.95189+/-0.00003d. We also argue that the components of the {lambda} Sco system are some 30% more massive than previously thought. The binary light curve solution of {mu}^1^ Sco requires inclusion of the irradiation effect to explain the u light curve, and the system could show additional low amplitude variations on top of the orbital light changes. {zeta}^1^ Sco shows long-term variability on a time scale of at least two weeks that we prefer to interpret in terms of a variable wind or strange mode pulsations.
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- ID:
- ivo://CDS.VizieR/J/AJ/129/809
- Title:
- B-star rotational velocities in h and {chi} Persei
- Short Name:
- J/AJ/129/809
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Projected rotational velocities (vsini) have been measured for 216 B0-B9 stars in the rich, dense h and {chi} Persei double cluster and compared with the distribution of rotational velocities for a sample of field stars having comparable ages (t~12-15Myr) and masses (M~4-15M_Sun_).
- ID:
- ivo://CDS.VizieR/J/A+A/610/A30
- Title:
- B stars in 4 open clusters
- Short Name:
- J/A+A/610/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar physical properties of star clusters are poorly known and the cluster parameters are often very uncertain. Our goals are to perform a spectrophotometric study of the B star population in open clusters to derive accurate stellar parameters, search for the presence of circumstellar envelopes, and discuss the characteristics of these stars. The BCD spectrophotometric system is a powerful method to obtain stellar fundamental parameters from direct measurements of the Balmer discontinuity. To this end, we wrote the interactive code MIDE3700. The BCD parameters can also be used to infer the main properties of open clusters: distance modulus, color excess, and age. Furthermore, we inspected the Balmer discontinuity to provide evidence for the presence of circumstellar disks and identify Be star candidates. We used an additional set of high-resolution spectra in the H{alpha} region to confirm the Be nature of these stars. We provide Teff, logg, Mv, Mbol, and spectral types for a sample of 68 stars in the field of the open clusters NGC6087, NGC6250, NGC6383, and NGC6530, as well as the cluster distances, ages, and reddening. Then, based on a sample of 230 B stars in the direction of the 11 open clusters studied along this series of three papers, we report 6 new Be stars, 4 blue straggler candidates, and 15 B-type stars (called Bdd) with a double Balmer discontinuity, which indicates the presence of circumstellar envelopes. We discuss the distribution of the fraction of B, Be, and Bdd star cluster members per spectral subtype. The majority of the Be stars are dwarfs and present a maximum at the spectral type B2-B4 in young and intermediate-age open clusters (<40Myr). Another maximum of Be stars is observed at the spectral type B6-B8 in open clusters older than 40Myr, where the population of Bdd stars also becomes relevant. The Bdd stars seem to be in a passive emission phase. Our results support previous statements that the Be phenomenon is present along the whole main sequence band and occurs in very different evolutionary states.We find clear evidence of an increase of stars with circumstellar envelopes with cluster age. The Be phenomenon reaches its maximum in clusters of intermediate age (10-40Myr) and the number of B stars with circumstellar envelopes (Be plus Bdd stars) is also high for the older clusters (40-100Myr).
- ID:
- ivo://CDS.VizieR/J/other/ApSS/203.53
- Title:
- B stars UBV and SpType catalogue
- Short Name:
- J/other/ApSS/203
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The present work represents a catalogue of spectral classification and photometric data of 2047 B type stars using the {Delta}Q method.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/591/A92
- Title:
- BVR polarimetry of HD 48099
- Short Name:
- J/A+A/591/A92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the structure of the O-type binary system HD 48099 by measuring linear polarization that arises due to light scattering process. High-precision polarimetry provides independent estimates of the orbital parameters and gives important information on the properties of the system. Linear polarization measurements of HD 48099 in the B, V and R passbands with the high-precision Dipol-2 polarimeter have been carried out. The data have been obtained with the 60cm KVA (Observatory Roque de los Muchachos, La Palma, Spain) and T60 (Haleakala, Hawaii, USA) remotely controlled telescopes during 31 observing nights.Polarimetry in the optical wavelengths has been complemented by observations in the X-rays with the SWIFT space observatory. Optical polarimetry revealed small intrinsic polarization in HD 48099 with 0.1% peak to peak variation over the orbital period of 3.08d. The variability pattern is typical for binary systems, showing strong second harmonic of the orbital period. We apply our model code for the electron scattering in the circumstellar matter to put constraints on the system geometry. A good model fit is obtained for scattering of light on a cloud produced by the colliding stellar winds. The geometry of the cloud, with a broad distribution of scattering particles away from the orbital plane, helps in constraining the (low) orbital inclination. We derive from the polarization data the inclination i=17{deg}+/-2{deg} and the longitude of the ascending node Omega=82{deg}+/-1{deg} of the binary orbit. The available X-ray data provide additional evidence for the existence of the colliding stellar winds in the system. Another possible source of the polarized light could be scattering from the stellar photospheres. The models with circumstellar envelopes, or matter confined to the orbital plane, do not provide good constraints on the low inclination, better than i<=27{deg}, as is already suggested by the absence of eclipses.
- 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/ApJ/705/32
- Title:
- Diffuse interstellar bands from HD 183143
- Short Name:
- J/ApJ/705/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Echelle spectra of HD 183143 [B7Iae, E(B-V)=1.27] were obtained on three nights, at a resolving power R=38000 and with a signal-to-noise ratio ~1000 at 6400{AA} in the final, combined spectrum. A catalog is presented of 414 diffuse interstellar bands (DIBs) measured between 3900 and 8100{AA} in this spectrum. The central wavelengths, the widths (FWHM), and the equivalent widths of nearly all of the bands are tabulated, along with the minimum uncertainties in the latter. Among the 414 bands, 135 (or 33%) were not reported in four previous, modern surveys of the DIBs in the spectra of various stars, including HD 183143. The principal result of this study is that the great majority of the bands in the catalog are very weak and fairly narrow. Typical equivalent widths amount to a few m{AA}, and the bandwidths (FWHM) are most often near 0.7{AA}.
