- ID:
- ivo://CDS.VizieR/J/A+A/412/447
- Title:
- Velocities of {lambda} Bootis stars
- Short Name:
- J/A+A/412/447
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We demonstrate that it is arduous to define the {lambda} Boo stars as a class of objects exhibiting uniform abundance peculiarities which would be generated by a mechanism altering the structure of their atmospheric layers. We collected the stars classified as {lambda} Boo up to now and discuss their properties, in particular the important percentage of confirmed binaries producing composite spectra (including our adaptive optics observations) and of misclassified objects. The unexplained RV variables (and thus suspected binaries), the known SB for which we lack information on the companion, the stars with an UV flux inconsistent with their classification, and the fast rotating stars for which no accurate abundance analysis can be performed, are also reviewed.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/130/2838
- Title:
- Velocity and light curves of RW Lac
- Short Name:
- J/AJ/130/2838
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 3004 differential observations in the V bandpass measured by a robotic telescope, as well as 36 pairs of radial velocities from high-resolution spectroscopic observations, of the detached, eccentric, EA-type, 10.37day period, double-lined eclipsing binary star RW Lac.
- ID:
- ivo://CDS.VizieR/J/A+A/455/1037
- Title:
- V360 Lac spectroscopy
- Short Name:
- J/A+A/455/1037
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We include existing photometric and spectroscopic material with new observations in a detailed study of the Be+F binary V360 Lac. We used the programs FOTEL and KOREL to derive an improved linear ephemeris and to disentangle the line profiles of both binary components and telluric lines. The BINSYN software suite (described in the paper) is used to calculate synthetic light curves and spectra to fit the UBV photometry, an IUE spectrum, blue and red ground-based spectra, and observed radial-velocity curves.
- ID:
- ivo://CDS.VizieR/J/A+A/580/A93
- Title:
- VLTS. B stars multiplicity
- Short Name:
- J/A+A/580/A93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the multiplicity properties of 408 B-type stars observed in the 30 Doradus region of the Large Magellanic Cloud with multi-epoch spectroscopy from the VLT-FLAMES Tarantula Survey (VFTS). We use a cross-correlation method to estimate relative radial velocities from the helium and metal absorption lines for each of our targets. Objects with significant radial-velocity variations (and with an amplitude larger than 16km/s) are classified as spectroscopic binaries. We find an observed spectroscopic binary fraction (defined by periods of <10^3.5^d and mass ratios >0.1) for the B-type stars, f_B_(obs)=0.25+/-0.02, which appears constant across the field of view, except for the two older clusters (Hodge 301 and SL 639). These two clusters have significantly lower binary fractions of 0.08+/-0.08 and 0.10+/-0.09, respectively. Using synthetic populations and a model of our observed epochs and their potential biases, we constrain the intrinsic multiplicity properties of the dwarf and giant (i.e. relatively unevolved) B-type stars in 30 Dor. We obtain a present-day binary fraction f_B_(true)=0.58+/-0.11, with a flat period distribution. Within the uncertainties, the multiplicity properties of the B-type stars agree with those for the O stars in 30 Dor from the VFTS.
- ID:
- ivo://CDS.VizieR/J/A+A/337/183
- Title:
- V1046 Ori uvby photometry and radial velocities
- Short Name:
- J/A+A/337/183
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a detailed spectroscopic and photometric study of V1046 Orionis undertaken to resolve uncertainties about the period(s) and causes of the spectroscopic and photometric variations of this helium-strong star. We have detected the lines of the secondary star in an extensive series of photographic and electronic spectra. This eliminates any doubt about the duplicity of this star. The orbital elements we derive from our measures of these spectra confirm the unusually large orbital eccentricity, e=0.433, for the short, P=18.65612d, orbital period. The line profiles, V/R ratio of the double H{alpha} emission, residuals of the primary radial velocities from the orbital velocity curve, brightness and colour of the object, magnetic field, and radio emission of this system all vary with a period of 0.9011836d. We tentatively follow earlier investigators in interpreting this as the rotational period of the primary and summarize the evidence of the phase shifts among the different phenomena, using the accurate value of the 0.9d period, to put tight constraints on any future model of these changes. We postpone our own attempt at a quantitative modelling of the variations with the 0.9d period for a separate study.
- ID:
- ivo://CDS.VizieR/J/A+A/319/867
- Title:
- V436 Persei = 1 Persei byBV photometry
- Short Name:
- J/A+A/319/867
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Outline of a project aimed at testing the presence of rapid line-profile variations in the atmospheres of hot components of close binaries is presented and its first results are described. An analysis of new electronic spectra of the eclipsing binary V436 Per from three observatories and of photoelectric observations, obtained earlier by several authors, leads to a unique determination of all basic physical elements of this interesting object. The first practical application of a new method of spectral disentangling allowed us to obtain, for the first time, individual accurate line profiles of both binary components and to derive their rotational velocities and orbital radial-velocity curves. We also detected absorption sub-features travelling from blue to red accross the He I 6678 line profile, in a series of six spectra taken during one night. At least one of the components of V436 Per is, therefore, a new hot line-profile variable.
- ID:
- ivo://CDS.VizieR/J/A+A/408/611
- Title:
- V436 Persei UBV photometry
- Short Name:
- J/A+A/408/611
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An analysis of new spectroscopic and photoelectric UBV observations, satisfactorily covering the whole orbital period of V436 Per, together with existing data allowed us to improve the knowledge of the basic physical characteristics of the binary and its components. In several aspects, our new results differ from the findings of Paper I (Harmanec et al., 1997, Cat. <J/A+A/319/867>) of this series: In particular, we found that it is the star eclipsed in the secondary minimum which is slightly more massive and larger than the optical primary. We also conclude that the apsidal advance -- if present at all -- is much slower than that estimated in a previous study. The orbital period might be increasing by 0.28 s per year but also this finding is very uncertain and needs verification by future observations. It is encouraging to note that two completely independent sets of programs for light-curve solutions lead to identical results. A notable finding is that both binary components rotate with very similar -- if not identical -- rotational periods of 1.45d and 1.40d, much shorter than what would correspond to a 10.9d spin-orbit synchronization period at periastron. Rapid line-profile changes reported earlier could not be confirmed from new, dedicated series of high-resolution and S/N spectra.
- ID:
- ivo://CDS.VizieR/J/A+A/542/A53
- Title:
- VR + velocity variations of IRAS 11472-0800
- Short Name:
- J/A+A/542/A53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We focus here on one particular and poorly studied object, IRAS 11472-0800. It is a highly evolved post-asymptotic giant branch (post-AGB) star of spectral type F, with a large infrared excess produced by thermal emission of circumstellar dust. We deployed a multi-wavelength study that includes the analyses of optical and IR spectra as well as a variability study based on photometric and spectroscopic time-series.
- ID:
- ivo://CDS.VizieR/J/ApJ/578/943
- Title:
- vsini of binaries with evolved component
- Short Name:
- J/ApJ/578/943
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the present study we analyze the behavior of the rotational velocity, vsini, for a large sample of 134 spectroscopic binary systems with a giant star component of luminosity class III, along the spectral region from middle F to middle K.
330. WDMS from LAMOST DR1
- ID:
- ivo://CDS.VizieR/J/A+A/570/A107
- Title:
- WDMS from LAMOST DR1
- Short Name:
- J/A+A/570/A107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- White dwarf-main sequence (WDMS) binaries are used to study several different important open problems in modern astrophysics. The Sloan Digital Sky Survey (SDSS) identified the largest catalogue of WDMS binaries currently known. However, this sample is seriously affected by selection effects and the population of systems containing cool white dwarfs and early-type companions is under-represented. Here we search for WDMS binaries within the spectroscopic data release 1 of the LAMOST (Large sky Area Multi-Object fiber Spectroscopic Telescope) survey. LAMOST and SDSS follow different target selection algorithms. Hence, LAMOST WDMS binaries may be drawn from a different parent population and thus help in overcoming the selection effects incorporated by SDSS on the current observed population. We develop a fast and efficient routine based on the wavelet transform to identify LAMOST WDMS binaries containing a DA white dwarf and a M dwarf companion, and apply a decomposition/fitting routine to their LAMOST spectra to estimate their distances and measure their stellar parameters, namely the white dwarf effective temperatures, surface gravities and masses, and the secondary star spectral types. We identify 121 LAMOST WDMS binaries, 80 of which are new discoveries, and estimate the sample to be about 90 per cent complete. The LAMOST and SDSS WDMS binaries are found to be statistically different. However, this result is not due to the different target selection criteria of both surveys, but likely a simple consequence of the different observing conditions. Thus, the LAMOST population is found at considerably shorter distances (50-450pc) and is dominated by systems containing early-type companions and hot white dwarfs. Even though WDMS binaries containing cool white dwarfs are also missed by the LAMOST survey, the LAMOST WDMS binary sample dominated by systems containing early-type companions is an important addition to the current known spectroscopic catalogue. Future LAMOST observations however are required to increase the small number of LAMOST WDMS binaries.
