- ID:
- ivo://CDS.VizieR/J/A+A/496/191
- Title:
- Spectral analysis of 636 SDSS WD-M binaries
- Short Name:
- J/A+A/496/191
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 857 WD-M star binaries from the Sloan Digital Sky Survey (SDSS), most of which were previously identified by other authors, and the results of our spectral analysis for a subsample of 636 WD-M composite spectra. Our automatic fitting procedure bases on a chi^2^ minimization technique, yielding a decomposition of each combined spectrum and a derivation of independent parameter estimates for both components. On the respective photometric data from the SDSS, we also find 41 optically resolved binaries. We also investigated the spectra for hydrogen and helium emission.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/143/513
- Title:
- Spectral classification of close binaries
- Short Name:
- J/ApJS/143/513
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of 135 stars with composite spectra has been observed in the near-UV spectral region with the Aurelie spectrograph at the Observatoire de Haute-Provence. Using the spectral classifications of the cool components previously determined with near infrared spectra, we obtained reliable spectral types of the hot components of the sample systems. The hot components were isolated by the subtraction method using MK standards as surrogates of the cool components. We also derived the visual magnitude differences between the components using Willstrop's normalized stellar flux ratios. We propose a photometric model for each of these systems on the basis of our spectroscopic data and the Hipparcos data.
253. Spectra of HD 120678
- ID:
- ivo://CDS.VizieR/J/A+A/546/A92
- Title:
- Spectra of HD 120678
- Short Name:
- J/A+A/546/A92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of a shell-like event in the Oe-type star HD 120678. HD 120678 has been intensively observed as part of a high-resolution spectroscopic monitoring program of southern Galactic O stars and Wolf-Rayet stars of the nitrogen sequence. An optical spectrogram of HD 120678 obtained in June 2008 shows strong H and HeI absorption lines instead of the double-peaked emission profiles observed both previously and subsequently, as well as a variety of previously undetected absorption features, mainly of OII, SiIII and FeIII. Photometric data reveal that the development of the absorption spectrum coincided with a remarkable dip in the V-band lightcurve. The "shell phase" of HD 120678 did not persist for very long: the V magnitude recovered its previous average value in fewer than 120 days, whereas H and He emission lines became detectable one year later. Similar spectral variations have been observed in a few Be stars, and they are usually interpreted as changes in the circumstellar disk.
- ID:
- ivo://CDS.VizieR/J/A+A/567/A49
- Title:
- Spectra of IPHAS symbiotic stars
- Short Name:
- J/A+A/567/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The IPHAS H{alpha} survey provides a rich database to search for emission-line sources in the northern Galactic plane. We are systematically searching for symbiotic stars in the Milky Way using IPHAS. Our final goal, a complete census of this class of objects in the Galaxy, is a fundamental figure for discussing their overall properties and relevance to other classes of stars. Candidate symbiotic stars were selected using a refined combination of IPHAS and 2MASS photometric colours. Optical spectroscopy, together with the analysis of their spectral energy distribution in the IR, were obtained to confirm their nature and determine their main properties.
- ID:
- ivo://CDS.VizieR/J/A+A/659/A35
- Title:
- Spectra of IRAS 17449+2320
- Short Name:
- J/A+A/659/A35
- Date:
- 04 Mar 2022 00:58:00
- Publisher:
- CDS
- Description:
- We report the first detection of the magnetic field in a star of FS CMa type, a subgroup of objects characterized by the B[e] phenomenon. The split of magnetically sensitive lines in IRAS 17449+2320 determines the magnetic field modulus of 6.2+/-0.2kG. Spectral lines and their variability reveal the presence of a B-type spectrum and a hot continuum source in the visible. The hot source confirms GALEX UV photometry. Because there is a lack of spectral lines for the hot source in the visible, the spectral fitting gives only the lower temperature limit of the hot source, which is 50000K, and the upper limit for the B-type star of 11100K. The V/R ratio of the Halpha line shows quasiperiodic behavior on timescale of 800 days. We detected a strong red-shifted absorption in the wings of Balmer and OI lines in some of the spectra. The absorption lines of helium and other metals show no, or very small, variations, indicating unusually stable photospheric regions for FS CMa stars. We detected two events of material infall, which were revealed to be discrete absorption components of resonance lines. The discovery of the strong magnetic field together with the Gaia measurements of the proper motion show that the most probable nature of this star is that of a post-merger object created after the leaving the binary of the birth cluster. Another possible scenario is a magnetic Ap star around Terminal-Age Main Sequence (TAMS). On the other hand, the strong magnetic field defies the hypothesis that IRAS 17449+2320 is an extreme classical Be star. Thus, IRAS 17449+2320 provides a pretext for exploring a new explanation of the nature of FS CMa stars or, at least, a group of stars with very similar spectral properties.
- ID:
- ivo://CDS.VizieR/J/A+A/557/A79
- Title:
- Spectra of KIC10661783
- Short Name:
- J/A+A/557/A79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- KIC 10661783 is an eclipsing binary that shows delta Sct-like oscillations. More than 60 pulsation frequencies have been detected in its light curve as observed by the Kepler satellite. We want to determine the fundamental stellar and system parameters of the eclipsing binary as a precondition for asteroseismic modelling of the pulsating component and to establish whether the star is a semi-detached Algol-type system. We measured the radial velocities of both components from new high-resolution spectra using TODCOR and compute the orbit using PHOEBE. We used the KOREL program to decompose the observed spectra into its components, and analysed the decomposed spectra to determine the atmospheric parameters. For this, we developed a new computer program for the normalisation of the KOREL output spectra. Fundamental stellar parameters are determined by combining the spectroscopic results with those from the analysis of the Kepler light curve. We obtain Teff, logg, vsini, and the absolute masses and radii of the components, together with their flux ratio and separation. Whereas the secondary star rotates synchronously with the orbital motion, the primary star rotates subsynchronously by a factor of 0.75. The newly determined mass ratio of 0.0911 is higher than previously thought and means a detached configuration is required to fit the light curve. With its low orbital period and very low mass ratio, the system shows characteristics of the R CMa-type stars but differs from this group by being detached. Its current state is assumed to be that of a detached post-Algol binary system with a pulsating primary component.
- ID:
- ivo://CDS.VizieR/J/MNRAS/424/1925
- Title:
- Spectrocopic Binarity of O and B type stars
- Short Name:
- J/MNRAS/424/1925
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation of stars above about 20M_{sun}_ and their apparently high multiplicity remain heavily debated subjects in astrophysics. We have performed a vast high-resolution radial velocity spectroscopic survey of about 250 O- and 540 B-type stars in the southern Milky Way which indicates that the majority of stars (>82%) with masses above 16M_{sun}_ form close binary systems while this fraction rapidly drops to 20% for stars of 3M_{sun}_. The binary fractions of O-type stars among different environment classes are: clusters (72+/-13%), associations (73+/-8%), field (43+/-13%) and runaways (69+/-11%). The high frequency of close pairs with components of similar mass argues in favour of a multiplicity originating from the formation process rather than from a tidal capture in a dense cluster. The high binary frequency of runaway O stars that we found in our survey (69% compared to 19-26% in previous surveys) points to the importance of ejection from young star clusters and thus supports the competitive accretion scenario.
- ID:
- ivo://CDS.VizieR/J/ApJ/660/1398
- Title:
- Spectro. monitoring of HDE 245770 and X Per
- Short Name:
- J/ApJ/660/1398
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from an H{alpha} monitoring campaign of the Be X-ray binary systems HDE 245770 = A0535+26 and X Per. We use the H{alpha} equivalent widths together with adopted values of the Be star effective temperature, disk inclination, and disk outer boundary to determine the half-maximum emission radius of the disk as a function of time.
- ID:
- ivo://CDS.VizieR/J/ApJ/821/8
- Title:
- Spectroscopic binary population of ONC and NGC2264
- Short Name:
- J/ApJ/821/8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine the spectroscopic binary population for two massive nearby regions of clustered star formation, the Orion Nebula Cluster (ONC) and NGC 2264, supplementing the data presented by Tobin et al. (2009, J/ApJ/697/1103) with more recent observations and more extensive analysis. The inferred multiplicity fraction up to 10 au based on these observations is 5.3+/-1.2% for NGC 2264 and 5.8+/-1.1% for the ONC; these values are consistent with the distribution of binaries in the field in the relevant parameter range. Eight of the multiple systems in the sample have enough epochs to perform an initial fit for the orbital parameters. Two of these sources are double-lined spectroscopic binaries; for them, we determine the mass ratio. Our reanalysis of the distribution of stellar radial velocities toward these clusters presents a significantly better agreement between stellar and gas kinematics than was previously thought.
- ID:
- ivo://CDS.VizieR/J/A+A/328/551
- Title:
- Spectroscopic data of 4 Herculis
- Short Name:
- J/A+A/328/551
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A collection of spectroscopic data of 4 Her at our disposal (RV and spectrophotometric measurements) consist of spectra obtained at the Ondrejov and Haute Provence Observatories. Table 1 summarizes the measurements of radial velocities and line intensities carried out in the red spectra. In Table 2 a list of the spectra and RV measurements for the violet-blue region is given.
