- ID:
- ivo://CDS.VizieR/J/MNRAS/373/687
- Title:
- Spectra of 5 faint cataclysmic variables
- Short Name:
- J/MNRAS/373/687
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present medium-resolution VLT/FORS2 spectroscopy of six cataclysmic variables (CVs) discovered by the Sloan Digital Sky Survey (SDSS). We determine orbital periods for SDSS J023322.61+005059.5 (96.08+/-0.09min), SDSS J091127.36+084140.7 (295.74+/-0.22min), SDSS J103533.02+055158.3 (82.10+/-0.09min) and SDSS J121607.03+052013.9 (most likely 98.82+/-0.16min, but the one-day aliases at 92 and 107min are also possible) using radial velocities measured from their H{alpha} and H{beta} emission lines. Three of the four orbital periods measured here are close to the observed 75-80min minimum period for CVs, indicating that the properties of the population of these objects discovered by the SDSS are substantially different to those of the CVs found by other means. Additional photometry of SDSS J023322.61+005059.5 reveals a periodicity of approximately 60min which we interpret as the spin period of the white dwarf, suggesting that this system is an intermediate polar with a low accretion rate. SDSS J103533.02+055158.3 has a period right at the observed minimum value, a spectrum dominated by the cool white dwarf primary star and exhibits deep eclipses, so is an excellent candidate for an accurate determination of the parameters of the system. The spectroscopic orbit of SDSS J121607.03+052013.9 has a velocity amplitude of only 13.8+/-1.6km/s, implying that this system has an extreme mass ratio. From several physical constraints we find that this object must contain either a high-mass white dwarf or a brown-dwarf-mass secondary component or both.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/559/A12
- Title:
- Spectra of 2 halo red horizontal branch stars
- Short Name:
- J/A+A/559/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-velocity halo stars provide important information about the properties of the extreme Galactic halo. The study of Population II unbound and bound stars enables us better estimate the mass of the halo. We carried out a detailed spectroscopic and kinematic study of two red horizontal branch stars, CD-41 5048 and HD 214362.
- ID:
- ivo://CDS.VizieR/J/A+A/547/A85
- Title:
- Spectra of 7 H{alpha} emission line stars in MBM 18
- Short Name:
- J/A+A/547/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate star formation in translucent, high-latitude clouds. Our aim is to understand the star-formation history and rate in the solar neighbourhood. We used spectroscopic observations of newly found candidate H{alpha} emission-line stars to establish their pre-main-sequence nature. The environment was studied through molecular line observations of the cloud (MBM 18/LDN 1569) in which the stars are presumably embedded.
2414. 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/590/A122
- Title:
- Spectra of high-mass X-ray binaries
- Short Name:
- J/A+A/590/A122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-mass X-ray binaries are bright X-ray sources. The high-energy emission is caused by the accretion of matter from the massive companion onto a neutron star. The accreting material comes from either the strong stellar wind in binaries with supergiant companions or the circumstellar disk in Be/X-ray binaries. In either case, the H{alpha} line stands out as the main source of information about the state of the accreting material. We present the results of our monitoring program to study the long-term variability of the H{alpha} line in high-mass X-ray binaries. Our aim is to characterise the optical variability timescales and study the interaction between the neutron star and the accreting material. We fitted the H{alpha} line with Gaussian profiles and obtained the line parameters and equivalent width. The peak separation in split profiles was used to determine the disk velocity law and estimate the disk radius. The relative intensity of the two peaks (V/R ratio) allowed us to investigate the distribution of gas particles in the disk. The equivalent width was used to characterise the degree of variability of the systems. We also studied the variability of the H{alpha} line in correlation with the X-ray activity.
- 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.
2418. Spectra of KIC10661783
- 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/III/114
- Title:
- Spectra of Late-Type Standards, 2.0-2.5 Microns
- Short Name:
- III/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains a collection of K-band spectra for 26 stars with near-solar abundances, ranging in spectral class from F8 to M7 and in luminosity from dwarfs to supergiants. The spectra cover the wavelength region from 4150 to 4950 /cm and generally exhibit a signal to noise ratio above 400. Five stars here are supergiants, 15 are giants, and six are dwarfs. Data included: observation date, starting wavenumber, wavenumber increment, scale factor of relative intensity, and offset of relative intensity.
- ID:
- ivo://CDS.VizieR/J/A+AS/117/93
- Title:
- Spectra of 21 late-type stars
- Short Name:
- J/A+AS/117/93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical spectra of 21 stars from 4800 to 8920A, covering essentially the late spectral types, G, K, M and the luminosity classes I and III. Half of the stars are super metal rich (SMR) ones. The spectra were obtained at a resolution of 1.25A using the Aurelie spectrograph, equipped with a linear array CCD-like detector, attached to the OHP 1.52m telescope. Also presented are the spectra of 7 stars, covering the region 5000-9783A at a resolution of 8.5A, observed at the CFHT with the Herzberg spectrograph. The spectral types are F, G, K, M and the luminosity classes III and V. Five stars are SMR. These spectra have been obtained with the aim of extending existing libraries used for population synthesis purposes. The inclusion of SMR stars in a stellar library dedicated to the study of stellar populations in the central part of galaxies is crucial as abundance gradients have been observed in the optical range.
