- ID:
- ivo://CDS.VizieR/J/MNRAS/489/2595
- Title:
- Spectro-interferometry of 8 evolved stars
- Short Name:
- J/MNRAS/489/2595
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determine the physical parameters of the outer atmosphere of a sample of eight evolved stars, including the red supergiant {alpha} Scorpii, the red giant branch stars {alpha} Bootis and {gamma} Crucis, the K giant {lambda} Velorum, the normal M giants BK Virginis and SW Virginis, and the Mira star W Hydrae (in two different luminosity phases) by spatially resolving the stars in the individual carbon monoxide (CO) first overtone lines. We used the Astronomical Multi-BEam combineR (AMBER) instrument at the Very Large Telescope Interferometer (VLTI), in high-resolution mode ({lambda}/{Delta}{lambda}~=12000) between 2.28 and 2.31um in the K band. The maximal angular resolution is 10mas, obtained using a triplet telescope configuration, with baselines from 7 to 48m. By using a numerical model of a molecular atmosphere in a spherical shells (MOLsphere), called PAMPERO (an acronym for the 'physical approach of molecular photospheric ejection at high angular resolution for evolved stars'), we add multiple extended CO layers above the photospheric MARCS model at an adequate spatial resolution. We use the differential visibilities and the spectrum to estimate the size (R) of the CO MOLsphere, its column density (NCO) and temperature (Tmol) distributions along the stellar radius. The combining of the {chi}^2^ minimization and a fine grid approach for uncertainty analysis leads to reasonable NCO and Tmol distributions along the stellar radius of the MOLsphere.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/383/188
- Title:
- Spectrophotometric atlas of symbiotic stars
- Short Name:
- J/A+A/383/188
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A multi-epoch, absolute-fluxed spectral atlas extending from about 3200 to 9000{AA} is presented for 130 symbiotic stars, including members of the LMC, SMC and Draco dwarf galaxies. The fluxes are accurate to better than 5% as shown by comparison with Tycho and ground-based photometric data. The spectra of 40 reference objects (MK cool giant standards, Mira and Carbon stars, planetary nebulae, white dwarfs, hot sub-dwarfs, Wolf-Rayet stars, classical novae, VV Cep and Herbig Ae/Be objects) are provided to assist the interpretation of symbiotic star spectra. Astrometric positions and counterparts in astrometric catalogues are derived for all program symbiotic stars. The spectra are available in electronic form from the authors.
- ID:
- ivo://CDS.VizieR/J/PAZh/32/672
- Title:
- Spectrophotometry of 77 variable stars
- Short Name:
- J/PAZh/32/672
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of visual and near-infrared spectrophotometric observations for 77 variable stars obtained during 1971-1991 in Chile, Armenia and Bolivia. The quasi-monochromatic extra-atmospheric fluxes from the stars are given in absolute energy units (W/m^2^/m) at all wavelengths of the spectral range at 2.5 nm intervals.
- ID:
- ivo://CDS.VizieR/J/AJ/134/1877
- Title:
- Spectropolarimetry of R CrB in 1998-2003
- Short Name:
- J/AJ/134/1877
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an extended optical spectropolarimetry of R CrB from 1998 January to 2003 September. The polarization was almost constant in the phase of maximum brightness, being consistent with past observations. We detected, however, temporary changes of the polarization (~0.5%) in 2001 March and August, which were the first detections of large polarization variability in R CrB near maximum brightness. The amplitude and the position angle of the "transient polarization" were almost constant with wavelength in both events. There was a difference of about 20{deg} in the position angle between the two events. Each event could be explained by light scattering due to a short-lived dust puff occasionally ejected off the line of sight.
- ID:
- ivo://CDS.VizieR/J/AJ/159/43
- Title:
- Spectroscopically identified CVs from LAMOST survey. I.
- Short Name:
- J/AJ/159/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of cataclysmic variables (CVs) is presented including spectroscopically identified 380 spectra of 245 objects, of which 58 CV candidates are new discoveries. The BaggingTopPush and the Random Forest algorithms are applied to the Fifth Data Release (DR5) of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) to retrieve CVs with strong emission lines and with broad absorption lines respectively. Based on spectroscopic classification, 134 dwarf novae, 41 nova-like variables, and 19 magnetic CVs are identified from the sample. In addition, 89 high-inclination systems and 33 CVs showing companion stars are recognized and discussed for their distinct spectral characteristics. Comparisons between CVs from LAMOST and from published catalogs are made in spatial and magnitude distribution, and the difference of their locus in the Gaia color-absolute magnitude diagram (CaMD) are also investigated. More interestingly, for two dwarf novae observed through LAMOST and SDSS in different epochs, their spectra both in quiescence phase and during outburst are exhibited.
- ID:
- ivo://CDS.VizieR/J/AJ/152/207
- Title:
- Spectroscopic Indicators in SeisMic Archive (SISMA)
- Short Name:
- J/AJ/152/207
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We created a large database of physical parameters and variability indicators by fully reducing and analyzing the large number of spectra taken to complement the asteroseismic observations of the COnvection, ROtation and planetary Transits (CoRoT) satellite. 7103 spectra of 261 stars obtained with the ESO echelle spectrograph HARPS have been stored in the VO-compliant database Spectroscopic Indicators in a SeisMic Archive (SISMA), along with the CoRoT photometric data of the 72 CoRoT asteroseismic targets. The remaining stars belong to the same variable classes of the CoRoT targets and were observed to better characterize the properties of such classes. Several useful variability indicators (mean line profiles, indices of differential rotation, activity and emission lines) together with vsini and radial-velocity measurements have been extracted from the spectra. The atmospheric parameters T_eff_,logg, and [Fe/H] have been computed following a homogeneous procedure. As a result, we fully characterize a sample of new and known variable stars by computing several spectroscopic indicators, also providing some cases of simultaneous photometry and spectroscopy.
- ID:
- ivo://CDS.VizieR/J/ApJ/881/104
- Title:
- Spectroscopic obs. of RR Lyrae in NGC5139
- Short Name:
- J/ApJ/881/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed spectroscopic analysis of RR Lyrae (RRL) variables in the globular cluster NGC5139 ({omega} Cen). We collected optical (4580-5330{AA}), high-resolution (R~34000), high signal-to-noise ratio (~200) spectra for 113 RRLs with the multifiber spectrograph M2FS at the Magellan/Clay Telescope at Las Campanas Observatory. We also analyzed high- resolution (R~26000) spectra for 122 RRLs collected with FLAMES/GIRAFFE at the Very Large Telescope, available in the ESO archive. The current sample doubles the literature abundances of cluster and field RRLs in the Milky Way based on high-resolution spectra. Equivalent-width measurements were used to estimate atmospheric parameters, iron, and abundance ratios for {alpha} (Mg, Ca, Ti), iron peak (Sc, Cr, Ni, Zn), and s-process (Y) elements. We confirm that {omega}Cen is a complex cluster, characterized by a large spread in the iron content: -2.58<~[Fe/H]<~-0.85. We estimated the average cluster abundance as <[Fe/H]>=-1.80{+/-}0.03, with {sigma}=0.33dex. Our findings also suggest that two different RRL populations coexist in the cluster. The former is more metal-poor ([Fe/H]<~-1.5), with almost solar abundance of Y. The latter is less numerous, more metal-rich, and yttrium enhanced ([Y/Fe]>~0.4). This peculiar bimodal enrichment only shows up in the s-process element, and it is not observed among lighter elements, whose [X/Fe] ratios are typical for Galactic globular clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/136/1645
- Title:
- Spectroscopy of bright QUEST RR Lyrae stars
- Short Name:
- J/AJ/136/1645
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a sample of 43 bright (V<16.1, distance <13kpc) RR Lyrae stars (RRLs) from the QUasar Equatorial Survey with spectroscopic radial velocities and metallicities, we find that several separate halo substructures contribute to the Virgo overdensity (VOD). While there is little evidence of a halo substructure in the spatial distribution of these stars, their distribution in radial velocity reveals two moving groups. These results are reinforced when the sample is combined with a sample of blue horizontal branch stars that were identified in the Sloan Digital Sky Survey, and the combined sample provides evidence for one additional moving group.
- ID:
- ivo://CDS.VizieR/J/AJ/142/136
- Title:
- Spectroscopy of Cepheids. l=30-250{deg}
- Short Name:
- J/AJ/142/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper reports on the spectroscopic investigation of 238 Cepheids in the northern sky. Of these stars, about 150 are new to the study of the galactic abundance gradient. These new Cepheids bring the total number of Cepheids involved in abundance distribution studies to over 400. In this work, we also consider systematics between various studies and also those which result from the choice of models.
- ID:
- ivo://CDS.VizieR/J/A+A/549/A104
- Title:
- Spectroscopy of {delta} Scuti star KIC 5988140
- Short Name:
- J/A+A/549/A104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used high-quality Kepler photometry and spectroscopic data to investigate the Kepler binary candidate KIC 5988140. Using the spectrum synthesis method, we derived the fundamental parameters (T_eff_, logg, [M/H], vsini) and the abundances. Frequency analyses of both the photometric and the spectroscopic data revealed the same two dominant frequencies. We also detected in the photometry the signal of nine more, significant frequencies located in the range 10-15c/d. The light and radial velocity curves follow a similar, stable double-wave pattern. We considered three different scenarios: binarity, co-existence of Gamma Doradus and Delta Scuti pulsations and rotational modulation. We confirm the occurrence of various independent Delta Scuti-type pressure modes in the Kepler light curve. However, we argue that the physical cause of low frequencies in the light and radial velocity variations of this late A-type star remain unexplained by any of the presently considered scenarios.
