- ID:
- ivo://CDS.VizieR/J/ApJS/197/29
- Title:
- Chemical compositions of 11 RR Lyrae
- Short Name:
- J/ApJS/197/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed abundance study of 11 RR Lyrae ab-type variables: AS Vir, BS Aps, CD Vel, DT Hya, RV Oct, TY Gru, UV Oct, V1645 Sgr, WY Ant, XZ Aps, and Z Mic. High-resolution and high signal-to-noise ratio echelle spectra of these variables were obtained with the 2.5m du Pont telescope at the Las Campanas Observatory. We obtained more than 2300 spectra, roughly 200 spectra per star, distributed more or less uniformly throughout the pulsational cycles. A new method has been developed to obtain the initial effective temperatures of our sample stars at a specific pulsational phase. We find that the abundance ratios are generally consistent with those of similar metallicity field stars in different evolutionary states and throughout the pulsational cycles for RR Lyrae stars. TY Gru remains the only n-capture enriched star among the RRab in our sample.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/159/292
- Title:
- Chromospheric activity of SZ Piscium
- Short Name:
- J/AJ/159/292
- Date:
- 08 Dec 2021
- Publisher:
- CDS
- Description:
- To continue our study on chromospheric activity and detection for possible prominence events of the very active RS Canum Venaticorum star SZ Piscium (SZ Psc), long-term high-resolution spectroscopic observations were obtained during several observing runs from 2014 to 2018. Based on the spectral subtraction technique, the chromospheric emission of the CaII IRT ({lambda}8662, {lambda}8542, and {lambda}8498), H_{alpha}_, NaI D_1_, D_2_ doublet, H_{beta}_, and CaII H & K lines is mainly associated with the K1 IV primary star of the SZ Psc system, in good agreement with the previous studies, and the F8 V secondary star also shows some chromospheric emission, implying its active chromosphere. Moreover, an optical flare characterized by the HeI D3 line emission together with stronger emission in the other indicators was detected. Furthermore, two chromospheric active longitudes around the two quadratures of the system were identified for most of the time, and the chromospheric activity shows significant changes during a few orbital cycles. The chromospheric activity level seems to show a long-term variation during our observations. There were some excess absorption features in the subtracted H{alpha} line and the other activity indicators, which would be caused by prominence-like materials associated with the K1 IV primary star of the system. Prominence materials could absorb the chromospheric emission and continuum from the K1 IV primary star and even the F8 V secondary one.
- ID:
- ivo://CDS.VizieR/V/76
- Title:
- Chromospherically Active Binaries
- Short Name:
- V/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains 206 spectroscopic binary systems with at least one late-type component that shows Ca II H and K emission in its spectrum. These systems include the classical RS CVn binaries and BY Dra binaries. The catalog summarizes information on the photometric, spectroscopic, orbital, and physical properties of the systems as well as space motions and positions. Up to 42 "parameters" for each stellar system are listed followed by the appropriate reference to direct interested colleagues to the original papers. A comprehensive selection of further information for each star is given in the individual notes. In addition, the catalog contains a candidate list of 138 stars that have similar characteristics but are not definitely known binaries or have not had Ca II H and K emission observed. This version updates and replaces the 1988 catalog of similar information. (Strassmeier et al., 1988).
- ID:
- ivo://CDS.VizieR/V/128
- Title:
- Chromospherically Active Binaries. Third version
- Short Name:
- V/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chromospherically Active Binaries (CAB) catalogue have been revised and updated. With 203 new identifications, the number of CAB stars is increased to 409. Catalogue is available in electronic format where each system has various number of lines (sub-orders) with a unique order number. Columns contain data of limited number of selected cross references, comments to explain peculiarities and position of the binarity in case it belongs to a multiple system, classical identifications (RS CVn, BY Dra), brightness and colours, photometric and spectroscopic data, description of emission features (Ca II H&K, H{alpha}, UV, IR), X-Ray luminosity, radio flux, physical quantities and orbital information, where each basic entry are referenced so users can go original sources.
- ID:
- ivo://CDS.VizieR/J/AJ/131/1044
- Title:
- Chromospherically active stars in the Bulge
- Short Name:
- J/AJ/131/1044
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results from the discovery and study of ~3000 chromospherically active giant and subgiant stars toward the Galactic bulge.
- ID:
- ivo://CDS.VizieR/J/A+A/544/A26
- Title:
- CI Aql spectra during 2000 outburst
- Short Name:
- J/A+A/544/A26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High- and low-resolution optical spectra of CI Aql were obtained during the outburst in 2000. Multiple absorption components of HI and FeII lines were detected at the early decline stage. Their radial velocities were roughly -2500km/s, -2200km/s , -1700km/s, and -1400km/s, among which only the last components were likely still accelerating during the early decline stage. Prominent emission lines of [OIII] and [NII] appeared about one month after light maximum. The duration of the nebular stage, however, was only one month and a few weeks. The ejected gas shells seem to have started to shrink about 70 days after light maximum. The amount of interstellar extinction is estimated to be E(B-V)=0.92+/-0.15 from the equivalent widths of the diffuse interstellar absorption bands. The helium abundance in the ejecta is estimated to be N(He)=0.19+/-0.05 and the mass of the ejecta to be about 2x10^-6^M_{sun}_. This object has been classified as a U Sco type recurrent nova, but its spectral evolution during the outburst resembled those of T Pyx type recurrent novae. It is doubtful whether the peak of m_V_~9mag on 2000 May 5 was the true light maximum or an earlier brighter peak had been overlooked, because the spectral data suggest that the ejections of gas shells occurred prior to the discovery of the outburst on 2000 April 28.
- ID:
- ivo://CDS.VizieR/J/MNRAS/399/2139
- Title:
- CI Cyg BVRcIc light curves
- Short Name:
- J/MNRAS/399/2139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we discuss the early phases of the ongoing outburst that CI Cyg, a prototype symbiotic star, is currently undergoing after 30-year quiescence. We have tightly monitored CI Cyg in B V R_C_ I_C_ bands, starting a whole year before the onset of the outburst, and in addition we obtained numerous Echelle high- and low-resolution absolutely flux-calibrated spectra. The outburst started while the accreting white dwarf (WD) was being eclipsed by the Roche lobe filling M giant companion, and it was discovered during the egress phase on the second half of 2008 August. The system reached peak V-band brightness in early 2008 October and has been characterized by amplitudes {delta}B=1.9, {delta}V=1.5, {delta}R_C_=0.9, {delta}I_C_=0.4mag. At maximum V-band brightness, the outbursting WD had expanded to closely resemble an F3 II/Ib star, with MV=-3.5, Teff~6900K and R=28R_{sun}_. The high-ionization emission lines ([NeV], [FeVII], HeII) disappeared and only lower ionization lines were visible. Balmer and He I emission lines declined in equivalent width but increased in absolute flux. The output radiated by the hot component during the outburst corresponds to nuclear burning proceeding at a 2x10^-8^M_{sun}_/yr rate.
- ID:
- ivo://CDS.VizieR/J/ApJ/813/29
- Title:
- Classical and type II Cepheids IR excesses
- Short Name:
- J/ApJ/813/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectral energy distributions for 132 classical and type II Cepheids were searched for evidence of excess flux above the photospheric level in the mid-infrared. Eight of them were found to have unambiguously strong excess emission while a further 13 showed evidence of weak emission. The presence of emission appears to be unrelated to either the pulsational amplitude or the effective temperature while strong emission is limited to stars with periods longer than 11 days, with a single exception. For the stars with strong emission we attempted to fit the energy distribution with a stellar wind model. No acceptable fit could be found for silicate grains. With graphite or iron grains we could only obtain an acceptable fit if the maximum dust temperature was significantly lower than the condensation temperature. We conclude that the excess emission is not evidence of mass loss.
- ID:
- ivo://CDS.VizieR/J/PAZh/41/27
- Title:
- Classical Cepheids BVIc observations
- Short Name:
- J/PAZh/41/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In 2013-2014, we obtained 14959 CCD frames in the BVIc photometric system for 170 classical Cepheids from the General Catalogue of Variable Stars. We performed our observations with the 76-cm telescope of the South African Astronomical Observatory (SAAO, South Africa) using the SBIG ST-10XME CCD camera. The tables of observations, the plots of light curves, and the current light elements are presented.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A37
- Title:
- Classical Cepheids consistent radial velocities
- Short Name:
- J/A+A/631/A37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate radial velocities (vrad) of Cepheids are mandatory within the context of Cepheid distance measurements using the Baade-Wesselink technique. The most common vrad derivation method consists in cross-correlating the observed stellar spectra with a binary template and measuring a velocity on the resulting mean profile. Nevertheless, for Cepheids and other pulsating stars, the spectral lines selected within the template as well as the way of fitting the cross-correlation function (CCF) have a direct and significant impact on the measured vrad. Our first aim is to detail the steps to compute consistent CCFs and vrad of Cepheids. Next, this study aims at characterising the impact of Cepheid spectral properties and vrad computation methods on the resulting line profiles and vrad time series. We collected more than 3900 high-resolution spectra from seven different spectrographs of 64 Classical Milky Way (MW) Cepheids. These spectra were normalised and standardised using a single custom-made process on pre-defined wavelength ranges.We built six tailored correlation templates selecting unblended spectral lines of different depths based on a synthetic Cepheid spectrum, on three different wavelength ranges from 3900 to 8000{AA}. Each observed spectrum was cross-correlated with these templates to build the corresponding CCFs, adopted as the proxy for the spectrum mean line profile. We derived a set of line profile observables as well as three different vrad measurements from each CCF and two custom proxies for the CCF quality and amount of signal. This study presents a large catalogue of consistent Cepheid CCFs and vrad time series. It confirms that each step of the process has a significant impact on the deduced vrad: the wavelength, the template line depth and width, and the vrad computation method. The way towards more robust Cepheid vrad time series seems to go through steps that minimise the asymmetry of the line profile and its impact on the vrad. Centroid or first-moment vrad, that exhibit slightly smaller amplitudes but significantly smaller scatter than Gaussian or biGaussian vrad, should therefore be favoured. Stronger or deeper spectral lines also tend to be less asymmetric and lead to more robust vrad than weaker lines.
