- ID:
- ivo://CDS.VizieR/J/A+A/463/243
- Title:
- Variations of O-B stars in Mercator observations
- Short Name:
- J/A+A/463/243
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We selected a large sample of O-B stars that were considered as (candidate) slowly pulsating B, beta Cep, and Maia stars after the analysis of their Hipparcos data. We analysed both the Hipparcos data and our new seven passband Geneva data collected for these stars during the first three years of scientific operations of the Mercator telescope. We performed a frequency analysis for 28 targets with more than 50 high-quality Mercator observations to improve their variability classification. We searched for frequencies by using two independent frequency analysis methods and we applied a 3.6 S/N-level criterion to locate the significant peaks in the periodograms. In total we detected 60 frequencies, among which 32 new ones. We classified 21 objects as pulsating variables (7 new confirmed pulsating stars, including 2 hybrid beta Cep/SPB stars), 6 as non-pulsating variables (binaries or spotted stars), and 1 as photometrically constant stars. For the 27 confirmed variable stars in our sample, we give the values and the corresponding standard errors of the accepted frequencies, the amplitudes, the phases, the constant terms, and the residual standard deviations as found in the seven filters of the Geneva photometric system and in the Hp filter of the Hipparcos photometric system by fitting the data with a superposition of sinusoidal models with reference epoch HJD=2450000.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AcA/63/91
- Title:
- V-band light curves of variables in M80
- Short Name:
- J/AcA/63/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a search for variable stars in the globular cluster M 80. Application of the image subtraction method to the ground-based times-series of CCD frames resulted in finding nine new RR Lyr stars, six of the RRc and three of the RRab type, and four SX Phe variables.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/23
- Title:
- V-band photometric follow-up of RR Lyrae from SEKBO
- Short Name:
- J/ApJ/756/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the steepening of the power-law slope beyond the Galactocentric radius of R~45kpc in the RR Lyrae (RRL) space density distribution found by Keller et al. (2008, Cat. J/ApJ/678/851). They identified 2016 RRL candidates derived from the analysis of archival observations of the Southern Edgeworth-Kuiper Belt Object (SEKBO) survey. Our aim is to verify the completeness of RRLs and ultimately the space density distribution function given by Keller et al. We followed up on a subset of 137 candidates with a range of magnitudes (V~14-20) using the Faulkes Telescope (FT) database and confirmed 57 candidates as real RRLs. A cross-match between SEKBO RRL survey and Sloan Digital Sky Survey Data Release-7 (SDSS DR-7) revealed 272 RRL candidates in common. Applying the color selection criteria proposed by Ivezi\'c et al. (2005AJ....129.1096I) resulted in 193 likely RRLs. The completeness as a function of magnitude was calculated empirically from the combined set of SEKBO RRL candidates from current FT data, SDSS cross-matched data, and the Prior et al. catalog (2009, Cat. J/ApJ/691/306). This resulted in a spatial density distribution characterized by two power laws with a break radius R within a range between 45kpc and 50kpc, similar to the results of Keller et al. We find the power-law slopes for the inner halo as n_inner_=-2.78+/-0.02 and for the outer halo as n_outer_=-5.0+/-0.2.
- ID:
- ivo://CDS.VizieR/J/A+A/445/617
- Title:
- V823 Cas BV(RI)c differential photometry
- Short Name:
- J/A+A/445/617
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using extended multicolour CCD photometry of the triple-mode radial pulsator V823 Cas we studied the properties of the coupling frequencies invoked by nonlinear processes. Our results support that a resonance connection affects the mode coupling behaviour. The P1/P0 period ratio of V823 Cas has an "out of range" value if compared with the period ratios of the known double mode pulsators, while the P2/P1 period ratio is normal. The periods and period ratios cannot be consistently interpreted without conflict with pulsation and/or evolution models. We describe this failure with the suggestion that at present, the periods of V823 Cas are in a transient, resonance affected state, thus do not reflect the true parameters of the object. The anomalous period change behaviour of the fundamental and second overtone modes supports this idea. We have also raised the possibility that a f0+f2=2f1 resonance may act in triple mode pulsators.
- ID:
- ivo://CDS.VizieR/J/other/RAA/17.20
- Title:
- V977 Cep and V982 Cep long-term photometry
- Short Name:
- J/other/RAA/17.2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Long-term BVRI photometric light curves of the pre-main sequence stars V977 Cep and V982 Cep during the period from 2000 October to 2016 August are presented. The stars are located in the vicinity of the reflection nebula NGC 7129. Our photometric data show that both stars exhibit strong photometric variability in all optical passbands, which is typical for Classical T Tauri stars. Using our observational data we analyze the reasons for the observed brightness variations. In the case of V977 Cep we identify previously unknown periodicity in its light curve.
- ID:
- ivo://CDS.VizieR/J/AN/336/70
- Title:
- Velocities and proper motions of Galactic Cepheids
- Short Name:
- J/AN/336/70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The kinematics and distribution of classical Cepheids within ~3 kpc from the Sun suggest the existence of the outer ring R1R2' in the Galaxy. The optimum value of the solar position angle with respect to the major axis of the bar, theta_b, providing the best agreement between the distribution of Cepheids and model particles is theta_b_=37+/-13{deg}. The kinematical features obtained for Cepheids with negative Galactocentric radial velocity V_R_ are consistent with the solar location near the descending segment of the outer ring R2. The sharp rise of extinction toward of the Galactic center can be explained by the presence of the outer ring R1 near the Sun.
- 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.
- ID:
- ivo://CDS.VizieR/J/AcA/57/249
- Title:
- VIc photometry of NGC 6755 stars
- Short Name:
- J/AcA/57/249
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results from a search for variable stars in the field of a young open cluster NGC 6755. Altogether seventy one variable stars have been discovered. Thirty one of them are eclipsing systems. This group contains ten EA, four EB and seventeen EW-type systems. Photometric variability of four late type stars is most probably caused by their chromospherical activity. Another seven detected variable stars have light curves typical for pulsating stars from the main instability strip. Four of them we tentatively classified as gamma Dor, one as delta Sct and two as Population II Cepheid variable stars, respectively. Star designated as V40 can be either another population II Cepheid or an ellipsoidal binary system. The remaining twenty eight variable stars found in the field of this open cluster are most probably highly obscured background red giants (OSARG, irregular). For all detected variable stars we provide their light curves, preliminary classification, discussion on the possible cluster membership, equatorial coordinates, finding charts and periods when possible.
- ID:
- ivo://CDS.VizieR/J/AcA/61/285
- Title:
- VI light curves of Galactic Bulge Cepheids
- Short Name:
- J/AcA/61/285
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The fourteenth part of the OGLE-III Catalog of Variable Stars (OIII-CVS) contains Cepheid variables detected in the OGLE-II and OGLE-III fields toward the Galactic bulge. The catalog is divided into two main categories: 32 classical Cepheids (21 single-mode fundamental-mode F, four first-overtone 1O, two double-mode F/1O, three double-mode 1O/2O and two triple-mode 1O/2O/3O pulsators) and 335 type II Cepheids (156 BL Her, 128 W Vir and 51 RV Tau stars). Six of the type II Cepheids likely belong to the Sagittarius Dwarf Spheroidal Galaxy. The catalog data include the time-series photometry collected in the course of the OGLE survey, observational parameters of the stars, finding charts, and cross-identifications with the General Catalogue of Variable Stars.
- ID:
- ivo://CDS.VizieR/J/AcA/64/177
- Title:
- VI light curves of Galactic Bulge RR Lyrae
- Short Name:
- J/AcA/64/177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the most comprehensive picture ever obtained of the central parts of the Milky Way probed with RR Lyr variable stars. This is a collection of 38257 RR Lyr stars detected over 182 square degrees monitored photometrically by the Optical Gravitational Lensing Experiment (OGLE) in the most central regions of the Galactic bulge. The sample consists of 16804 variables found and published by the OGLE collaboration in 2011 and 21453 RR Lyr stars newly detected in the photometric databases of the fourth phase of the OGLE survey (OGLE-IV). 93% of the OGLE-IV variables were previously unknown. The total sample consists of 27 258 RRab, 10825 RRc, and 174 RRd stars. We provide OGLE-IV I- and V-band light curves of the variables along with their basic parameters. About 300 RR Lyr stars in our collection are plausible members of 15 globular clusters. Among others, we found the first pulsating variables that may belong to the globular cluster Terzan 1 and the first RRd star in the globular cluster M54. Our survey also covers the center and outskirts of the Sagittarius Dwarf Spheroidal Galaxy enabling studies of the spatial distribution of the old stellar population from this galaxy.
