- ID:
- ivo://CDS.VizieR/J/MNRAS/431/2106
- Title:
- CU Vir Stroemgren differential photometry
- Short Name:
- J/MNRAS/431/2106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to measure the variations of the magnetic chemically peculiar star CU Vir, we obtained 2821 good Stroemgren uvby photometric values from the Four College Automated Photometric Telescope in the period 1998-2012 and 5529 values from the Solar Mass Ejection Imager in the period 2003-2006, allowing us to further clarify the situation concerning its rotational period, described previously by Pyper et al. (1998A&A...339..822P). Our main result is that the O-C data since 1993 are consistent with a constant period of 0.5207137+/-0.0000010d, which is longer than the period 0.52070308d of Pyper et al. (1998A&A...339..822P). The data during the time period 1993-2012 show no evidence of glitches. The data between 1987 and 1993 correspond to a shorter period of 0.520701d, and the inclusion of those data in the previous study made the published period come out shorter. We also cannot rule out a constantly lengthening period if the data since 1987 are included; however, the fit is slightly better for a constant period. At least five more years of consistent data will be required to distinguish between these two models. Radio astronomy data published since 1998 show phase shifts in the radio emission peaks that are inconsistent with the rotation period inferred from the optical photometry. These shifts may be due to instabilities in the region where the radio emissions originate; they indicate that the photosphere and the upper atmosphere are not rigidly coupled.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/other/JAD/24.4
- Title:
- CY Aqr CCD photometry 2016-2017-2018 seasons
- Short Name:
- J/other/JAD/24.4
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Based on more than 37 partial nights of CCD monitoring, we derive 64 new times of maximum light of the SX Phoenicis star CY Aquarii. These times support a linear ephemeris for the time interval 2013-2018.
- ID:
- ivo://CDS.VizieR/J/other/JAD/26.1
- Title:
- CY Aqr CCD photometry 2019-2020 seasons
- Short Name:
- J/other/JAD/26.1
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Based on 28 partial nights of CCD monitoring, we derive 49 new times of maximum light of the SX Phoenicis star CY Aquarii. These times extend the linear ephemeris for a time interval covering the last eight years.
- ID:
- ivo://CDS.VizieR/J/other/JAD/17.2
- Title:
- CY Aqr differential light curves
- Short Name:
- J/other/JAD/17.2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 24 new times of maximum of the SX Phoenicis star CY Aquarii. These times lead to a slightly more precise local linear ephemeris for 2003-2010.
- ID:
- ivo://CDS.VizieR/J/other/JAD/18.2
- Title:
- CY Aqr multiband photometry: 2011 season
- Short Name:
- J/other/JAD/18.2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on more than a dozen partial nights of filterless CCD photometry combined with Stromgren uvby photomultiplier photometry, we derive 29 new times of maximum light of the SX Phoenicis star CY Aquarii. These times support a linear ephemeris for 2003-2011. In addition, we present uvby light curves for this star. Our dataset displays the smallest residual spread compared to any other substantial dataset published during the last decade.
- ID:
- ivo://CDS.VizieR/J/A+A/608/A103
- Title:
- 43 Cyg decorrelated 156-day light curve
- Short Name:
- J/A+A/608/A103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometric time series of the gamma Doradus star 43 Cyg obtained with the BRITE-Constellation nano-satellites allow us to study its pulsational properties in detail and to constrain its interior structure. We aim to find a g-mode period spacing pattern that allows us to determine the near-core rotation rate of 43 Cyg and redetermine the star's fundamental atmospheric parameters and chemical composition. We conducted a frequency analysis using the 156-days long data set obtained with the BRITE-Toronto satellite and employed a suite of MESA/GYRE models to derive the mode identification, asymptotic period spacing and near-core rotation rate. We also used high-resolution, high signal-to-noise ratio spectroscopic data obtained at the 1.2m Mercator telescope with the HERMES spectrograph to redetermine the fundamental atmospheric parameters and chemical composition of 43 Cyg using the software Spectroscopy Made Easy (SME). We detected 43 intrinsic pulsation frequencies and identified 18 of them to be part of a period spacing pattern consisting of prograde dipole modes with an asymptotic period spacing of 2970(+700,-570)s. The near-core rotation rate was determined to be 0.56(+0.12,-0.14)c/d. The atmosphere of 43 Cyg shows solar chemical composition at an effective temperature of 7150+/-150K, a logg of 4.2+/-0.6dex and a projected rotational velocity, vsini, of 44+/-4km/s. The morphology of the observed period spacing patterns shows indications of the presence of a significant chemical gradient in the stellar interior.
- ID:
- ivo://CDS.VizieR/J/A+A/640/A128
- Title:
- Cygnus OB2 association NIR light curves
- Short Name:
- J/A+A/640/A128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a J, H, and K photometric variability survey of the central 0.78 square degrees of the young OB association Cygnus OB2. We used data observed with the Wide-Field CAMera at the United Kingdom Infrared Telescope in 2007 (spanning 217 days) to investigate the light curves of 5083 low mass candidate members in the association and explore the occurrence and main characteristics of their near-infrared variability. We identified 2529 stars (~50% of the sample) with significant variability with time-scales ranging from days to months. We classified the variable stars into the following three groups according to their light curve morphology: periodic variability (1697 stars), occultation variability (124 stars), and other types of variability (726 stars). We verified that the disk-bearing stars in our sample are significantly more variable in the near-infrared than diskless stars, with a steep increase in the disk-fraction among stars with higher variability amplitude. We investigated the trajectories described by variable stars in the color-space and measured slopes for 335 stars describing linear trajectories. Based on the trajectories in the color-space, we inferred that the sample analyzed is composed of a mix of young stars presenting variability due to hot and cold spots, extinction by circumstellar material, and changes in the disk emission in the near-infrared. We contemplated using the use of near- infrared variability to identify disk-bearing stars and verified that 53.4% of the known disk-bearing stars in our sample could have been identified as such based solely on their variability. We present 18 newly identified disk- bearing stars and 14 eclipsing binary candidates among CygOB2 lower-mass members.
- ID:
- ivo://CDS.VizieR/J/A+A/447/245
- Title:
- Cyg X-1 Spectral Evolution 1999-2004
- Short Name:
- J/A+A/447/245
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Continuing the observational campaign initiated by our group, we present the long term spectral evolution of the Galactic black hole candidate Cygnus X-1 in the X-rays and at 15GHz. We present about 200 pointed observations taken between early 1999 and late 2004 with the Rossi X-ray Timing Explorer and the Ryle radio telescope. The X-ray spectra are remarkably well described by a simple broken power law spectrum with an exponential cutoff. Physically motivated Comptonization models, e.g., by Titarchuk (1994ApJ...434..570T, compTT) and by Coppi (1999, eqpair), can reproduce this simplicity; however, the success of the phenomenological broken power law models cautions against ``over-parameterizing'' the more physical models. Broken power law models reveal a significant linear correlation between the photon index of the lower energy power law and the hardening of the power law at about 10keV. This phenomenological soft/hard power law correlation is partly attributable to correlations of broad band continuum components, rather than being dominated by the weak hardness/reflection fraction correlation present in the Comptonization model. Specifically, the Comptonization models show that the bolometric flux of a soft excess (e.g., disk component) is strongly correlated with the compactness ratio of the Comptonizing medium, with L_disk{propto}(l_h_/l_s_)^-0.19^. Over the course of our campaign, Cyg X-1 transited several times into the soft state, and exhibited a large number of ``failed state transitions''. The fraction of the time spent in such low radio emission/soft X-ray spectral states has increased from about 10% in 1996-2000 to about 34% since early 2000. We find that radio flares typically occur during state transitions and failed state transitions (at l_h_/l_s_~3), and that there is a strong correlation between the 10-50keV X-ray flux and the radio luminosity of the source. We demonstrate that rather than there being distinctly separated states, in contrast to the timing properties the spectrum of Cyg X-1 shows variations between extremes of properties, with clear cut examples of spectra at every intermediate point in the observed spectral correlations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/411/1585
- Title:
- CZ Lac multiperiodic Blazhko modulation
- Short Name:
- J/MNRAS/411/1585
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A thorough analysis of the multicolour CCD observations of the RRab-type variable, CZ Lacertae, is presented. The observations were carried out in two consecutive observing seasons in 2004 and 2005 within the framework of the Konkoly Blazhko Survey of bright, northern, short-period RRab variables.
320. Dahlmark variables
- ID:
- ivo://CDS.VizieR/II/238
- Title:
- Dahlmark variables
- Short Name:
- II/238
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Since 1967 32 fields in the Milky Way were observed for variable stars. * New variable stars in Cygnus (1982IBVS.2157....1D) [8/65] Survey of an area of 20{deg}x15{deg} centered at 20h50m, +45{deg} in Cygnus. This area has been followed photographically in two colours during the period 1967 to 1981. As a rule one observation per summer was obtained. * New variable stars in Cassiopeia (1986IBVS.2878....1D) [66/105] Survey in an area 20{deg}x15{deg} centered at 1h06m, +60{deg}01'. Seventeen plate pairs exposed in the period 1967 to 1981 were collected and treated in the same way as described in the previous report. These observations provide approximate B and V magnitudes. In addition, six exposures were obtained in the period August 8 to September 23, 1985 on Technical Pan film. * New variable stars in Cygnus, Lyra and Vulpecula (1993IBVS.3855....1D) [106/185] Area of 20{deg}x15{deg} centred at 19h46m +30{deg}. * New variable stars in Cygnus, Lacerta and Andromeda (1996IBVS.4329....1D) [186/220] Area of 20{deg}x15{deg} centered at 20h40m, +45{deg} (1950). * New variable stars in the northern Milky Way (1997IBVS.4458....1D) [221/280] Area of 20{deg}x15{deg} centered at 22h42m, +60{deg} (1950) * New variable stars in the northern Milky Way (1998IBVS.4642....1D) [281/315] Results of a variable-star search in the 20{deg}x15{deg} area centered at 20h18m, +60{deg} (1950). * New variable stars in Andromeda and Cassiopeia (1999IBVS.4734....1D [316/341] Results of a variable-star search in the 20{deg}x15{deg} area centered at 0h30m, +45{deg} (1950). * New variable stars in Lyra and Cygnus (2000IBVS.4898....1D) [342/366] Results of a variable-star search in the 20{deg}x15{deg} area centered at 19h00m/+45{deg} (1950). * New variable stars along the northern Milky way (2001IBVS.5181....1D) [367/420] Results of a variable-star search in the 20{deg}x15{deg} area centered at 21h22m/+{deg} (1950).
