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4571. V873 Per BVR light curves
ID:
ivo://CDS.VizieR/J/other/NewA/36.50
Title:
V873 Per BVR light curves
Short Name:
J/other/NewA/36.
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a photometric study of a weak-contact binary V873 Per. New observations in BVR filter bands showed asymmetric light curves to be a negative type of the O'Connell effect, which can be described by magnetic activity of a cool spot on the more massive component. Our photometric solutions showed that V873 Per is a W-type with a mass ratio of q=2.504(+/-0.0029), confirming the results of Samec et al. (2009IBVS.5901....1S). The derived contact degree was found to be f=18.10%(+/-1.36%). Moreover, our analysis found the cyclic variation with the period of about 4yr that could be due to existence of the third companion in the system or the mechanism of magnetic activity cycle in the binary. While available data indicated that the long-term orbital period tends to be stable rather than decreasing.
4572. V436 Persei UBV photometry
ID:
ivo://CDS.VizieR/J/A+A/408/611
Title:
V436 Persei UBV photometry
Short Name:
J/A+A/408/611
Date:
21 Oct 2021
Publisher:
CDS
Description:
An analysis of new spectroscopic and photoelectric UBV observations, satisfactorily covering the whole orbital period of V436 Per, together with existing data allowed us to improve the knowledge of the basic physical characteristics of the binary and its components. In several aspects, our new results differ from the findings of Paper I (Harmanec et al., 1997, Cat. <J/A+A/319/867>) of this series: In particular, we found that it is the star eclipsed in the secondary minimum which is slightly more massive and larger than the optical primary. We also conclude that the apsidal advance -- if present at all -- is much slower than that estimated in a previous study. The orbital period might be increasing by 0.28 s per year but also this finding is very uncertain and needs verification by future observations. It is encouraging to note that two completely independent sets of programs for light-curve solutions lead to identical results. A notable finding is that both binary components rotate with very similar -- if not identical -- rotational periods of 1.45d and 1.40d, much shorter than what would correspond to a 10.9d spin-orbit synchronization period at periastron. Rapid line-profile changes reported earlier could not be confirmed from new, dedicated series of high-resolution and S/N spectra.
4573. VPHAS+ DR2 survey
ID:
ivo://CDS.VizieR/II/341
Title:
VPHAS+ DR2 survey
Short Name:
II/341
Date:
21 Oct 2021
Publisher:
CDS
Description:
The primary goal of the VST Photometric H{alpha} Survey of the Southern Galactic Plane and Bulge (VPHAS+) is to collect single-epoch ugri broad-band and Ha narrow-band photometry across the southern Galactic Plane within the latitude range -5{deg}<b<+5{deg} down to point source magnitudes of ~21 or better. The VPHAS+ footprint also includes the inner Galactic Bulge, defined as a 20x20 deg^2^ box around the Galactic Centre: this assures optical coverage of the full VVV footprint. For all massive OBA stars this survey is deep enough to explore all but the most heavily obscured locations of the southern Plane, reaching to >4kpc from the Sun. These data will increase the number of known southern emission line stars by up to an order of magnitude, yielding much better statistics on important short-lived types of object. The wide-area uniform photometry obtained will also facilitate stellar population studies, capable of tracing structure over much of the southern Plane. VPHAS+ will trawl the star-formation history of the Galaxy as seen in stellar remnants of all types.
4574. VPHAS+ survey synthetic colours
ID:
ivo://CDS.VizieR/J/MNRAS/440/2036
Title:
VPHAS+ survey synthetic colours
Short Name:
J/MNRAS/440/2036
Date:
21 Oct 2021
Publisher:
CDS
Description:
The VST Photometric H{alpha} Survey of the Southern Galactic Plane and Bulge (VPHAS+) is surveying the southern Milky Way in u, g, r, i and H{alpha} at ~1arcsec angular resolution. Its footprint spans the Galactic latitude range -5{deg}<b<+5{deg} at all longitudes south of the celestial equator. Extensions around the Galactic Centre to Galactic latitudes +/-10{deg} bring in much of the Galactic bulge. This European Southern Observatory public survey, begun on 2011 December 28, reaches down to ~20th magnitude (10{sigma}) and will provide single-epoch digital optical photometry for ~300 million stars. The observing strategy and data pipelining are described, and an appraisal of the segmented narrow-band H{alpha} filter in use is presented. Using model atmospheres and library spectra, we compute main-sequence (u-g), (g-r), (r-i) and (r-H{alpha}) stellar colours in the Vega system. We report on a preliminary validation of the photometry using test data obtained from two pointings overlapping the Sloan Digital Sky Survey. An example of the (u-g, g-r) and (r-H{alpha}, r-i) diagrams for a full VPHAS+ survey field is given. Attention is drawn to the opportunities for studies of compact nebulae and nebular morphologies that arise from the image quality being achieved. The value of the u band as the means to identify planetary-nebula central stars is demonstrated by the discovery of the central star of NGC 2899 in survey data. Thanks to its excellent imaging performance, the VLT Survey Telescope (VST)/OmegaCam combination used by this survey is a perfect vehicle for automated searches for reddened early-type stars, and will allow the discovery and analysis of compact binaries, white dwarfs and transient sources.
4575. V646 Pup TESS and ground photometry and spectrum
ID:
ivo://CDS.VizieR/J/A+A/644/A135
Title:
V646 Pup TESS and ground photometry and spectrum
Short Name:
J/A+A/644/A135
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate small-scale light variations in V646 Pup occurring in the timescales of days, weeks and years. To check if this variability is similar to that observed in FU Ori. We observed V646 Pup on six occasions at the SAAO and CTIO during 2013-2018 in Johnson and Sloan filters, typically with 1 d cadence maintained for 2-4 weeks. We also utilise the public-domain 1512 day long ASAS-SN light curve and TESS photometry obtained in 2019 during 24.1 days with 30 min cadence. New SAAO low-resolution spectra help to update major disc parameters, while the archival high-resolution Keck spectra are used to search for temporal changes in the disc rotational profiles. The ground-based observations confirm the constantly decreasing brightness of V646 Pup at the rate of 0.018mag per year. Precise i-band sensitive TESS data show that the little 0.005-0.01mag light variations imposed on this general trend do consist of a few independent wave trains of apparently time-coherent nature. Assuming that this is typical situation, from analysis of colour-magnitude diagrams obtained on earlier epochs we preliminarily inferred that the bulk of observed light changes could be owing to rotation of disc photosphere inhomogeneities, arising between 10-12 solar radii from the star. It is not excluded that these inhomogeneities could also manifest themselves in rotational profiles of the disc, as obtained from the high-resolution spectra. Assuming Keplerian rotation of these inhomogeneities, we preliminarily determine the stellar mass at 0.7-0.9 solar masses. At least during certain weeks V646 Pup shows time-coherent light variability pattern(s) that could be explained by rotation of an inhomogeneous disc photosphere. These preliminary results are similar to those better established for FU Ori, what suggests a common driving mechanism(s).
4576. V, R and I light curves of 4 new low-mass M-type EBs
ID:
ivo://CDS.VizieR/J/AJ/156/220
Title:
V, R and I light curves of 4 new low-mass M-type EBs
Short Name:
J/AJ/156/220
Date:
21 Oct 2021
Publisher:
CDS
Description:
We performed multicolor photometric and spectroscopic observations of four new low-mass M-type eclipsing binaries (HAT 225-03429, CRTS J085623.0+282620, CRTS J110302.4+201611, 2MASS J16344899+3716423) in 2017. We obtained new VRI light curves and minimum times of these four systems. Based on our minimum times, we updated the orbital periods and the linear ephemerides using the least squares method. We analyzed these four systems using the Wilson-Devinney program, and obtained the orbital and starspot parameters. The results of our analysis of the light curves indicate that HAT 225-03429 and CRTS J085623.0+282620 are detached eclipsing binaries, CRTS J110302.4+201611 is a semi-detached eclipsing binary, and 2MASS J16344899+3716423 is a contact binary. We performed LAMOST spectroscopic studies of chromospheric activity indicators (H{alpha}, H{beta}, H{gamma}, H{delta}, and Ca II H&K lines) for these four systems for the first time. We first determined their spectral types and calculated the equivalent widths of their chromospheric active indicators. These indicators show that the four low-mass M-type eclipsing binaries are active. Furthermore, the radii of these stars are notably larger than model predictions for their masses, except for the secondary component of HAT 225-03429 and the primary component of CRTS J110302.4+201611.
4577. VR CCD photometry of variable stars in the GC NGC 4147
ID:
ivo://CDS.VizieR/J/AJ/158/51
Title:
VR CCD photometry of variable stars in the GC NGC 4147
Short Name:
J/AJ/158/51
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results of a search for variable stars in a region of the globular cluster NGC 4147 based on photometric observations with a 4Kx4K CCD imager mounted at the axial port of the recently installed 3.6 m Devasthal optical telescope (DOT) at Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, India. We performed time series photometry of NGC 4147 in the V and R bands, and identified 42 periodic variables in the region of NGC 4147, 28 of which have been detected for the first time. Seventeen variable stars are located within the half-light radius ~<0.48', of which 10 stars are newly identified variables. Two of the 10 variables are located within the core radius ~<0.09'. Based on their location in the V/(V-R) color-magnitude diagram and variability characteristics, seven, eight, five, and one newly identified probable member variables are classified as RRc, EA/E, EW, and SX Phe, respectively. The metallicity of NGC 4147 estimated from the light curves of RRab and RRc stars with the help of Fourier decomposition is found to be characteristic of Oosterhoff II. The distance derived using the light curves of RRab stars is consistent with that obtained from the observed V/(V-R) color-magnitude diagram.
4578. VRc light curves of SBSG 1520+530
ID:
ivo://CDS.VizieR/J/A+A/440/53
Title:
VRc light curves of SBSG 1520+530
Short Name:
J/A+A/440/53
Date:
21 Oct 2021
Publisher:
CDS
Description:
The files table1.dat and table2.dat contain light curves of the double quasar SBS1520+530 obtained at Maidanak observatory from April 2003 to August 2004. table1.dat contains the R-band light curve. table2.dat contains the V-R light curve.
4579. VRI and K-band light curves of type 1 AGNs
ID:
ivo://CDS.VizieR/J/ApJ/886/150
Title:
VRI and K-band light curves of type 1 AGNs
Short Name:
J/ApJ/886/150
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a dust-reverberation survey of quasars at redshifts z<0.6. We found a delayed response of the K-band flux variation after the optical flux variation in 25 out of 31 targets, and obtained the lag time between them for 22 targets. Combined with the results for nearby Seyfert galaxies, we provide the largest homogeneous collection of K-band dust-reverberation data for 36 type 1 active galactic nuclei (AGNs). This doubles the sample and includes the most distant AGN and the largest lag so far measured. We estimated the optical luminosity of the AGN component of each target using three different methods: spectral decomposition, the flux-variation-gradient method, and image decomposition. We found a strong correlation between the reverberation radius for the innermost dust torus and the optical luminosity over a range of approximately four orders of magnitude in luminosity, as is already known for Seyfert galaxies. We estimated the luminosity distances of the AGNs based on their dust-reverberation lags, and found that the data in the redshift-distance diagram are consistent with the current standard estimates of the cosmological parameters. We also present the radius-luminosity relations for isotropic luminosity indicators such as the hard X-ray (14-195keV), [OIV]25.89{mu}m, and mid-infrared (12{mu}m) continuum luminosities, which are applicable to obscured AGNs.
4580. VRI CCD photometry of NGC 2126
ID:
ivo://CDS.VizieR/J/A+A/410/879
Title:
VRI CCD photometry of NGC 2126
Short Name:
J/A+A/410/879
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first CCD photometric observations of the northern open cluster NGC 2126. Data were taken on eight nights in February and December 2002 with a total time span of ~57 hours. Almost 1000 individual V-band frames were examined to find short-period variable stars. We discovered six new variable stars, of which one is a promising candidate for an eclipsing binary with a pulsating component. Here we present single-epoch colours and magnitudes for ~800 stars in the field and the light curve data for the six variables. Note that the coordinates in ngc2126.dat are not particularly accurate because of the applied crude astrometry (errors up to +/-1-2arcsec are quite likely close to the edge). For variable star identification, consult table3.dat.