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3301. VRIJHK photometry of 3C 279
ID:
ivo://CDS.VizieR/J/AJ/151/54
Title:
VRIJHK photometry of 3C 279
Short Name:
J/AJ/151/54
Date:
21 Oct 2021
Publisher:
CDS
Description:
We searched for quasi-periodicities on year-like timescales in the light curves of six blazars in the optical--near-infrared bands and we made a comparison with the high energy emission. We obtained optical/NIR light curves from Rapid Eye Mounting photometry plus archival Small & Moderate Aperture Research Telescope System data and we accessed the Fermi light curves for the {gamma}-ray data. The periodograms often show strong peaks in the optical and {gamma}-ray bands, which in some cases may be inter-related. The significance of the revealed peaks is then discussed, taking into account that the noise is frequency dependent. Quasi-periodicities on a year-like timescale appear to occur often in blazars. No straightforward model describing these possible periodicities is yet available, but some plausible interpretations for the physical mechanisms causing periodic variabilities of these sources are examined.
3302. VRI light curve of 5 eclipsing binaries
ID:
ivo://CDS.VizieR/J/MNRAS/442/2620
Title:
VRI light curve of 5 eclipsing binaries
Short Name:
J/MNRAS/442/2620
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report 15 new VRI light curves of five low-mass eclipsing binaries (NSVS 02502726, NSVS 07453183, NSVS 11868841, NSVS 06550671 and NSVS 10653195) that were observed between 2010 and 2012. We analysed our new data together with three published spectroscopic observations and seven published light curves using a modified version of the Wilson-Devinney program. Orbital solutions of the five low-mass eclipsing binaries were revised and new star-spot parameters were obtained. We found that spot locations on the five low-mass eclipsing binaries changed over several years. However, the star-spots for NSVS 07453183 and NSVS 06550671 were stable for several months. More interestingly, for NSVS 02502726, the spots within a star-spot longitude region of 180{deg}-360{deg} indicated a magnetic activity cycle of 5.9(+/-0.2)yr. Moreover, we detected the first flare-like event on NSVS 07453183 at phase 0.39. The observations of the chromospheric activity indicators (H{beta} and H{gamma} lines) revealed that NSVS 10653195 and NSVS 06550671 were active. For NSVS 02502726, we found a weak continuous secular decrease at a smaller rate of dp/dt=-2.1(0.8)x10^-7^d/yr than the previous result. For NSVS 07453183, the O-C times appeared to increase at cycle 6000, and this was followed by a decrease at cycle 6500.
3303. VRI light curves of four contact binaries
ID:
ivo://CDS.VizieR/J/AJ/152/57
Title:
VRI light curves of four contact binaries
Short Name:
J/AJ/152/57
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new, high-quality multicolor observations of four recently discovered contact binaries, 1SWASP J064501.21+342154.9, 1SWASP J155822.10-025604.8, 1SWASP J212808.86+151622.0, and UCAC4 436-062932, and analyze their light curves to determine orbital and physical parameters using the modeling program of G. Djurasevic. In the absence of spectroscopic observations, the effective temperatures of the brighter components are estimated from the color indices, and the mass ratios are determined with the q-search method. The analysis shows that all four systems are W UMa type binaries in shallow contact configurations, consisting of late-type main-sequence primaries and evolved secondaries with active surface regions (dark or bright spots) resulting from magnetic activity or ongoing transfer of thermal energy between the components. We compare the derived orbital and stellar parameters for these four variables with a large sample of previously analyzed W UMa stars and find that our results fit it well.
3304. VRI photometry and theta values in open clusters
ID:
ivo://CDS.VizieR/J/ApJS/176/262
Title:
VRI photometry and theta values in open clusters
Short Name:
J/ApJS/176/262
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper, new Cousins VRI data are presented for NGC 752 and Praesepe, and new and extant data are combined into an augmented database for M67. For those three clusters, catalogs containing Cousins VRI photometry, reddening-corrected values of (V-K)J, and temperatures are produced. The same is done for Coma by using both previously published and newly derived Cousins photometry. An extant set of catalogs for the Hyades is updated to include V magnitudes and values of (R-I)C that were published after the original catalogs appeared. Finally, M67 V magnitudes published previously by Sandquist are corrected for an effect that depends on location on the face of the cluster. The corrected data and values of (V-I)C given by Sandquist are then set out in a supplementary catalog.
3305. VRI photometry in NGC 7129
ID:
ivo://CDS.VizieR/J/AJ/149/200
Title:
VRI photometry in NGC 7129
Short Name:
J/AJ/149/200
Date:
21 Oct 2021
Publisher:
CDS
Description:
NGC7129 is a bright reflection nebula located in the molecular cloud complex near l=105.4{deg}, b=+9.9{deg}, about 1.15kpc distant. Embedded within the reflection nebula is a young cluster dominated by a compact grouping of four early-type stars: BD+65{deg}1638 (B3V), BD+65{deg}1637 (B3e), SVS 13 (B5e), and LkH{alpha} 234 (B8e). About 80 H{alpha} emission sources brighter than V~23 are identified in the region, many of which are presumably T Tauri star members of the cluster. We also present deep (V~23), optical (VR_C_I_C_) photometry of a field centered on the reflection nebula and spectral types for more than 130 sources determined from low dispersion, optical spectroscopy. The narrow pre-main sequence evident in the color-magnitude diagram suggests that star formation was rapid and coeval. A median age of about 1.8Myr is inferred for the H{alpha} and literature-identified X-ray emission sources having established spectral types, using pre-main sequence evolutionary models. Our interpretation of the structure of the molecular cloud and the distribution of young stellar objects is that BD+65{deg}1638 is primarily responsible for evacuating the blister-like cavity within the molecular cloud. LkH{alpha} 234 and several embedded sources evident in near-infrared adaptive optics imaging have formed recently within the ridge of compressed molecular gas. The compact cluster of low-mass stars formed concurrently with the early-type members, concentrated within a central radius of ~0.7pc. Star formation is simultaneously occurring in a semi-circular arc some ~3pc in radius that outlines remaining dense regions of molecular gas. High dispersion, optical spectra are presented for BD+65{deg}1638, BD+65{deg}1637, SVS 13, LkH{alpha} 234, and V350 Cep. These spectra are discussed in the context of the circumstellar environments inferred for these stars.
3306. VRI photometry of Abell 3921 galaxies
ID:
ivo://CDS.VizieR/J/A+A/430/19
Title:
VRI photometry of Abell 3921 galaxies
Short Name:
J/A+A/430/19
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the analysis and results of a new VRI photometric and spectroscopic survey of the central ~1.8x1.2Mpc^2^ region of the galaxy cluster A3921 (z=0.094). We detect the presence of two dominant clumps of galaxies with a mass ratio of ~5: a main cluster centred on the Brightest Cluster Galaxy (BCG) (A3921-A), and an NW sub-cluster (A3921-B) hosting the second brightest cluster galaxy. The distorted morphology of the two sub-clusters suggests that they are interacting, while the velocity distribution of 104 confirmed cluster members does not reveal strong signatures of merging.
3307. VRI photometry of IC5070 variable stars
ID:
ivo://CDS.VizieR/J/A+A/627/A135
Title:
VRI photometry of IC5070 variable stars
Short Name:
J/A+A/627/A135
Date:
21 Oct 2021
Publisher:
CDS
Description:
We observed a field of 16'x16' in the star-forming region Pelican Nebula (IC 5070) at BVRI wavelengths for 90 nights spread over one year in 2012-2013. More than 250 epochs in VRI-bands are used to identify and classify variables up to V~21mag. We present a catalogue of optical time-series photometry with periods, mean-magnitudes and classifications for 95 variable stars including 67 pre-main-sequence variables towards star-forming region IC 5070. The pre-main-sequence variables are further classified as candidate classical T Tauri and weak-line T Tauri stars based on their light curve variations and the locations on the color-color and color-magnitude diagrams using optical and infrared data together with Gaia DR2 astrometry. Classical T Tauri stars display variability amplitudes up to three times the maximum fluctuation in disk-free weak-line T Tauri stars, which show strong periodic variations. Short-term variability is missed in our photometry within single nights. Several classical T Tauri stars display long-lasting (>10 days) single or multiple fading and brightening events up to a couple of magnitudes at optical wavelengths.
3308. VRI photometry of {lambda} Ori PMS stars
ID:
ivo://CDS.VizieR/J/AJ/118/2409
Title:
VRI photometry of {lambda} Ori PMS stars
Short Name:
J/AJ/118/2409
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have found 72 premain-sequence (PMS) stars near the center of the {lambda} Orionis star-forming region by spectroscopically testing a magnitude-limited sample for the presence of lithium {lambda}6708 absorption, a diagnostic of youth. All of these stars show large lithium equivalent widths and radial velocities consistent with Orion membership, but only two were discovered previously via H{alpha} or X-ray surveys.
3309. VRI photometry of {lambda} Ori star-forming region
ID:
ivo://CDS.VizieR/J/AJ/123/387
Title:
VRI photometry of {lambda} Ori star-forming region
Short Name:
J/AJ/123/387
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present VRI photometry of 320,917 stars with 11<~R<~18 throughout the {lambda} Ori star-forming region. Using the more spatially limited spectroscopic surveys of Dolan & Mathieu (1999, Cat. <J/AJ/118/2409>, 2001, Cat. <J/AJ/121/2124>) to define the color-magnitude domain of young low-mass members of the association and removing statistically the field stars in this domain, we use our photometry to identify a representative pre-main-sequence (PMS) population throughout the interior of the molecular ring.
3310. VRI photometry of M35
ID:
ivo://CDS.VizieR/J/ApJ/546/1006
Title:
VRI photometry of M35
Short Name:
J/ApJ/546/1006
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present very deep and accurate photometry of the open cluster M35. We have observed this association in the Cousins R, I filters, together with the Johnson V filter. We have covered a region of 27.5x27.5 square arcmin, equivalent to a fifth of the total area of the cluster. The data range from I_c_=12.5 to 23.5mag, and the color intervals are 0.4<=(V-I)_c_<=3.0, 0.5<=(R-I)_c_<=2.5. Roughly, these values span from 1.6M_{sun}_ down to the substellar limit, in the case of cluster members. By using the location of the stars on color-magnitude and color-color diagrams, we have selected candidate members of this cluster. We have merged our sample with previously published data and obtained a color-magnitude diagram for the complete stellar population of the cluster, covering the spectral range early B-mid M. Based on the distribution of field and cluster stars in color-magnitude and color-color diagrams, we estimate that two-thirds of these candidates are likely to be true members of M35. These stars approximately double the number of stars identified as candidate members of this cluster (~2700). We provide the photometry and accurate positions of these stars.