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5911. 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.
5912. VRIJHK photometry of IRAS 09149-4743 region
ID:
ivo://CDS.VizieR/J/ApJ/751/138
Title:
VRIJHK photometry of IRAS 09149-4743 region
Short Name:
J/ApJ/751/138
Date:
21 Oct 2021
Publisher:
CDS
Description:
The RCW41 star-forming region is embedded within the Vela Molecular Ridge, hosting a massive stellar cluster surrounded by a conspicuous HII region. Understanding the role of interstellar magnetic fields and studying the newborn stellar population is crucial to building a consistent picture of the physical processes acting on this kind of environment. We carried out a detailed study of the interstellar polarization toward RCW41 with data from an optical and near-infrared polarimetric survey. Additionally, deep near-infrared images from the 3.5 meter New Technology Telescope were used to study the photometric properties of the embedded young stellar cluster, revealing several YSO candidates. By using a set of pre-main-sequence isochrones, a mean cluster age in the range 2.5-5.0 million years was determined, and evidence of sequential star formation was revealed. An abrupt decrease in R-band polarization degree was noticed toward the central ionized area, probably due to low grain alignment efficiency caused by the turbulent environment and/or the weak intensity of magnetic fields. The distortion of magnetic field lines exhibits dual behavior, with the mean orientation outside the area approximately following the borders of the star-forming region and directed radially toward the cluster inside the ionized area, in agreement with simulations of expanding H II regions. The spectral dependence of polarization allowed a meaningful determination of the total-to-selective extinction ratio by fittings of the Serkowski relation. Furthermore, a large rotation of polarization angle as a function of wavelength was detected toward several embedded stars.
5913. VRIJHK photometry of the Serpens cloud core
ID:
ivo://CDS.VizieR/J/A+A/330/990
Title:
VRIJHK photometry of the Serpens cloud core
Short Name:
J/A+A/330/990
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from a deep optical (VRI) and near infrared (JHK) survey of the central part of the Serpens molecular cloud. A total of 138 sources were detected in the 19 arcmin^2^ surveyed area down to a limiting magnitude of 16.3 in K. We find that the form of the observed K Luminosity Function (KLF) of stars belonging to the Serpens Molecular cloud is consistent with that predicted from a Miller & Scalo (1979ApJS...41..513M) Interstellar Mass Function (IMF). We have investigated the KLF evolution with the age of a cluster by modeling KLFs of hypothetical clusters. Our results suggest that two phases of star formation could have taken place in the Serpens core.
5914. 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.
5915. 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.
5916. VrI light curves of NGC6981 variables
ID:
ivo://CDS.VizieR/J/MNRAS/413/1275
Title:
VrI light curves of NGC6981 variables
Short Name:
J/MNRAS/413/1275
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results from 10 nights of observations of the globular cluster NGC 6981 (M72) in the V, R and I Johnson wavebands. We employed the technique of difference image analysis to perform precision differential photometry on the time-series images, which enabled us to carry out a census of the understudied variable star population of the cluster. We show that 20 suspected variables in the literature are actually non-variable, and we confirm the variable nature of another 29 variables while refining their ephemerides. We also detect 11 new RR Lyrae variables and three new SX Phe variables, bringing the total confirmed variable star count in NGC 6981 to 43. We performed Fourier decomposition of the light curves for a subset of RR Lyrae stars and used the Fourier parameters to estimate the fundamental physical parameters of the stars using relations available in the literature. Mean values of these physical parameters have allowed us to estimate the physical parameters of the parent cluster. We derive a metallicity of [Fe/H]_ZW_~-1.48+/-0.03 on the Zinn & West scale (or [Fe/H]_UVES_~-1.38+/-0.03 on the new Carretta et al. scale) for NGC 6981, and distances of ~16.73+/-0.36 and ~16.68+/-0.36kpc from analysis of the RR0 and RR1 stars separately. We also confirm the Oosterhoff type I classification for the cluster, and show that our colour-magnitude data are consistent with the age of ~12.75+/-0.75Gyr derived by Dotter et al.
5917. VrI light curves of NGC1904 variables
ID:
ivo://CDS.VizieR/J/A+A/548/A92
Title:
VrI light curves of NGC1904 variables
Short Name:
J/A+A/548/A92
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the analysis of 11 nights of V and I time-series observations of the globular cluster NGC 1904 (M 79). Using this we searched for variable stars in this cluster and attempted to refine the periods of known variables, making use of a time baseline spanning almost 8 years. We use our data to derive the metallicity and distance of NGC 1904. We used difference imaging to reduce our data to obtain high-precision light curves of variable stars. We then estimated the cluster parameters by performing a Fourier decomposition of the light curves of RR Lyrae stars for which a good period estimate was possible. We also derive an estimate for the age of the cluster by fitting theoretical isochrones to our colour-magnitude diagram (CMD). Out of 13 stars previously classified as variables, we confirm that 10 are bona fide variables. We cannot detect variability in one other within the precision of our data, while there are two which are saturated in our data frames, but we do not find sufficient evidence in the literature to confirm their variability. We also detect a new RR Lyrae variable, giving a total number of confirmed variable stars in NGC 1904 of 11. Using the Fourier parameters, we find a cluster metallicity [Fe/H]_ZW_=-1.63+/-0.14, or [Fe/H]_UVES_=-1.57+/-0.18, and a distance of 13.3+/-0.4kpc (using RR0 variables) or 12.9kpc (using the one RR1 variable in our sample for which Fourier decomposition was possible).
5918. VrI light curves of NGC7099 variables
ID:
ivo://CDS.VizieR/J/A+A/555/A36
Title:
VrI light curves of NGC7099 variables
Short Name:
J/A+A/555/A36
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the analysis of 26 nights of V and I time-series observations from 2011 and 2012 of the globular cluster M 30 (NGC 7099). We used our data to search for variable stars in this cluster and refine the periods of known variables; we then used our variable star light curves to derive values for the cluster's parameters. We used difference image analysis to reduce our data to obtain high-precision light curves of variable stars. We then estimated the cluster parameters by performing a Fourier decomposition of the light curves of RR Lyrae stars for which a good period estimate was possible. We also derive an estimate for the age of the cluster by fitting theoretical isochrones to our colour-magnitude diagram (CMD). Out of 13 stars previously catalogued as variables, we find that only 4 are bona fide variables. We detect two new RR Lyrae variables, and confirm two additional RR Lyrae candidates from the literature. We also detect four other new variables, including an eclipsing blue straggler system, and an SX Phoenicis star. This amounts to a total number of confirmed variable stars in M 30 of 12. We perform Fourier decomposition of the light curves of the RR Lyrae stars to derive cluster parameters using empirical relations. We find a cluster metallicity [Fe/H]_ZW_=-2.01+/-0.04, or [Fe/H]_UVES_=-2.11+/-0.06, and a distance of 8.32+/-0.20kpc (using RR0 variables), 8.10 kpc (using one RR1 variable), and 8.35+/-0.42kpc (using our SX Phoenicis star detection in M 30). Fitting isochrones to the CMD, we estimate an age of 13.0+/-1.0Gyr for M 30.
5919. 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.
5920. 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.