Search

Start Over Capability Type Simple Cone Search
17191. 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.
17192. VRIg'i' photometry of 7 M15 giants
ID:
ivo://CDS.VizieR/J/MNRAS/405/1711
Title:
VRIg'i' photometry of 7 M15 giants
Short Name:
J/MNRAS/405/1711
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a search for long-period variable (LPV) stars among giant branch stars in M15 which, at [Fe/H]~-2.3, is one of the most metal-poor Galactic globular clusters. We use multicolour optical photometry from the 0.6-m Keele Thornton and 2-m Liverpool Telescopes. Variability of {delta}V~0.15mag is detected in K757 and K825 over unusually long time-scales of nearly a year, making them the most metal-poor LPVs found in a Galactic globular cluster. K825 is placed on the long secondary period sequence, identified for metal-rich LPVs, though no primary period is detectable. We discuss this variability in the context of dust production and stellar evolution at low metallicity, using additional spectra from the 6.5-m Magellan (Las Campanas) telescope. A lack of dust production, despite the presence of gaseous mass loss raises questions about the production of dust and the intracluster medium of this cluster.
17193. VRIH{alpha} photometry in NGC 2264
ID:
ivo://CDS.VizieR/J/AJ/135/441
Title:
VRIH{alpha} photometry in NGC 2264
Short Name:
J/AJ/135/441
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have performed deep wide-field CCD photometry of the young open cluster NGC 2264 to study the extent of star-forming regions (SFRs) and the shape of the initial mass function. In this paper, we present VRI and H{alpha} photometry for more than 67,000 stars. From the spatial distribution of the selected H{alpha} emission stars, we identify two active SFRs and a less active halo region surrounding these two SFRs. There are several H{alpha} emission stars in the field region outside the halo region, and these may be newly formed stars in the Mon OB1 association surrounding the cluster. The locus of pre-main-sequence (PMS) stars in the I_C_ versus V-I_C_ diagram is revised from the distribution of H{alpha} and X-ray emission stars in the diagram.
17194. VRIHalpha photometry of M34
ID:
ivo://CDS.VizieR/J/MNRAS/370/954
Title:
VRIHalpha photometry of M34
Short Name:
J/MNRAS/370/954
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on the results of a V- and i-band time-series photometric survey of M34 (NGC 1039) using the Wide Field Camera (WFC) on the Isaac Newton Telescope (INT), achieving better than 1 per cent precision per data point for 13~<i~<17. Candidate cluster members were selected from a V versus VI colour-magnitude diagram over 14<V<24 (0.12<M/M_{sun}_<1.0), finding 714 candidates, of which we expect ~400 to be real cluster members (taking into account contamination from the field). The mass function was computed, and found to be consistent with a lognormal distribution in dN/dlogM. Searching for periodic variable objects in the candidate members gave 105 detections over the mass range 0.25<M/M_{sun}_<1.0. The distribution of rotation periods for 0.4<M/M_{sun}_<1.0 was found to peak at ~7d, with a tail of fast rotators down to periods of ~0.8d. For 0.25<M/M_{sun}_<0.4 we found a peak at short periods, with a lack of slow rotators (e.g. P>5d), consistent with the work of other authors at very low masses. Our results are interpreted in the context of previous work, finding that we reproduce the same general features in the rotational period distributions. A number of rapid rotators were found with velocities ~ a factor of 2 lower than in the Pleiades, consistent with models of angular momentum evolution assuming solid body rotation without needing to invoke core-envelope decoupling.
17195. VRIH{alpha} photometry of NGC 2264 variables
ID:
ivo://CDS.VizieR/J/A+A/430/1005
Title:
VRIH{alpha} photometry of NGC 2264 variables
Short Name:
J/A+A/430/1005
Date:
21 Oct 2021
Publisher:
CDS
Description:
Table 1 lists 405 periodic variable stars we found in the area of NGC 2264 between. It contains information of the position, brightness, colours, and period of these stars. It also lists the spectral type taken from the literature (if available) as well as the alternative identification numbers of the stars which we used in the analysis process. The results presented here are based on a photometric monitoring program of a 34'x34' field in NGC 2264 carried out with the Wide-Field-Imager (WFI) attached to the ESO/MPG 2.2m telescope on La Silla, Chile. Observations were obtained on 44 nights in the I_C_ band during a period of two months between Dec. 2000 and March 2001. We also obtained several additional images through V, R_C_ and H{alpha} filters.
17196. 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.
17197. 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.
17198. 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.
17199. 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.
17200. 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.

Limit your search

more »

more »

more »

more »

more »

more »