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24321. VRI and H polarization toward Sh 2-29
ID:
ivo://CDS.VizieR/J/ApJ/783/1
Title:
VRI and H polarization toward Sh 2-29
Short Name:
J/ApJ/783/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
Sh 2-29 is a conspicuous star-forming region marked by the presence of massive embedded stars as well as several notable interstellar structures. In this research, our goals were to determine the role of magnetic fields and to study the size distribution of interstellar dust particles within this turbulent environment. We have used a set of optical and near-infrared polarimetric data obtained at OPD/LNA (Brazil) and CTIO (Chile), correlated with extinction maps, Two Micron All Sky Survey data, and images from the Digitized Sky Survey and Spitzer. The region's most striking feature is a swept out interstellar cavity whose polarimetric maps indicate that magnetic field lines were dragged outward, piling up along its borders. This led to a higher magnetic strength value ({approx}400{mu}G) and an abrupt increase in polarization degree, probably due to an enhancement in alignment efficiency. Furthermore, dense cloud fragmentations with peak A_V_ between 20 and 37mag were probably triggered by its expansion. The presence of 24{mu}m point-like sources indicates possible newborn stars inside this dense environment. A statistical analysis of the angular dispersion function revealed areas where field lines are aligned in a well-ordered pattern, seemingly due to compression effects from the HII region expansion. Finally, Serkowski function fits were used to study the ratio of the total-to-selective extinction, revealing a dual population of anomalous grain particle sizes. This trend suggests that both effects of coagulation and fragmentation of interstellar grains are present in the region.
24322. 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.
24323. 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.
24324. V(RI)C differential photometry of V861 Her
ID:
ivo://CDS.VizieR/J/A+A/417/745
Title:
V(RI)C differential photometry of V861 Her
Short Name:
J/A+A/417/745
Date:
21 Oct 2021
Publisher:
CDS
Description:
First Cousins V(RI)_C_ light curves of the W UMa-type eclipsing variable star V861 Herculis are presented. The system was observed in 2000 and 2003. The light curves obtained at different epochs showed significant deviation from each other. The O'Connell effect (usually explained by spots on the surface which are responsible for variations in the intensity of the system) was about {Delta}V=0.05mag in 2000 but it vanished in 2003 (except the night of February 22/23, 2003 when we observed a small O'Connell effect ({Delta}V=0.020)). Further peculiarities of the light curves are also discussed.
24325. V(RI)c light-curves of EQ Tauri
ID:
ivo://CDS.VizieR/J/AJ/132/960
Title:
V(RI)c light-curves of EQ Tauri
Short Name:
J/AJ/132/960
Date:
21 Oct 2021
Publisher:
CDS
Description:
New V, R_C_, and I_C_ light curves of EQ Tau have been obtained in 2002 and 2003. These show the secondary minimum to be a total eclipse. These new light curves have been analyzed, together with the published radial velocity observations, using the Wilson-Devinney code. The binary has an overcontact configuration, with an orbital inclination of 85{deg}, a difference in component temperature of 80K, and an overcontact fill-out factor of 16%. Absolute parameters of the component stars have been determined: M1=1.28M_{sun}_, R1=1.17R_{sun}_, L1=1.39 L_{sun}_, and M2=0.47M_{sun}_, R2=0.81R_{sun}_, L2=0.63L_{sun}_. The calculated distance is 180+/-20pc. A critical review of our new timings of minimum light together with previously published ones suggests a change from one constant period to another one around 1974 rather than a cyclical variation. When corrected for energy transfer in the common envelope, the physical parameters of the two components are in good agreement with those of unevolved single stars of similar masses.
24326. VRI Cousins photometry of Am stars
ID:
ivo://CDS.VizieR/J/A+A/343/446
Title:
VRI Cousins photometry of Am stars
Short Name:
J/A+A/343/446
Date:
21 Oct 2021
Publisher:
CDS
Description:
Tablea1 contains photoelectric VRI Cousins photometry for 63 Am stars observed on the 17th June, 1996 with the 1.52m telescope of the Observatorio Astronomico Nacional (O.A.N.) at Calar Alto (Almeria, Spain), and on the 25th and 26th of the same month using the 1m Jakobus Kapteyn telescope at the Observatorio del Roque de los Muchachos (O.R.M., Canary Islands, Spain). The reduction procedure followed is explained in Rossello et al. (1985A&AS...59..399R) and Landolt (1983, Cat. <II/118>; 1983AJ.....88..853L) standard stars were used. We provide the V magnitude, the (V-R) and (V-I) colour indices, their associated standard errors and the number of observations performed for each star.
24327. V(RI)C Phot of Cepheids in the Magellanic Clouds
ID:
ivo://CDS.VizieR/J/PASP/111/812
Title:
V(RI)C Phot of Cepheids in the Magellanic Clouds
Short Name:
J/PASP/111/812
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present V(RI)C data for 13 Cepheids in the Large Magellanic Cloud and eight in the Small Magellanic Cloud. The total number of new measures is 55 in each wavelength band. The median uncertainty in the photometry is 0.03 mag. These results supplement a larger photometric program presented in the second paper in this series which contained 1000 measures (0.01 mag) in each wavelength band on 22 variables with periods in the range 8133 days.
24328. 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.
24329. 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.
24330. 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.

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