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1791. BV photometry of dwarf Cepheids in Carina
ID:
ivo://CDS.VizieR/J/AJ/146/141
Title:
BV photometry of dwarf Cepheids in Carina
Short Name:
J/AJ/146/141
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the detection of 388 pulsating variable stars (and some additional miscellaneous variables) in the Carina dwarf spheroidal galaxy over an area covering the full visible extent of the galaxy and extending a few times beyond its photometric (King) tidal radius along the direction of its major axis. Included in this total are 340 newly discovered dwarf Cepheids (DCs), which are mostly located ~2.5mag below the horizontal branch and have very short periods (<0.1days), typical of their class and consistent with their location on the upper part of the extended main sequence of the younger populations of the galaxy. Several extra-tidal DCs were found in our survey up to a distance of ~1{deg} from the center of Carina. Our sample also includes RR Lyrae stars and anomalous Cepheids, some of which were found outside the galaxy's tidal radius as well. This supports past works that suggest that Carina is undergoing tidal disruption. We use the period-luminosity relationship for DCs to estimate a distance modulus of {mu}_0_=20.17+/-0.10mag, in very good agreement with the estimate from RR Lyrae stars. We find some important differences in the properties of the DCs of Carina and those in Fornax and the LMC, the only extragalactic samples of DCs currently known. These differences may reflect a metallicity spread, depth along the line of sight, and/or different evolutionary paths of the DC stars.
1792. BV photometry of 3 globular clusters
ID:
ivo://CDS.VizieR/J/A+A/448/171
Title:
BV photometry of 3 globular clusters
Short Name:
J/A+A/448/171
Date:
21 Oct 2021
Publisher:
CDS
Description:
Some of the Galactic outer halo globular clusters are excellent tools to probe gravitational theories in the regime of weak accelerations. The measurement of the line-of-sight velocity dispersion among stars in these clusters will differentiate between the validity of Newtonian dynamics (low velocity dispersion) and the possibility of modified Newtonian dynamics (MOND) or dark matter dominated globular clusters (high velocity dispersion). In this paper, the properties of probable member stars of the three best-case gravitational theory-testing clusters AM 1, Pal 3 and Pal 14 are presented. The member selection is based on VLT photometry in Johnson BV. The positions of the stars were determined with an accuracy of the order of <=0.2", allowing their direct use for follow-up spectroscopy. The distance, reddening, age and metallicities of the clusters were estimated from isochrone fitting. Furthermore, improved structural parameters, like central coordinates, ellipticity, half-light radius, King model core and tidal radius, are presented.
1793. BV photometry of LW 55 in LMC
ID:
ivo://CDS.VizieR/J/AJ/126/237
Title:
BV photometry of LW 55 in LMC
Short Name:
J/AJ/126/237
Date:
21 Oct 2021
Publisher:
CDS
Description:
The field of the moderately old open cluster LW 55 in the outer parts of the Large Magellanic Cloud disk was monitored for detection of short-period variable stars over two nights. Eight variables were found; all but one (a detached eclipsing binary) are small-amplitude ({Delta}V<=0.1mag) pulsating stars of the {delta} Scuti, SX Phoenicis, or Doradus type. The BV color-magnitude diagram extends down to the solar-type stars at V=24 (M_V_~5.2). The cluster age is estimated at 1.5Gyr for Z=0.004 ([Fe/H]=-0.67); the surrounding stellar field is older, with an age greater than 4Gyr.
1794. BV photometry of M71
ID:
ivo://CDS.VizieR/J/A+AS/144/227
Title:
BV photometry of M71
Short Name:
J/A+AS/144/227
Date:
21 Oct 2021
Publisher:
CDS
Description:
File table2 contains coordinates (J2000) and B,V magnitudes and B-V colours with corresponding errors of 4450 stars in a 20'x20' region centered on the globular cluster M 71 (NGC 6838). The limiting magnitude of the catalogue is about V=18.0 The observations were made in 1995 at Calar Alta Observatory.
1795. BV photometry of M31 eclipsing binaries
ID:
ivo://CDS.VizieR/J/A+A/459/321
Title:
BV photometry of M31 eclipsing binaries
Short Name:
J/A+A/459/321
Date:
21 Oct 2021
Publisher:
CDS
Description:
Broad band photometry (in Johnson B and V) has been obtained in a region (34'x34') at the North-Eastern quadrant of M31 over 5 years (1999-2003) at the Isaac Newton Telescope (La Palma, Spain). The data, containing more than 250 observations per filter, have been reduced by means of the so-called difference image analysis technique and the DAOPHOT program. A catalog with 236238 objects with photometry in both B and V passbands has been obtained. The catalog is the deepest (V<25.5mag) obtained so far in the studied region and contains 3964 identified variable stars, with 437 eclipsing binaries and 416 Cepheids.
1796. BV photometry of M11 stars
ID:
ivo://CDS.VizieR/J/PASP/119/1233
Title:
BV photometry of M11 stars
Short Name:
J/PASP/119/1233
Date:
21 Oct 2021
Publisher:
CDS
Description:
V-band time-series CCD photometric observations of the intermediate-age open cluster M11 were performed to search for variable stars.
1797. BV photometry of NGC 3680
ID:
ivo://CDS.VizieR/J/AJ/113/1045
Title:
BV photometry of NGC 3680
Short Name:
J/AJ/113/1045
Date:
21 Oct 2021
Publisher:
CDS
Description:
A new CCD BV color-magnitude diagram (CMD) has been derived for the intermediate age open cluster NGC 3680. The quality of photometry coupled with the best-to-date knowledge of cluster memberships allows for a detailed isochrone fit to the CMD. The theoretical isochrones have been constructed using the Yale Rotating Evolution Code (YREC) in its non-rotating mode and the OPAL opacities (circa 1991). Four sets of isochrones have been calculated: one for the standard stellar model calibrated to the Sun and three others for models with different amounts of convective overshoot at the edge of the convective core, namely, 0.15, 0.20, and 0.25H_p_, where H_p_ is the pressure scale height at the core edge. All four sets of theoretical isochrones were adjusted to an adopted distance modulus of V_0_-M_V_=10.20 and reddening E(B-V)=0.075 which leads to ages of 1.3+/-0.15, 1.5+/-0.15, 1.6+/-0.15, and 1.7+/-0.15Gyr, respectively The uncertainties in age mainly reflect a subjective decision in differentiating a good fit from a poorer one The model with a convective overshoot of 0.20H_p_ seems to yield the best fit to the sharply curved upper main sequence. Hence, the estimated age of NGC 3680 is 1.6+/-0.15Gyr. The adopted overshoot parameter ostensibly is uncertain by +/-0.05H_p_. For comparison, the same stellar models with overshoot of 0.25H_p_ were fit to the color-magnitude diagram of the cluster NGC 752, which is similar in age and composition to NGC 3680 The age estimate for NGC 752 is 1.6+/-0.2Gyr, assuming V_0_-M_V_=8.20 and E(B-V)=0.030 for the cluster.
1798. BV photometry of NGC 1866
ID:
ivo://CDS.VizieR/J/AJ/118/2839
Title:
BV photometry of NGC 1866
Short Name:
J/AJ/118/2839
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a new deep (down to V~24) photometry of a wide region (~6'x6') around the Large Magellanic Cloud globular cluster NGC 1866. Our sample is much larger (by more than a factor of 3) than any previous photometry and with a main sequence (MS) that may be considered complete, down to at least 3 mag below the brightest MS star; such an occurrence allows a meaningful and robust comparison with various theoretical scenarios produced by means of models computed with the evolutionary code FRANEC.
1799. BV Photometry of NGC 6791
ID:
ivo://CDS.VizieR/J/MNRAS/243/492
Title:
BV Photometry of NGC 6791
Short Name:
J/MNRAS/243/492
Date:
21 Oct 2021
Publisher:
CDS
Description:
CCD BV photometry to V=20.5 of stars in the old open cluster NGC 6791 is presented. Comparison with the theoretical isochrones of VandenBerg gives a cluster age in the range of 10 to 12.5Gyr, and an apparent distance modulus of 13.45mag, adopting a solar metallicity. This cluster is only marginally younger than Palomar 12, which is the youngest globular cluster known. A search for short-period variables in the cluster field led to the discovery of only one low-amplitude variable, probably belonging to the FK Com-type stars. A very blue star was detected which may be an extremely young white dwarf formed in the cluster.
1800. BV photometry of NGC 6822 variables
ID:
ivo://CDS.VizieR/J/A+A/431/1189
Title:
BV photometry of NGC 6822 variables
Short Name:
J/A+A/431/1189
Date:
21 Oct 2021
Publisher:
CDS
Description:
Deep B, V time-series photometry obtained with the ESO Very Large Telescope has been used to identify variable stars in the dwarf irregular galaxy NGC 6822. We surveyed a 6.8x6.8 arcmin area of the galaxy and detected a total number of 390 candidate variables with the optimal image subtraction technique (Alard C., 2000A&AS..144..363A). Light curves on a magnitude scale were obtained for 262 of these variables. Differential flux light curve are available for the remaining sample. We were able to determine periods and pulsation characteristics for 69 out of the 262 variables with light curves in magnitude scale, they include: 18 RR Lyrae stars (16 ab-type and 2 c-type), 45 Cepheids and 6 binary systems. We also tentatively calibrated 8 of the 128 objects with light curves on a differential flux scale on the assumption that they are ab-type RR Lyrae stars.

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