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541. BV photometry of active K-M dwarfs
ID:
ivo://CDS.VizieR/J/AZh/79/542
Title:
BV photometry of active K-M dwarfs
Short Name:
J/AZh/79/542
Date:
21 Oct 2021
Publisher:
CDS
Description:
Variability of the photospheric radiation of 40 (dKe-dMe) dwarfs due to variations in the spottedness of their surfaces is analyzed based on the behavior of their mean annual brightnesses over long time intervals.
542. BV photometry of Andromeda II variables
ID:
ivo://CDS.VizieR/J/AJ/127/318
Title:
BV photometry of Andromeda II variables
Short Name:
J/AJ/127/318
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a variable star search in Andromeda II, a dwarf spheroidal galaxy companion to M31, using Hubble Space Telescope Wide Field Planetary Camera 2 observations. Seventy-three variables were found, one of which is an anomalous Cepheid while the others are RR Lyrae stars. The anomalous Cepheid has properties consistent with those found in other dwarf spheroidal galaxies. For the RR Lyrae stars, the mean periods are 0.571 and 0.363 days for the fundamental mode and first-overtone mode stars, respectively. With this fundamental mode mean period and the mean metallicity determined from the red giant branch (<[Fe/H]>=-1.49), Andromeda II follows the period-metallicity relation defined by the Galactic globular clusters and other dwarf spheroidal galaxies. We also find that the properties of the RR Lyrae stars themselves indicate a mean abundance that is consistent with that determined from the red giants.
543. BV photometry of Blanco 1 stars
ID:
ivo://CDS.VizieR/J/A+AS/121/213
Title:
BV photometry of Blanco 1 stars
Short Name:
J/A+AS/121/213
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of H{alpha}(6562A) and Li I(6708A) observations of 114 low-mass stars of the young open cluster Blanco 1. We also present observations of 30 stars in Ca II(K). This work extends the first Blanco 1 spectroscopic study of Panagi et al. (1994A&A...285..233D). From a sample of four well-studied clusters, including Blanco 1, we find that the fraction of H{alpha} emission-line stars amongst K dwarfs is a good indicator of relative age, with a smaller fraction indicative of older age. Blanco 1 shows a relatively small fraction of emitters, inconsistent with previous age estimates for the cluster. We estimate the cluster age to to be 90+/-25Myr, slightly older than the Pleiades. The method is shown to be more sensitive to age than lithium and a useful alternative to other age measurement techniques. The variation of H{alpha} with (B-V) is similar to that observed in the older solar neighbourhood dwarfs, suggesting that, at least for the absorption-line stars, the contribution of stellar rotation to the equivalent width is unclear. We combine both spectroscopy and photometry to revise cluster membership and give accurate positions for all these stars.
544. BV photometry of Bochum 7 members
ID:
ivo://CDS.VizieR/J/A+A/616/A40
Title:
BV photometry of Bochum 7 members
Short Name:
J/A+A/616/A40
Date:
21 Oct 2021
Publisher:
CDS
Description:
We plan to identify the members of the Bochum 7 association by performing simultaneous astrometric and spectrophotometric analyses, and estimate its distance and evolutionary stage. We used our own visual spectroscopic and UBV photometric data of a 30{deg}x30{deg} region centered at RA=8:44:47.2, DE=-45:58:55.5. This information enabled us to estimate the spectral classification and distance of all stars present in the region. The proper motion was analyzed with data of the UCAC 5 catalog and was used to identify the members of this association. We added JHK data from 2MASS and IRAS catalogs to check for the presence of infrared (IR) excess stars. We found that Bochum 7 is an OB association with at least 27 identified stellar members (l=265.12{deg}, b=-2{deg}) at a distance of ~=5640pc. Its proper motion is pm_RA_cosDE=-4.92+/-0.08mas/yr, pm_DE_=3.26+/-0.08mas/yr. We derived an average heliocentric radial velocity of ~35km/s and were able to confirm the binary nature of the (ALS 1135) system and detect four new binary star candidates. Analysis of data for massive Bo 7 star candidates points towards a young age (<=3x10^6^ years old) for the association, although the presence of a previous episode of star formation remains to be analyzed.
545. 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.
546. 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.
547. 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.
548. 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.
549. 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.
550. 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.