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421. BV photometry of NGC 300 variables
ID:
ivo://CDS.VizieR/J/MNRAS/350/679
Title:
BV photometry of NGC 300 variables
Short Name:
J/MNRAS/350/679
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have performed a search for variable stars in the Sculptor Group spiral galaxy NGC 300 using wide-field multi-epoch BV photometry up to a limiting magnitude V~23. Apart from the Cepheid variables in this galaxy already reported in an earlier paper by Pietrzynski et al. (2002, Cat. <J/AJ/123/789>) and the variable blue supergiants reported by Bresolin et al. (2002ApJ...567..277B), we have identified 26 additional periodic variables, with periods ranging from 0.2 to 190d, and 121 slow variables. Two of these newly discovered variables are Galactic foreground stars (one of them is a W UMa system), and three correspond to previously identified Wolf-Rayet stars. 16 stars are new Cepheids, and the other objects span a huge range in colours and represent a mixture of different types of luminous variables.
422. BV photometry of NGC 2099 variables
ID:
ivo://CDS.VizieR/J/A+A/483/253
Title:
BV photometry of NGC 2099 variables
Short Name:
J/A+A/483/253
Date:
21 Oct 2021
Publisher:
CDS
Description:
Rotation and solar-type magnetic activity are closely related to each other in main-sequence stars of G or later spectral types. The presence and level of magnetic activity depend on star's rotation, and rotation itself is strongly influenced by strength and topology of the magnetic fields. Open clusters represent especially useful targets to investigate the connection between rotation and activity. The open cluster NGC 2099 has been studied as a part of the RACE-OC project (Rotation and ACtivity Evolution in Open Clusters), which is aimed at exploring the evolution of rotation and magnetic activity in the late-type members of open clusters of different ages. We collected time series CCD photometric observations of this cluster in January 2004, and we determined the presence of periodicities in the flux variation related to the stellar rotation by Fourier analysis. We investigate the relations between activity manifestations, such as the light curve amplitude, and global stellar parameters. We have discovered 135 periodic variables, 122 of which are candidate cluster members. Determination of rotation periods of G- and K-type stars has allowed us to better explore the evolution of angular momentum at an age of about 500Myr. In our analysis, we have also identified 3 new detached eclipsing binary candidates among cluster members. A comparison with the older Hyades cluster (~625Myr) shows that the newly-determined distribution of rotation periods is consistent with the scenario of rotational braking of main-sequence spotted stars as they age. However, a comparison with the younger M34 cluster (~200Myr) shows that the G8-K5 members of these clusters have the same rotation period distribution. That is, G8-K5 members in NGC 2099 seem to have experienced no significant braking in the age range from ~200 to ~500Myr. Finally, NGC 2099 members have a smaller level of photospheric magnetic activity, as measured by light curve amplitude, than in younger stars of the same mass and rotation, suggesting that the activity level also depends on some other age-dependent parameters.
423. BV photometry of RT Lac
ID:
ivo://CDS.VizieR/J/A+A/388/298
Title:
BV photometry of RT Lac
Short Name:
J/A+A/388/298
Date:
21 Oct 2021
Publisher:
CDS
Description:
Contemporaneous spectroscopic and photometric BV observations of the RS CVn type eclipsing binary RT Lacertae were performed in summer 2000. The photometric observations were obtained at the Ege University Observatory, while the spectroscopic ones were carried out at Catania Astrophysical Observatory in the spectral range 5860-6700{AA}. We obtained a high quality radial velocity curve of the system that allowed us to give more accurate values of the orbital parameters.
424. BV photometry of 6 SMC stellar clusters
ID:
ivo://CDS.VizieR/J/A+A/561/A106
Title:
BV photometry of 6 SMC stellar clusters
Short Name:
J/A+A/561/A106
Date:
21 Oct 2021
Publisher:
CDS
Description:
Stellar clusters in the Small Magellanic Cloud (SMC) are useful probes to study the chemical and dynamical evolution of this neighbouring dwarf galaxy, enabling inspection of a large period covering over 10Gyr. The main goals of this work are the derivation of age, metallicity, distance modulus, reddening, core radius and central density profile for six sample clusters, in order to place them in the context of the Small Cloud evolution. The studied clusters are: AM 3, HW 1, HW 34, HW 40, Lindsay 2, and Lindsay 3, where HW 1, HW 34, and Lindsay 2 are studied for the first time. Optical Colour-Magnitude Diagrams (V, B-V CMDs) and radial density profiles were built from images obtained with the 4.1m SOAR telescope, reaching V~23. The determination of structural parameters were carried out applying King profile fitting. The other parameters were derived in a self-consistent way by means of isochrone fitting, which uses the likelihood statistics to identify the synthetic CMDs that best reproduce the observed ones. Membership probabilities were determined comparing the cluster and control field CMDs. Completeness and photometric uncertainties were obtained performing artificial star tests. The results confirm that these clusters (except HW 34, identified as a field fluctuation) are intermediate-age clusters, with ages between 1.2Gyr (Lindsay 3) and ~5.0Gyr (HW 1). In particular HW 1, Lindsay 2, and Lindsay 3 are located in a region that we called West Halo, where studies on ages and metallicity gradients are still lacking. Moreover Lindsay 2 was identified as a moderately metal-poor cluster with [Fe/H]=-1.4+/-0.2dex, lower than expected from the age-metallicity relation by Pagel & Tautvaisiene (1998MNRAS.299..535P). We also found distances varying from ~53 to 66kpc, compatible with the large depth of the SMC.
425. BV photometry of stars in NGC 6866
ID:
ivo://CDS.VizieR/J/AcA/59/193
Title:
BV photometry of stars in NGC 6866
Short Name:
J/AcA/59/193
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery of 19 variable stars and two blue stragglers in the field of the open cluster NGC 6866. Three of the variable stars we classify as delta Sct, two as g Dor, four as WUMa, two as ellipsoidal variables, and one as an eclipsing binary. Seven stars show irregular variability. Two of the pulsators, delta Sct star NGC 6866-29 and gamma Dor star NGC 6866-21, are multiperiodic.
426. BV photometry of stars in the LMC
ID:
ivo://CDS.VizieR/J/AJ/131/407
Title:
BV photometry of stars in the LMC
Short Name:
J/AJ/131/407
Date:
21 Oct 2021
Publisher:
CDS
Description:
We observed a field in the disk of the LMC on two consecutive nights in search of rapid variable stars. We found two pulsating stars of type RRab and Scuti and four binary stars; among the latter we found one sdB or cataclysmic variable below the LMC blue main sequence and three very close binary systems on the main sequence.
427. BV photometry of Trumpler 14 and 16
ID:
ivo://CDS.VizieR/J/ApJ/549/578
Title:
BV photometry of Trumpler 14 and 16
Short Name:
J/ApJ/549/578
Date:
21 Oct 2021
Publisher:
CDS
Description:
H-R diagrams are presented for the very young galactic clusters Trumpler 14 and Trumpler 16, which are the two most populous clusters in the region of vigorous star formation surrounding {eta} Carinae. Point spread function photometry of UBV CCD images is presented down to V~19 for over 560 stars in Tr 16 and 290 stars in Tr 14. We have also obtained similar data for a local background field. After determining cluster membership through proper motions from a previous work, we find that the reddening of cluster members is significantly lower than that of the local background stars. Thus, we are able to use individual reddenings to identify likely members at far deeper levels than possible with proper motions. This work has revealed a significant population of pre-main-sequence (PMS) stars in both clusters. The location of the PMS stars in the H-R diagram indicates that the theoretical "stellar birthline" of Palla & Stahler (1990ApJ...360L..47P, follows the locus of stars far better than that of Beech & Mitalas (1994ApJS...95..517B). Comparison with both pre- and post-main-sequence isochrones also reveals that although intermediate-mass stars have been forming continuously over the last 10Myr, the high-mass stars formed within the last 3Myr. There is no evidence that the formation of the intermediate-mass stars was truncated by the formation of the high-mass stars.
428. BV photometry of UX Ari in 1987-2002
ID:
ivo://CDS.VizieR/J/A+A/402/1033
Title:
BV photometry of UX Ari in 1987-2002
Short Name:
J/A+A/402/1033
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present 14.3 years of previously unpublished photometric observations of UX Ari. The observations were obtained between 1987.9 and 2002.2 using the T3 0.4-metre Automatic Photoelectric Telescope at Fairborn Observatory and consist of 1228 B band and 1213 V band measurements. The comparison star was 62 Ari and the check star was 59 Ari. We have analyzed the new data together with previously published photometric observations. The V magnitude shows variations with dominant periods of about 12 and 25 years, where the longest period seems to correspond to an activity cycle. The previously reported anticorrelation between the B V colour and V magnitude variations is confirmed.
429. BV photometry of variables in NGC 6397
ID:
ivo://CDS.VizieR/J/A+AS/122/1
Title:
BV photometry of variables in NGC 6397
Short Name:
J/A+AS/122/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
Tables 5 and 6 contain BV photometry of stars from NGC 6397 field which is presented in Figs. 1 and 2, respectively. File template.fits is a FITS format image of the surveyed field. Stars coordinates listed in the paper correspond to positions on this image.
430. BV photometry of variable stars in SMC
ID:
ivo://CDS.VizieR/J/AJ/123/3216
Title:
BV photometry of variable stars in SMC
Short Name:
J/AJ/123/3216
Date:
21 Oct 2021
Publisher:
CDS
Description:
B and V photometry has been obtained for variable stars in the northeast arm of the Small Magellanic Cloud (SMC). Periods and light curves have been determined for 237 periodic variables, including 201 Cepheids, 68 of which are newly discovered. Fundamental-mode Cepheids and first-overtone mode Cepheids are generally well separated in the BV color-magnitude diagram, with the latter having bluer mean colors than the former. The Cepheid period-color relationship for this outlying SMC field is indistinguishable from that seen in more centrally located SMC fields and is bluer than theoretical predictions. The red edge to the populated portion of the instability strip shifts to bluer colors for fainter Cepheids. There is support from our sample for a previously reported steepening in the slope of the period-luminosity relation for fundamental-mode Cepheids near a period of 2 days. The Cepheids of the northeast arm may be closer to us than are those of the main body of the SMC, but the difference is smaller than or equal to about 4kpc, comparable to the tidal radius of the SMC.