Search

Start Over Subject variable stars
161. BVI photometry of Variables in M33
ID:
ivo://CDS.VizieR/J/AJ/121/870
Title:
BVI photometry of Variables in M33
Short Name:
J/AJ/121/870
Date:
21 Oct 2021
Publisher:
CDS
Description:
The DIRECT project aims to determine direct distances to two important galaxies in the cosmological distance ladder - M31 and M33 - using detached eclipsing binaries (DEBs) and Cepheids. We present the results of the first large-scale CCD-based search for variables in M33. We have observed two fields located in the central region of M33 for a total of 95 nights on the F. L. Whipple Observatory 1.2 m telescope and 36 nights on the Michigan-Dartmouth-MIT 1.3 m telescope. We have found a total of 544 variables, including 251 Cepheids and 47 eclipsing binaries. The catalog of variables is available on-line, along with finding charts and BVI light curve data (consisting of 8.2x10^4^ individual measurements). The complete set of CCD frames is available upon request.
162. BVI photometry of V728 Her
ID:
ivo://CDS.VizieR/J/AJ/110/2400
Title:
BVI photometry of V728 Her
Short Name:
J/AJ/110/2400
Date:
21 Oct 2021
Publisher:
CDS
Description:
The W UMa system V728 Her has been observed photometrically in B, V, and I_c passbands at the RAO over five seasons and spectroscopically at DAO over three seasons to obtain radial velocities. New times of minima are provided and a period analysis confirms previous ephemerides. The light and radial velocity curves were analyzed with the latest University of Calgary enhancements to the Wilson-Devinney program and new solutions found. The best model is that involving a contact system with convective atmospheres. In probing the best solution possible, use was made of the enhanced reflection and second-order limb-darkening calculations available in the 1993 version of the WD program. The mass ratio is found to be 0.1786+/-0.0023. The contact parameter is found to be f=0.71+/-0.11. The masses are determined to be 1.654+/-0.037M_{sun}_ and 0.295+/-0.009M_{sun}_ and the radii are 1.784+/-0.015R_{sun}_ and 0.867+/-0.054R_{sun}_, respectively. The determined temperature difference, T2-T1 is 165+/-19K, and the luminosities for components 1 and 2 are 5.5+/-0.5L_{sun}_ and 1.4+/-0.3L_{sun}_, respectively.
163. BV light curves of 33 ASAS-3 Cepheids
ID:
ivo://CDS.VizieR/J/PAZh/35/44
Title:
BV light curves of 33 ASAS-3 Cepheids
Short Name:
J/PAZh/35/44
Date:
21 Oct 2021
Publisher:
CDS
Description:
Cepheids, the principal distance indicators, point to the existence of two inner Galactic spiral arms in the immediate solar neighborhood (within 5kpc). However, the available Cepheids are clearly insufficient for a detailed study of the structure of these arms. Fortunately, southern-sky monitoring (the ASAS project) has led to the discovery of many new variable stars, more than one thousand of which have been identified as possible Cepheids. To improve the classification and to construct reliable light curves for new Cepheids, we have begun their regular photometric observations. Here, we present the first results: 1192 photoelectric BVIc observations were performed for 33 classicalCepheidswith the 76-cm telescope of the South-African Astronomical Observatory (SAAO, the South-African Republic) from December 2006 to January 2008.We provide tables of observations and V light and B-V and V-Ic color curves. The new observations together with ASAS-3 data have been used to improve the elements of the light variations.
164. BV light curves of 2MASS J06451725+4122158
ID:
ivo://CDS.VizieR/J/PASP/122/17
Title:
BV light curves of 2MASS J06451725+4122158
Short Name:
J/PASP/122/17
Date:
21 Oct 2021
Publisher:
CDS
Description:
The results of extensive time-series photometry of a new variable star, 2MASS 06451725+4122158, are presented. The B, V observations (over 4000 individual measurements) were made over 23 nights between 2006 and 2007. To investigate the star's physical characteristics additional Stroemgren photometric observations (uvbyHbeta) were made on another four nights in 2007 and 2009. Thirteen frequencies were found from a multifrequency analysis of the V and B photometry. All but two of the frequencies, 19.99716cycles/d (corresponding to the pulsation period of 0.0500071d) and 25.84662cycles/d (0.0386898d), have been identified as combination frequencies.
165. BV light curves of 11 RR Lyrae
ID:
ivo://CDS.VizieR/J/AJ/139/2014
Title:
BV light curves of 11 RR Lyrae
Short Name:
J/AJ/139/2014
Date:
21 Oct 2021
Publisher:
CDS
Description:
It is not easy to identify and classify low-amplitude variables, but it is important that the classification is done correctly. We use photometry and spectroscopy to classify low-amplitude variables in a 246deg^2^ part of the Akerlof et al. (2000, Cat. J/AJ/119/1901) field. Akerlof and Collaborators found that 38% of the RR Lyrae stars in their 2000deg^2^ test field were RR1 (type c). This suggests that these RR Lyrae stars belong to an Oosterhoff Type II population, while their period distribution is primarily Oosterhoff Type I. Our observations support their RR0 (type ab) classifications; however, six of the seven stars that they classified as RR1 (type c) are eclipsing binaries. Our classifications are supported by spectroscopic metallicities, line-broadening, and Galactic rotation measurements. Our 246deg^2^ field contains 16 RR Lyrae stars that are brighter than m_R_=14.5; only four of these are RR1 (type c). This corresponds to an Oosterhoff Type I population in agreement with the period distribution.
166. BV light curves of V511 Lyr in 1994-1996
ID:
ivo://CDS.VizieR/J/A+A/383/197
Title:
BV light curves of V511 Lyr in 1994-1996
Short Name:
J/A+A/383/197
Date:
21 Oct 2021
Publisher:
CDS
Description:
Our time series analysis of sixteen BV light curves of the chromospherically active binary V511 Lyr confirmed the 2.7days rotation period uniquely. The seasonal periodicity changes of 3.8% indicated the presence of detectable surface differential rotation. The significant 2.67455days periodicity in the light curve minimum epochs suggested that the strongest starspot formation in V511 Lyr was concentrated on one stable active longitude. The differential BV photometry of V511 Lyr was made between May 1994 and June 1996 with the Vanderbilt-Tennessee State 0.4m Automated Photoelectric Telescope (APT). The comparison and check stars were HDE 337663 (C1) and HD 179422 (C2).
167. BV light curves of WX Eridani
ID:
ivo://CDS.VizieR/J/A+A/418/249
Title:
BV light curves of WX Eridani
Short Name:
J/A+A/418/249
Date:
21 Oct 2021
Publisher:
CDS
Description:
WX Eri is an eclipsing binary system for which one component was reported to show Delta Scuti type pulsations with periods close to integer fractions of the orbital period. This makes it an interesting candidate for investigating the interaction between binarity and pulsation and a potential new member of the recently defined group of mass-accreting pulsating components (gainers) in semi-detached Algol binaries called 'oscillating EA' stars. We present new photometric time-series observations of this star. The Wilson-Devinney code was applied to find the best fitting model for the eclipsing binary's light curve. The aim of the observations was to investigate the short-period Delta Scuti type pulsations of WX Eri. However, no evidence for the presence of such oscillations was found in our data.
168. BV photometry in M2 (NGC 7089)
ID:
ivo://CDS.VizieR/J/AJ/117/2868
Title:
BV photometry in M2 (NGC 7089)
Short Name:
J/AJ/117/2868
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present BV CCD photometry for 30 RR Lyrae variables, including 13 newly discovered, in the Oosterhoff type II globular cluster M2. New light curves and ephemerides are presented. Our observations cover magnitudes ranging from the red giant branch tip to ~3mag below the turnoff, allowing us to determine accurate fundamental photometric parameters. With the discovery of new RR Lyrae variables, the mean periods of the RRab and RRc variables are <P_ab_>=0.685+/-0.022days and <P_c_>=0.333+/-0.013days, respectively. The number ratio of the RRc type variables to the total number of RR Lyrae type variables is n(c)/n(ab+c)=0.40. The RR Lyrae pulsational mode transition occurs between the fundamental period of 0.528-days and 0.556-days. From star counts along the horizontal branch (HB), we obtain two HB color distribution indices, (B-R)/(B+V+R)=0.92 and B2/(B+V+R)=0.46. The period-change rates are also derived. The mean period-change rate from six RRab variables is <{beta}>=0.06+/-0.04days/Myr, which agrees well with the predictions of Lee's 1991 model. Our color-magnitude diagram shows a very extended blue HB tail, and there are no significant blue HB gaps in M2.
169. 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.
170. 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.