- ID:
- ivo://CDS.VizieR/J/ApJS/244/12
- Title:
- A search for variable stars in M4 with K2 LCs
- Short Name:
- J/ApJS/244/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We extract light curves for 4554 objects with 9<G<19 in the K2 superstamp observations of the globular cluster M4, including 3784 cluster members, and search for variability. Among cluster-member objects, we detect 66 variables, of which 52 are new discoveries. Among objects not belonging to the cluster, we detect 24 variables, of which 20 are new discoveries. We additionally discover 57 cluster-member suspected variables, 10 cluster-non-member suspected variables, and four variables with ambiguous cluster membership. Our light curves reach sub-millimagnitude precision for the cluster horizontal branch, permitting us to detect asteroseismic activity in six horizontal branch stars outside the instability strip and one inside the strip but with only ~1mmag amplitude variability. Nineteen additional stars along the red giant branch also have detected asteroseismic variability. Several eclipsing binaries are found in the cluster, including a 4.6 day detached eclipsing binary and an EW-class eclipsing binary, as well as an EW with uncertain cluster membership and three other candidate EWs. A 22 day detached eclipsing binary is also found outside the cluster. We identify a candidate X-ray binary that is a cluster member with quiescent and periodic ~20mmag optical variability. We also obtain high-precision light curves for 10 of the previously known RR Lyrae variables in the cluster and identify one as a candidate Blazhko variable with a Blazhko period in excess of 78d.
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- ID:
- ivo://CDS.VizieR/J/AJ/108/1786
- Title:
- Blue stragglers and variable stars in M3
- Short Name:
- J/AJ/108/1786
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper describes Hubble Space Telescope (HST)/Planetary Camera-I images of the core of the dense globular cluster M3 (NGC 5272). Stellar photometry in the F555W (V) and F785LP (I) bands, with a 1 sigma photometric accuracy of about 0.1mag, has been used to construct color-magnitude diagrams of about 4700 stars above the main-sequence turnoff within r<~1' of the cluster center. We have also analyzed archival HST F336W (U) images of M3 obtained by the Wide Field/Planetary Camera-I Instrument Definition Team. The UVI data are used to identify 28 blue straggler (BS) stars within the central 0.29arcmin^2. The specific frequency of BSs in this region of M3, N(BS)/N(V<V(HB)+2)=0.094+/-0.019, is about a factor of 2-3 higher than that found by Bolte et al. [1993, ApJ, 408, L89] in a recent ground-based study of the same region, but comparable to that seen in the sparse outer parts of the same cluster and in HST observations of the core of the higher density cluster 47 Tuc. The BSs in M3 are slightly more centrally concentrated than red giant branch stars while horizontal branch stars are somewhat less concentrated than red giants. The radial distribution of V-selected subgiant and turnoff stars is well fit by a King model with a core radius r(core)=28"+/-2" (90% confidence limits), which corresponds to 1.4pc. Red giant and horizontal branch stars selected in the ultraviolet data (U<18) have a somewhat more compact distribution (r(core)=22.5"). The HST U data consist of 17 exposures acquired over a span of three days. We have used these data to isolate 40 variable stars for which relative astrometry, brightnesses, colors, and light curves are presented. A Kolmogorov-Smirnov test indicates that, typically, the variability for each star is significant at the 95% level. We identify two variable BS candidates (probably of the SX Phe type) out of a sample of ~25 BSs in which variability could have been detected. Most of the variables are RR Lyrae stars on the horizontal branch. All of them have periods P>~8h.
- ID:
- ivo://CDS.VizieR/J/AJ/139/2300
- Title:
- BVIc light curves of 3 type II Cepheids
- Short Name:
- J/AJ/139/2300
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Light curves in the B, V, and Ic passbands have been obtained for the type II Cepheids V154 in M3 and V42 and V84 in M5. Alternating cycle behavior, similar to that seen among RV Tauri variables, is confirmed for V84. Old and new observations, spanning more than a century, show that V154 has increased in period while V42 has decreased in period. V84, on the other hand, has shown large, erratic changes in period that do not appear to reflect the long-term evolution of V84 through the Hertzsprung-Russel diagram.
- ID:
- ivo://CDS.VizieR/J/MNRAS/372/1657
- Title:
- BVI(c) light curves of variables in M3
- Short Name:
- J/MNRAS/372/1657
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present time-series data on the variable stars of the galactic globular cluster Messier 3 (M3). We give BVI_C_ light curves for 226 RR Lyrae, 2 SX Phe and 1 W Vir type variables, along with estimated fundamental photometric parameters such as intensity and magnitude-averaged brightness and pulsation periods. In some cases, the periods we have found significantly differ from the previously published ones. This is the first published light curve and period determination for variable V266. The I-band light curve has not been observed previously for numerous (76) variables. Three new RR Lyrae variables have been discovered. Groups of RR Lyrae variables that belong to different evolutionary stages and have been separated previously on the basis of V data were found here for all colours and colour indices by cluster analysis. The I-band period-luminosity relation is also discussed. From the 66 modulated (Blazhko type) RR Lyrae stars we investigated, six are newly identified and two of them are first overtone pulsators. In the case of 13 RR Lyrae, the period of Blazhko cycle has been estimated for the first time. V252 is identified as a new RRd variable. Amplitude ratios of RRd stars have been investigated to search possible mode content changes. In contrast to previous publications no changes have been found. Problems with the sampling of the time-series of typical cluster variability surveys are demonstrated.
- ID:
- ivo://CDS.VizieR/J/AJ/129/1596
- Title:
- BVI photometric variability survey of M3
- Short Name:
- J/AJ/129/1596
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a three-band (BVI) variability survey of the globular cluster M3. This is the first three-band survey of the cluster using modern image subtraction techniques. Observations were made over nine nights in 1998 on the 1.2m telescope at the F. L. Whipple Observatory in Arizona. We present photometry for 180 variable stars in the M3 field, 12 of which are newly discovered. New discoveries include six SX Phoenicis-type variables that all lie in the blue straggler region of the color-magnitude diagram, two new first-overtone RR Lyrae variables, a candidate multimode RR Lyrae variable, a detached eclipsing binary, and two unclassified variables. We also provide revised periods for 52 of the 168 previously known variables that we observe.
- ID:
- ivo://CDS.VizieR/J/PASP/117/1325
- Title:
- BVRI photometry in NGC4147
- Short Name:
- J/PASP/117/1325
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New BVRI broadband photometry and astrometry are presented for the globular cluster NGC 4147, based upon measurements derived from 524 ground-based CCD images mostly either donated by colleagues or retrieved from public archives. We have also reanalyzed five exposures of the cluster obtained with WFPC2 on the Hubble Space Telescope in the F439W and F555W (B and V) filters.
- ID:
- ivo://CDS.VizieR/J/PAZh/21/596
- Title:
- BVR photometry of NGC 6584
- Short Name:
- J/PAZh/21/596
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Automatic stellar photographic BVR photometry reaching 1mag below the horizontal branch of NGC 6584, located at V~16.5mag, has been performed for this poorly studied globular cluster. One of the photoelectric standard stars used in our reductions appears to be variable. We also determined accurate coordinates of 52 variable stars in the cluster and around it.
- ID:
- ivo://CDS.VizieR/J/AJ/103/460
- Title:
- CCD photometry of M 71
- Short Name:
- J/AJ/103/460
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Two sets of observations of the metal-rich globular cluster M 71 are presented. The first uses deep CCD exposures to derive a fiducial in V, B-V and compares this with a cluster of similar metallicity, 47 Tuc. Comparison with oxygen enhanced theoretical isochrones leads to age estimates for M 71 of from ~14+/-2Gyr to ~16+/-2Gyr. Within the limits imposed by the quality of the data, no significant age difference between the two clusters is found. The second set of 73 frames is used to search an overlapping 67"x104" area of the cluster for variable stars. Light curves and phase diagrams (where appropriate) are presented for all four of the variables discovered. One variable blue straggler (or SX Phe star) has been identified with a period of 0.050d. Values for its mass depend, of course, on the assumed pulsation mode-(0.90+/-0.47)M_{sun}_ for the first overtone mode, and (1.57+/-0.83)M_{sun}_ for the fundamental mode. One of the variables, with a 0.0582d period, but with a magnitude 1.75mag below the main sequence turnoff may be a field star. Two candidate eclipsing binary systems were also found. The most likely orbital period of one is 0.372d. This value, and the shape of the light curve, suggest that it could be a W UMa type variable. No period was obtainable for the other candidate binary due to a lack of phase coverage. Further data is needed to confirm and strengthen these claims, and to check for cluster membership.
- ID:
- ivo://CDS.VizieR/J/AJ/112/618
- Title:
- CCD photometry of variable stars in M9
- Short Name:
- J/AJ/112/618
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD observations have been used to derive precise light curves for six of the previously known RR Lyrae variables in the Oosterhoff type II globular cluster M9 and to search for additional variables. Nine variables have been discovered, eight of the RR Lyrae type. As a result, the total number of RR Lyrae variables has been revised from 9 to 17 (9 RRc and 8 RRab), the mean period of the RRc stars has been revised from 0.341d to 0.342d and that of the RRab stars from 0.621d to 0.638d. Simon's method that relates physical properties of RRc stars to the pulsation period and Fourier phase parameter {phi}_31_ has been used to determine the mass, luminosity, and temperature for one of the RRc stars. Published observations of RR Lyrae stars in M15 have been used to test Simon's method (1993ApJ...410..526S, 1993, IAUCo, 139, 315) and the results are promising. The formulae of Jurcsik and Kovacs (1996A&A...312..111J) for relating Fourier parameters of RRab stars to [Fe/H] have been used to derive a metal abundance for M9.
- ID:
- ivo://CDS.VizieR/J/other/RMxAA/42.75
- Title:
- CCD RV light curve of M15 RR Lyrae
- Short Name:
- J/other/RMxAA/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results of CCD photometry using V and R filters are reported for 33 RR Lyrae stars in M15. Applying the approach of Fourier decomposition of the light curves, the physical parameters of the type RRab and RRc variables were estimated. The cluster is Oosterhoff type II and the values for the iron content and distance are: [Fe/H]=-1.98+/-0.24 and d=8.67+/-0.41kpc, respectively. The mean values of the physical parameters determined for the RR Lyrae stars place the cluster precisely into the sequences Oosterhoff type - metallicity and metallicity - effective temperature, valid for globular clusters. Evidences of evolution from the ZAHB are found for the RRc but not for the RRab stars.
