Search

Start Over Capability Type Table Access Protocol Result Type text/xml+votable
20501. Variable stars in M4 primary field
ID:
ivo://CDS.VizieR/J/MNRAS/442/2381
Title:
Variable stars in M4 primary field
Short Name:
J/MNRAS/442/2381
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a photometric search for variable stars in the core of the Galactic globular cluster Messier 4 (M 4). The input data are a large and unprecedented set of deep Hubble Space Telescope WFC3 images (large programme GO-12911; 120 orbits allocated), primarily aimed at probing binaries with massive companions by detecting their astrometric wobbles. Though these data were not optimized to carry out a time-resolved photometric survey, their exquisite precision, spatial resolution and dynamic range enabled us to firmly detect 38 variable stars, of which 20 were previously unpublished. They include 19 cluster-member eclipsing binaries (confirming the large binary fraction of M 4), RR Lyrae and objects with known X-ray counterparts. We improved and revised the parameters of some among published variables.
20502. Variable stars in NGC 2244
ID:
ivo://CDS.VizieR/J/MNRAS/487/3505
Title:
Variable stars in NGC 2244
Short Name:
J/MNRAS/487/3505
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results of the UBVIc variability search for variable stars in the young open cluster NGC 2244. In total, we found 245 variable stars. Most of them, are pre-main sequence variables with irregular variations typical for classical T Tauri stars (CTTSs). We found also 23 periodic variables, probably weak-lined T Tauri stars (WTTSs). We detected also four candidates for {delta} Scuti stars and 7 eclipsing binaries. Based on the mid-infrared Spitzer and WISE photometry and near infrared JHKS 2MASS photometry, we classified 104 young stellar sources among our variables: 1 Class I object, 1 Class I/flat spectrum object, 4 flat spectrum objects, 91 Class II objects, and 7 transition disc objects. This classification, together with r'i'H{alpha} IPHAS photometry and JHK UKIDSS photometry, were used for identification of pre-main sequence stars among irregular and periodic variables. In this way, 97 CTTS candidates (96 irregular and one periodic variable), 68 WTTS candidates (54 irregular and 14 periodic variables), and 6 Herbig Ae/Be stars were found. For 223 variable stars we calculated membership probability based on proper motions from Gaia DR2 catalogue. Majority of them, 143 stars, are cluster members with probability greater than 70 per cent. For only 36 variable stars the membership probability is smaller than 20 per cent.
20503. Variable stars in NGC 6715
ID:
ivo://CDS.VizieR/J/A+A/592/A120
Title:
Variable stars in NGC 6715
Short Name:
J/A+A/592/A120
Date:
21 Oct 2021
Publisher:
CDS
Description:
We show the benefits of using Electron-Multiplying CCDs and the shift-and-add technique as a tool to minimise the effects of the atmospheric turbulence such as blending between stars in crowded fields and to avoid saturated stars in the fields observed. We intend to complete, or improve, the census of the variable star population in globular cluster NGC 6715. Our aim is to obtain high-precision time-series photometry of the very crowded central region of this stellar system via the collection of better angular resolution images than has been previously achieved with conventional CCDs on ground-based telescopes. Observations were carried out using the Danish 1.54-m Telescope at the ESO La Silla observatory in Chile. The telescope is equipped with an Electron-Multiplying CCD that allowed to obtain short-exposure-time images (ten images per second) that were stacked using the shift-and-add technique to produce the normal-exposure-time images (minutes). The high precision photometry was performed via difference image analysis employing the DanDIA pipeline. We attempted automatic detection of variable stars in the field. We statistically analysed the light curves of 1405 stars in the crowded central region of NGC 6715 to automatically identify the variable stars present in this cluster. We found light curves for 17 previously known variable stars near the edges of our reference image (16 RR Lyrae and 1 semi-regular) and we discovered 67 new variables (30 RR Lyrae, 21 long-period irregular, 3 semi-regular, 1 W Virginis, 1 eclipsing binary, and 11 unclassified).
20504. Variable stars in NGC 6791
ID:
ivo://CDS.VizieR/J/AJ/129/2856
Title:
Variable stars in NGC 6791
Short Name:
J/AJ/129/2856
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have undertaken a long-term project, Planets in Stellar Clusters Extensive Search (PISCES), to search for transiting planets in open clusters. In this paper we present the results for NGC 6791, a very old, populous, metal-rich cluster. We have monitored the cluster for over 300hr, spread over 84 nights. We have not detected any good transiting planet candidates. Given the photometric precision and temporal coverage of our observations and the current best estimates for the frequency and radii of short-period planets, the expected number of detectable transiting planets in our sample is 1.5. We have discovered 14 new variable stars in the cluster, most of which are eclipsing binaries, and present high-precision light curves spanning 2 years for these new variables and also the previously known variables.
20505. Variable stars in NGC 1466
ID:
ivo://CDS.VizieR/J/AJ/142/107
Title:
Variable stars in NGC 1466
Short Name:
J/AJ/142/107
Date:
21 Oct 2021
Publisher:
CDS
Description:
This is the first in a series of papers studying the variable stars in Large Magellanic Cloud globular clusters. The primary goal of this series is to better understand how the RR Lyrae stars in Oosterhoff-intermediate systems compare to those in Oosterhoff I/II systems. In this paper, we present the results of our new time-series BV photometric study of NGC 1466. A total of 62 variables were identified in the cluster, of which 16 are new discoveries. The variables include 30 RRab stars, 11 RRc stars, 8 RRd stars, 1 candidate RR Lyrae, 2 long-period variables, 1 potential anomalous Cepheid, and 9 variables of undetermined classification. We present photometric parameters for these variables.
20506. Variable stars in NGC 6934
ID:
ivo://CDS.VizieR/J/other/RMxAA/54.15
Title:
Variable stars in NGC 6934
Short Name:
J/other/RMxAA/54
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report an analysis of new V and I CCD time-series photometry of the globular cluster NGC 6934. Through the Fourier decomposition of the RR Lyrae light curves, the mean values of [Fe/H] and the distance of the cluster were estimated, we found; [Fe/H]_UVES_=-1.48+/-0.14 and d=16.03+/-0.42kpc, and [Fe/H]_UVES_=-1.43+/-0.11 and d=15.91+/-0.39kpc, from the calibrations of RRab and RRc stars respectively. Independent distance estimations from SX Phe and SR stars are also discussed. Individual absolute magnitudes, radii and masses are also reported for RR Lyrae stars. We found 12 new variables: 4 RRab, 3 SX Phe, 2 W Virginis (CW) and 3 semi-regular (SR). The inter-mode or "either-or" region in the instability strip is shared by the RRab and RRc stars. This characteristic, observed only in some OoI clusters and never seen in an OoII, is discussed in terms of mass distribution in the ZAHB.
20507. Variable stars in NGC 5286
ID:
ivo://CDS.VizieR/J/AJ/139/357
Title:
Variable stars in NGC 5286
Short Name:
J/AJ/139/357
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a search for variable stars in the globular cluster (GC) NGC 5286, which has recently been suggested to be associated with the Canis Major dwarf spheroidal galaxy. Fifty-seven variable stars were detected, only 19 of which had previously been known. Among our detections one finds 52 RR Lyrae (22 RRc and 30 RRab), 4 long-period variables, and 1 type II Cepheid of the BL Herculis type. Periods are derived for all of the RR Lyrae as well as the Cepheid, and BV light curves are provided for all the variables.
20508. Variable stars in NGC 6819 field
ID:
ivo://CDS.VizieR/J/MNRAS/358/795
Title:
Variable stars in NGC 6819 field
Short Name:
J/MNRAS/358/795
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on the discovery of 141 further variable stars found in the field of the open cluster NGC 6819. The stars were identified from time-series photometric data obtained on the Isaac Newton Telescope, La Palma, during two observing runs covering the 19 nights between 1999 June 22-30 and 1999 July 22-31. The variables found include 53 eclipsing binaries, of which eight stars appear to be RS CVns, in addition to 70 stars showing spot activity, 13 showing long-period variability and five variables of other types.
20509. Variable stars in NGC 7039 field
ID:
ivo://CDS.VizieR/J/PASP/123/671
Title:
Variable stars in NGC 7039 field
Short Name:
J/PASP/123/671
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report variable stars identified in the field of the Galactic open cluster, NGC 7039. In the fall/winter of 2009, imaging photometry has been acquired, mainly in the R band, for eight open clusters using the 81 cm Tenagra telescope in Arizona. We present the results for our first target, NGC 7039. We have found 42 new variable stars and six suspected variable stars.
20510. Variable stars in NGC 2257. I.
ID:
ivo://CDS.VizieR/J/AJ/138/1310
Title:
Variable stars in NGC 2257. I.
Short Name:
J/AJ/138/1310
Date:
21 Oct 2021
Publisher:
CDS
Description:
The variable stars in the Large Magellanic Cloud star cluster NGC 2257 are reinvestigated using photometry (to ~20th mag) of over 400 new B, V CCD images taken with the CTIO 0.9m telescope on 14 nights in 2007 December and 2008 January. New period searches have been made using two independent algorithms (CLEAN, Period04); the resultant periods of most of the stars are consistent with the pulsation periods derived previously, and where there are discrepancies these have been resolved. For the B and V light curves, accurate Fourier coefficients and parameters are given. Six new variable stars have been discovered (V45-50), including a bright candidate long-period variable star showing secondary oscillations (V45) and two anomalously bright RRc stars (V48 and V50), which are shown to be brightened and reddened by nearby red giant stars. Also discovered among the previously known variable stars are three double-mode RR Lyrae stars (V8, V16, and V34) and several Blazhko variables. Archival Hubble Space Telescope images and the photometry by Johnson et al. (Cat. J/ApJ/527/199) have been used to define better the properties of the most crowded variable stars. The total number of cluster variable stars now stands at forty-seven: 23 RRab stars, four of which show Blazhko amplitude variations; 20 RRc stars, one showing clear Blazhko variations and another showing possible Blazhko variations; the three RRd stars, all having the dominant period ~0.36 day and period ratios P1/P0 ~0.7450; and an LPV star located near the tip of the red giant branch. A comparison of the RRd stars with those in other environments shows them to be most similar to those in IC4499.