- ID:
- ivo://CDS.VizieR/J/AJ/110/1141
- Title:
- Variables in the Sagittarius dSph
- Short Name:
- J/AJ/110/1141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present time-series CCD photometry of a field in the newly discovered dwarf spheroidal galaxy in Sagittarius (hereafter Sgr), and of a nearby control field. These data, which consist of VI images obtained during the 1994 OGLE season, were used to identify and study variable stars in both fields. We discovered ten variable stars in the Sgr field, nine of which have light curves and periods consistent with RR Lyr stars or anomalous Cepheids. The control field contains four short-period contact eclipsing binaries, but no pulsating variables. The variables in the Sgr field include a bright RR Lyr star that is almost certainly located in front of Sgr in the galactic bulge, a short-period contact binary located near or within Sgr, and a short-period pulsating star that may either be a foreground halo RR Lyr star or an anomalous Cepheid within Sgr. The seven remaining variables in the Sgr field are RR Lyr stars with very similar mean apparent magnitudes; we conclude that they are members of Sgr. We estimate the total number of RR Lyr stars in Sgr to be 1930+/-730 if M(V,Sgr)=-13, or 310+/-120 if M(V,Sgr)=-11. The frequency of pulsating variables in Sgr is consistent with earlier conclusions that the galaxy consists of a predominant old (age>~10Gyr) population.
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Search Results
1482. Variables in 47 Tuc
- ID:
- ivo://CDS.VizieR/J/ApJ/559/1060
- Title:
- Variables in 47 Tuc
- Short Name:
- J/ApJ/559/1060
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Differential time series photometry has been derived for 46,422 main-sequence stars in the core of 47 Tucanae. The observations consisted of near-continuous 160 s exposures alternating between the F555W and F814W filters for 8.3 days in 1999 July with the Wide Field Planetary Camera 2 on the Hubble Space Telescope. Using Fourier and other search methods, 11 detached eclipsing binaries and 15 W Ursa Majoris stars have been discovered plus an additional 10 contact or near-contact noneclipsing systems. After correction for nonuniform area coverage of the survey, the observed frequencies of detached eclipsing binaries and W UMa stars within 90" of the cluster center are 0.022% and 0.031%, respectively. The data were taken over an 8.3 day period, 1999 July 3-11, during which HST was pointed continuously at 47 Tuc.
1483. Variables near NGC 7635
- ID:
- ivo://CDS.VizieR/J/other/IBVS/4441
- Title:
- Variables near NGC 7635
- Short Name:
- J/other/IBVS/444
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A group of new and known variable stars in the field of the emission nebula NGC 7635 was studied by Rosino, Bianchini, and Martino (1976A&AS...24....1R)). In the source paper, approximate positions, spectral types, and elements of variation were presented along with finder charts for the thirty-two new variables. All but one of these are now named variables. Although the positions provided are generally accurate, they are not precise. For the fainter stars especially, precise positions are required both for their recovery for further study at the telescope and for linkage within other surveys such as IRAS.
- ID:
- ivo://CDS.VizieR/J/ApJ/551/973
- Title:
- Variables near SN 1991T in NGC 4527
- Short Name:
- J/ApJ/551/973
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Repeated imaging observations have been made of NGC 4527 with the Hubble Space Telescope between 1999 April and June, over an interval of 69 days. Images were obtained on 12 epochs in the F555W band and on five epochs in the F814W band. The galaxy hosted the Type Ia supernova SN 1991T, which showed relatively unusual behaviour by having both an abnormal spectrum near light maximum, and a slower declining light curve than the prototypical Branch-normal SNe Ia. A total of 86 variables that are putative Cepheids have been found, with periods ranging from 7.4 days to over 70 days.
- ID:
- ivo://CDS.VizieR/J/AJ/153/104
- Title:
- Variables observed in the Galactic disk by AST3-1
- Short Name:
- J/AJ/153/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- AST3-1 is the second-generation wide-field optical photometric telescope dedicated to time-domain astronomy at Dome A, Antarctica. Here, we present the results of an i-band images survey from AST3-1 toward one Galactic disk field. Based on time-series photometry of 92583 stars, 560 variable stars were detected with i magnitude {<=}16.5mag during eight days of observations; 339 of these are previously unknown variables. We tentatively classify the 560 variables as 285 eclipsing binaries (EW, EB, and EA), 27 pulsating variable stars ({delta} Scuti, {gamma} Doradus, {delta} Cephei variable, and RR Lyrae stars), and 248 other types of variables (unclassified periodic, multiperiodic, and aperiodic variable stars). Of the eclipsing binaries, 34 show O'Connell effects. One of the aperiodic variables shows a plateau light curve and another variable shows a secondary maximum after peak brightness. We also detected a complex binary system with an RS CVn-like light-curve morphology; this object is being followed-up spectroscopically using the Gemini South telescope.
- ID:
- ivo://CDS.VizieR/J/A+A/463/589
- Title:
- Variables stars in NGC 362
- Short Name:
- J/A+A/463/589
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 362 is a bright southern globular cluster in the foreground of the Small Magellanic Cloud (SMC), for which no extensive variability survey has ever been done. Finding regularly pulsating RR Lyrae stars in the cluster can lead to improved metallicity and distance estimates of the system, while other types of variable objects may be used to confirm the results. Time-series CCD photometric observations have been obtained. Light curves have been derived with both profile fitting photometry and image subtraction. We developed a simple method to convert flux phase curves to magnitudes, which allows the use of empirical light curve shape vs. physical parameters calibrations. Periods and light curve parameters of the detected variable stars have been determined with Fourier analysis, phase dispersion minimization and string-length minimization. Using the RR Lyrae metallicity and luminosity calibrations, we have determined the relative iron abundances and absolute magnitudes of the stars. The color-magnitude diagram has been fitted with Yale-Yonsei isochrones to determine reddening and distance independently. For five RR Lyrae stars we obtained radial velocity measurements from optical spectra. We found 45 RR Lyr stars, of which the majority are new discoveries. While most of them are cluster members, as shown by their radial velocities and positions in the color-magnitude diagram, we also see a few stars in the galactic field and in the outskirts of the SMC. About half of the RR Lyraes exhibit light curve changes (Blazhko effect). The RR Lyrae-based metallicity of the cluster is [Fe/H]=-1.16+/-0.25, the mean absolute magnitude of the RR Lyrae stars is M_V=0.82+/-0.04mag implying a distance of 7.9+/-0.6kpc. The mean period of RRab stars is 0.585+/-0.081days. These properties place NGC 362 among the Oosterhoff type I globular clusters. The isochrone fit implies a slightly larger distance of 9.2+/-0.5kpc and an age of 11+/-1Gyr. We also found 11 eclipsing binaries, 14 pulsating stars of other types, including classical Cepheids in the SMC and 15 variable stars with no firm classification. NGC 362 hosts a large number of RR Lyrae stars, which makes the cluster a potentially important test object for studying the Blazhko effect in a chemically homogeneous environment.
- ID:
- ivo://CDS.VizieR/J/A+AS/123/115
- Title:
- Variables stars in Palomar-Groningen field 3
- Short Name:
- J/A+AS/123/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalogue is presented with variable (RR Lyrae, semiregular and Mira) stars located inside field #3 (PG3) of the Palomar-Groningen Survey at the outer edge of the Sagittarius dwarf galaxy. One of the semiregular variables is a carbon star, comparable with those found by Azzopardi et al. (1991A&AS...88..265A). Serendipity provides the suggestion, that their carbon stars might not be located inside, but behind the bulge on the Sagittarius dwarf galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJS/239/5
- Title:
- Variable stars and cand. planets from K2
- Short Name:
- J/ApJS/239/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We produce light curves for all ~34000 targets observed with K2 in Campaign 17 (C17), identifying 34 planet candidates, 184 eclipsing binaries, and 222 other periodic variables. The forward-facing direction of the C17 field means follow-up can begin immediately now that the campaign has concluded and interesting targets have been identified. The C17 field has a large overlap with C6, so this latest campaign also offers an infrequent opportunity to study a large number of targets already observed in a previous K2 campaign. The timing of the C17 data release, shortly before science operations begin with the Transiting Exoplanet Survey Satellite (TESS), also lets us exercise some of the tools and methods developed for identification and dissemination of planet candidates from TESS. We find excellent agreement between these results and those identified using only K2-based tools. Among our planet candidates are several planet candidates with sizes <4R_{Earth}_ and orbiting stars with Kp<~10 (indicating good RV targets of the sort TESS hopes to find) and a Jupiter-sized single-transit event around a star already hosting a 6 day planet candidate.
- ID:
- ivo://CDS.VizieR/J/AJ/150/107
- Title:
- Variable stars from TNTS. I. 2012-2014
- Short Name:
- J/AJ/150/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we report the detections of stellar variabilities from the first two years of observations of a sky area of about 1300 square degrees from the Tsinghua University-NAOC Transient Survey. A total of 1237 variable stars (including 299 new ones) were detected with a brightness <18.0mag and a magnitude variation >~0.1mag on a timescale from a few hours to a few hundred days. Among such detections, we tentatively identified 661 RR Lyrae stars, 431 binaries, 72 semi-regular pulsators, 29 Mira stars, 11 slow irregular variables, 11 RS Canum Venaticorum stars, 7 Gamma Doradus stars, 5 long-period variables, 3 W Virginis stars, 3 Delta Scuti stars, 2 Anomalous Cepheids, 1 Cepheid, and 1 nova-like star based on their time-series variability index J_s_ and their phased diagrams. Moreover, we found that 14 RR Lyrae stars show the Blazhko effect and 67 contact eclipsing binaries exhibit the O'Connell effect. Since the period and amplitude of light variations of RR Lyrae variables depend on their chemical compositions, their photometric observations can be used to investigate the distribution of metallicity along the direction perpendicular to the Galactic disk. We find that the metallicity of RR Lyrae stars shows large scatter at regions closer to the Galactic plane (e.g., -3.0<[Fe/H]<0) but tends to converge at [Fe/H]~-1.7 at larger Galactic latitudes. This variation may be related to the fact that the RRAB Lyrae stars in the Galactic halo come from globular clusters with different metallicities and vertical distances, i.e., OoI and OoII populations, favoring the dual-halo model.
- ID:
- ivo://CDS.VizieR/J/AJ/135/649
- Title:
- Variable stars in a Lupus field
- Short Name:
- J/AJ/135/649
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a wide-field photometric survey in a single 52'x52' field towards the Lupus Galactic Plane in an effort to detect transiting Hot Jupiter planets. The data set also led to the detection of 494 field variables, all of which are new discoveries. This paper presents an overview of the project, along with the total catalog of variables, which comprises 190 eclipsing binaries (of contact, semi-contact, and detached configurations), 51 miscellaneous pulsators of various types, 237 long-period variables (P>=2d), 11 {delta} Scuti stars, 4 field RR Lyrae (3 disk and 1 halo) and 1 irregular variable. Our survey provides a complete catalog of W UMa eclipsing binaries in the field to V=18.8, which display a Gaussian period distribution of 0.277+/-0.036d.
