- ID:
- ivo://CDS.VizieR/J/ApJS/218/20
- Title:
- Photometric variability search in the CSTAR field
- Short Name:
- J/ApJS/218/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Chinese Small Telescope Array (CSTAR) is the first telescope facility built at Dome A, Antarctica. During the 2008 observing season, the installation provided long-baseline and high-cadence photometric observations in the i-band for 18145 targets within 20deg^2^ CSTAR field around the South Celestial Pole for the purpose of monitoring the astronomical observing quality of Dome A and detecting various types of photometric variability. Using sensitive and robust detection methods, we discover 274 potential variables from this data set, 83 of which are new discoveries. We characterize most of them, providing the periods, amplitudes, and classes of variability.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/389/439
- Title:
- Photometry in field of RX J004404.8+411820
- Short Name:
- J/A+A/389/439
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We propose the first association of an optical counterpart with a luminous supersoft X-ray source in M31, RX J0044.0+4118, observed with ROSAT in July 1991. The PSPC position is at 1.644 angular distance from a candidate nova in outburst in September of 1990. This is interesting because the incidence of classical novae among supersoft X-ray sources is an open question. The proposed optical counterpart was measured at R~=17.7 in September of 1990, and it had faded to R>19.2 when it was observed again after 70 days. The light curve was too sparsely monitored for definite conclusions on the speed class of the nova. No other variable objects with V<23.5 were found in the ROSAT spatial error box. We evaluate that the probability that a classical or recurrent nova was in outburst in the ROSAT error box in the few years preceding the observation is very small, so the proposed identification is meaningful. We also show evidence that the associated supersoft X-ray source turned off in the third year after the outburst.
- ID:
- ivo://CDS.VizieR/J/PASP/105/78
- Title:
- Photometry in open cluster NGC 5822
- Short Name:
- J/PASP/105/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The study presents photoelectric photometry of stars in NGC 5822 on the UBVR and DDO systems. The BV data are employed to calibrate a photographic survey of the cluster, while UBV and DDO data are used to constrain the cluster reddening and metallicity. Taken in conjunction with previous photometric analysis, it is found that the cluster has a reddening of 0.15+/-0.015(pe) as defined for the stars at the turnoff, and a metallicity relative to the sun of -0.15+/-0.05(pe).
- ID:
- ivo://CDS.VizieR/J/AJ/152/113
- Title:
- Pleiades members with K2 light curves. I. Periods
- Short Name:
- J/AJ/152/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Young (125Myr), populous (>1000 members), and relatively nearby, the Pleiades has provided an anchor for stellar angular momentum models for both younger and older stars. We used K2 to explore the distribution of rotation periods in the Pleiades. With more than 500 new periods for Pleiades members, we are vastly expanding the number of Pleiades with periods, particularly at the low-mass end. About 92% of the members in our sample have at least one measured spot-modulated rotation period. For the ~8% of the members without periods, non-astrophysical effects often dominate (saturation, etc.), such that periodic signals might have been detectable, all other things being equal. We now have an unusually complete view of the rotation distribution in the Pleiades. The relationship between P and (V-K_s_)_0_ follows the overall trends found in other Pleiades studies. There is a slowly rotating sequence for 1.1<~(V-K_s_)_0_<~3.7 and a primarily rapidly rotating population for (V-K_s_)_0_>~5.0. There is a region in which there seems to be a disorganized relationship between P and (V-K_s_)_0_ for 3.7<~(V-K_s_)_0_<~5.0. Paper II continues the discussion, focusing on multiperiod structures, and Paper III speculates about the origin and evolution of the period distribution in the Pleiades.
- ID:
- ivo://CDS.VizieR/J/ApJ/721/369
- Title:
- PNe in the elliptical galaxy NGC 821
- Short Name:
- J/ApJ/721/369
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a slitless spectroscopy method with the 8.2m Subaru telescope and its FOCAS Cassegrain spectrograph, we have increased the number of planetary nebula (PN) detections and PN velocity measurements in the flattened elliptical galaxy NGC 821. A comparison with the detections reported previously by the Planetary Nebulae Spectrograph group indicates that we have confirmed most of their detections. The velocities measured by the two groups, using different telescopes, spectrographs, and slitless techniques, are in good agreement. We have built a combined sample of 167 PNs and have confirmed the Keplerian decline of the line-of-sight velocity dispersion reported previously. We also confirm misaligned rotation from the combined sample. A dark matter halo may exist around this galaxy, but it is not needed to keep the PN velocities below the local escape velocity as calculated from the visible mass. We have measured the m(5007) magnitudes of 145 PNs and produced a statistically complete sample of 40 PNs in NGC 821. The resulting PN luminosity function (PNLF) was used to estimate a distance modulus of 31.4mag, equivalent to 19Mpc.
- ID:
- ivo://CDS.VizieR/J/ApJ/733/69
- Title:
- Polarized DRAO sources
- Short Name:
- J/ApJ/733/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Dominion Radio Astrophysical Observatory Deep Field polarization study has been matched with the Spitzer Wide-Area Infrared Extragalactic Survey of the European Large Area Infrared Space Observatory Survey North 1 field. We have used Very Large Array observations with a total intensity rms of 87uJy/beam to match SWIRE counterparts to the radio sources. Infrared color analysis of our radio sample shows that the majority of polarized sources are elliptical galaxies with an embedded active galactic nucleus. Using available redshift catalogs, we found 429 radio sources of which 69 are polarized with redshifts in the range of 0.04<z<3.2. We find no correlation between redshift and percentage polarization for our sample. However, for polarized radio sources, we find a weak correlation between increasing percentage polarization and decreasing luminosity.
- ID:
- ivo://CDS.VizieR/J/A+A/442/381
- Title:
- Precise positions of RR Lyrae Stars with Vmax>12.5
- Short Name:
- J/A+A/442/381
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- RR Lyrae stars are of great importance for investigations of Galactic structure. However, a complete compendium of all RR-Lyraes in the solar neighbourhood with accurate classifications and coordinates does not exist to this day. Here we present a catalogue of 561 local RR-Lyrae stars (V_max_>=12.5mag) according to the magnitudes given in the Combined General Catalogue of Variable Stars (GCVS) and 16 fainter ones. The Tycho2 catalogue contains ~100 RR Lyr stars. However, many objects have inaccurate coordinates in the GCVS, the primary source of variable star information, so that a reliable cross-identification is difficult. We identified RR Lyrae from both catalogues based on an intensive literature search. In dubious cases we carried out photometry of fields to identify the variable. Mennessier & Colome (2002, Cat. <J/A+A/390/173>) have published a paper with Tyc2-GCVS identifications, but we found that many of their identifications are wrong.
- ID:
- ivo://CDS.VizieR/J/ApJS/209/32
- Title:
- Probable young stars in the MYStIX project
- Short Name:
- J/ApJS/209/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Massive Young star-forming complex Study in Infrared and X-rays (MYStIX) project requires samples of young stars that are likely members of 20 nearby Galactic massive star-forming regions. Membership is inferred from statistical classification of X-ray sources, from detection of a robust infrared excess that is best explained by circumstellar dust in a disk or infalling envelope and from published spectral types that are unlikely to be found among field stars. We present the MYStIX membership lists here, and describe in detail the statistical classification of X-ray sources via a "Naive Bayes Classifier."
- ID:
- ivo://CDS.VizieR/I/177
- Title:
- Proper motions in NGC 752
- Short Name:
- I/177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue was prepared during the study of proper motions (Platais 1991A&AS...87...69P) in and around the open cluster NGC 752 (C0154+374) which belongs to the poorly-populated open cluster class. Relative proper motions of 1777 stars have been determined from the PDS measurements of 11 Pulkovo normal astrograph plates (scale is 59.57"/mm) in a 110'-diameter circle around the cluster. The catalogue of proper motions is complete down to mpg=15.0m, the limiting value is 15.4m. The average standard error of the catalogue proper motions varies from 0.75mas/yr (milliarcseconds per year) for stars with mpg<14.0m to 1.1mas/yr for the rest. These errors refer to the highest weight group (the star is present on all or nearly all plate pairs). In order to calculate the standard error of a star belonging to the lower weight group, it is necessary to use a unit weight error of 3.7 mas/yr and the appropriate weights from Table I for the plate pairs used in the determination of the star's proper motion, as given in the Catalogue. For stars located far from the field centre as well for fainter stars, an additional factor proportional to the accuracy degradation should be applied. Table I. Assigned weights. ------------------------------------------------------------------- | Pair No.| 1 | 2 | 3 | 4 | 5 | 6 | 7 | |---------|-------|-------|-------|-------|-------|-------|-------| | Weight | 7.0 | 7.0 | 2.5 | 2.3 | 2.8 | 3.0 | 1.0 | ------------------------------------------------------------------- Example: For the star No. 40 the weighted standard error of the proper motion is as follows: 3.7/sqrt(2.3+2.8)*1.5=2.5 mas/yr. The degradation factor of 1.5 comes from the decreased accuracy for the faint stars located at the edge of the field investigated. More detailed information on measured plates, standard errors, assigned weights, membership probabilities etc. is given in Platais (1991A&AS...87...69P). The membership probabilities were calculated assuming that on the vector-point diagram the distribution of field stars is essentially flat within a limited area around the centroid of the cluster member proper motion distribution. A clear separation of field and cluster stars is achieved.
- ID:
- ivo://CDS.VizieR/J/AJ/155/183
- Title:
- Properties of variables in the NGC 1846 field
- Short Name:
- J/AJ/155/183
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Intermediate-age (IA) star clusters in the Large Magellanic Cloud (LMC) present extended main-sequence turn-offs (MSTO) that have been attributed to either multiple stellar populations or an effect of stellar rotation. Recently it has been proposed that these extended main sequences can also be produced by ill-characterized stellar variability. Here we present Gemini-S/Gemini Multi-Object Spectrometer (GMOS) time series observations of the IA cluster NGC 1846. Using differential image analysis, we identified 73 new variable stars, with 55 of those being of the Delta Scuti type, that is, pulsating variables close the MSTO for the cluster age. Considering completeness and background contamination effects, we estimate the number of {delta} Sct belonging to the cluster between 40 and 60 members, although this number is based on the detection of a single {delta} Sct within the cluster half-light radius. This amount of variable stars at the MSTO level will not produce significant broadening of the MSTO, albeit higher-resolution imaging will be needed to rule out variable stars as a major contributor to the extended MSTO phenomenon. Though modest, this amount of {delta} Sct makes NGC 1846 the star cluster with the highest number of these variables ever discovered. Lastly, our results present a cautionary tale about the adequacy of shallow variability surveys in the LMC (like OGLE) to derive properties of its {delta} Sct population.
