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4251. RR Lyrae variables in M33. II.
ID:
ivo://CDS.VizieR/J/ApJ/724/799
Title:
RR Lyrae variables in M33. II.
Short Name:
J/ApJ/724/799
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of an extensive survey of RR Lyrae (RRL) stars in three fields along the major axis of the Triangulum Galaxy (M33). From images taken with the Advanced Camera for Surveys (ACS) Wide Field Channel on board the Hubble Space Telescope through two passbands (F606W and F814W), we have identified and characterized a total of 119 RRL variables (96 RRab (RR0) and 23 RRc (RR1)) in M33. Using the properties of 83 RRL stars (65 RRab and 18 RRc) in the innermost ACS field (hereafter DISK2), we find mean periods of <P_ab_>=0.553+/-0.008(error1)+/-0.05(error2) and <P_c_>=0.325+/-0.008(error1)+/-0.05(error2), where the "error1" value represents the standard error of the mean and the "error2" value is based on the error of an individual RRL period calculated from our synthetic light curve simulations. The VI minimum-light colors of the RRab stars are used to calculate a mean line-of-sight reddening toward the DISK2 field of <E(V-I)>=0.175.
4252. RR Lyrae variables in NGC 5272
ID:
ivo://CDS.VizieR/J/AJ/129/267
Title:
RR Lyrae variables in NGC 5272
Short Name:
J/AJ/129/267
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have performed a detailed study of the pulsational and evolutionary characteristics of 133 RR Lyrae stars in the globular cluster NGC 5272 (M3) using highly accurate BVI data taken on five separate epochs.
4253. RR Lyrae variables in the central region of M54
ID:
ivo://CDS.VizieR/J/AJ/140/1500
Title:
RR Lyrae variables in the central region of M54
Short Name:
J/AJ/140/1500
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have analyzed archival Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) observations of the central region of the globular cluster M54. The 12 irregularly timed observations (6 F555W, 6 F814W) were reduced using the HSTphot stellar photometry package. Our statistical analysis of the HSTphot photometry yielded 50 variable stars that are likely RR Lyrae candidates. These candidates were missed by previous ground-based searches for RR Lyraes due to the extreme crowding in the core of M54. We performed two checks on our sample of RR Lyrae candidates to determine how different they were from the other variable candidates.
4254. RR Lyrae variables in the Crater II dwarf galaxy
ID:
ivo://CDS.VizieR/J/ApJ/861/23
Title:
RR Lyrae variables in the Crater II dwarf galaxy
Short Name:
J/ApJ/861/23
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the detection of RR Lyrae variable stars in Crater II, a recently discovered large and diffuse satellite dwarf galaxy of the Milky Way (MW). Based on B, V time-series photometry obtained with the Korea Microlensing Telescope Network 1.6m telescope at Cerro Tololo Inter-American Observatory, we identified 83 ab-type and 13 c-type pulsators by fitting template light curves. The detected RR Lyrae stars are centrally concentrated, which ensures that most of them are members of Crater II. In terms of the distribution of RRab stars in the period-amplitude diagram, Crater II is clearly different from ultra-faint dwarf (UFD) galaxies, but very similar to the two classical MW dwarf spheroidal (dSph) galaxies Draco and Carina with Oosterhoff-intermediate (Oo-int) properties. Combined with the mean period of ab-type variables (<P_ab_>=0.631+/-0.004days) and the c-type fraction (~0.14) in Crater II, this suggests an Oo-int classification for Crater II and implies that its nature is more like a dSph rather than a UFD. We also estimated the mean metallicity, reddening, and distance of Crater II, from the photometric and pulsation properties of the RR Lyrae stars. The stellar population model we have constructed indicates that Crater II is dominated by an old population, but is relatively younger than the oldest globular clusters in the MW. With a lack of high-amplitude short-period RRab stars, Crater II, like most of the other less massive dSphs, is probably not a surviving counterpart of the major building blocks of the MW halo.
4255. RR Lyrae variables NIR light-curve templates
ID:
ivo://CDS.VizieR/J/A+A/625/A1
Title:
RR Lyrae variables NIR light-curve templates
Short Name:
J/A+A/625/A1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We provide homogeneous optical (UBVRI) and near-infrared (NIR, JHK) time series photometry for 254 cluster (omega Cen, M4) and field RR Lyrae (RRL) variables. We ended up with more than 551000 measurements. For 94 fundamental (RRab) and 51 first overtones (RRc) we provide a complete optical/NIR characterization (mean magnitudes, luminosity amplitudes, epoch of the anchor point). The NIR light curves of these variables were adopted to provide new light-curve templates for both RRc and RRab variables. The templates for the J and the H bands are newly introduced, together with the use of the pulsation period to discriminate among the different RRab templates. To overcome uncertainties in the fit of secondary features of the light curves we provide two independent sets of analytical functions (Fourier and periodic Gaussian series).
4256. RR Lyrae V light curves
ID:
ivo://CDS.VizieR/J/AJ/115/193
Title:
RR Lyrae V light curves
Short Name:
J/AJ/115/193
Date:
21 Oct 2021
Publisher:
CDS
Description:
I present V-band CCD photometry for a sample of 103 RR Lyrae variables selected from the General Catalogue of Variable Stars to lie in the inner halo of the Galaxy. I also describe a method for obtaining the mean apparent magnitude and the epoch at maximum light of an RR Lyrae star. The method requires as few as five photometric observations, and simulations demonstrate that the associated errors are relatively small. I employ this method to derive the mean magnitudes and maximum light epochs of the 103 RR Lyrae stars observed. These stars were selected, based on their Galactic coordinates and original photographic photometry, to lie near their orbital tangent points, thus providing a sample well suited for measuring the rotational kinematics of the inner halo. Using interstellar reddenings from the literature and the observed mean V magnitudes, I derive distances for these stars and show that their actual locations in the Galaxy are indeed suitable for use in a kinematic study, despite the large zero-point errors in the survey photographic photometry.
4257. RR Lyr light curves in NGC 3201
ID:
ivo://CDS.VizieR/J/other/RMxAA/50.307
Title:
RR Lyr light curves in NGC 3201
Short Name:
J/other/RMxAA/50
Date:
21 Oct 2021
Publisher:
CDS
Description:
CCD time-series observations of the central region of the globular cluster NGC 3201 were obtained with the aim of performing the Fourier decomposition of the light curves of the RR Lyrae stars present in that field. This procedure gave the mean values, for the metallicity, of [Fe/H]_ZW_=-1.483+/-0.006 (statistical) +/-0.090 (systematical), and for the distance, 5.000+/-0.001kpc (statistical) +/-0.220 (systematical). The values found from two RRc stars are consistent with those derived previously. The differential reddening of the cluster was investigated and individual reddenings for the RR Lyrae stars were estimated from their V-I curves. We found an average value of E(B-V)=0.23+/-0.02. An investigation of the light curves of stars in the blue stragglers region led to the discovery of three new SX Phe stars. The period-luminosity relation of the SX Phe stars was used for an independent determination of the distance to the cluster and of the individual reddenings. We found a distance of 5.0kpc
4258. RRLyr stars in the Catalina Sky Survey (CS2)
ID:
ivo://CDS.VizieR/J/MNRAS/441/1230
Title:
RRLyr stars in the Catalina Sky Survey (CS2)
Short Name:
J/MNRAS/441/1230
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalog of RR Lyrae stars distributed across ~14000deg^2^ of the sky from the combined data of the Sloan Digital Sky Survey (SDSS, http://www.sdss.org), the Panoramic Survey Telescope and Rapid Response System 1 (PS1, Kaiser et al., 2002, SPIE, 4836, 154), and the second photometric catalogue from the Catalina Survey (CS2, http://nesssi.cacr.caltech.edu/DataRelease), out of these, ~2021 RRL stars (~572 RRab and 1449 RRc) are new discoveries. The RRL stars have heliocentric distances in the 4-28kpc distance range. Our catalog has a completeness level of ~50 per cent for both RRab and RRc stars, and an efficiency of ~99 and ~87 per cent for RRab and RRc stars, respectively. We provide the positions, CSDR2 mean magnitudes, CSDR2 amplitudes, subtypes, periods, ephemeris, and the heliocentric distances of our RRab and RRc stars.
4259. RR Lyr variable stars in M32
ID:
ivo://CDS.VizieR/J/A+A/539/A138
Title:
RR Lyr variable stars in M32
Short Name:
J/A+A/539/A138
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using archival multi-epoch ACS/WFC images in the F606W and F814W filters of a resolved stellar field in Local Group dwarf elliptical galaxy M 32 we have made an accurate Colour-Magnitude Diagram and a careful search for RR Lyr variable stars. We identified 416 bona fide RR Lyr stars over our field of view, and their spatial distribution shows a rising number density towards the centre of M 32. These new observations clearly confirm the tentative result of Fiorentino et al. (2010ApJ...708..817F), on a much smaller field of view, associating an ancient population of RR Lyr variables to M 32. We associate at least 83 RR Lyr stars in our field to M 32.
4260. RSG and foreground candidates in M31
ID:
ivo://CDS.VizieR/J/ApJ/826/224
Title:
RSG and foreground candidates in M31
Short Name:
J/ApJ/826/224
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the red supergiant (RSG) population of M31, obtaining the radial velocities of 255 stars. These data substantiate membership of our photometrically selected sample, demonstrating that Galactic foreground stars and extragalactic RSGs can be distinguished on the basis of B-V, V-R two-color diagrams. In addition, we use these spectra to measure effective temperatures and assign spectral types, deriving physical properties for 192 RSGs. Comparison with the solar metallicity Geneva evolutionary tracks indicates astonishingly good agreement. The most luminous RSGs in M31 are likely evolved from 25-30 M_{sun}_ stars, while the vast majority evolved from stars with initial masses of 20 M_{sun}_ or less. There is an interesting bifurcation in the distribution of RSGs with effective temperatures that increases with higher luminosities, with one sequence consisting of early K-type supergiants, and with the other consisting of M-type supergiants that become later (cooler) with increasing luminosities. This separation is only partially reflected in the evolutionary tracks, although that might be due to the mis-match in metallicities between the solar Geneva models and the higher-than-solar metallicity of M31. As the luminosities increase the median spectral type also increases; i.e., the higher mass RSGs spend more time at cooler temperatures than do those of lower luminosities, a result which is new to this study. Finally we discuss what would be needed observationally to successfully build a luminosity function that could be used to constrain the mass-loss rates of RSGs as our Geneva colleagues have suggested.