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1161. RR Lyrae in 15 Galactic globular clusters
ID:
ivo://CDS.VizieR/J/MNRAS/439/3765
Title:
RR Lyrae in 15 Galactic globular clusters
Short Name:
J/MNRAS/439/3765
Date:
21 Oct 2021
Publisher:
CDS
Description:
The period-metallicity-WISE W1- and W2-band luminosity relations are derived for RR Lyrae stars based on WISE epoch photometry for 360 and 275 stars in 15 and 9 Galactic globular clusters, respectively. Our final relations have the form <M_W1_>={gamma}_W1-(2.381+/-0.097)logP_F_+(0.096+/-0.021)[Fe/H] and <M_W2_>={gamma}_W2_-(2.269+/-0.127)logP_F_+(0.108+/-0.021)[Fe/H], where [Fe/H] values are on the scale of Carretta et al. (2009A&A...508..695C). We obtained two appreciably discrepant estimates for the zero-points {gamma}_W1_ and {gamma}_W2_ of both relations: one based on a statistical-parallax analysis - {gamma}_W1_=-0.829+/-0.093 and {gamma}_W2_=-0.776+/-0.093 and another, significantly brighter one, based on Hubble Space Telescope (HST) Fine Guidance Sensor (FGS) trigonometric parallaxes - {gamma}_W1,HST_=-1.150+/-0.077 and {gamma}_W2,HST_=-1.105+/-0.077. The period-metallicity-luminosity relations in the two bands yield highly consistent distance moduli for the calibrator clusters and the distance moduli computed using the W1- and W2-band relations with the HST zero-points agree well with those computed by Sollima, Cacciari & Valenti based on their derived period-metallicity-K-band luminosity relation whose zero-point is tied to the HST trigonometric parallax of RR Lyrae itself ({Delta}DM0 =0.04 and 0.06, respectively, with a scatter of only 0.06).
1162. RR Lyrae in M32
ID:
ivo://CDS.VizieR/J/MNRAS/425/1459
Title:
RR Lyrae in M32
Short Name:
J/MNRAS/425/1459
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present time series photometry of two fields near M32 using archival observations from the Advanced Camera for Surveys Wide Field Channel on-board the Hubble Space Telescope. One field is centred about 2arcmin from M32, while the other is located 15arcmin to the south-east of M31. The imaging covers a time baseline sufficient for the identification and characterization of a total number of 1139 RR Lyrae variables of which 821 are ab-type and 318 are c-type.
1163. RR Lyrae in M62 (NGC6266)
ID:
ivo://CDS.VizieR/J/AJ/140/1766
Title:
RR Lyrae in M62 (NGC6266)
Short Name:
J/AJ/140/1766
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new time-series CCD photometry, in the B and V bands, for the moderately metal-rich ([Fe/H]=~-1.3) Galactic globular cluster M62 (NGC 6266). The present data set is the largest obtained so far for this cluster and consists of 168 images per filter, obtained with the Warsaw 1.3m telescope at the Las Campanas Observatory and the 1.3m telescope of the Cerro Tololo Inter-American Observatory, in two separate runs over the time span of 3 months.
1164. RR Lyrae in new galactic bulge window
ID:
ivo://CDS.VizieR/J/AJ/114/2596
Title:
RR Lyrae in new galactic bulge window
Short Name:
J/AJ/114/2596
Date:
21 Oct 2021
Publisher:
CDS
Description:
Identifications, light curves, periods, and other pertinent data are presented for RR Lyrae variables found in a galactic bulge region not previously surveyed for these stars. The region (centered at l=0.2, b=-5.8) includes the globular cluster NGC 6558 where probable RR Lyrae members are discussed.
1165. RR Lyrae in NGC 6101
ID:
ivo://CDS.VizieR/J/other/PASA/29.72
Title:
RR Lyrae in NGC 6101
Short Name:
J/other/PASA/29.
Date:
21 Oct 2021
Publisher:
CDS
Description:
V- and I-band observations were taken over 9 months to study the RR Lyrae population in the metal-poor diffuse globular cluster NGC 6101. We identify one new variable, which is either a potential long-period red giant variable or eclipsing binary, and recover all previously identified RR Lyraes. One previously studied RR Lyrae is reclassified as an RRc type, while two period estimations have been significantly refined. We confirm that NGC 6101 is Oosterhoff type II with a high ratio of n(c)/n(ab+c)=0.833 with a very long mean RRab period of 0.86d. By using theoretical RR Lyrae period-luminosity-metallicity relations, we use our V- and I-band RR Lyrae data to gain an independent estimate of the reddening towards this cluster of E(B-V)=0.15+/-.04 and derive a distance of 12.8+/-0.8kpc. The majority of the work in this study was undertaken by upper secondary school students involved in the Space to Grow astronomy education project in Australia.
1166. RR Lyrae in NGC 6171
ID:
ivo://CDS.VizieR/J/AJ/113/1711
Title:
RR Lyrae in NGC 6171
Short Name:
J/AJ/113/1711
Date:
21 Oct 2021
Publisher:
CDS
Description:
CCD observations have been used to derive precise light curves and Fourier parameters for sixteen RR Lyrae variables in the Oosterhoff type I globular cluster NGC 6171. It is found that, for the RRab stars, the Fourier phase differences {phi}_21_, {phi}_31_ and {phi}_41_ all correlate with period, but the amplitude ratios R_21_, R_31_, and R_41_ do not. For the RRc stars, R_21_, {phi}_31_, and {phi}_41_ correlate with period, but {phi}_21_, R_31_, and R_41_ do not. It is also found that a plot of R_21_ against {phi}_21_ is a useful tool for distinguishing between RRc and RRab stars, regardless of color or chemical composition. 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, temperature and a helium parameter for the RRc stars. A comparison with the parameters determined from CCD observations of RRc stars in six other galactic globular clusters indicates that mean masses and mean luminosities increase and mean temperatures and helium abundances decrease with decreasing cluster metal abundance. The formulae of Jurcsik & Kovacs (1996, Cat. <J/A+A/312/111>) for relating Fourier parameters of RRab stars to [Fe/H] and luminosity have been tested and the results are reasonable. (c) 1997 American Astronomical Society.
1167. RR Lyrae in Northern Sky Variability Survey
ID:
ivo://CDS.VizieR/J/AJ/132/1202
Title:
RR Lyrae in Northern Sky Variability Survey
Short Name:
J/AJ/132/1202
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use data from the Northern Sky Variability Survey (NSVS), obtained from the first-generation Robotic Optical Transient Search Experiment (ROTSE-I), to identify and study RR Lyrae variable stars in the solar neighborhood. We initially identified 1197 RRab (RR0) candidate stars brighter than the ROTSE median magnitude V=14. Periods, amplitudes, and mean V magnitudes are determined for a subset of 1188 RRab stars with well-defined light curves. Metallicities are determined for 589 stars by the Fourier parameter method and by the relationship between period, amplitude, and [Fe/H]. We comment on the difficulties of clearly classifying RRc (RR1) variables in the NSVS data set. Distances to the RRab stars are calculated using an adopted luminosity-metallicity relation with corrections for interstellar extinction. The 589 RRab stars in our final sample are used to study the properties of the RRab population within 5kpc of the Sun. The Bailey diagram of period versus amplitude shows that the largest component of this sample belongs to Oosterhoff type I. Metal-rich ([Fe/H]>-1) RRab stars appear to be associated with the Galactic disk. Our metal-rich RRab sample may include a thin-disk, as well as a thick-disk population, although the uncertainties are too large to establish this. There is some evidence among the metal-rich RRab stars for a decline in scale height with increasing [Fe/H], as was found by Layden. The distribution of RRab stars with -1<[Fe/H]<-1.25 indicates that within this metallicity range the RRab stars are a mixture of stars belonging to halo and disk populations.
1168. RR Lyrae in omega Cen
ID:
ivo://CDS.VizieR/J/A+A/574/A15
Title:
RR Lyrae in omega Cen
Short Name:
J/A+A/574/A15
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a survey of RR Lyrae stars in an area of 50deg^2^ around the globular cluster {omega} Centauri, aimed at detecting debris material from the alleged progenitor galaxy of the cluster. We detected 48 RR Lyrae stars, only 11 of which have been previously reported. Ten of the eleven previously known stars were found inside the tidal radius of the cluster. The rest were located outside the tidal radius up to distances of ~6-degrees from the center of the cluster. Several of these stars are located at distances similar to that of {omega} Centauri. We investigate the probability that they may have been stripped off the cluster. To do this, we studied their properties (mean periods) by calculating the expected halo and thick-disk population of RR Lyrae stars in this part of the sky, analyzing the radial velocity of a sub-sample of the RR Lyrae stars, and finally, studying the probable orbits of this sub-sample around the Galaxy. The results of these investigations do not support the scenario that there is significant tidal debris around {omega} Centauri, which confirms previous studies on the region. It is puzzling that tidal debris has been found elsewhere but not near the cluster itself.
1169. RR Lyrae in SDSS Stripe 82
ID:
ivo://CDS.VizieR/J/MNRAS/424/2528
Title:
RR Lyrae in SDSS Stripe 82
Short Name:
J/MNRAS/424/2528
Date:
21 Oct 2021
Publisher:
CDS
Description:
We propose a robust principal component analysis framework for the exploitation of multiband photometric measurements in large surveys. Period search results are improved using the time-series of the first principal component due to its optimized signal-to-noise ratio. The presence of correlated excess variations in the multivariate time-series enables the detection of weaker variability. Furthermore, the direction of the largest variance differs for certain types of variable stars. This can be used as an efficient attribute for classification. The application of the method to a subsample of Sloan Digital Sky Survey Stripe 82 data yielded 132 high-amplitude delta Scuti variables. We also found 129 new RR Lyrae variables, complementary to the catalogue of Sesar et al., extending the halo area mapped by Stripe 82 RR Lyrae stars towards the Galactic bulge. The sample also comprises 25 multiperiodic or Blazhko RR Lyrae stars.
1170. RR Lyrae members of the Pal 5 stellar stream
ID:
ivo://CDS.VizieR/J/AJ/158/223
Title:
RR Lyrae members of the Pal 5 stellar stream
Short Name:
J/AJ/158/223
Date:
21 Oct 2021
Publisher:
CDS
Description:
Thin stellar streams, formed from the tidal disruption of globular clusters, are important gravitational tools, sensitive to both global and small-scale properties of dark matter. The Palomar 5 stellar stream (Pal 5) is an exemplar stream within the Milky Way: its ~20{deg} tidal tails connect back to the progenitor cluster, and the stream has been used to study the shape, total mass, and substructure fraction of the dark matter distribution of the Galaxy. However, most details of the phase-space distribution of the stream are not fully explained, and dynamical models that use the stream for other inferences are therefore incomplete. Here we aim to measure distance and kinematic properties along the Pal 5 stream in order to motivate improved models of the system. We use a large catalog of RR Lyrae-type stars (RRLs) with astrometric data from the Gaia mission to probabilistically identify RRLs in the Pal 5 stream. RRLs are useful because they are intrinsically luminous standard candles and their distances can be inferred with small relative precision (~3%). By building a probabilistic model of the Pal 5 cluster and stream in proper motion and distance, we find 27 RRLs consistent with being members of the cluster (10) and stream (17). Using these RRLs, we detect gradients in distance and proper motion along the stream, and provide an updated measurement of the distance to the Pal 5 cluster using the RRLs, d=20.6+/-0.2 kpc. We provide a catalog of Pal 5 RRLs with inferred membership probabilities for future modeling work.