- ID:
- ivo://CDS.VizieR/J/MNRAS/345/747
- Title:
- RR Lyrae in 4 Fornax globular clusters
- Short Name:
- J/MNRAS/345/747
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have surveyed four of the globular clusters in the Fornax dwarf galaxy (clusters 1, 2, 3 and 5) for RR Lyrae stars, using archival F555W and F814W Hubble Space Telescope observations. We identify 197 new RR Lyrae stars in these four clusters, and 13 additional candidate horizontal-branch variable stars. Although somewhat restricted by our short observational baseline, we derive periods and light curves for all of the stars in the sample, and calculate photometric parameters such as mean magnitudes and colours. This is the first time that RR Lyrae stars in the Fornax globular clusters have been quantitatively identified and measured.
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Search Results
- 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).
- 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.
764. 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.
765. 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.
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/AJ/155/171
- Title:
- RR Lyrae stars in and around NGC 6441
- Short Name:
- J/AJ/155/171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Detailed elemental abundance patterns of metal-poor ([Fe/H]~-1 dex) stars in the Galactic bulge indicate that a number of them are consistent with globular cluster (GC) stars and may be former members of dissolved GCs. This would indicate that a few per cent of the Galactic bulge was built up from destruction and/or evaporation of GCs. Here, an attempt is made to identify such presumptive stripped stars originating from the massive, inner Galaxy GC NGC 6441 using its rich RR Lyrae variable star (RRL) population. We present radial velocities of 40 RRLs centered on the GC NGC 6441. All 13 of the RRLs observed within the cluster tidal radius have velocities consistent with cluster membership, with an average radial velocity of 24+/-5 km/s and a star-to-star scatter of 11 km/s. This includes two new RRLs that were previously not associated with the cluster. Eight RRLs with radial velocities consistent with cluster membership but up to three time the distance from the tidal radius are also reported. These potential extra-tidal RRLs also have exceptionally long periods, which is a curious characteristic of the NGC 6441 RRL population that hosts RRLs with periods longer than seen anywhere else in the Milky Way. As expected of stripped cluster stars, most are inline with the cluster's orbit. Therefore, either the tidal radius of NGC 6441 is underestimated and/or we are seeing dissolving cluster stars stemming from NGC 6441 that are building up the old spheroidal bulge.
- ID:
- ivo://CDS.VizieR/J/ApJ/808/11
- Title:
- RR Lyrae stars in M4. II. Spitzer/IRAC phot.
- Short Name:
- J/ApJ/808/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New mid-infrared (MIR) period-luminosity (PL) relations are presented for RR Lyrae variables in the globular cluster M4 (NGC 6121). Accurate photometry was obtained for 37 RR Lyrae variables using observations from the Infrared Array Camera on board the Spitzer Space Telescope. The dispersion of M4's PL relations is 0.056, and the uncertainty in the slope is 0.11mag. Additionally, we established calibrated PL relations at 3.6 and 4.5{mu}m using published Hubble Space Telescope geometric parallaxes of five Galactic RR Lyrae stars. The resulting band-averaged distance modulus for M4 is {mu}=11.399+/-0.007(stat)+/-0.080(syst)+/-0.015(cal)+/-0.020(ext). The systematic uncertainty will be greatly reduced when parallaxes of more stars become available from the GAIA mission. Optical and infrared period-color (PC) relations are also presented, and the lack of an MIR PC relation suggests that RR Lyrae stars are not affected by CO absorption in the 4.5{mu}m band.
- ID:
- ivo://CDS.VizieR/J/AJ/109/618
- Title:
- RR Lyrae Stars in NGC 5053
- Short Name:
- J/AJ/109/618
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The RR Lyrae stars in NGC 5053 are investigated using B,V photometry derived from CCD frames taken on 15 nights between 1985 and 1994. Estimates of fundamental photometric parameters are presented for the ten stars, including mean B and V magnitudes, pulsation periods, pulsation amplitudes, <B>-<V> colors, and period change rates. Until now the mean B,V magnitudes were unknown because the previous photographic photometry by Baade [Mitteilungen der Hamburger, Sternwarte, B6, n.29 (1928)], Sawyer [Pub. DDO 1, No. 18, p. 357 (1946)], Rosino [MSAIt, 20, 3 (1949)], and Mannino [Pub. Obs. Bologna, 8, No. 12 (1963)] is not on the Johnson system and is not readily transformed to that system.
