Near-Infrared Observations of RR Lyrae Variables in Galactic Globular Clusters. I. The Case of M92

Principe, M.; Piersimoni, A. M.; Bono, G.; Paola, Andrea; Dolci, M.; Marconi, M.

doi:10.1086/430148

Cited by 41 publications

(38 citation statements)

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“…As a whole, these distances are too short with respect to µ 0 (RR) = 14.65 mag, as derived by the relation M V (RR) = 0.89 + 0.22 [Fe/H] using the values listed in Table 6. On the other hand, comparing the K magnitudes of RR Lyrae stars from Del Principe et al (2005) with the predicted PM K relations presented by Del Principe et al (2006), we derive µ 0 (RR) = 14.63 ± 0.08 mag. Since the relations given in the present paper and those reported by Del Principe et al (2006) are based on model computations which adopt homogeneous physics and numerical procedures, we can conclude that V7 is not a BL Her star but, due to the evidence that it is brighter than expected for its period, it may be an Anomalous Cepheid.…”

Section: Comparison With Observationssupporting

confidence: 73%

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Synthetic properties of bright metal-poor variables

Criscienzo

Caputo

Marconi³

et al. 2007

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We investigate the properties of the so-called BL Her stars, i.e., Population II Cepheids with periods shorter than 8 days, using updated pulsation models and evolutionary tracks computed by adopting a metal abundance in the range of Z = 0.0001 to Z = 0.004. We derive the predicted period-magnitude (PM) and period-Wesenheit (PW) relations at the various photometric bands and we show that the slopes of these relations are in good agreement with the slopes determined by observed variables in Galactic globular clusters, independently of the adopted M V (RR)−[Fe/H] relation to get the cluster RR Lyrae-based distance. Moreover, we show that the distances provided by the predicted PM and PW relations for BL Her stars agree within the errors with the RR Lyrae-based values. Using the predicted relations with W Vir stars, which are Population II Cepheids with periods longer than 8 days, provides no clear evidence for or against a change in the PM and PW slopes around P ∼ 10 days.

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Section: Comparison With Observationssupporting

confidence: 73%

“…Here, we add that this holds also for the PW relations based on VJHK s magnitudes (lower panels). The arrow in this figure refers to NGC 6341 V7 (Del Principe et al 2005) which will be discussed separately. Turning to the Pr03 optical magnitudes, some comments should be made to the data plotted in Fig.…”

Section: Comparison With Observationsmentioning

confidence: 99%

Synthetic properties of bright metal-poor variables

Criscienzo

Caputo

Marconi³

et al. 2007

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“…RR Lyr stars are old and low-mass stars (≈0.7 M ; Smith 2004) that are in the horizontal branch (HB) stage (helium-burning phase) and have a very tight period-luminosity (P − L) relation in the near-IR bands (Longmore et al 1990;Catelan et al 2004). This relation is a powerful tool that has previously provided distances to Galactic globular clusters (Longmore et al 1990;Del Principe et al 2005Sollima et al 2006;Coppola et al 2011), extragalactic globular clusters, dSph galaxies (Dall'Ora et al 2004;Pietrzyński et al 2008;Borissova et al 2009), and the Galactic center (Carney et al 1995;Groenewegen et al 2008;Dékány et al 2013). Dékány et al (2013) searched for near-IR counterparts of the RR Lyr stars that were found by the OGLE III survey (Soszyński et al 2011) in the Galactic bulge in an area limited by 2…”

Section: Introductionmentioning

confidence: 99%

Bulge RR Lyrae stars in the VVV tile b201

Gran

Minniti

Saito

et al. 2015

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Context. The VISTA Variables in the Vía Láctea (VVV) Survey is one of the six ESO public surveys currently ongoing at the VISTA telescope on Cerro Paranal, Chile. VVV uses near-IR (ZY JHK s ) filters that at present provide photometry to a depth of K s ∼ 17.0 mag in up to 36 epochs spanning over four years, and aim at discovering more than 10 6 variable sources as well as trace the structure of the Galactic bulge and part of the southern disk. Aims. A variability search was performed to find RR Lyrae variable stars. The low stellar density of the VVV tile b201, which is centered at ( , b) ∼ (−9• , −9 • ), makes it suitable to search for variable stars. Previous studies have identified some RR Lyrae stars using optical bands that served to test our search procedure. The main goal is to measure the reddening, interstellar extinction, and distances of the RR Lyrae stars and to study their distribution on the Milky Way bulge. Methods. For each star in the tile with more than 25 epochs (∼90% of the objects down to K s ∼ 17.0 mag), the standard deviation and χ 2 test were calculated to identify variable candidates. Periods were determined using the analysis of variance. Objects with periods in the RR Lyrae range of 0.2 ≤ P ≤ 1.2 days were selected as candidate RR Lyrae. They were individually examined to exclude false positives. Results. A total of 1.5 sq deg were analyzed, and we found 39 RR Lyr stars, 27 of which belong to the ab-type and 12 to the c-type. Our analysis recovers all the previously identified RR Lyrae variables in the field and discovers 29 new RR Lyr stars. The reddening and extinction toward all the RRab stars in this tile were derived, and distance estimations were obtained through the period-luminosity relation. Despite the limited amount of RR Lyrae stars studied, our results are consistent with a spheroidal or central distribution around ∼8.1 and ∼8.5 kpc. for either the Cardelli or Nishiyama extinction law. Our analysis does not reveal a stream-like structure. Nevertheless, a larger area must be analyzed to definitively rule out streams.

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“…of the physical assumptions adopted to construct both evolutionary and pulsation models of low-mass stars (Del Principe et al 2005). In recent years, their atmosphere has been considered as a laboratory of hypersonic shock wave simulation (Chadid et al 2008).…”

Section: Introductionmentioning

confidence: 99%

First CoRoT light curves of RR Lyrae stars

Chadid¹,

Benkő

Szabo

et al. 2010

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Context. The CoRoT -Convection Rotation and planetary Transits -space mission is a great opportunity for monitoring stars with excellent time-sampling and unprecedented photometric precision for up to 150 days. As an important benefit, high-quality RR Lyrae light curves are obtained with a quasi-uninterrupted coverage over several pulsation and Blazhko cycles. Aims. The Blazhko effect in RR Lyrae stars is an unsolved problem of astrophysics. We used the high-precision space data to contribute more precise knowledge to explain the possible physical processes behind the phenomenon. Methods. We applied different period-finding techniques including Period04, MuFrAn, PDM and SigSpec. Amplitude and phase modulation were investigated by an analytical function method as well as with the traditional O-C diagrams. Results. The Blazhko modulation frequency is directly detected in the spectrum, as well as its first and second harmonics. It shows the non-linear nature of the Blazhko modulation. Besides the triplets, further higher-order modulation side peaks appear around the pulsation frequency as quintuplet, septuplet, nonuplet, undecaplet, tredecaplet, quindecaplet and sepdecaplet structures. Additional frequencies, not belonging to the classical multiplet structures, are detected, as well as their linear combinations with the fundamental radial mode. We interpret these additional terms as non-radial modes. During the five consecutive Blazhko cycles, there is a shift of the maximum phase around 0.011 pulsation phase which is likely the consequence of a long term modulation.

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Near-Infrared Observations of RR Lyrae Variables in Galactic Globular Clusters. I. The Case of M92

Cited by 41 publications

References 77 publications

Synthetic properties of bright metal-poor variables

Synthetic properties of bright metal-poor variables

Bulge RR Lyrae stars in the VVV tile b201

First CoRoT light curves of RR Lyrae stars

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