Photographic photometry of RR Lyrae variables in the globular cluster M15

Bingham, E.A.; Cacciari, C.; Dickens, R. J.; Pecci, F. Fusi

doi:10.1093/mnras/209.4.765

Cited by 57 publications

(63 citation statements)

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“…Perhaps not surprisingly, we do find most of these RRc variables located close to the transition line between RRc and RRab variables-see, for example, Figure 13 in Walker (1994). In the case of M15, the lack of a CCD study of its variables based on state-of-the-art photometric data obtained under good seeing conditions limits our current possibilities; however, interesting indications are already provided by the Bingham et al (1984) photographic study, as well as by the V, R data obtained by Silbermann & Smith (1995). In the CMD showing the detailed topology of the IS from Bingham et al (1984;see their Fig.…”

Section: Breakdown Of the Canonical Framework?mentioning

confidence: 70%

“…In the case of M15, the lack of a CCD study of its variables based on state-of-the-art photometric data obtained under good seeing conditions limits our current possibilities; however, interesting indications are already provided by the Bingham et al (1984) photographic study, as well as by the V, R data obtained by Silbermann & Smith (1995). In the CMD showing the detailed topology of the IS from Bingham et al (1984;see their Fig. 14), one again encounters a clear pileup of the RRc variables close to the c-ab transition line.…”

Section: Breakdown Of the Canonical Framework?mentioning

confidence: 99%

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The Evolutionary Status of M3 RR Lyrae Variable Stars: Breakdown of the Canonical Framework?

Catelan

2004

ApJ

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In order to test the prevailing paradigm of horizontal-branch (HB) stellar evolution, we use the large databases of measured RR Lyrae parameters for the globular cluster M3 (NGC 5272) recently provided by Bakos et al. and Corwin & Carney. We compare the observed distribution of fundamentalized periods against the predictions of synthetic HBs. The observed distribution shows a sharp peak at P f % 0:55 days, which is primarily due to the RRab variables, whereas the model predictions instead indicate that the distribution should be more uniform in P f , with a buildup of variables with shorter periods (P f < 0:5 days). Detailed statistical tests show, for the first time, that the observed and predicted distributions are incompatible with one another at a high significance level. This indicates either that canonical HB models are inappropriate, or that M3 is a pathological case that cannot be considered representative of the Oosterhoff type I (OoI) class. In this sense, we show that the OoI cluster with the next largest number of RR Lyrae variables, M5 (NGC 5904), presents a similar, although less dramatic, challenge to the models. We show that the sharp peak in the M3 period distribution receives a significant contribution from the Blazhko variables in the cluster. We also show that M15 (NGC 7078) and M68 (NGC 4590) show similar peaks in their P f distributions, which in spite of being located at a P f value similar to that of M3, can, however, be primarily ascribed to the RRc variables. Again similar to M3, a demise of RRc variables toward the blue edge of the instability strip is also identified in these two globulars. This is again in sharp contrast to the evolutionary scenario, which also foresees a strong buildup of RRc variables with short periods in OoII globulars. We speculate that in OoI systems RRab variables may somehow get ''trapped'' close to the transition line between RRab and RRc pulsators as they evolve to the blue in the H-R diagram, whereas in OoII systems it is the RRc variables that may get similarly trapped instead, as they evolve to the red, before changing their pulsation mode to RRab. Such a scenario is supported by the available CMDs and Bailey diagrams for M3, M15, and M68.

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Section: Breakdown Of the Canonical Framework?mentioning

confidence: 70%

Section: Breakdown Of the Canonical Framework?mentioning

confidence: 99%

The Evolutionary Status of M3 RR Lyrae Variable Stars: Breakdown of the Canonical Framework?

Catelan

2004

ApJ

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“…For example, by adopting a mass range of M ¼ 0:65 0:80M , the expected dispersion in the reduced period, at constant A V , is D log P 0 F $ 0:09. Figure 7 shows the A V versus log P 0 F diagram for the Carina RRab stars, together with similar diagrams for variables in M3 (hV i m ¼ 15:62 mag; Corwin & Carney 2001) and M15 (hV i m ¼ 15:82 mag; Bingham et al 1984). We selected these two clusters because they host sizable samples of RR Lyrae stars (207 in M3, 88 in M15) for which accurate pulsation parameters are available, and they are the typical OoI (M3) and OoII (M15) Galactic prototypes.…”

Section: Identification Of Variablesmentioning

confidence: 84%

The Carina Project. I. Bright Variable Stars

et al. 2003

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We present new BV time series data of the Carina dwarf spheroidal galaxy (dSph). Current data cover an area of %0.3 deg 2 around the center of the galaxy and allow us to identify 92 variables. Among them 75 are RR Lyrae stars, 15 are bona fide anomalous Cepheids, one might be a Galactic field RR Lyrae star, and one is located along the Carina red giant branch. Expanding upon the seminal photographic investigation by Saha, Monet, & Seitzer we supply, for the first time, accurate estimates of their pulsation parameters (periods, amplitudes, mean magnitudes, and colors) on the basis of CCD photometry. Approximately 50% of both RR Lyrae stars and anomalous Cepheids are new identifications. Among the RR Lyrae sample, six objects are new candidate double-mode (RRd ) variables. On the basis of their pulsation properties we estimate that two variables (V158, V182) are about 50% more massive than typical RR Lyrae stars, while the bulk of the anomalous Cepheids are roughly a factor of 2 more massive than fundamental-mode (RRab) RR Lyrae stars. This finding supports the evidence that these objects are intermediate-mass stars during central He-burning phases. We adopted three different approaches to estimate the Carina distance modulus, namely, the first-overtone blue edge method, the period-luminosity-amplitude relation, and the periodluminosity-color relation. We found DM ¼ 20:19 AE 0:12, a result that agrees quite well with similar estimates based on different distance indicators. The data for Carina, together with data available in the literature, strongly support the conclusion that dSph's can barely be classified into the classical Oosterhoff dichotomy. The mean period of RRab's in Carina resembles that found for Oosterhoff type II clusters, whereas the ratio between first-overtone (RRc) pulsators and the total number of RR Lyrae stars is quite similar to that found in Oosterhoff type I clusters.

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“…While a couple of M15 RRab with "" normal ÏÏ light curves are found near either Oosterho † line, there are a few that are found between the lines. We do note that the Bingham et al (1984) data for M15 is photographic, which may lead to some discrepancies in the amplitudes. There are also some possible uncertainties in the compatibility condition (see°5.1).…”

Section: Period-amplitude Diagrammentioning

confidence: 94%

“…We have applied the compatibility test on the M15 RRab variables with the best light curves. Bingham et al 1984. RRab variables from Silbermann & Smith (1995). While a couple of M15 RRab with "" normal ÏÏ light curves are found near either Oosterho † line, there are a few that are found between the lines.…”

Section: Period-amplitude Diagrammentioning

confidence: 94%

Variable Stars in the Unusual, Metal-rich, Globular Cluster NGC 6441

Pritzl

Smith

Catelan

et al. 2001

The Astronomical Journal

130

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We have undertaken a search for variable stars in the metal-rich globular cluster NGC 6441 using time-series BV photometry. The total number of variables found near NGC 6441 has been increased to D104, with 48 new variables being found in this survey. A signiÐcant number of the variables are RR Lyrae stars (D46), most of which are probable cluster members. As was noted by Layden et al. in 1999, the periods of the fundamental-mode RR Lyrae stars are unusually long compared with Ðeld stars of similar metallicity. The existence of these long-period RRab stars is consistent with Sweigart & CatelanÏs prediction that the horizontal branch of NGC 6441 is unusually bright. This result implies that the metallicity-luminosity relationship for RR Lyrae stars is not universal. We discuss the difficulty in determining the Oosterho † classiÐcation of NGC 6441 because of the unusual nature of its RR Lyrae stars. A number of ab-type RR Lyrae stars are found to be both brighter and redder than the other probable RRab found along the horizontal branch, which may be a result of blending with stars of redder color. A smaller than usual gap is found between the shortest period fundamental-mode and the longest period Ðrst-overtoneÈmode RR Lyrae stars. We determine the reddening of the cluster to be E(B[V ) \ 0.51^0.02 mag, with substantial di †erential reddening across the face of the cluster. The mean V magnitude of the RR Lyrae is found to be 17.51^0.02 mag, resulting in a distance of 10.4È11.9 kpc, for a range of assumed values of for RR Lyrae stars. The possibility that stars in NGC 6441 SM V T may span a range in [Fe/H] is also discussed.

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Photographic photometry of RR Lyrae variables in the globular cluster M15

Cited by 57 publications

References 0 publications

The Evolutionary Status of M3 RR Lyrae Variable Stars: Breakdown of the Canonical Framework?

The Evolutionary Status of M3 RR Lyrae Variable Stars: Breakdown of the Canonical Framework?

The Carina Project. I. Bright Variable Stars

Variable Stars in the Unusual, Metal-rich, Globular Cluster NGC 6441

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