CCD Photometry of the Globular Cluster M53. I. Color-Magnitude Data and Blue Straggler Stars

Rey, Soo-Chang; Lee, Young-Wook; Byun, Yong Ik; Chun, Mun-Suk

doi:10.1086/300555

Cited by 32 publications

(58 citation statements)

References 38 publications

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“…3.3 we needed accurate B − V and V − I color indices for a number of red giant stars in M53. Since our observations covered only the V and I bands, we took the B−V values from the catalog of Rey et al (1998). We selected a large number of stars from this catalog with V and B−V values consistent with an RGB evolutionary state according to the color-magnitude diagram published by Rey et al (1998).…”

Section: Appendix A: Red Giant Starsmentioning

confidence: 99%

Study of globular cluster M53: new variables, distance, metallicity

Dékány

Kovács

2009

A&A

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Aims. We study the variable star content of the globular cluster M53 to compute the physical parameters of the constituting stars and the distance of the cluster. Methods. Covering two adjacent seasons in 2007 and 2008, new photometric data are gathered for 3048 objects in the field of M53. By using the OIS (optimal image subtraction) method and subsequently TFA (trend filtering algorithm), we search for variables in the full sample by using discrete Fourier transformation and box-fitting least squares methods. We select variables based on the statistics related to these methods combined with visual inspection. Results. We identified 12 new variables (2 RR Lyrae stars, 7 short periodic stars -3 of them are SX Phe stars -and 3 long-period variables). No eclipsing binaries were found in the present sample. Except for the 3 (hitherto unknown) Blazhko RR Lyrae (two RRab and an RRc) stars, no multiperiodic variables were found. We showed that after proper period shift, the PLC (period-luminositycolor) relation for the first overtone RR Lyrae sample tightly follows the one spanned by the fundamental stars. Furthermore, the slope is in agreement with that derived from other clusters. Based on the earlier Baade-Wesselink calibration of the PLC relations, the derived reddening-free distance modulus of M53 is 16.31 ± 0.04 mag, corresponding to a distance modulus of 18.5 mag for the Large Magellanic Cloud. From the Fourier parameters of the RRab stars we obtained an average iron abundance of −1.58 ± 0.03 (error of the mean). This is ∼0.5 dex higher than the overall abundance of the giants as given in the literature and derived in this paper from the three-color photometry of giants. We suspect that the source of this discrepancy (observable also in other, low-metallicity clusters) is the lack of a sufficient number of low-metallicity objects in the calibrating sample of the Fourier method.

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Section: Appendix A: Red Giant Starsmentioning

confidence: 99%

Study of globular cluster M53: new variables, distance, metallicity

Dékány

Kovács

2009

A&A

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“…Its apparent distance modulus and interstellar reddening has been estimated to be (m − M ) V = 16.32 mag and E(B − V ) = 0.02 mag, respectively (Harris 1996(Harris , 2010. Rey et al (1998), who carried out a photometric study of M53, reported that M53 has a dominantly blue horizontal branch (BHB) that extends down to ≈1 mag below the mean horizontalbranch (HB) level with some RR Lyrae variable stars. According to Lee et al (1994), the quantity of the morphology of the HB (B − R)/(B + V + R) of M53 is 0.76, where B, V , and R are the number of BHB stars, RR Lyrae variable stars, and red horizontal-branch (RHB) stars, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…According to Lee et al (1994), the quantity of the morphology of the HB (B − R)/(B + V + R) of M53 is 0.76, where B, V , and R are the number of BHB stars, RR Lyrae variable stars, and red horizontal-branch (RHB) stars, respectively. According to Rey et al (1998), M53 has many blue straggler stars (BSSs) throughout its face, showing a bimodal radial distribution. Beccari et al (2008) examined the BSSs of M53 in great detail using three different telescopes, and confirmed the bimodal radial distribution of the BSSs of M53, identifying almost 200 BSSs.…”

Section: Introductionmentioning

confidence: 99%

Relative Age Difference Between the Metal-Poor Globular Clusters M53 and M92

Cho¹,

Sung²,

Lee³

et al. 2016

Journal of The Korean Astronomical Society

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CCD photometric observations of the globular cluster (GC), M53 (NGC 5024), are performed using the 1.8 m telescope at the Bohyunsan Optical Astronomy Observatory in Korea on the same nights (2002 April and 2003 May) as the observations of the GC M92 (NGC 6341) reported by Cho and Lee using the same instrumental setup. The data for M53 is reduced using the same method as used for M92 by Cho and Lee, including preprocessing, point-spread function fitting photometry, and standardization etc. Therefore, M53 and M92 are on the same photometric system defined by Landolt, and the photometry of M53 and M92 is tied together as closely as possible. After complete photometric reduction, the V versus B − V , V versus V − I, and V versus B − I color-magnitude diagrams (CMDs) of M53 are produced to derive the relative ages of M53 and M92 and derive the various characteristics of its CMDs in future analysis. From the present analysis, the relative ages of M53 and M92 are derived using the ∆(B − V ) method reported by VandenBerg et al. The relative age of M53 is found to be 1.6 ± 0.85 Gyr younger than that of M92 if the absolute age of M92 is taken to be 14 Gyr. This relative age difference between M53 and M92 causes slight differences in the horizontal-branch morphology of these two GCs.

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“…= +18 10 0 09 00 , J2000.0; Harris 1996 3 ) has a very low metallicity, [Fe/H] = À1.99, a low interstellar reddening, E(BÀV ) = 0.02, and an apparent V distance modulus (m À M) V = 16.38 (Harris 1996). Many blue straggler stars are known to exist in M53 (Rey et al 1998). Some of these blue stragglers are expected to be SX Phoenicis stars, but no SX Phoenicis stars have been reported yet Clement 2001).…”

Section: Introductionmentioning

confidence: 99%

New SX Phoenicis Stars in the Globular Cluster M53

Jeon

Lee

2003

Astron J

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Through time-series CCD photometry of the metal-poor globular cluster M53 we have discovered eight new SX Phoenicis-type stars (labeled '' SXP1 '' to '' SXP8 ''). All the new SX Phoenicis stars are located in the blue straggler star region of the color-magnitude diagram of M53. One of these stars (SXP2) is found to have very closely separated pulsation frequencies: f 1 /f 2 = 0.9595, where f 1 and f 2 are the primary and secondary frequencies, respectively. This may be due to excitation of nonradial modes. Six of these SX Phoenicis stars are considered to be pulsating in the fundamental mode. They show a tight linear correlation between the period and luminosity. We derive a period-luminosity relation for the fundamental mode for the period range of À1.36 < log P(days) < À1.15: hVi = À3.010(AE0.262) log P + 15.310(AE0.048) with an rms scatter of 0.038, corresponding to hM V i = À3.010 log P À 1.070 for an adopted distance modulus of (m À M) V = 16.38.

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CCD Photometry of the Globular Cluster M53. I. Color-Magnitude Data and Blue Straggler Stars

Cited by 32 publications

References 38 publications

Study of globular cluster M53: new variables, distance, metallicity

Study of globular cluster M53: new variables, distance, metallicity

Relative Age Difference Between the Metal-Poor Globular Clusters M53 and M92

New SX Phoenicis Stars in the Globular Cluster M53

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