Period changes in the RR Lyrae stars of NGC 6171 (M107)

Ferro, A. Arellano; Rosenzweig, P.; Luna, A.; Deras, Dan; Muneer, S.; Giridhar, Sunetra; Michel, R.

doi:10.1002/asna.201813409

Cited by 6 publications

(7 citation statements)

References 23 publications

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“…None of the RRab stars falls near the evolved sequences, i.e., the segmented loci, thus none of them seems to be clearly ahead in its evolution towards the asymptotic giant branch. V17 was found to have a significant positive secular period change (Arellano Ferro et al ), as expected in stars advanced in their evolution. However, while in the V ‐band the scatter is larger and it may not preclude V17 from being inconsistent with the evolved stars locus, in the I ‐band all stable RRab stars are rather consistent with the non‐evolved sequence.…”

Section: The Rr Lyrae Starssupporting

confidence: 55%

“…The observations described above were published in electronic format by Arellano Ferro et al (). In that paper, only the V data of the RR Lyrae stars were employed to discuss the secular period variations.…”

Section: Observationsmentioning

confidence: 99%

“…These were converted to E ( B − V ) using the ratio E ( V − I )/ E ( B − V ) = 1.259 derived by Schlegel et al (). The light curves were phased with the periods listed in Table and were adopted from the analysis of Arellano Ferro et al (). The resulting values for the reddening are listed in the second‐to‐last column of Table .…”

Section: On the Reddening Of Ngc 6171mentioning

confidence: 99%

“…In the case of V23, the V light curve was taken from Clement & Shelton (). The data for all this light curves have been published in electronic format by Arellano Ferro et al ()…”

Section: The Rr Lyrae Starsmentioning

confidence: 99%

“…The historical data available for this cluster spans 82 years, which enabled Arellano Ferro et al () to perform an analysis of secular changes in the periods of the RR Lyrae stars present in the cluster. It was found that 82% of the sample had stable periods, while significant period variations were found only in four stars, three of which had decreasing periods; if interpreted as of evolutionary origin, it implies evolution toward the blue side of the horizontal branch (HB).…”

Section: Introductionmentioning

confidence: 99%

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Physical parameters of RR Lyrae stars in NGC 6171

et al. 2018

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We present an analysis of VI CCD time series photometry of the globular cluster NGC 6171. The main goal is to determine individual physical parameters for single-mode RR Lyrae stars present in the field of view of our images, by means of light curve Fourier decomposition and well-established calibrations and zero points. This leads to the estimation of the mean values of the metallicity and distance for the parental cluster. From the RRab stars, we find [Fe/H] ZW = −1.33 ± 0.12 and distance d = 5.3 ± 0.3 kpc, and from the RRc stars we find [Fe/H] ZW = −1.02 ± 0.19 and distance d = 5.3 ± 0.2 kpc. Independent methods such as the P-L (period-luminosity) relations for RRab and SX Phe stars enable the estimation of a weighted average distance to the cluster of 5.4 ± 0.1 kpc. We confirm the amplitude modulations of the Blazhko type of five RRab and the non-membership of V21 to the cluster. The color-magnitude diagram is consistent with an age of 11 Gyrs. The distribution of RRab and RRc stars seems well segregated around the first overtone red edge of the instability strip. This positions NGC 6171 among OoI-type clusters where the pulsating modes are neatly separated in the horizontal branch. We report two new irregular variables of the Lb type.

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Section: The Rr Lyrae Starssupporting

confidence: 55%

Section: Observationsmentioning

confidence: 99%

Section: On the Reddening Of Ngc 6171mentioning

confidence: 99%

“…In the case of V23, the V light curve was taken from Clement & Shelton (). The data for all this light curves have been published in electronic format by Arellano Ferro et al ()…”

Section: The Rr Lyrae Starsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Physical parameters of RR Lyrae stars in NGC 6171

et al. 2018

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Variable stars in the field of the Galactic bulge globular cluster NGC 6522

Arellano Ferro,

Prudil,

Yepez

et al. 2023

Astrophys Space Sci

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We present a comprehensive analysis of the variable stars projected on the field of the Galactic bulge globular cluster NGC 6522, offering valuable insights into their characteristics. Using proper motions from Gaia-DR3, we aim to distinguish between field stars and true cluster members. For an accurate color-magnitude diagram of the member stars, we produced a differential reddening map. We detect and discuss the peculiarities of variable stars of the types RR Lyrae, type II Cepheids, Long Period Variables (LPV) and eclipsing binaries, whose light curves are available through the OGLE III and IV databases. Notably, we explore the variable V24, which shows a prominent phase modulation resulting from period changes in a time scale of 1100 days. The variable stars among the cluster members serve as indicators of the cluster metallicity and distance; these determinations are based on their light curves. With the Fourier light curve decomposition of three RRc stars, we have derived the following cluster parameters: the metallicity in the spectroscopic scale $\text{[Fe/H]}_{\mathrm{UVES}}=-1.16 \pm 0.09$ [Fe/H] UVES = − 1.16 ± 0.09 ; and the mean distance $D=8.77 \pm 0.16$ D = 8.77 ± 0.16 kpc.

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Variable stars in Palomar 13; an evaporating globular cluster

et al. 2019

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We present new CCD V I photometry of the distant globular cluster Pal 13. Fourier decomposition of the light curves of the three cluster member RRab stars lead to estimations of [Fe/H]=-1.65, and a distance of 23.67±0.57 kpc. Light and colour near minimum phases for RRab stars leads to an estimate of E(B − V)=0.104 ± 0.001. A V/(V − I) colour-magnitude diagram, built exclusively with likely star members, shows consistency with the above parameters and an age of 12 Gyrs. A search of variable stars in the field of view of our images revealed the variability of a red giant cluster member and of three probably non-member stars; two RRab stars and one W Virginis star or CW. The GAIA proper motions of member stars in Pal 13 show a significant scatter, consistent with the scenario of the cluster being tidally stripped.

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Period changes in the RR Lyrae stars of NGC 6171 (M107)

Cited by 6 publications

References 23 publications

Physical parameters of RR Lyrae stars in NGC 6171

Physical parameters of RR Lyrae stars in NGC 6171

Variable stars in the field of the Galactic bulge globular cluster NGC 6522

Variable stars in Palomar 13; an evaporating globular cluster

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