NGC 6712: the variable star population of a tidally disrupted globular cluster

Deras, Dan; Ferro, A. Arellano; Lázaro, C.; Fierro, I. H. Bustos; Calderón, J. H.; Muneer, S.; Giridhar, Sunetra

doi:10.1093/mnras/staa196

Cited by 7 publications

(4 citation statements)

References 65 publications

(99 reference statements)

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“…A detailed description of the method and its caveats can be found in Bramich et al (2011). A good overview of all our procedures applied to the analysis of the individual clusters is found in Deras et al (2019) and Yepez et al (2020).…”

Section: Ccd Photometry Based On the Dia Approachmentioning

confidence: 99%

Globular cluster metallicities and distances from disentangling their RR Lyrae light curves

Arellano Ferro

2022

Proc. IAU

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We present mean horizontal branch absolute magnitudes and iron abundances for a sample of 39 globular clusters. These quantities were calculated in an unprecedented homogeneous fashion based on Fourier decomposition of ligt curves of RR Lyrae cluster members. Zero points for the luminosity calibrations are discussed. Our photometrically derived metallicities and distances compare very well with spectroscopic determinations of [Fe/H] and accurate distances obtained using Gaia and Hubble Space Telescope data. The need to distinguish between the results for RRab and RRc stars for a correct evaluation of the MV–[Fe/H] relation is discussed. For RRab stars, the relation is non-linear, and the horizontal branch structure plays a significant role. For RRc stars, the relation remains linear and tight, and the slope is very shallow. Hence, the RRc stars seem better indicators of the parental cluster distances. Systematic time-series CCD imaging performed over the last 20 years enabled to discover and classify 330 variables in our sample of globular clusters.

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Section: Ccd Photometry Based On the Dia Approachmentioning

confidence: 99%

Globular cluster metallicities and distances from disentangling their RR Lyrae light curves

Arellano Ferro

2022

Proc. IAU

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“…New CB that were confirmed to be members of globular clusters were added for M4 (Safonova et al 2016, 1 new CB added), M10 (Rozyczka et al 2018, 1 new CB added), M12 (Kaluzny et al 2015, 3 new CB added), M13 (Deras et al 2019, 1 new CB added), M22 (Rozyczka et al 2017, 6 new CB added), NGC4147 (Lata et al 2019, 5 new CB added) and NGC6712 (Deras et al 2020, 2 new CB added). Positions and periods for CB in M10, M22 and NGC6712 were also updated, whenever available, from Arellano Ferro et al (2020), Rozyczka et al (2017) and Deras et al (2020), respectively. KT-42 in M22 was reclassified as EW variable (Rozyczka et al 2017) hence it was added to the list.…”

Section: Selection Of Contact Binaries In Globular Clustersmentioning

confidence: 99%

“…Similarly, CB that turned out not a member of the globular clusters or being re-classified as other types of variable stars were removed. These include: V2 in M12 (Kaluzny et al 2015); KT-01, KT-03, KT-15, KT-39, KT-40 & KT-41 in M22 (Rozyczka et al 2017); V27, V28 & V29 in NGC6712 (Deras et al 2020); V97 in M14 (Contreras Peña et al 2018); and V10 in NGC288 (Lee et al 2016). Therefore, our final list consists of 79 CB in 15 globular clusters.…”

Section: Selection Of Contact Binaries In Globular Clustersmentioning

confidence: 99%

Zwicky Transient Facility and Globular Clusters: the Period–Luminosity and Period–Luminosity–Color Relations for Late-type Contact Binaries

Ngeow

Liao

Bellm

et al. 2021

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In this work, we aimed to derive the gri-band period-luminosity (PL) and period-luminosity-color (PLC) relations for late-type contact binaries, for the first time, located in the globular clusters, using the homogeneous light curves collected by the Zwicky Transient Factory (ZTF). We started with 79 contact binaries in 15 globular clusters, and retained 30 contact binaries in 10 globular clusters that have adequate number of data points in the ZTF light curves and unaffected by blending. Magnitudes at mean and maximum light of these contact binaries were determined using a fourth-order Fourier expansion, while extinction corrections were done using the Bayerstar2019 3D reddening map together with adopting the homogeneous distances to their host globular clusters. After removing early-type and "anomaly" contact binaries, our derived gri-band PL and period-Wesenheit (PW) relations exhibit a much larger dispersion with large errors on the fitted coefficients. Nevertheless, the gr-band PL and PW relations based on this small sample of contact binaries in globular clusters were consistent with those based on a larger sample of nearby contact binaries. Good agreements of the PL and PW relations suggested both samples of contact binaries in the local Solar neighborhood and in the distant globular clusters can be combined and used to derive and calibrate the PL, PW and PLC relations. The final derived gr-band PL, PW and PLC relations were much improved than those based on the limited sample of contact binaries in the globular clusters.

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“…A detailed search was conducted on the IAO2020 data. Two approaches were followed: first, the string length method (Burke et al 1970, Dworetsky 1983) (or see Deras et al (2020) for a detailed description of the method), that assigns a statistical indicator S Q , of the dispersion of individual observations in a given light curve phased with a trial period. The minimum value of S Q is obtained when the dispersion is least and hence the period likely the correct one.…”

Section: Search For New Variablesmentioning

confidence: 99%

The globular cluster M10: Reassessment of stellar membership, distance and age using its variable and HB stars

Ferro,

Yepez,

Muneer

et al. 2020

Preprint

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Time-series VI CCD photometry of the globular cluster M10 (NGC 6254) is employed to perform a detailed identification, inspection of their light curves, their classification and their cluster membership, of all the known variables reported up to 2018. The membership analysis is based on the Gaia-DR2 positions and proper motions. The metallicity of the cluster is estimated based on the sole RRc star known in the cluster. The Fourier decomposition of its light curve leads to [Fe/H] ZW =−1.59 ± 0.23 dex. The mean cluster distance, estimated by several independent methods is 5.0 ± 0.3 kpc. A multi-approach search in a region of about 10×10 arcmin 2 around the cluster revealed three new variables, one SX Phe (V35) and two sinusoidal variables on the red giant branch of unclear classification (V36,V37). Modelling the HB stars is very sensitive to the stellar hydrogen shell mass, which surrounds the 0.50 M helium core. To match the full stretch of the HB population, a range of total mass of 0.56 to 0.62 M is required. These models support a distance of 5.35 kpc and an age of about 13 Gyrs, and hints to some individual variation of the mass loss on the uppper RGB, perhaps caused by the presence of closed magnetic field in red giants.

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NGC 6712: the variable star population of a tidally disrupted globular cluster

Cited by 7 publications

References 65 publications

Globular cluster metallicities and distances from disentangling their RR Lyrae light curves

Globular cluster metallicities and distances from disentangling their RR Lyrae light curves

Zwicky Transient Facility and Globular Clusters: the Period–Luminosity and Period–Luminosity–Color Relations for Late-type Contact Binaries

The globular cluster M10: Reassessment of stellar membership, distance and age using its variable and HB stars

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