Variable stars in Palomar 13; an evaporating globular cluster

Yepez, Maria; Ferro, A. Arellano; Schröder, K.-P.; Muneer, S.; Giridhar, Sunetra; Allen, Christine

doi:10.1016/j.newast.2019.02.006

Cited by 13 publications

(21 citation statements)

References 56 publications

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“…2, where it is evident that the whole cluster moves as a compact entity, and the stars in solidarity maintain their identity. This is contrary to what is seen for instance in Pal 13 (Yepez et al 2019) (their figure 12), a rather loose cluster being tidally disrupted. However, we note in the bottom panel of Fig.…”

Section: Comments On the Blue-straggler Population Of Ngc 6712contrasting

confidence: 84%

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

Deras

Ferro

Lázaro

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We present an analysis of VI CCD time series photometry of globular cluster NGC 6712. Our main goal is to study the variable star population as indicators of the cluster mean physical parameters. We employed the Fourier decomposition of RR Lyrae light curves to confirm that [Fe/H] UVES = −1.0 ± 0.05 is a solid estimate. We estimated the reddening to the cluster as E(B − V) = 0.35 ± 0.04 from the RRab stars colour curves. The distance to the cluster was estimated using three independent methods which yielded a weighted mean distance d = 8.1 ± 0.2 kpc. The distribution of RRab and RRc stars on the HB shows a clear segregation around the first overtone red edge of the instability strip, which seems to be a common feature in OoI-type cluster with a very red horizontal branch. We carried out a membership analysis of 60,447 stars in our FoV using the data from Gaia-DR2 and found 1529 likely members; we possess the light curves of 1100 among the member stars. This allowed us to produce a clean colour-magnitude diagram, consistent with an age of 12 Gyrs, and enabled us to discover close unresolved contaminants for several variable stars. From the proper motion analysis we found evidence of non-member stars in the FoV of the cluster being tidally affected by the gravitational pull of the bulge of the Galaxy. We found that the RRab variable V6, shows a previously undetected Blazhko effect. Finally, we report sixteen new variables of the EW-type (9) and SR-type (7).

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Section: Comments On the Blue-straggler Population Of Ngc 6712contrasting

confidence: 84%

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

Deras

Ferro

Lázaro

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…Balbinot & Gieles (2018) found that cluster tails are more densely packed at apogalacticon, so that the cluster should be in the best condition of tails (extra-tidal features) observability. From Baumgardt et al (2019), Pal 13 is currently at a Galactocentric distance of 25.92 kpc, so that is 1.5 times farther from its apogalactic distance than from its perigalactic one (see also the cluster's orbit in Yepez et al (2019)). At that position, the cluster exhibits a moderate extended halo of low density.…”

Section: Analysis and Discussionmentioning

confidence: 99%

Pal 13: its moderately extended low-density halo and its accretion history

Piatti

Fernández-Trincado

2020

A&A

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We present results on the basis of Dark Energy Camera Legacy Survey (DECaLS) DR8 astrometric and photometric data sets of the Milky Way globular cluster Pal 13. Because of its relative small size and mass, there has not been yet a general consensus about the existence of extra-tidal structures around it. While some previous results claim for the absence of such features, others have shown that the cluster is under the effects of tidal stripping. From DECaLS g, r magnitudes of stars placed along the cluster Main Sequence in the color-magnitude diagram -previously corrected by interstellar reddening-, we built the cluster stellar density map. The resulting density map shows nearly smooth contours around Pal 13 out to ≈ 1.6 times the most recent estimate of its Jacobi radius, derived by taking into account its variation along its orbital motion. This outcome favors the presence of stars escaping the cluster, a phenomenon frequently seen in globular clusters that have crossed the Milky Way disc a comparable large number of times. Particularly, the orbital high eccentricity and large inclination angle of this accreted globular cluster could have been responsible for the relatively large amount of cluster mass lost.

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“…The method, originally developed to estimate distances to nearby galaxies (Lee et al ), has been used to corroborate the theoretical constrains that particle physics may impose on the extension of the RGB in globular clusters by comparing the predicted distance by the most luminous RGB with the results rendered by the RR Lyrae and SX Phe. Consistency between theoretical predictions and empirical calculations has been found for NGC 6229 by Arellano Ferro et al (), for M5 by Arellano Ferro et al (), and for NGC 6934 by Yepez et al . In brief, the bolometric absolute magnitude of the tip of the RGB was calibrated by Salaris & Cassisi () as:

M_{bol}^{tip} = - 3.949 - 0.178 ([], M false/ H) + 0.008 {[M / H]}^{2},

where [ M / H ] = [Fe/H] − log(0.638 f + 0.362), and log f = [ α /Fe], Salaris et al ().…”

Section: The Distance To Ngc 6362mentioning

confidence: 62%

“…The neat splitting of RRc and RRab stars is clear in Figure . This is significant given that, while the mode splitting has been found in all studied Oo II‐type clusters (nine so far) (Yepez et al ()), only some Oo I (three out of seven so far) have been observed. Figure , which is an updated version of fig.…”

Section: The Horizontal Branch Of Ngc 6362mentioning

confidence: 77%

Metallicity and distance of NGC 6362 from its RR Lyrae and SX Phoenicis stars

et al. 2018

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New time-series VI CCD photometry of the globular cluster NGC 6362 is studied with the aim of estimating the reddening, mean metallicity, and distance of the cluster from its population of RR Lyrae stars. The Fourier decomposition of carefully selected single-mode RR Lyrae light curves, and the use of well-established semiempirical calibrations and revised zero points, lead to the values of [Fe/H] UVES −1.066 ± 0.126 and −1.08 ± 0.16 and distances of 7.93 ± 0.32 and 8.02 ± 0.15 kpc from the RRab and RRc stars, respectively. The distribution of RR Lyrae stars in the horizontal branch shows a neat segregation of pulsating modes about the red edge of the first overtone instability strip, which is not necessarily expected in an OoI-type cluster like NGC 6362. Four RRab stars are found to be likely advanced in their evolution toward the AGB. One new foreground SX Phe star, some 4 kpc in front of the cluster and projected onto the field of our images, is reported. We comment on the heavy light contamination, by a very close neighbouring star, of the peculiar double-mode V37 variable, recently postulated as a non-typical RRc variable. KEYWORDS globular clusters: individual (NGC 6362) -horizontal branch -RR Lyrae starsblue stragglers 1

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Variable stars in Palomar 13; an evaporating globular cluster

Cited by 13 publications

References 56 publications

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

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

Pal 13: its moderately extended low-density halo and its accretion history

Metallicity and distance of NGC 6362 from its RR Lyrae and SX Phoenicis stars

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