A Chandra X-ray census of the interacting binaries in old open clusters – NGC 188

Vats, Smriti; Berg, M. van den; Wijnands, Rudy

doi:10.1093/mnras/sty2290

Cited by 3 publications

(4 citation statements)

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Section: Open Clustersmentioning

confidence: 99%

“…The key to our analysis is the careful collation of data on a variety of stellar populations. Recent work has added significantly to our understanding of X-ray emissivity in old open clusters (Gosnell et al 2012;van den Berg et al 2013;Vats & van den Berg 2017;Vats et al 2018) and dwarf ellipticals (Ge et al 2015). To understand the nature of X-ray sources Figure 1.…”

Section: Three Intriguing Claimsmentioning

confidence: 99%

“…A full catalogue of X-ray sources in NGC 188 observed by Chandra and XMM-Newton is reported by Vats et al (2018) (Gondoin 2005 gives a partial analysis), giving an estimated 0.5-2 keV L X for members of 2.45±0.55×10 31 erg/s. We also extract a spectrum from the half-mass region using the Chandra observation described in Vats et al (2018). We subtract stowed background data covering the same detector region from the half-mass spectrum, and also from a nearby background spectrum, and simultaneously fit the half-mass and background spectra to determine the emission from the half-mass region.…”

Section: Plmentioning

confidence: 99%

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The X-ray emissivity of low-density stellar populations

Heinke

Ivanov

Koch

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The dynamical production of low-mass X-ray binaries and brighter cataclysmic variables (CVs) in dense globular clusters is well-established. We investigate how the X-ray emissivity of fainter X-ray binaries (principally CVs and coronally active binaries) varies between different environments. We compile calculations (largely from the literature) of the X-ray emissivity of old stellar populations, including open and globular clusters and several galaxies. We investigate three literature claims of unusual X-ray sources in low-density stellar populations. We show that a suggested quiescent neutron star in the open cluster NGC 6819 is a foreground M dwarf. We show that the suggested diffuse X-ray emission from an old nova shell in the globular cluster NGC 6366 is actually a background galaxy cluster. And we show that a suggested population of quiescent X-ray binaries in the Sculptor Dwarf Galaxy is mostly (perhaps entirely) background galaxies. We find that above densities of 10 4 M /pc 3 , the X-ray emissivity of globular clusters increases, due to dynamical production of X-ray emitting systems. Below this density, globular clusters have lower X-ray emissivity than the other populations, and we do not see a strong dependence of X-ray emissivity due to density effects. We find significant correlations between X-ray emissivity and binary fraction, metallicity, and density. Sampling these fits via bootstrap techniques gives less significant correlations, but confirms the effect of metallicity on low-density populations, and that of density on the full globular cluster sample.

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Section: Open Clustersmentioning

confidence: 99%

Section: Three Intriguing Claimsmentioning

confidence: 99%

Section: Plmentioning

confidence: 99%

See 1 more Smart Citation

The X-ray emissivity of low-density stellar populations

Heinke

Ivanov

Koch

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…Series, 13, 363; [46] Makishima et al 1981, ApJ, 247, L23; [47] Cackett et al 2006, MNRAS, 369, 407; [48] Swank et al 1977,Old open clustersBefore Chandra, several nearby ( 1 kpc) old (4Gyr) open clusters had already been studied with ROSAT (e.g , Belloni & Tagliaferri 1998,. but Chandra and also XMM-Newton have brought the more distant-and often older-open clusters within reach (e.g Gosnell et al 2012, Vats & van den Berg 2017, Vats et al 2018…”

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confidence: 99%

X-ray sources in Galactic globular clusters and old open clusters

Berg

2019

Proc. IAU

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The features and make up of the population of X-ray sources in Galactic star clusters reflect the properties of the underlying stellar environment. Cluster age, mass, stellar encounter rate, binary frequency, metallicity, and maybe other properties as well, determine to what extent we can expect a contribution to the cluster X-ray emission from low-mass X-ray binaries, millisecond pulsars, cataclysmic variables, and magnetically active binaries. Sensitive X-ray observations with XMM-Newton and certainly Chandra have yielded new insights into the nature of individual sources and the effects of dynamical encounters. They have also provided a new perspective on the collective X-ray properties of clusters, in which the X-ray emissivities of globular clusters and old open clusters can be compared to each other and to those of other environments. I will review our current understanding of cluster X-ray sources, focusing on star clusters older than about 1 Gyr, illustrated with recent results.

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WIYN open cluster study: The old open cluster, NGC 188, and a re-evaluation of Lithium-richness among red giants

Sun

Deliyannis

Twarog

et al. 2022

Monthly Notices of the Royal Astronomical Society

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We present WIYN★/Hydra spectra of 34 red giant candidate members of NGC 188, which, together with WOCS† and Gaia data yield 23 single members, 6 binary members, 4 single nonmembers, and 1 binary nonmember. We report [Fe/H] for 29 members and derive [Fe/H]NGC188 = +0.064 ± 0.018 dex (σμ) (sky spectra yield A(Fe)⊙ = 7.520 ± 0.015 dex (σμ)). We discuss effects on the derived parameters of varying Yale-Yonsei isochrones to fit the turnoff. We take advantage of the coolest, lowest-gravity giants to refine the line list near Li 6707.8 Å. Using synthesis we derive detections of A(Li)‡ = 1.17, 1.65, 2.04, and 0.60 dex for stars 4346, 4705, 5027, and 6353, respectively, and 3σ upper-limits for the other members. Whereas only two of the detections meet the traditional criterion for ‘Li-richness’ of A(Li) > 1.5 dex, we argue that since the cluster A(Li) vanish as subgiants evolve to the base of the RGB, all four stars are Li-rich in this cluster’s context. An incidence of even a few Li-rich stars in a sample of 29 stars is far higher than what recent large surveys have found in the field. All four stars lie either slightly or substantially away from the cluster fiducial sequence, possibly providing clues about their Li-richness. We discuss a number of possibilities for the origin for the Li in each star, and suggest potentially discriminating future observations.

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A Chandra X-ray census of the interacting binaries in old open clusters – NGC 188

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Cited by 3 publications

References 60 publications

The X-ray emissivity of low-density stellar populations

The X-ray emissivity of low-density stellar populations

X-ray sources in Galactic globular clusters and old open clusters

WIYN open cluster study: The old open cluster, NGC 188, and a re-evaluation of Lithium-richness among red giants

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