X-ray observations of the old open stellar cluster NGC 188

Gondoin, P.

doi:10.1051/0004-6361:20052732

Cited by 24 publications

(47 citation statements)

References 67 publications

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“…We detect strong X-ray emission from 12 Belloni, et al 1998;Gondoin 2005). We have shown a comparison with the XLF of field RS CVn binaries (Singh, et al 1996).…”

Section: X-ray Emissionsupporting

confidence: 52%

A multiwavelength view of the open cluster NGC 2527: discovery of active stars

Shah

Singh

Subramaniam

2020

Monthly Notices of the Royal Astronomical Society

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Star clusters are ideal platforms for categorising X-ray emitting stars and to study X-ray emission as a function of stellar age and activity. We present a comprehensive study of an open star cluster, NGC2527, by combining data from XMM-UVOT-Gaia. Cluster membership of stars and their photometry are taken from Gaia and crossmatched with XMM and UVOT detections. We estimate the age of NGC2527 as ∼630 Myr, reddening as E(B−V)=0.13 mag, and a distance of 642±30 pc using PARSEC isochrones. We detect 5 sub-subgiants and 5 bandgap stars, which defy single star evolution. We estimate the temperature, mass, radius, and luminosity of 53 single stars and 10 potential binary stars using a python code which fits single and composite Kurucz spectra to broad-band Spectral Energy Distribution. Among the 12 X-ray emitting members, we find 5 are potential RS CVn type binaries, 2 are potential FK Comae type of RGB stars, and 5 are main sequence (MS) stars with high coronal activity. Members with strong UV emission comprise of 1 RGB star, and several MS stars with UV excess suggestive of chromospheric activity. Based on comparison with other clusters, we tentatively suggest that X-ray luminosity of both RS CVn and contact binaries increases with age suggesting more active binaries are present in older clusters as compared to younger clusters. This study suggests possible presence of W UMa and FK Comae type stars in younger (age 630 Myr) clusters.

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“…We detect strong X-ray emission from 12 Belloni, et al 1998;Gondoin 2005). We have shown a comparison with the XLF of field RS CVn binaries (Singh, et al 1996).…”

Section: X-ray Emissionsupporting

confidence: 52%

A multiwavelength view of the open cluster NGC 2527: discovery of active stars

Shah

Singh

Subramaniam

2020

Monthly Notices of the Royal Astronomical Society

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“…We estimate that the primary star is likely a red giant with a mass of < 1.12 M ⊙ , and the secondary star is on the main sequence with a mass of < 0.78 M ⊙ . This binary was observed to be one of the brightest X-ray sources, GX28, in the Gondoin (2005b) survey. They point out that one would not expect a giant star in NGC 188 to show rapid rotation or surface activity unless the star is a member of a tight binary system in which rapid rotation has been maintained by synchronization.…”

Section: Photometric Variables and X-ray Sourcesmentioning

confidence: 99%

“…This would allow for an upper main-sequence secondary star as predicted. Additionally, 4705 was found to be an X-ray variable, GX18, by Gondoin (2005b), who observed low-amplitude brightness variations on the time scale of weeks. They suggest that these variations are due to slow rotation, as rotating giants can produce high X-ray luminosities, possibly related to the existence of magnetic fields induced by turbulent motion in their deepening convective zones.…”

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confidence: 99%

Wiyn Open Cluster Study. Xxxvi. Spectroscopic Binary Orbits in NGC 188

Geller

Harris

McClure

2009

The Astronomical Journal

114

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We present 98 spectroscopic binary orbits resulting from our ongoing radial-velocity survey of the old (7 Gyr) open cluster NGC 188. All but 13 are high-probability cluster members based on both radial-velocity and proper-motion membership analyses. 15 of these member binaries are double lined. Our stellar sample spans a magnitude range of 10.8≤V≤16.5 (1.14-0.92 M ⊙ ) and extends spatially to 17 pc (∼13 core radii). All of our binary orbits have periods ranging from a few days to on the order of 10 3 days, and thus are hard binaries that dynamically power the cluster. For each binary, we present the orbital solutions and place constraints on the component masses. Additionally, we discuss a few binaries of note from our sample, identifying a likely blue straggler -blue straggler binary system (7782), a double-lined binary with a secondary star which is under-luminous for its mass (5080), two potential eclipsing binaries (4705 and 5762), and two binaries which are likely members of a quadruple system (5015a and 5015b).

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“…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).…”

Section: Open Clustersmentioning

confidence: 99%

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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X-ray observations of the old open stellar cluster NGC 188

Cited by 24 publications

References 67 publications

A multiwavelength view of the open cluster NGC 2527: discovery of active stars

A multiwavelength view of the open cluster NGC 2527: discovery of active stars

Wiyn Open Cluster Study. Xxxvi. Spectroscopic Binary Orbits in NGC 188

The X-ray emissivity of low-density stellar populations

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