Discussion

Grindlay, Jonathan E.; Philip, A. G. Davis

doi:10.1007/978-94-015-1104-9_58

Cited by 3 publications

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“…´-2.2 10 4 yr −1 and proposed that 4U 1820-30 could be a hierarchical triple with a third star orbiting the binary system with a period of ∼1.1 days, which induces binary orbital eccentricity modulations with a period of ∼171 days (Mazeh & Shaham 1979;Grindlay 1988). This long-term periodicity was further confirmed by Šimon (2003).…”

Section: Introductionmentioning

confidence: 79%

“…Conversely, even though our detection of orbital period sidebands with periods of P 1 = 691.6 ± 0.7 s and P 2 = 698.5 ± 0.8 s is possibly due to disk precession, such as the superhump detected in the FUV band (Wang & Chakrabarty 2010), we cannot exclude the possibility that the sidebands are induced by a distant third star orbiting around the binary system. To explain the ∼171 days long-term modulation of the 4U 1820-30 system, Grindlay (1986Grindlay ( , 1988 proposed that in the high-density star cluster core as NGC 6624, a star may be captured by the binary system and form a hierarchical triple system. As the third star orbiting the binary system, the eccentricity of the binary modulates with a period = P K P P long outer 2 orb , where P outer is the third star orbital period, P orb is the binary orbital period, and K is a constant of order unity, depending on the mass ratios and relative inclination of the third star orbit and binary (Mazeh & Shaham 1979).…”

Section: Superhump Modulation In 4u 1820-30mentioning

confidence: 99%

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Updated Orbital Ephemeris and Detection of Superhump Modulation in X-Ray Band for the Ultra-compact Low Mass X-Ray Binary 4U 1820-30

Chou

Jhang

2023

ApJ

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The 4U 1820-30 is an ultra-compact low-mass X-ray binary (LMXB) near the center of the globular cluster NGC 6624. Its negative orbital period derivative, observed from the phase evolution of its sinusoidal-like orbital variation, contradicts the positive value that was obtained from the theoretical prediction. In this paper, we present the analysis of the 4U 1820-30 orbital modulation from light curves obtained from the Neutron star Interior Composition ExploreR (NICER) observations from 2017 to mid-2022. Combined with historical records, the orbital derivative is measured from the orbital phase evolution between 1976 and 2002 is P ̇ / P = ( − 5.21 ± 0.13 ) × 10 − 8 yr−1. No significant second order orbital period derivative is detected with a 2σ upper limit of ∣ P ̈ ∣ < 5.48 × 10 − 22 s s−2. We discuss the possible intrinsic orbital period derivative of 4U 1820-30 and suggest that this binary system may have a significant mass outflow similar to some other LMXBs. In addition, a periodic modulation with a period of 691.6 ± 0.7 s, which is consistent with the superhump period discovered in the far-ultraviolet band of the Hubble Space Telescope, was also detected in the X-ray light curves that were collected by NICER. We conclude that this modulation is probably caused by a period of 0.8 ± 0.1 day apsidal precession of the accretion disk, similar to the SU UMa type dwarf novae and some LMXBs. However we cannot exclude the possibility that it is induced by a hierarchical third star that orbits around the binary system.

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Section: Introductionmentioning

confidence: 79%

Section: Superhump Modulation In 4u 1820-30mentioning

confidence: 99%

Updated Orbital Ephemeris and Detection of Superhump Modulation in X-Ray Band for the Ultra-compact Low Mass X-Ray Binary 4U 1820-30

Chou

Jhang

2023

ApJ

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“…THEIR PARENT GALAXIES This is not by its nature a break-through topic, since galaxies outside the Local Group yield up even the simplest statistical properties of their globular-cluster systems painfully, one by one. Thus Rip van Astronomer could have gone directly from the 1986 IAU Symposium on "globular-cluster systems in galaxies" (Grindlay and Philip 1988) to the 1992 Santa Cruz workshop on "globular clusters within the context of their parent galaxies" (Smith and Brodie 1993) without feeling at all lost. In any case, we want mostly to report a probable backward step (at the end of the section).…”

Section: Populations Of Globular Clusters Andmentioning

confidence: 99%

Astrophysics in 1994

Trimble¹,

Leonard²

1995

PASP

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1994 was the year in which we saw the first images from the repaired Hubble Space Telescope; the probable detection of a diffuse intergalactic medium, a black hole in M87, and an enormous primordial deuterium abundance; the discovery of the first (and second) superluminal objects within our own galaxy; not to mention the demise of the Jovian dinosaurs. But, as always, most astronomers continued to work away on the projects that have interested them for years or decades, and we attempt also to report some progress in broader areas, including cooling flows, extragalactic globular cluster populations, disk instabilities, phases of the interstellar medium, and brown dwarfs among microlenses and other populations. Several sections of short items range from the obvious to the remarkable to the unbelievable. As in previous years, the ordering of the topics attempts to preserve the near-to-far custom of elementary astronomy textbooks. INTRODUCTIONGreetings, and welcome to the fourth annual roundup of beasts for the astrophysical zoo. 2 It attempts, like its predecessors, to catch most of the obvious, newsworthy events, but also to highlight areas where less spectacular, yet hard and steady, effort is slowly pushing back the frontiers, or anyhow relocating them. We hope we are at least as successful as Carl Seyfert (of the eponymous galaxies) who used to ride his horse, Silver, in the annual roundup during his days at McDonald Observatory.The first item cited reached our library shelves on 5 October 1993 and the last on

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“…Not only are clusters optically brighter than the average extragalactic star, but they are effective factories for XRB formation: they boost the masses of already massive stars, harden already hard binaries, and promote the formation of new binaries through increased dynamical interactions (Fabian et al 1975;Hills 1976;Verbunt 1987;Kundu et al 2007;Garofali et al 2012;Ivanova 2013). Observations of low-mass XRBs (LMXBs; with donor stars of mass 1 M e ) indicate that they form hundreds of times more efficiently in GCs than in the field (Clark 1975;Katz 1975;Grindlay 1988;Hut et al 1992). Over the past 20 years, observations of nearby, massive elliptical galaxies with the Chandra X-ray Observatory and the Hubble Space Telescope (HST) have established that between 20% and 70% of bright (L X  5 × 10 37 erg s −1 ) LMXBs currently reside in GCs (e.g., Angelini et al 2001;Kundu et al 2002;Jordán et al 2004;Brassington et al 2010;Fabbiano et al 2010) and that a near constant 4%-10% of GCs in ellipticals host bright LMXBs (Maccarone et al 2003;Jordán et al 2007;Mineo et al 2013;Luan et al 2018).…”

Section: Introductionmentioning

confidence: 99%

The X-Ray Binary-star Cluster Connection in Late-type Galaxies

Hunt,

Chandar,

Gallo

et al. 2023

ApJ

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We conduct one of the largest systematic investigations of bright X-ray binaries (XRBs) in both young star clusters and ancient globular clusters (GCs) using a sample of six nearby star-forming galaxies. Combining complete CXO X-ray source catalogs with optical Physics at High Angular Resolution in Nearby Galaxies-Hubble Space Telescope cluster catalogs, we identify a population of 33 XRBs within or near their parent clusters. We find that GCs that host XRBs in spiral galaxies appear to be brighter, more compact, denser, and more massive than the general GC population. However, these XRB hosts do not appear to be preferentially redder or more metal-rich, pointing to a possible absence of the metallicity-boosted formation of low-mass X-ray binaries (LMXBs) that is observed in the GCs of older galaxies. We also find that a smaller fraction of LMXBs is found in spiral GC systems when compared with those in early-type galaxies: between 8% and 50%, or an average of 20% across galaxies in our sample. Although there is a non-negligible probability of a chance superposition between an XRB and an unrelated young cluster, we find that among clusters younger than 10 Myr, which most likely host high-mass XRBs, the fraction of clusters associated with an XRB increases at higher cluster masses and densities. The X-ray luminosity of XRBs appears to increase with the mass of the cluster host for clusters younger than ∼400 Myr, while the inverse relation is found for XRBs in GCs.

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Discussion

Cited by 3 publications

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Updated Orbital Ephemeris and Detection of Superhump Modulation in X-Ray Band for the Ultra-compact Low Mass X-Ray Binary 4U 1820-30

Updated Orbital Ephemeris and Detection of Superhump Modulation in X-Ray Band for the Ultra-compact Low Mass X-Ray Binary 4U 1820-30

Astrophysics in 1994

The X-Ray Binary-star Cluster Connection in Late-type Galaxies

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