The thermonuclear X-ray bursts of 4U 1730–22
The thermonuclear X-ray bursts of 4U 1730–22
We present observations of the historic transient 4U 1730–22 as observed with the Neutron Star Interior Composition Explorer (NICER). After remaining in quiescence since its 1972 discovery, this X-ray binary showed renewed outburst activity in 2021 and 2022. We observed 4U 173–22 extensively with NICER, detecting a total of 17 thermonuclear X-ray bursts. From a spectroscopic analysis, we find that these X-ray bursts can be divided into a group of bright and weak bursts. All bright bursts showed 1–2 s rise times and a photospheric radius expansion phase, while the weak bursts showed a slower ∼5 s rise with a tendency for concave shapes. From the photospheric radius expansion flux, we estimate the source distance at 6.9 ± 0.2 kpc. We consider various interpretations for our observations and suggest that they may be explained if accreted material is burning stably at the stellar equator and unstable ignition occurs at a range of higher latitudes.
Bult, Peter
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Mancuso, Giulio C.
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Strohmayer, Tod E.
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Albayati, Arianna C.
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Altamirano, Diego
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Buisson, Douglas J.K.
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Chenevez, Jérôme
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Guillot, Sebastien
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Güver, Tolga
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Iwakiri, Wataru
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Jaisawal, Gaurava K.
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Ng, Mason
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Sanna, Andrea
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Swank, Jean H.
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23 November 2022
Bult, Peter
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Mancuso, Giulio C.
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Strohmayer, Tod E.
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Albayati, Arianna C.
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Altamirano, Diego
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Buisson, Douglas J.K.
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Chenevez, Jérôme
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Guillot, Sebastien
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Güver, Tolga
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Iwakiri, Wataru
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Jaisawal, Gaurava K.
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Ng, Mason
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Sanna, Andrea
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Swank, Jean H.
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Bult, Peter, Mancuso, Giulio C., Strohmayer, Tod E., Albayati, Arianna C., Altamirano, Diego, Buisson, Douglas J.K., Chenevez, Jérôme, Guillot, Sebastien, Güver, Tolga, Iwakiri, Wataru, Jaisawal, Gaurava K., Ng, Mason, Sanna, Andrea and Swank, Jean H.
(2022)
The thermonuclear X-ray bursts of 4U 1730–22.
The Astrophysical Journal, 940 (1), [81].
(doi:10.3847/1538-4357/ac9b26).
Abstract
We present observations of the historic transient 4U 1730–22 as observed with the Neutron Star Interior Composition Explorer (NICER). After remaining in quiescence since its 1972 discovery, this X-ray binary showed renewed outburst activity in 2021 and 2022. We observed 4U 173–22 extensively with NICER, detecting a total of 17 thermonuclear X-ray bursts. From a spectroscopic analysis, we find that these X-ray bursts can be divided into a group of bright and weak bursts. All bright bursts showed 1–2 s rise times and a photospheric radius expansion phase, while the weak bursts showed a slower ∼5 s rise with a tendency for concave shapes. From the photospheric radius expansion flux, we estimate the source distance at 6.9 ± 0.2 kpc. We consider various interpretations for our observations and suggest that they may be explained if accreted material is burning stably at the stellar equator and unstable ignition occurs at a range of higher latitudes.
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Bult_2022_ApJ_940_81
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Accepted/In Press date: 15 October 2022
Published date: 23 November 2022
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Local EPrints ID: 490422
URI: http://eprints.soton.ac.uk/id/eprint/490422
ISSN: 0004-637X
PURE UUID: 630b27fd-9478-46bd-9e36-fa91de053383
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Date deposited: 24 May 2024 17:09
Last modified: 12 Nov 2024 02:49
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Contributors
Author:
Peter Bult
Author:
Giulio C. Mancuso
Author:
Tod E. Strohmayer
Author:
Douglas J.K. Buisson
Author:
Jérôme Chenevez
Author:
Sebastien Guillot
Author:
Tolga Güver
Author:
Wataru Iwakiri
Author:
Gaurava K. Jaisawal
Author:
Mason Ng
Author:
Andrea Sanna
Author:
Jean H. Swank
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