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
73bd0a3d-c566-4046-86c9-31f6e6cdac07
Mancuso, Giulio C.
ac7509c1-5491-4d83-8835-05ae6ba1db01
Strohmayer, Tod E.
bc4138dd-0a48-4abc-b18f-7f4fa0165d1c
Albayati, Arianna C.
a37b49d4-f72d-407f-b7dc-ee3ce0dccbd2
Altamirano, Diego
d5ccdb09-0b71-4303-9538-05b467be075b
Buisson, Douglas J.K.
f96b1210-d056-4948-9e4a-deeb669e6d1a
Chenevez, Jérôme
25a95602-9e3d-4553-a442-5f4317ff2cd6
Guillot, Sebastien
307953c0-47da-4e92-8caf-5ae719f02c52
Güver, Tolga
42c68e75-5602-4ddf-a230-07264c1308f4
Iwakiri, Wataru
f775fbdf-db7e-4f07-afdf-67067173a1c5
Jaisawal, Gaurava K.
4d5dcd39-0881-426d-8ad7-f378238405ae
Ng, Mason
1ea126a4-d65f-4ea4-a97b-dd8620d745e4
Sanna, Andrea
2c05dccc-d674-4ca7-b324-730eb73d6a36
Swank, Jean H.
2d9f4f0d-a2d0-4684-9384-e9c01e84aa0b
23 November 2022
Bult, Peter
73bd0a3d-c566-4046-86c9-31f6e6cdac07
Mancuso, Giulio C.
ac7509c1-5491-4d83-8835-05ae6ba1db01
Strohmayer, Tod E.
bc4138dd-0a48-4abc-b18f-7f4fa0165d1c
Albayati, Arianna C.
a37b49d4-f72d-407f-b7dc-ee3ce0dccbd2
Altamirano, Diego
d5ccdb09-0b71-4303-9538-05b467be075b
Buisson, Douglas J.K.
f96b1210-d056-4948-9e4a-deeb669e6d1a
Chenevez, Jérôme
25a95602-9e3d-4553-a442-5f4317ff2cd6
Guillot, Sebastien
307953c0-47da-4e92-8caf-5ae719f02c52
Güver, Tolga
42c68e75-5602-4ddf-a230-07264c1308f4
Iwakiri, Wataru
f775fbdf-db7e-4f07-afdf-67067173a1c5
Jaisawal, Gaurava K.
4d5dcd39-0881-426d-8ad7-f378238405ae
Ng, Mason
1ea126a4-d65f-4ea4-a97b-dd8620d745e4
Sanna, Andrea
2c05dccc-d674-4ca7-b324-730eb73d6a36
Swank, Jean H.
2d9f4f0d-a2d0-4684-9384-e9c01e84aa0b
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.
Text
Bult_2022_ApJ_940_81
- Version of Record
More information
Accepted/In Press date: 15 October 2022
Published date: 23 November 2022
Identifiers
Local EPrints ID: 490422
URI: http://eprints.soton.ac.uk/id/eprint/490422
ISSN: 0004-637X
PURE UUID: 630b27fd-9478-46bd-9e36-fa91de053383
Catalogue record
Date deposited: 24 May 2024 17:09
Last modified: 25 May 2024 01:47
Export record
Altmetrics
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
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics
