| Issue |
A&A
Volume 683, March 2024
|
|
|---|---|---|
| Article Number | A21 | |
| Number of page(s) | 12 | |
| Section | Galactic structure, stellar clusters and populations | |
| DOI | https://doi.org/10.1051/0004-6361/202347811 | |
| Published online | 29 February 2024 | |
eRASSU J060839.5–704014: A double degenerate ultra-compact binary in the direction of the LMC⋆
1
Max-Planck-Institut für Extraterrestrische Physik, Gießenbachstraße 1, 85748 Garching, Germany
e-mail: cmaitra@mpe.mpg.de
2
Université de Strasbourg, CNRS, Observatoire Astronomique de Strasbourg, UMR 7550, 67000 Strasbourg, France
3
Department of Physics, National and Kapodistrian University of Athens, University Campus Zografos, 15783 Athens, Greece
4
Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
5
South African Astronomical Observatory, PO Box 9, Observatory Rd, Observatory 7935, South Africa
6
Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
7
NSF’s National Optical/Infrared Research Laboratory (NOIRLab), 950 N. Cherry Ave, Tucson, AZ 85732, USA
8
Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, ON N2L 2Y5, Canada
Received:
26
August
2023
Accepted:
22
November
2023
Context. During four all-sky surveys (eRASS1–4), eROSITA, the soft X-ray instrument aboard Spektrum-Roentgen-Gamma (SRG) detected a new supersoft X-ray source, eRASSU J060839.5−704014, in the direction of the Large Magellanic Cloud (LMC).
Aims. We arranged follow-up observations in the X-ray and optical wavelengths and further searched in archival observations to reveal the nature of the object.
Methods. Using X-ray observations with XMM-Newton we investigated the temporal and spectral behaviour of the source.
Results. We discover pulsations at 374 s with a pulse profile consistent with 100% modulation. We identify two other periodicities in the eROSITA data, which we establish as aliases due to the sampling of the eROSITA light curve. We identify a multi-wavelength counterpart to the X-ray source in UVW1 and g, r, i, and z images obtained by the optical/UV monitor on XMM-Newton and the Dark Energy Camera at the Cerro Tololo Inter-American Observatory. The timing and spectral characteristics of the source are consistent with a double degenerate ultra-compact binary system in the foreground of the LMC. eRASSU J060839.5−704014 belongs to a rare class of AM CVns, which are important to study in the context of progenitors of SN Ia and for persistent gravitational wave detection.
Conclusions. We identify eRASSU J060839.5−704014 as a new double degenerate ultra-compact binary located in the foreground of the LMC.
Key words: white dwarfs / Magellanic Clouds / X-rays: binaries / X-rays: individuals: eRASSU J060839.5−704014
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Open Access funding provided by Max Planck Society.
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