<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Maitra, C.</style></author><author><style face="normal" font="default" size="100%">Haberl, F.</style></author><author><style face="normal" font="default" size="100%">Vasilopoulos, G.</style></author><author><style face="normal" font="default" size="100%">Rau, A.</style></author><author><style face="normal" font="default" size="100%">Schwope, A.</style></author><author><style face="normal" font="default" size="100%">Friedrich, S.</style></author><author><style face="normal" font="default" size="100%">Buckley, D. A. H.</style></author><author><style face="normal" font="default" size="100%">Valdes, F.</style></author><author><style face="normal" font="default" size="100%">Lang, D.</style></author><author><style face="normal" font="default" size="100%">Macfarlane, S. A.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">eRASSU J060839.5-704014: A double degenerate ultra-compact binary in the direction of the LMC</style></title><short-title><style face="normal" font="default" size="100%">Astronomy and Astrophysics</style></short-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Magellanic Clouds</style></keyword><keyword><style  face="normal" font="default" size="100%">white dwarfs</style></keyword><keyword><style  face="normal" font="default" size="100%">X-rays: binaries</style></keyword><keyword><style  face="normal" font="default" size="100%">X-rays: individuals: eRASSU J060839.5−704014</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2024</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2024/03/1</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://ui.adsabs.harvard.edu/abs/2024A&amp;A...683A..21M</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">683</style></volume><pages><style face="normal" font="default" size="100%">A21</style></pages><isbn><style face="normal" font="default" size="100%">0004-6361</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">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). &lt;BR /&gt; 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. &lt;BR /&gt; Methods: Using X-ray observations with XMM-Newton we investigated the temporal and spectral behaviour of the source. &lt;BR /&gt; 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. &lt;BR /&gt; Conclusions: We identify eRASSU J060839.5−704014 as a new double degenerate ultra-compact binary located in the foreground of the LMC. &lt;P /&gt;Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.</style></abstract></record></records></xml>