A newborn spider system at the core of a radio shell: Evidence of a low-energy supernova

¹ Western Sydney University, Locked Bag 1797, Penrith South DC, NSW 2751, Australia
² Australia Telescope National Facility, CSIRO, Space and Astronomy, PO Box 76, Epping, NSW 1710, Australia
³ Astronomical Observatory, Volgina 7, 11060 Belgrade, Serbia
⁴ Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany
⁵ School of Physical Sciences and Centre for Astrophysics & Relativity, Dublin City University, Glasnevin, Dublin D09 W6Y4, Ireland
⁶ Astronomy & Astrophysics Section, School of Cosmic Physics, Dublin Institute for Advanced Studies, DIAS Dunsink Observatory, Dublin D15 XR2R, Ireland
⁷ Department of Physics, The George Washington University, 725 21st St. NW, Washington, DC 20052, USA
⁸ Max-Planck-Institut für extraterrestrische Physik, Gießenbachstraße 1, 85748 Garching bei München, Germany
⁹ Inter University Centre for Astronomy& Astrophysics, Ganesh-khind, Pune 411007, India
¹⁰ Departament de Física, EEBE, Universitat Politècnica de Catalunya, c/Eduard Maristany 16, 08019 Barcelona, Spain
¹¹ Instituto de Física y Astronomía, Universidad de Valparaíso, ave. Gran Bretaña, 1111, Casilla 5030, Valparaíso, Chile
¹² Millennium Institute of Astrophysics, Nuncio Monseñor Sotero Sanz 100, Of. 104, Providencia, Santiago, Chile
¹³ Department of Physics, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
¹⁴ South African Astronomical Observatory, PO Box 9, Observatory 7935 Cape Town, South Africa
¹⁵ Department of Physics, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa
¹⁶ Dominion Radio Astrophysical Observatory, Herzberg Astronomy & Astrophysics, National Research Council Canada, PO Box 248, Penticton, BC V2A 6J9, Canada
¹⁷ School of Physics, Chemistry and Earth Sciences, The University of Adelaide, Adelaide 5005, Australia
¹⁸ Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
¹⁹ Australia Telescope National Facility, CSIRO, Space and Astronomy, PO Box 1130, Bentley, WA 6151, Australia
²⁰ Department of Physics, University of Wisconsin-Madison, 1150 University Ave., Madison, WI 53706, USA
²¹ School of Mathematical and Physical Sciences, Macquarie University, 12 Wally’s Walk, Macquarie Park 2109, NSW, Australia
²² Department of Physics and Astronomy, University of Calgary, Calgary, Alberta T2N 1N4, Canada
²³ School of Natural Sciences, University of Tasmania, PO Box 807, Sandy Bay, TAS 7006, Australia

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Received: 20 January 2026
Accepted: 9 April 2026

Abstract

In a search for radio nebulae with a low surface brightness within the ASKAP-EMU survey, we discovered a faint radio shell, G289.6+5.8, and its central point radio source at the position of the soft γ-ray source IGR J11187-5438. The central radio source is spatially coincident with a previously known low-mass X-ray binary (LMXB) with an M-type donor star. However, the newly determined Gaia DR3 distance of 267 pc and correspondingly low X-ray luminosity (3×10³¹ erg s⁻¹) cast doubt on the LMXB classification. Neither radio nor X-ray pulsations are detected. Chance alignments between radio shell, central radio source, optical star, γ-ray, and X-ray sources appear unlikely. By combining all currently available evidence, we conclude that G289.6+5.8 is a remnant of a low-energy core-collapse explosion of an intermediate-mass star (~8M_⊙) in a binary system with an M-type secondary that remained bound after the explosion. In this scenario, G289.6+5.8 is a supernova remnant, while the central γ- and X-ray source is associated with a young neutron star whose pulsar wind interacts with its M-type stellar companion, making IGR J11187-5438 a nascent spider-type X-ray binary.