2024/11/28 by Shu-Rui Zhang, J. A. Rueda, Zhang, Shu-Rui +3 · 3 citations
Earth and Planetary Sciences · Physics and Astronomy · #Astrophysical Phenomena and Observations #FOS: Physical sciences #Geophysics and Gravity Measurements #High Energy Astrophysical Phenomena (astro-ph.HE) #Pulsars and Gravitational Waves Research #Solar and Stellar Astrophysics (astro-ph.SR)
paper · pdf · doi:10.48550/arxiv.2411.19382
openalex publication_date 2024/11/28 · openalex created_date 2024/12/05 · openalex updated_date 2026/07/28
The exceptionally low mass of 0.77-0.17+0.2 M\odot for the central compact object (CCO) XMMU J173203.3 -- 344518 (XMMU J1732) in the supernova remnant (SNR) HESS J1731 -- 347 challenges standard neutron star (NS) formation models. The nearby post-AGB star IRAS 17287 -- 3443 (≈ 0.6 M_\odot), also within the SNR, enriches the scenario. To address this puzzle, we advance the possibility that the gravitational collapse of a rotating pre-SN iron core (≈ 1.2 M_\odot) could result in a low-mass NS. We show that angular momentum conservation during the collapse of an iron core rotating at ≈ 45% of the Keplerian limit results in a mass loss of ≈ 0.3 M_\odot, producing a stable newborn NS of ≈ 0.9 M_\odot. Considering the possible spin-down, this indicates that the NS is now slowly rotating, thus fulfilling the observed mass-radius relation. Additionally, the NS's surface temperature (≈ 2 × 106 K) aligns with canonical thermal evolution for its ≈ 4.5 kyr age. We propose the pre -- SN star, likely an ultra-stripped core of ≈ 4.2 M_\odot, formed a tidally locked binary with IRAS 17287 -- 3443, having a 1.43-day orbital period. The supernova led to a ≈ 3 M_\odot mass loss, imparting a kick velocity \lesssim 670 km s-1, which disrupted the binary. This scenario explains the observed 0.3 pc offset between XMMU J1732 and IRAS 17287 -- 3443 and supports the possibility of CCOs forming in binaries, with rotation playing a key role in core-collapse, and the CCO XMMU J1732 being the lightest NS ever observed.