2025/05/23 by Anna J. G. O’Grady, O'Grady, Anna J. G., Brendan O’Connor +19
Computer Science · #Computational Physics and Python Applications #Computer Graphics and Visualization Techniques #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Parallel Computing and Optimization Techniques #Solar and Stellar Astrophysics (astro-ph.SR)
paper · pdf · doi:10.48550/arxiv.2505.18376
openalex publication_date 2025/05/23 · openalex created_date 2025/09/28 · openalex updated_date 2026/07/28
The ∼2100d Long Secondary Period of Betelgeuse's optical lightcurve and radial velocity motivated the prediction of a low-mass stellar companion, expected to be at maximal apparent separation from Betelgeuse around December 2024. We carried out Director's Discretionary Time observations with the Chandra X-ray Observatory to identify any X-ray emission from the companion and constrain its nature as either a compact object or young stellar object (YSO). Past X-ray observations occurred at the wrong phase of the companion's orbit for optimal detection prospects and/or lacked the deep exposure required to constrain the typical X-ray luminosities of YSOs. In our 41.85 ks exposure with Chandra, we do not detect an X-ray source at the position of Betelgeuse. For an estimated hydrogen column density NH=6×1022 cm-2, we place a limit on the X-ray luminosity of LX\lesssim2×1030 erg s-1 (\lesssim4.7×10-4L_\odot) in 0.5-8 keV for a 10 MK plasma temperature spectral model, or LX\lesssim5×1029 erg s-1 (\lesssim1.2×10-4L_\odot) for an absorbed power law with photon index Γ=2. These limits robustly exclude an accreting compact object (white dwarf or neutron star) as the companion. Solar mass YSOs with an age similar to Betelgeuse (∼10 Myr) display a range of X-ray luminosities (1028-32 erg s-1), and we can place upper bounds within this range for most absorbing columns. Based on these considerations, we conclude that the companion to Betelgeuse is likely a low-mass YSO.