High-Resolution X-ray Study Reveals Clumpy Structure in X Persei's Circumstellar Disk
Researchers analyzed over 1,200 high-resolution X-ray spectra from XMM-Newton and Chandra observations of the Be/X-ray binary X Persei to study its circumstellar disk structure. The study used spin-resolved spectroscopy—measuring X-ray emissions at different rotational phases of the neutron star—to detect transient iron emission linked to dense clumps in the disk. The findings provide new constraints on disk density and structure, helping astronomers understand how material accumulates around Be stars in binary systems.
Researchers conducted a detailed X-ray spectroscopic analysis of X Persei, a classical Be/X-ray binary system consisting of a Be-type star and a neutron star with an ~837-second spin period. Using five targeted observations spanning 10 years from XMM-Newton and Chandra, the team generated approximately 1,200 individual spectra by performing spin-resolved spectroscopy at intervals as short as 210 seconds, allowing them to track how X-ray emission varies across the neutron star's rotation. The analysis revealed that the circumstellar disk contains over-dense regions called clumps, which produce transient iron K-alpha emission features during high-density epochs (occurring in 8-9% of observations) and cause dips in the X-ray light curve. Spectral modeling indicates the disk has a compact structure with a radial density exponent of 2.4-3.3 and an inner disk density of (6-20) × 10⁻¹⁰ g cm⁻³, consistent with previous optical and infrared observations. This work demonstrates how high time-resolution X-ray spectroscopy can resolve fine structural details in circumstellar disks that would be obscured in standard averaged spectra.
What different sources said
- arXiv astro-phCenter
A thousand looks at X Persei: X-ray spectroscopy at high time resolution
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