Abstract
THERE is still the problem of the identification of galactic X-ray sources in the energy interval of 4–8 keV, and it seems reasonable to consider whether they can be identified with such common objects of the galactic disk as planetary nebulae. A planetary nebula is a slowly expanding gaseous shell with a very hot star inside, and in such a system X-ray emission could originate both in the nebula and in the star. We consider the nebula as a uniform spherical shell with a radius of ∼ 2 × 1017 cm and mass 0.1 M⊙; the radius of the central star can be taken as 1 R⊙ and its temperature as ≥2 × 105 °K (ref. 1). A value of 1 kpc seems a suitable characteristic distance.
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KHROMOV, G. Planetary Nebulae as Possible X-ray Sources. Nature 220, 1111 (1968). https://doi.org/10.1038/2201111a0
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DOI: https://doi.org/10.1038/2201111a0
