Abstract
The nature of the ionizing UV radiation field in the inner Galaxy is investigated by searching for radio continuum emission from the outer envelope of the population of OH/IR stars toward the Galactic center region. Radio continuum observations of a sample of OH/IR stars have been made at 3.6 cm using the VLA in its A, B, and DnC configurations. A highly scattered OH/IR star has been detected with a flux density of ∼1 mJy, which suggests that the star is photoionized by an external radiation field. The UV flux responsible for ionization is estimated to be 2.5 × 109(Ṁ-5)-4 photons cm-2 s-1, where Ṁ-5 is the mass-loss rate in units of 10-5 M⊙ yr-1. We note that the continuum emission should become optically thick below a few hundred megahertz and that measurements at these frequencies will be able to determine both the UV flux and Ṁ.
Original language | English |
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Journal | Astrophysical Journal |
Volume | 458 |
Issue number | 1 PART II |
Publication status | Published - 1996 |
Externally published | Yes |
Keywords
- Galaxy: Center
- H ii regions
- Stars: Late-type
- Stars: Mass loss