G25.5+0.2: A Ring Nebula around a Luminous Blue Star
Abstract
We have obtained infrared images and infrared spectroscopy of the Galactic radio source G25.5+0.2, previously suggested to be a young supernova remnant. The 2.2 micrometers image exhibits a similar nebular structure to that seen in the radio. Spectroscopic measurements at 2.17 micrometers show a Br gamma line that has the line-to-continuum ratio expected from ionized hydrogen at a temperature near 10,000 K. The line is resolved and has a total extent of 300 km/s. Ten micron photometry clearly establishes a physical connection between G25.5+0.2 and the IRAS source 18344-0632. Most important, the infrared image reveals a point source in the center of the nebula that has properties of a blue supergiant star that could excite an ionized ring nebula with the observed radio properties. G25.5+0.2 is almost certainly a ring nebula around a mass losing luminous blue star approximately 13.5 kpc distant and reddened by 20 mag of visual extinction.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 1994
- DOI:
- 10.1086/174447
- Bibcode:
- 1994ApJ...430..774B
- Keywords:
-
- Blue Stars;
- Infrared Spectra;
- Line Spectra;
- Nebulae;
- Radio Sources (Astronomy);
- Stellar Luminosity;
- Supergiant Stars;
- Supernova Remnants;
- Cosmic Dust;
- Hydrogen Ions;
- Infrared Astronomy;
- Radio Emission;
- Spectrum Analysis;
- Stellar Temperature;
- Astrophysics;
- ISM: SUPERNOVA REMNANTS;
- ISM: INDIVIDUAL ALPHANUMERIC: G25.5;
- 0.2;
- STARS: SUPERGIANTS