18 centimeter OH emission of IC 4553 (Arp 220)

Journal Article · Wed Jul 01 04:00:00 EDT 1987 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/165356· OSTI ID:6118299

Baan, W A; Haschick, A D

All transitions of hydroxyl have been found in emission in IC 4553 (Arp 220). The line shapes have been decomposed and interpreted in terms of three distinct emission regions: one region at the systemic velocity of the galaxy, and a second at a 334 km/s higher velocity. A third region represents a nuclear outflow with a terminal velocity of approximately 700 km/s. The emission lines for the region I are the strongest and originate in a molecular disk surrounding the nucleus of the galaxy. The infalling foreground region II is thought to be rather extended and has a very prominennt 1612 MHz line. The line ratios of regions I and II are quite different indicating that, although the primary pump for both regions is the infrared radiation field, there are differences in the (secondary) excitation conditions. Regions I and II may represent the two nuclei of the galaxies, which make up the merging IC 4553. The excitation of region III is collisional. 19 references.

• Research Organization: Arecibo Observatory, Puerto Rico; Haystack Observatory, Westford, MA
• OSTI ID: 6118299
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 318; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ELECTROMAGNETIC RADIATION
EMISSION SPECTRA
GALAXIES
GALAXY NUCLEI
HYDROXYL RADICALS
INTERSTELLAR SPACE
MOTION
RADIAL VELOCITY
RADIATIONS
RADICALS
RADIOWAVE RADIATION
ROTATION
SPACE
SPECTRA
VELOCITY