2006/02/28 by John W. Hewitt, Farhad Yusef-Zadeh, F. Yusef‐Zadeh +6 · 5 citations
Physics and Astronomy · #Absorption (acoustics) #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Astrophysics and Star Formation Studies #Emission spectrum #Galaxy #Gamma-ray bursts and supernovae #Geometry #Green Bank Telescope #Line (geometry) #Line-of-sight #Maser #Molecular cloud #Optics #Physics #Radio telescope #Shock (circulatory) #Shock wave #Spectral line #Stars #Supernova #Supernova remnant #Telescope #astro-ph
paper · pdf · doi:10.1086/508331
published as Astrophys.J.652:1288-1296,2006 · 20 pages, 4 figures, 3 tables, submitted to ApJ
arxiv created 2006/08/10 · openalex publication_date 2006/11/27 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present spectral line observations of the ground-state transitions of hydroxyl (OH) toward supernova remnant (SNR) IC 443 carried out with the Green Bank Telescope. Weak, extended OH (1720 MHz) maser emission with OH (1667, 1665, 1612 MHz) absorption is detected along the southern extent of the remnant where no bright compact maser sources have been previously observed. These newly detected SNR-type masers are coincident with well-known molecular clumps and a ridge of shocked H 2 emission indicative of the SNR shock front interacting with the adjacent molecular cloud. Simultaneous observation of all four ground-state transitions of OH permits us to fit physical conditions of the shocked gas at the interaction site. A simple two-component model for the line profiles yields the physical parameters for detected regions of maser emission, including excitation temperature, OH column density, and filling factor. Observed line profiles suggest the shock is largely propagating toward the line of sight in the region of these newly identified weak masers. The implications of shock geometry and physical parameters in producing spatially extended OH maser emission in SNRs are explored. We also present VLA radio continuum observations at 330 MHz for comparison with OH line observations of the remnant.