2007/03/01 by Mark Wardle · 5 citations
Earth and Planetary Sciences · Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Astrophysics and Star Formation Studies #Atmospheric Ozone and Climate #Excitation #Excitation temperature #Excited state #Line (geometry) #Maser #Molecular cloud #Range (aeronautics) #Supernova remnant #astro-ph
paper · pdf · doi:10.1017/s1743921307013300
published in Proceedings of the International Astronomical Union 3(S242), 336-337 (Cambridge University Press) · 2 pages, 2 figs, iaus.cls. To appear in IAU 242, Astrophysical Masers and Their Environments, eds. J. Chapman & W. Baan. Addition of two references and minor changes to wording
openalex publication_date 2007/03/01 · arxiv created 2007/04/16 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Abstract OH (1720 MHz) masers serve as indicators of SNR – molecular cloud interaction sites. These masers are collisionally excited in warm (50–100 K) shocked gas with densities of order 10 5 cm −3 when the OH column density is in the range 10 16 −10 17 cm −2 . Here I present excitation calculations which show that when the OH column density exceeds 10 17 cm −2 at similar densities and temperatures, the inversion of the 1720 MHz line switches off and instead the 6049 MHz transition in the first excited rotational state of OH becomes inverted. This line may serve as a complementary signal of warm, shocked gas when the OH column density is large.