2010/06/28 by P. Schilke, C. Comito, H. S. P. Müller +77 · 1 citation
Chemistry · Physics and Astronomy · #Absorption (acoustics) #Advanced Chemical Physics Studies #Analytical Chemistry (journal) #Astrophysics #Astrophysics and Star Formation Studies #Atomic physics #Center (category theory) #Chemistry #Crystallography #Galaxy #Hyperfine structure #Molecular Spectroscopy and Structure #Physics #Spin (aerodynamics) #Spiral galaxy #astro-ph.GA
paper · pdf · doi:10.1051/0004-6361/201015087
published as Astron. Astrophys. 521 (2010) Art. No. L11 · A&A, HIFI special issue, accepted
openalex publication_date 2010/06/28 · arxiv created 2010/07/05 · arxiv updated 2014/09/08 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
H<sub>2<sub/>O<sup>+<sup/> has been observed in its <i>ortho<i/>- and <i>para<i/>- states toward the massive star forming core Sgr B2(M), located close to the Galactic center. The observations show absorption in all spiral arm clouds between the Sun and Sgr B2. The average o/p ratio of H<sub>2<sub/>O<sup>+<sup/> in most velocity intervals is 4.8, which corresponds to a nuclear spin temperature of 21 K. The relationship of this spin temperature to the formation temperature and current physical temperature of the gas hosting H<sub>2<sub/>O<sup>+<sup/> is discussed, but no firm conclusion is reached. In the velocity interval 0–60 km s<sup>-1<sup/>, an <i>ortho<i/>/<i>para<i/> ratio of below unity is found, but if this is due to an artifact of contamination by other species or real is not clear.