Excitation gradient of the molecular gas in the Sgr A circum-nuclear ring

Conference · Wed Apr 15 00:00:00 EDT 1987 · AIP Conf. Proc.; (United States)

OSTI ID:7149861

Lugten, J B; Stacey, G J; Harris, A I; Genzel, R; Townes, C H

We present new measurements of CO submillimeter (J = 7 ..-->..6) and far-infrared (J = 14 ..-->.. 13, J = 21 ..-->.. 20) lines in the Galactic center. The new data, together with earlier CO measurements, are used to derive the physical conditions of the dense, warm molecular gas at different positions in the Sgr a circum-nuclear ring. From the inner edge of the ring at Rapprox.1.7 pc to Rapprox.6 pc the gas pressure decreases proportional to R/sup -1.6//sup +- //sup 0.4/. The best fit excitation curves indicate that both density and temperature decrease with distance from the center. There is also an azimuthal excitation gradient in the ring. If the molecular gas is directly heated from the center by UV radiation or mass outflow the decrease of excitation is a natural consequence of the R/sup -2/ dependence of the energy density. In the more likely scenario of shock heating fed by the large turbulence of the gas throughout the ring, the excitation gradient may reflect variations in gas density and heating efficiency.

• Research Organization: University of California, Berkeley, CA 94720
• OSTI ID: 7149861
• Report Number(s): CONF-8610211-
• Conference Information: Journal Name: AIP Conf. Proc.; (United States) Journal Volume: 155:1
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMISTRY
COSMIC DUST
COSMOCHEMISTRY
DISTRIBUTION
DUSTS
GALAXIES
GALAXY NUCLEI
INFRARED SPECTRA
MILKY WAY
OXIDES
OXYGEN COMPOUNDS
SPATIAL DISTRIBUTION
SPECTRA