13CO(1-0) and 12CO(2-1) in the center of the barred galaxy NGC 1530

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dc.creatorReynaud, D.
dc.creatorDownes, D.
dc.date1999-04-26
dc.date.accessioned2026-07-07T02:31:23Z
dc.date.available2026-07-07T02:31:23Z
dc.descriptionWe present 13CO(1-0) and 12CO(2-1) aperture synthesis maps of the barred spiral galaxy NGC1530. The angular resolutions are respectively 3''.1 and 1''.6. Both transitions show features similar to the 12CO(1-0) map, with a nuclear feature (a ring or unresolved spiral arms) surrounded by two curved arcs. The average line ratios are 12CO(1-0)/13CO(1-0)=9.3 and 12CO(2-1)/12CO(1-0)=0.7. The 12CO/13CO ratio is lower in the circumnuclear ring (6-8) than in the arcs (11-15). We fit the observed line ratios by escape probability models, and deduce that the gas density is probably higher in the nuclear feature (>= 5 10^2 cm^{-3}) than in the arcs (~2 10^2 cm^{-3}), confirming earlier HCN results. The kinetic temperatures are in the range 20-90K, but are weakly constrained by the model. The average filling factor of the 12CO(1-0) emitting gas is low, ~0.15. The cm-radio continuum emission also peaks in the nuclear feature, indicating a higher rate of star formation than in the arcs. We derive values for the CO luminosity to molecular gas mass conversion factor between 0.3 and 2.3 Msolar (K km/s pc^2)^{-1}, significantly lower than the standard Galactic value.
dc.description11 pages, 8 Postscript figures, A&A accepted
dc.identifierhttps://arxiv.org/abs/astro-ph/9904354
dc.identifierhttp://arxiv.org/abs/astro-ph/9904354
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/14137
dc.subjectAstrophysics
dc.title13CO(1-0) and 12CO(2-1) in the center of the barred galaxy NGC 1530
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