we have mapped the large magellanic cloud (the lmc) in the c ii 158 mm fine-structure line with the balloon-borne infrared carbon explorer (bice) system. the c ii line emission was detected over most of the lmc. the mean c ii/co (j = 1-0) line intensity ratio was 23000, 18 times larger than the typical value observed in the galactic plane (1300). this result implies that each clump of the molecular clouds in the lmc has a larger c+ envelope relative to its co core than those in our galaxy. lower dust abundance due to its lower metallicity allows uv photons, which convert co molecules into c+ ions, to penetrate deeper into the clumps in the lmc than in our galaxy. however, the lmc has different points from normal spiral galaxies other than metallicity. the lmc is a irregular, and has no spiral arms, which are shown by density wave. in spiral arms, where density of interstellar clouds are high, formation of molecules may be enhanced. hence, the dominant factor enhanced c ii/co intensity ratio in the lmc might be due to the luck of strong density wave. the galaxies with low metallicity are not restricted to irregulars. observing the galaxies which has low metallicity and spiral arms is good method to know the effect of density wave for c ii/co intensity ratio. nearby galaxy m33 is one of such galaxies.
Instrument
LWS02 , SWS02
Temporal Coverage
1997-01-27T23:18:34Z/1998-01-10T03:19:19Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
European Space Agency, MOCHIZUKI et al., 1998, 'FIR SPECTROSCOPY OF M33 INTERSTELLAR PHYSICS IN A LOW METAL SPIRAL', 1.0, European Space Agency, https://doi.org/10.5270/esa-5c28l0l
