Computer Science
Scientific paper
Feb 2000
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000noao.prop..293g&link_type=abstract
NOAO Proposal ID #2000A-0293
Computer Science
Scientific paper
Microwave emission lines and optical resonance lines have been used to image circumstellar shells on the sky. Now it is possible to image resonance scattering from infrared vibration-rotational carbon monoxide lines (see Ryde et al. A& A 347, L35, 1999). Infrared CO is formed closer to the star than microwave CO and provides complementary information. Infrared CO mapping is especially powerful because many CO lines of differing excitation are present, allowing the extraction of excitation temperature and abundance from the measured column densities. Previous on-star observations have led to the detection of multiple velocity components in the CO lines, formed in different parts of the circumstellar shell. We have found in an earlier observing run with this method that the shell of CO gas around Mira (4 arcsec-10 arcsec from the star) is spherically symmetric and homogeneous. But we also trace from the data a region close to the star devoid of gas or at least of CO (Ryde et al. ApJ, soon to be submitted). Each CO line can be used to image the circumstellar outflow at different stellar radii. Information on the velocity structure and the development of clumps in the flow will be extracted. The present proposal focuses on the study of shells around carbon stars for which we have complementary mm and optical data. We will furthermore for the first time map detached shells with this method.
Eriksson Kjell
Gustafsson Bengt
Lambert David L.
Olofsson Hans
Ryde Nils
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