Astronomy and Astrophysics – Astrophysics
Scientific paper
2006-05-19
Astrophys.J.649:965-972,2006
Astronomy and Astrophysics
Astrophysics
Accepted for publication in ApJ, 9 pages, 9 figures
Scientific paper
10.1086/506199
New interferometric observations of SiO J=5-4 circumstellar line emission around the carbon star IRC+10216, using the Submillimeter Array, are presented. Complemented by multi-transition single-dish observations, including infrared observations of ro-vibrational transitions, detailed radiative transfer modelling suggests that the fractional abundance of SiO in the inner part of the envelope, between approximately 3-8 stellar radii, is as high as 1.5E-6. This is more than an order of magnitude higher than predicted by equilibrium stellar atmosphere chemistry in a carbon-rich environment and indicative of the importance of non-LTE chemical processes. In addition to the compact component, a spatially more extended (2.4E16 cm) low-fractional-abundance (1.7E-7) region is required to fit the observations. This suggests that the majority of the SiO molecules are effectively accreted onto dust grains in the inner wind while the remaining gas-phase molecules are eventually photodissociated at larger distances. Evidence of departure from a smooth wind is found in the observed visibilities, indicative of density variations of a factor 2 to 5 on an angular scale corresponding to a time scale of about 200 years. Additionally, constraints on the velocity structure of the wind are obtained.
Fong Dave
Olofsson Hans
Patel Nilanchal
Schoeier Fredrik L.
Zhang Qian
No associations
LandOfFree
The distribution of SiO in the circumstellar envelope around IRC+10216 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The distribution of SiO in the circumstellar envelope around IRC+10216, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The distribution of SiO in the circumstellar envelope around IRC+10216 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-352865