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Statistical equilibrium of O and CO in disks around young A stars

Published online by Cambridge University Press:  26 May 2016

Inga Kamp  and
Gerd-Jan van Zadelhoff
Inga Kamp
Affiliation:
Leiden Observatory, PO Box 9513, 2300 RA Leiden, The Netherlands
Gerd-Jan van Zadelhoff
Affiliation:
Leiden Observatory, PO Box 9513, 2300 RA Leiden, The Netherlands

Abstract

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The frequently made assumption that gas and dust temperatures are equal cannot be applied to the low density disks (104 cm−3 < ntot < 108 cm−3) around young A stars (“Vega-type” stars), because the collisional coupling is too weak. It turns out that OI fine structure lines and CO rotational lines are two very important cooling terms in the heating/cooling balance for the gas. Their level population numbers are far from LTE and depend strongly on the background radiation field, given by the thermal dust emission of the disk and the cosmic microwave background.

Type
Part IV: Protoplanetary and β Pic disks
Information
Symposium - International Astronomical Union , Volume 202: Planetary Systems in the Universe – Observation, Formation and Evolution , 2004 , pp. 344 - 346
Copyright
Copyright © Astronomical Society of the Pacific 2004 

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