Warm water vapour in the sooty outflow from a luminous carbon starPublication date: 01 Sep 2010 Authors: Decin, L. et al.
Journal: Nature Copyright: © 2010 Nature Publishing Group The detection of circumstellar water vapour around the ageing carbon star IRC +10216 challenged the current understanding of chemistry in old stars, because water was predicted to be almost absent in carbon-rich stars. Several explanations for the water were postulated, including the vaporization of icy bodies (comets or dwarf planets) in orbit around the star, grain surface reactions, and photochemistry in the outer circumstellar envelope. With a single water line detected so far from this one carbon-rich evolved star, it is difficult to discriminate between the different mechanisms proposed. Here we report the detection of dozens of water vapour lines in the far-infrared and sub-millimetre spectrum of IRC +10216 using the Herschel satellite. This includes some high-excitation lines with energies corresponding to ~1000 K, which can be explained only if water is present in the warm inner sooty region of the envelope. A plausible explanation for the warm water appears to be the penetration of ultraviolet photons deep into a clumpy circumstellar envelope. This mechanism also triggers the formation of other molecules, such as ammonia, whose observed abundances are much higher than hitherto predicted.
Last Update: 02 Sep 2010
|
- Missions
- Show All Missions
- Mission Home
- Summary
- Fact Sheet
- Objectives
- Participants
- Mission Team
- Industrial Team
- Spacecraft
- 3D Model
- Instruments
- Test Campaign
- Mission Operations
- Launch Information
- Orbit/Navigation
- Launch Vehicle
- Launch Campaign
- Status Reports
- Science Operations
- Science Ground Segment
- Data Archive
- Astronomers' Website
- Outreach Resources
- Resources
- News Archive
- Multimedia Gallery
- Publication Archive
- Status Report Archive
- Calendar of Events
- Services
- Contact Us
- Subscribe
- Terms and Conditions
