|6th of March 2015|
|The first "water fountain" in a planetary nebula|
|by José-Francisco Gómez (Instituto de Astrofísica de Andalucía, CSIC, Granada, Spain)|
|Gómez et al. (2015) have used the Australia
Telescope Compact Array (ATCA) to map the water maser emission in IRAS
15103-5754, an object that has just become a planetary nebula. Its water
maser emission spreads over a large velocity range (75 km/s) and most
of it traces a collimated jet aligned with the infrared nebula. This is
characteristic of a special type of evolved stars called "water fountains".
IRAS 15103-5754 is the first known case of a water fountain that is
already a planetary nebula (all others are in previous evolutionary stages.
However, the velocity pattern of masers is different from that in other
water fountains: it is consistent with a short-lived, explosive event,
rather than with a steady jet. This suggests a fundamental change in the
characteristics of mass-loss as a star enters the planetary nebula phase.
The figure represents the maser components (crosses) superposed on a mid-infrared image (at 12.81 microns) obtained with the Very Large Telescope (VLT) by Lagadec et al. (2011).
Credits: 2015. The American Astronomical Society.