Luis F. Miranda

A complete survey of mm line emission from CO and 13CO in water fountain stars

“Water fountains” (WF) are post-AGB stars characterized by very fast and often bipolar jets in the water maser line at 22 GHz. We conducted a survey of the CO and 13 CO line emission using the IRAM 30m radio telescope of all the sources visible from the observatory. Over a total of 10 WFs observed, we identified CO and 13 CO associated to IRAS 18460-0151 and IRAS 18596+0315. As the CO line emission is ubiquitous in the Galactic plane, the confirmed detections have met strict criteria to consider these cases as confirmed detections. The velocity components associated to the WFs are ~ 40 km s −1 wide, centered at the star velocity, present only at the star position, and detected in the four observed transitions, the CO and 13 CO J =1→0 and 2→1 lines. A preliminary study, based on line ratios, indicates that this molecular component has a high opacity, and a very low 12 C/ 13 C isotopic ratio.

Kn 26: a textbook case hourglass planetary nebula with a twist

Kn 26 is a recently identified planetary nebula (PN). To confirm its nature and study its spatio-kinematical structure, we have obtained high spatial-resolution optical and near-IR narrowband images, high-dispersion long-slit echelle spectra, and intermediate-resolution spectroscopic observations. The new data confirm the PN nature of Kn 26 and reveal features typical of bipolar PNe: hourglass morphology, H 2 emission, and nitrogen enrichment. A detailed analysis of its morphology and kinematics, however, suggests the presence of one additional pair of bipolar lobes that would make Kn 26 a new member of the class of quadrupolar PNe.