Related papers: Maser emission in planetary nebulae

We intended to study the incidence and characteristics of water masers in the envelopes of stars in the post-AGB and PN evolutionary stages. We have used the 64-m antenna in Parkes (Australia) to search for water maser emission at 22 GHz,…

Observations of H$_2$O masers towards the post-AGB star and water fountain source OH 009.1--0.4 were made as part of HOPS (The H$_2$O southern galactic Plane Survey), with the Mopra radiotelescope. Together with followup observations using…

Early-type galaxies possess a dilute hot (2-10E6 K) gas that is probably the thermalized ejecta of the mass loss from evolving stars. We investigate the processes by which the mass loss from orbiting stars interacts with the stationary hot…

We present Spitzer/IRS observations of a small sample of heavily obscured IRAS sources displaying both the infrared and OH maser emission characteristic of OH/IR stars on the asymptotic giant branch (AGB), but also radio continuum emission…

Planetary nebulae are formed by the matter ejected by low-to-intermediate mass stars (~0.8-8 times the mass of the Sun) towards the end of their lives. As hydrogen and then helium fuel sources run out, stars expand. During these giant…

Aim: The late stages of stellar evolution are mainly governed by the mass of the stars. Low- and intermediate-mass stars lose copious amounts of mass during the asymptotic giant branch (AGB) which obscure the central star making it…

Most of PNe are not spherical. The loss of spherical symmetry occurs somewhere between the AGB and PN phase. The cause of this change of morphology is not yet well known, but magnetic fields are one of the possible agents. Its origin…

A sensitive search for 6.7--GHz methanol maser emission has been made towards 10 galaxies that have yielded detectable microwave molecular--line transitions. These include several which show OH megamaser or superluminous \water\/ maser…

With the VLBA, we have observed water masers associated with the OH/IR star, W43A, which trace a birth and growth of a molecular jet. The water masers exhibit the collimated distribution (1700 AU: 20 AU) and fast motions (+/-150 km/s). The…

The high mass loss rates of stars in their asymptotic giant branch (AGB) stage of evolution is one of the most important pathways for mass return from stars to the ISM. In the planetary nebulae (PNe) phase, the ejected material is…

Water maser emitting planetary nebulae (H$_2$O-PNe) are believed to be among the youngest PNe. We present new optical narrow- and broad-band images, intermediate- and high-resolution long-slit spectra, and archival optical images of the…

We conducted radio observations searching for OH 18-cm maser emission from a sample of 169 unclassified MIPSGAL compact Galactic bubbles. These sources are thought to be the circumstellar envelopes of different kinds of evolved stars. Our…

We report on OH maser emission toward G336.644-0.695 (IRAS 16333-4807), which is a H2O maser-emitting Planetary Nebula (PN). We have detected 1612, 1667 and 1720 MHz OH masers at two epochs using the Australia Telescope Compact Array…

An astrophysical MASER (Microwave Amplification by Stimulated Emission of Radiation) is a source of stimulated spectral line emission. Maser emission is observed from the circumstellar envelopes of evolved stars, molecular…

K 3-35 is a planetary nebula (PN) where H2O maser emission has been detected, suggesting that it departed from the proto-PNe phase only some decades ago. Interferometric VLA observations of the OH 18 cm transitions in K~3-35 are…

We report the detection of nebular emission lines in the optical and mid-infrared spectra of IRAS 17347-3139, a heavily obscured OH/IR star which may be rapidly evolving from the AGB to the PN stage. The presence of emission lines is…

The aim of this study is to investigate the physical properties of molecular envelopes of planetary nebulae in their earliest stages of evolution. Using the 100m telescope at Effelsberg, we have undertaken a high sensitivity discrete source…

We report the results of a multi-epoch survey of water maser observations at 22.2 GHz with the Medicina radiotelescope from 44 bright rimmed clouds (BRCs) of the northern hemisphere identified by Sugitani et al. (1989) as potential sites of…

We present radio continuum observations of the planetary nebula (PN) IRAS 17347-3139 (one of the only two known to harbour water maser emission), made to derive its spectral index and the turnover frequency of the emission. The spectrum of…

The evolution of asymptotic giant branch stars from the spherical symmetry into the diverse shapes of planetary nebulae (PNe) is a topic of intensive research. Young PNe provide a unique opportunity to characterize the onset of this…