Related papers: Precessing collimated outflows in the planetary ne…
Many round or nearly roundish Planetary Nebulae (PNe) show multiple shells and halo structures during their evolutionary stage near the maximum temperature of their central star. Controversial debate is currently ongoing if these structures…
We present the results of differential proper-motion analyses of the Egg Nebula (RAFGL 2688, V1610 Cyg) based on the archived two-epoch optical data taken with the Hubble Space Telescope. First, we determined that the polarization…
(Abridged) We present narrow-band images in several emission lines, and high- and intermediate-resolution long-slit spectra of Me2-1 to investigate its morphology and 3D structure, its physical parameters and chemical abundances. We…
Most stars form in binaries, and both stars may grow by accreting material from a circumbinary disc onto their personal discs. We suspect that in many cases a wide molecular wind will envelope a collimated atomic jet emanating from close to…
We report optical long-slit spectra and direct imaging (ground-based and with HST) of the pre-planetary nebula (pPN) M2-56 obtained at different epochs. The optical nebula is composed by shock-excited material distributed in two pairs of…
We present interferometric observations in the 12CO (2-1) line and at 1.3 mm dust continuum of the low-mass protostellar binary system in the cometary globule CG30, using the Submillimeter Array. The dust continuum images resolve two…
This paper presents new near-infrared observations of the planetary nebula NGC 2346. The data include a broad K-band image, an image in the H2 vibrationally excited 1-0S(1) line and K band slit spectra at three positions in the nebula. In…
Studying outflows is important as they may significantly contribute to angular momentum removal from the star/disk system, affecting disk evolution and planet formation. To investigate the different outflow components; the collimated jet,…
We analyse the point-symmetric planetary nebula NGC 6309 in terms of its three-dimensional structure and of internal variations of the physical conditions to deduce the physical processes involved in its formation. We used VLA-D 3.6-cm…
Spatially resolved profiles of the Halpha and [NII] lines have been obtained at unprecendented signal--to--noise ratios over the outflowing lobes of the high--excitation, poly--polar planetary nebula NGC~6302. A deep image in the light of…
Asymmetric shapes and evidence for binary central stars suggest a common-envelope origin for many bipolar planetary nebulae. The bipolar components of the nebulae are observed to expand faster than the rest and the more slowly expanding…
In this paper we present the results of optical high-resolution imaging and spectroscopy of the complex planetary nebula (PN) NGC~3242. Our study is based on the analysis of the narrowband H$\alpha$ $\lambda$6563\AA , [O III]…
We present an extensive, long-slit, high-resolution coverage of the complex planetary nebula (PN), NGC 7026. We acquired ten spectra using the Manchester Echelle Spectrometer at San Pedro Martir Observatory in Baja California, Mexico, and…
We present the results of numerical hydrodynamic models for the collimation of outflows from young stellar objects. We show that the presence of a toroidal environment can lead to efficient formation of jets and bipolar outflows from…
A highly and rapidly variable bipolar mass outflow from StHa 190 has been discovered, the first time in a yellow symbiotic star. Permitted emission lines are flanked by symmetrical jet features and multi-component P-Cyg profiles, with…
CRL 618 is a well-studied pre-planetary nebula. It has multiple highly collimated optical lobes, fast molecular outflows along the optical lobes, and an extended molecular envelope that consists of a dense torus in the equator and a tenuous…
Most bipolar outflows are associated with individual young stellar objects and have small opening angles. Here we report the discovery of an extremely wide-angle ($\sim$180$\arcdeg$) bipolar outflow ("EWBO") in a cluster forming region AFGL…
Many aspects of the evolutionary phase in which Asymptotic Giant Branch stars (AGB stars) are in transition to become Planetary Nebulae (PNe) are still poorly understood. An important question is how the circumstellar envelopes of AGB stars…
We study the molecular gas content and distribution in the Coma cluster spiral galaxy NGC 4848. Plateau de Bure interferometric CO(1-0) observations reveal a lopsided H_2 distribution with an off-center secondary maximum coincident with the…
M1-92 can be considered an archetype of bipolar pre-planetary nebulae. It shows a clear axial symmetry, along with the kinematics and momentum excess characteristic of this class of envelopes around post-AGB stars. By taking advantage of…