Related papers: The Classification of M1-78
Planetary nebulae are traditionally considered to represent the final evolutionary stage of all intermediate-mass stars ($\sim$0.7-8Msol). Recent evidence seems to contradict this picture. In particular, since the launch of the Hubble Space…
This review discussed near- and mid- infrared observations of ultracompact (UC) HII regions. The importance of ISO mid-IR fine-structure nebular lines is emphasised since only a small fraction of UCHII regions are observed directly in the…
The results of long-term spectral observations were used to search for changes in planetary nebulae and emission-line stars. Significant increase of excitation degree is found in two objects: M1-6 and M1-11.
We present a brief review on the formation and evolution of hydrogen deficient central stars of planetary nebulae. We include a detailed description of the main observable features of both the central stars and their surrounding nebulae and…
We present 2 to 2.4 micron integral field spectroscopy of a sample of hot post-AGB stars with early-B spectral types, using the NIFS instrument on Gemini North. These stars are just beginning to ionize their immediate environments and turn…
Context. There are more than 3000 known Galactic planetary nebulae (PNe), but only 492 central stars of Galactic planetary nebulae (CSPN) have known spectral types. It is vital to increase this number in order to have reliable statistics,…
Close binary central stars of planetary nebulae are key in constraining the poorly-understood common-envelope phase of evolution, which in turn is critical in understanding the formation of a wide-range of astrophysical phenomena (including…
We present the discovery and characterisation of the post-common-envelope central star system in the planetary nebula PN G283.7$-$05.1. Deep images taken as part of the POPIPlaN survey indicate that the nebula may possess a bipolar…
Mid-IR observations of planetary nebulae (PNe) have revealed diffuse emission associated to their main nebular shells and outer envelopes or haloes. The interpretation of this emission is uncertain because the broad-band mid-IR images may…
Radio continuum observations trace thermal emission of ionized plasma in planetary nebulae and bring useful information on nebular geometries. A model of homogeneous sphere or shell cannot fit the nebular spectra and brightness…
We have analyzed ISO SWS 01 observations for 61 proto-planetary nebulae candidates and classified their spectra according to their dominant chemistry. On the basis of our classification and the more general classification of SWS 01 spectra…
We present narrow-band optical and near-IR imaging and optical long-slit spectroscopic observations of Hu1-2, a Galactic planetary nebula (PN) with a pair of [N II]-bright, fast-moving (> 340 km/s) bipolar knots. Intermediate-dispersion…
The Planetary Nebula (PN) population of M33 is studied via multi-fiber spectroscopy with Hectospec at the MMT. In this paper we present the spectra of 102 PNe, whereas plasma diagnostic and chemical abundances were performed on the 93 PNe…
We compile published spectroscopic data and [O III] magnitudes of almost 500 extragalactic planetary nebulae (PNe) in 13 galaxies of various masses and morphological types. This is the first paper of a series that aims to analyze the PN…
In this paper we present a re-analysis of the criteria used to characterize the Peimbert classes I, IIa, IIb, III and IV, through a statistical study of a large sample of planetary nebulae previously classified according to these groups. In…
The link between the shaping of bipolar planetary nebulae and their central stars is still poorly understood. The kinematics and shaping of the multipolar nebula M 1-75 are hereby investigated, and the location and nature of its central…
We summarize the status of our program of near-infrared adaptive optics observations of ultracompact HII regions. By means of selected results we demonstrate the usefulness of this technique for disentangling the complexity of massive…
We have obtained deep optical spectrophotometry of 16 planetary nebulae in M33, mostly located in the central two kpc of the galaxy, with the Subaru and Keck telescopes. We have derived electron temperatures and chemical abundances from the…
Super Star Clusters are one of the most extreme star forming environments in the universe, and the most massive and dense of these may be proto globular clusters. Like individual massive stars, the earliest stages of super star cluster…
While most of the low-mass stars stay hydrogen-rich on their surface throughout their evolution, a considerable fraction of white dwarfs as well as central stars of planetary nebulae have a hydrogen-deficient surface composition. The…