Related papers: The Origin of the Consistent Planetary Nebula Lumi…

Low-ionization nuclear emission-line regions (LINERs), which exist in a large fraction of galaxies, may be the least luminous manifestation of quasar activity. The nature of LINERs has, however, remained controversial because an AGN-like…

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…

We make new Non-LTE calculations to deduce abundances of neon from visible-region echelle spectra of selected Ne I lines in 7 normal stars and 20 HgMn stars. We find that the best strong blend-free Ne line which can be used at the lower end…

(Abridged) Planetary nebulae (PNe) around Wolf-Rayet [WR] central stars ([WR]PNe) constitute a particular photoionized nebula class that represents about 10% of the PNe with classified central stars. We analyse deep high-resolution…

Planetary Nebulae (PNe) abundance patterns have long been used to note signatures of nuclear processing and to trace the distribution of metals throughout galaxies. We present abundance gradients and heavy element ratios based upon newly…

We present images and spectra of a ~10 kpc-sized emission-line nebulosity discovered in the prototypical merger remnant NGC 7252 and dubbed the `[O III] nebula' because of its dominant [O III]_5007 line. This nebula seems to yield the first…

We present a homogeneous set of spectroscopic measurements secured with 4-meter class telescopes for a sample of 90 planetary nebulae (PNe) located in the direction of the Galactic bulge. We derive their plasma parameters and chemical…

We measure the rest-frame UV luminosity function (LF) at $z \sim 4$ self-consistently over a wide range in absolute magnitude ($-27 \lesssim M_{\rm UV} \lesssim -20$). The LF is measured with 46,904 sources selected using a photometric…

We present spectroscopy of three planetary nebulae (PNe) in the Northern Spur of the Andromeda Galaxy (M31) obtained with the Double Spectrograph on the 5.1 m Hale Telescope at the Palomar Observatory. The samples are selected from the…

We obtained [O III] narrow-band imaging and multi-slit MXU spectroscopy of the blue compact dwarf (BCD) galaxy NGC 1705 with FORS2@VLT to derive chemical abundances of PNe and H II regions and, more in general, to characterize the…

The recent HST optical images, and the optical and ultraviolet spectra, of Magellanic planetary nebulae (PNe), together with the large data-base that has been collected in the past decade, allows unprecedented insight in the evolution of…

The cluster and field luminosity functions (LFs) determined on large homogeneous samples (N>2200 galaxies each) are almost indistinguishable, down to M^*+4 in the r and i filters, hence suggesting that the effect of the cluster environment…

Chandra X-ray Observatory (CXO) images have revealed that the X-ray emitting regions of the molecule-rich young planetary nebulae (PNs) BD+30 3639 (BD+30) and NGC 7027 are much more asymmetric than their optical nebulosities. To evaluate…

We perform a systematic study of outflow in the narrow-line region (NLR) of active galactic nuclei (AGNs) at $z\sim0.4-0.8$ basing upon a large sample of $\sim900$ quasars at $z\sim 0.4-0.8$. The sample is extracted from the Sloan Digital…

This work presents the properties of 42 objects in the group of the most luminous, highest star formation rate LINERs at z = 0.04 - 0.11. We obtained long-slit spectroscopy of the nuclear regions for all sources, and FIR data (Herschel and…

We have made the first detections of the 88 micron [OIII] line from galaxies in the early Universe, detecting the line from the lensed AGN/starburst composite systems APM 08279+5255 at z = 3.911 and SMM J02399-0136 at z = 2.8076. The line…

We investigate the origin of extragalactic continuum emission and its relation to the stellar population of a recently discovered peculiar z=3.344 Lyman alpha emitter. Based on an analysis of the broad-band colors and morphology we find…

We have studied the relationship between the [O IV] lambda 25.89 micron emission line luminosities, obtained from Spitzer spectra, the X-ray continua in the 2-10 keV band, primarily from ASCA, and the 14-195 keV band obtained with the…

The presentation of new results from an [O III] 5007 A survey in a search for planetary nebulae (PNe) in the galactic bulge is continued. A total of 60 objects, including 19 new PNe, have been detected in the remaining 34 per cent of the…

Bipolar planetary nebulae (PNe) are thought to result from binary star interactions and, indeed, tens of binary central stars of PNe have been found, in particular using photometric time-series that allow detecting post-common envelope…