相关论文: Angular dimensions of planetary nebulae
In this review/tutorial we explore planetary nebulae as a stage in the evolution of low-to-intermediate-mass stars, as major contributors to the mass and chemical enrichment of the interstellar medium, and as astrophysical laboratories. We…
Diagnostic diagrams of electron density - excitation for a sample of 613 planetary nebulae are presented. The present extensive sample allows the definition of new statistical limits for the distribution of planetary nebulae in the log…
(Abridged) In the first part of this thesis, a general methodology for applying image deconvolution to wide-field CCD imagery. Results show that wavelet-based deconvolution can increase limiting magnitude up to 0.6 mag and improve limiting…
New observations and derived chemical abundances are reported for a sample of 57 bulge planetary nebulae (PN). Together with our previous results, a total of over a hundred objects have been analyzed, which constitute one of the largest…
We present ESO NTT high resolution echelle spectroscopy of the central stars (CSs) of eight southern bipolar planetary nebulae (PNe) selected for their asymmetry. Our aim was to determine or place limits on the magnetic fields of the CSs of…
I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. There are two broad categories of measurements. The first…
Optical integral-field spectroscopy was used to investigate the planetary nebula NGC 3242. We analysed the main morphological components of this source, including its knots, but not the halo. In addition to revealing the properties ofthe…
We present the Halpha imaging observations of 273 late-type galaxies in the nearby rich galaxy clusters Virgo, A1367, Coma, Cancer, Hercules and in the Great Wall, carried out primarily with the 2.1m telescope of the San Pedro Martir…
We present an advance in the use of Cassini observations of stellar occultations by the rings of Saturn for stellar studies. Stewart et al. (2013) demonstrated the potential use of such observations for measuring stellar angular diameters.…
The bright, well-known K5 giant Aldebaran, alpha Tau, is probably the star with the largest number of direct angular diameter determinations, achieved over a long time by several authors using various techniques. In spite of this wealth of…
We have constructed a grid of photoionization models of spherical, elliptical and bipolar planetary nebulae. Assuming different velocity fields, we have computed line profiles corresponding to different orientations, slit sizes and…
Very recently, the discovery of the largest known planetary nebula on the sky surrounding the DO white dwarf PG1034+001 with an apparent diameter of about 2 degrees, corresponding to a linear diameter of 3.5 - 7.0 pc at the likely distance…
The determination of reliable distances to Planetary Nebulae (PNe) is one of the major limitations in the study of this class of objects in the Galaxy. The availability of new photometric surveys such as IPHAS covering large portions of the…
It is attempted to obtain the masses of the celestial bodies, the initial conditions of their motion, and the constant of gravitation, by a global parameter optimization. First, a numerical solution of the N-bodies problem for mass points…
Light from `point sources' such as supernovae is observed with a beam width of order of the sources' size - typically less than 1 AU. Such a beam probes matter and curvature distributions that are very different from coarse-grained…
We carry out plasma diagnostic analyses for 123 planetary nebulae (PNe) and 42 H II regions using the N II and O II optical recombination lines (ORLs). New effective recombination coefficients for the N II and O II optical recombination…
ISO and IUE spectra of the round planetary nebula Me 2-1 are combined with visual spectra taken from the literature to obtain for the first time a complete extinction-corrected spectrum. With this, the physico-chemical characteristics of…
Context. We have compiled a catalogue of central stars of planetary nebulae (CSPN) with reliable distances and positions obtained from Gaia Data Release 2 (DR2) astrometry. Distances derived from parallaxes allow us to analyse the galactic…
The propagation of a shock wave into a medium is expected to heat the material beyond the shock, producing noticeable effects in intensity line ratios such as [O III]/Halpha. To investigate the occurrence of shocks in planetary nebulae…
We observed the large and faint planetary nebula (PN) around IN Com in H-alpha and [NII] light with a coronagraphic CCD device on the Wise Observatory reflector blocking the light from the central star. Our goal was to provide a second…