A sample of planetary nebulae observed by HIPPARCOS
نویسنده
چکیده
By using HIPPARCOS data (magnitudes, parallaxes, proper motions), (1) we determine new values of the apparent luminosity of the central stars of 19 planetary nebulae, (2) we discuss their distance and position on the T/L diagram. By comparison with the distances determined by individual or statistical methods, we see that most of these “ground” distances look overestimated when we trust the HIPPARCOS trigonometric parallaxes. It seems that for compact nebulae, the nebula itself could influence the parallax measurement. In particular, the very small HIPPARCOS distances to SwSt 1 and Hu 2-1 are unexpected and are not trustworthy. Peculiar motions are analyzed, in terms of astrophysical parameters of the binary system A 35, and in relation with asymmetric morphology.
منابع مشابه
Letter to the Editor A comparison of Hipparcos parallaxes with planetary nebulae spectroscopic distances
The Hipparcos satellite has measured the parallax of a small sample of planetary nebulae. In this paper we consider the results for 3 planetary nebulae (PN) for which spectroscopic distances have also been determined from stellar gravities. These gravities in turn have been derived fromprofile fitting of selected hydrogen and helium lines (Mendez et al., 1988 a, b, 1992). A comparison of these ...
متن کاملRadial velocities of planetary nebulae towards the Galactic bulge
Accurate radial velocities for a sample of 71 planetary nebulae, mostly located in the direction of the Galactic Centre, are presented. Most of the nebulae discussed in this paper are likely members of the Galactic bulge, based on their radial velocity, longitude and derived distance. The data give a large improvement over existing catalogues, doubling the sample of bulge planetary nebulae with...
متن کاملInternational Ultraviolet Explorer satellite observations of seven high-excitation planetary nebulae.
Observations of seven high-excitation planetary nebulae secured with the International Ultraviolet Explorer (IUE) satellite were combined with extensive ground-based data to obtain electron densities, gas kinetic temperatures, and ionic concentrations. We then employed a network of theoretical model nebulae to estimate the factors by which observed ionic concentrations must be multiplied to obt...
متن کاملObserved Planetary Nebulae as Descendants of Interacting Binary Systems
We examine recent studies on the formation rate of planetary nebulae and find this rate to be about one-third of the formation rate of white dwarfs. This implies than only about one-third of all planetary nebulae that evolve to form white dwarfs are actually bright enough to be observed. This finding corresponds with the claim that it is necessary for a binary companion to interact with the asy...
متن کاملNarrow - Band Imaging of Bipolar Planetary Nebulae
We present near-IR narrow-band continuum-subtracted images in the H2 2:122 m, and Br 2:166 m emission lines for a sample of 15 bipolar planetary nebulae. H2 emission was definitely detected for most of the objects in this sample (13 out of 15). The very high H2 detection rate supports the idea that bipolar planetary nebulae have important reservoirs of molecular material and offer suitable phys...
متن کامل