Results 11 to 20 of about 335 (184)
Planetary Nebulae with Binary Nuclei [PDF]
Symposium - International Astronomical Union, 1993 High resolution images of planetary nebulae have revealed a variety of non-spherical morphologies. In addition, some planetary nebulae were found to produce highly collimated jets. It is argued that binary central stars may play a crucial role in the production of all of these morphologies.
Mario Livio
core +3 more sources
Nuclei of Planetary Nebulae [PDF]
Symposium - International Astronomical Union, 1973 In 1969 Aller and I collected information about the spectra of emission-line nuclei of planetary nebulae. (See also Aller, 1967, for classification of both emission and absorption spectra.) We classified them and compared them to the spectra of Population I stars. Our idea was to follow this general classification by detailed observation and comparison
Lindsey F. Smith
openaire +2 more sources
Planetary Nebulae with Massive Nuclei [PDF]
Symposium - International Astronomical Union, 1983 Massive central stars (M > 1 Mo) of planetary nebulae burn nuclear fuel on a time scale of hundreds or tens of years which is shorter than the recombination time in a typical planetary nebula. Consequently the ionization and thermal structure of a nebula with such a nucleus is expected to be far from equilibrium conditions.
R. Tylenda
openaire +2 more sources
Revealing the ionising star of evolved planetary nebulae [PDF]
, 2023 Context. Planetary nebulae represent a late stage of the evolution of stars of ordinary mass. The nucleus of a planetary nebula, a stellar remnant, is a faint star for which it is usually difficult to gather spectroscopic data.
K. Werner +9 more
core +1 more source
Apparent Magnitudes of Planetary Nebulae Nuclei [PDF]
Symposium - International Astronomical Union, 1983 B and V magnitudes for the central stars of a number of planetary nebulae are presented. The observations were obtained between 1971 and 1981 with the University of Illinois one-meter telescope at Prairie Observatory. The average magnitudes presented are accurate extractions of the stellar continuum flux from the total (stellar plus nebular) measured ...
R. A. Shaw, J. R. Kaler
openaire +2 more sources
A Catalog of Candidate Double and Lensed Quasars from Gaia and WISE Data
The Astrophysical Journal Supplement Series, 2022 Making use of strong correlations between closely separated multiple or double sources and photometric and astrometric metadata in Gaia Early Data Release 3 (EDR3), we generate a catalog of candidate double- and multiply imaged lensed quasars and active ...
Valeri V. Makarov, Nathan J. Secrest
doaj +1 more source
The Formation of Planetary Nebulae with Close Binary Nuclei [PDF]
Monthly Notices of the Royal Astronomical Society, 1979 Recent observations of nuclei of planetary nebula have shown that some of the central stars are binaries and even close binaries with periods of hours to few days.
J. Saltzman, M. Livio, G. Shaviv
openaire +2 more sources
Quantitative classification of [WC] nuclei of Planetary Nebulae [PDF]
Symposium - International Astronomical Union, 1997 We have carried out spectral classification of 65 [WC] stars, using spectra obtained at ESO in 1994-1995 with a spectral resolution of 1500 and high signal to noise ratio. We quantify the visual classification, by using the line ratios of CIII, CIV, OV, OVI in the 530-580 nm range, correlated with the blue CIII - IV lines.
A. Acker +4 more
openaire +1 more source
Close-Binary Nuclei of Planetary Nebulae [PDF]
Symposium - International Astronomical Union, 1992 Close-binary planetary-nebula nuclei (PNNs) provide direct evidence for occurrence of a common-envelope phase in binary-star evolution. Their descendants are V471 Tauri-type detached binaries, cataclysmic binaries, and possibly Type I supernovae. Thirteen close-binary PNNs are now known from periodic photometric or radial-velocity variations, or from ...
Howard E. Bond +2 more
openaire +1 more source
Spectroscopy of planetary nebulae with [WR] nuclei [PDF]
Symposium - International Astronomical Union, 1999 We have started an extensive program of systematic observations of planetary nebulae excited by [WR] nuclei with the aim of understanding the evolutionary status of the central stars. Detailed analysis of the nebular and stellar properties might reveal the presence of abundance variations across the nebulae, and allows to detect possible interactions ...
Pena, M. +5 more
openaire +2 more sources