Results 11 to 20 of about 163 (129)
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.B. Kaler
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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
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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
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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
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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
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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
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Spectroscopic observations of nuclei of planetary nebulae [PDF]
Symposium - International Astronomical Union, 1984 Up to date, 1518 true, possible, and probable planetary nebulae (PN) are known in our Galaxy; 463 nuclei (NPN) were observed. For about 150 stars, a spectral study has been done; only about 30 NPN have a well studied spectrum. (Acker, Gleizes et al, 1982 “Catalogue of the central stars of true and possible PN”) It must be remembered that this is a ...
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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.
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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
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Temperatures and Luminosities of Planetary Nebulae Nuclei [PDF]
Symposium - International Astronomical Union, 1989 The location of Planetary Nebulae Nuclei (PNNi) on the H-R diagram is a very important clue to understand the evolution of these objects.
Luciana Bianchi +2 more
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