Results 21 to 30 of about 6,433 (179)
Recalibrating the Wide-field Infrared Survey Explorer (WISE) W4 Filter [PDF]
, 2014 We present a revised effective wavelength and photometric calibration for the Wide-field Infrared Survey Explorer (WISE) W4 band, including tests of empirically motivated modifications to its pre-launch laboratory-measured relative system response curve.
Brown, M. J. I. +2 more
core +2 more sources
The Abundances of Light Neutron-Capture Elements in Planetary Nebulae [PDF]
, 2006 We present preliminary results from a large-scale survey of the neutron(n)-capture elements Se and Kr in Galactic planetary nebulae (PNe). These elements may be produced in PN progenitors by s-process nucleosynthesis, and brought to the stellar envelope ...
Dinerstein, Harriet L., Sterling, N. C.
core +2 more sources
CCD Images of Three Planetary Nebulae With Binary Nuclei [PDF]
Symposium - International Astronomical Union, 1989 A 14, H 3-75 and K 1-2, three planetary nebulae with binary nuclei, were imaged with narrow-band [N II], Ha, [O III] and He II filters by using the TI CCD chip on the 0.9-m telescope at CTIO. The purpose of doing the observing was to see if planetaries with known binary nuclei exhibit particularly peculiar morphologies.
Julie Lutz, Nancy Jo Lame
openaire +1 more source
Fluorescent Excitation of Spectral Lines in Planetary Nebulae [PDF]
, 2000 Fluorescent excitation of spectral lines is demonstrated as a function of temperature-luminosity and the distance of the emitting region from the central stars of planetary nebulae.
Ahern F. J. +12 more
core +3 more sources
Binary Nuclei of Planetary Nebulae [PDF]
Symposium - International Astronomical Union, 1978 In view of the spectral similarity and the probable evolutionary relation between certain planetary nebulae (PN) and other objects that are generally binaries (symbiotic stars, Be stars, or slow novae), it is probable that many nuclei of PN are double.
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
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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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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 ...
openaire +1 more source
Abell-35 Phenomena in Symbiotic Stars: Discovery of 1.2 and 6.4 Day Periods in VV8 (V471 Per)
Open Astronomy, 2012 We have collected high precision optical photometry of VV8, so far 782 individual observing runs uniformly distributed over the period 2005 - 2011. This dataset allows us to refine the known long periodicity of VV8 to P = 16.8 yr, with peak-to-valley ...
Munari U. +10 more
doaj +1 more source
Atoms, 2014 We review studies of two kinds of dips in spectral line profiles emitted by plasmas—dips that have been predicted theoretically and observed experimentally: Langmuir-wave-caused dips (L-dips) and charge-exchange-caused dips (X-dips). There is a principal
Elisabeth Dalimier +2 more
doaj +1 more source