Results 11 to 20 of about 6,433 (179)

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

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.
openaire   +1 more source

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, M. Parthasarathy, W. Leindecker, J. Koeppen, B. Stenholm   +4 more
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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
openaire   +1 more source

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.
openaire   +1 more source

Luminosity indicators in dusty photoionized environments [PDF]

, 1998
The luminosity of the central source in ionizing radiation is an essential parameter in a photoionized environment, and one of the most fundamental physical quantities one can measure.
Dejan  Vinković, Ekaterina  Verner, Emmanuel  Momjian, Engelbracht C. W., Gary  Ferland, Hummer D., Joseph  LaMothe, Mark  Bottorff, Oliveira S. A., Storey P. J., van de Steene G. C.   +10 more
core   +2 more sources

SBS 1150+599A: an extremely oxygen-poor planetary nebula in the Galactic halo? [PDF]

, 2001
We report results of a spectrophotometric study of SBS 1150+599A and discuss the nature of this object based upon our data. Our study shows that SBS 1150+599A is most probably a planetary nebula located in the Galactic halo and not a cataclysmic variable
Aguilar, Allen, Aller, Aller, Anders, Balayan, Beers, Beers, Bełczynski, Bicay, Binette, Bobrowsky, Boesgaard, Bragaglia, Brocklehurst, C. Gutierrez, Charbonnel, Conlon, Dopita, Dopita, Drabek, Elitzur, F. Prada, Forestini, G. H. Tovmassian, G. Stasińska, Garnavich, Gratton, Henry, Howard, Ivans, Ivison, Izotov, Jacoby, Kingsburgh, Leitherer, Markarian, McGaugh, McWilliam, Mellema, Morris, Napiwotzki, Raimann, Richer, Richer, S. V. Zharikov, Salzer, Schwope, Skillman, Stasinska, Stasinska, Stepanian, V. H. Chavushyan, van den Bergh, Weideman, Weinberger, Weiss, Williams, Williams, Zickgraf   +59 more
core   +2 more sources

Chemical compositions and plasma parameters of planetary nebulae with Wolf-Rayet and wels type central stars [PDF]

, 2006
Aims: Chemical compositions and other properties of planetary nebulae around central stars of spectral types [WC], [WO], and wels are compared with those of `normal' central stars, in order to clarify the evolutionary status of each type and their ...
A. Acker, Acker, Acker, Acker, Acker, Acker, Aller, Aller, Aller, Aller, Barker, Berrington, Brocklehurst, Corradi, Crowther, Cuisinier, Gesicki, Górny, Górny, Górny, Górny, J. Köppen, Kingsburgh, Köppen, Mendoza, Méndez, P. Girard, Peimbert, Peña, Samland, Shaw, Siebenmorgen, Tylenda, Tylenda, Wood, Zijlstra   +35 more
core   +3 more sources

Planetary Nebulae by Binary Nuclei [PDF]

Symposium - International Astronomical Union, 1993
Planetary nebulae with close binary nuclei are reviewed. It is shown that these systems can be used as a source of information for the physics of the common envelope phase in the evolution of binary systems. Mechanisms for the production of bipolar planetary nebulae are examined and it is concluded that presently the action of binary companions to the ...
openaire   +1 more source

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, Elsa Recillas, Michael Grewing   +2 more
openaire   +1 more source