Monochromatic isophotometry of NGC 2440 and 7009
نویسندگان
چکیده
منابع مشابه
The 3 - D ionization structure and evolution of NGC 7009 ( Saturn Nebula ) ⋆
Tomographic and 3-D analyses for extended, emission-line objects are applied to long-slit ESO NTT + EMMI high-resolution spectra of the intriguing planetary nebula NGC 7009, covered at twelve position angles. We derive the gas expansion law, the diagnostics and ionic radial profiles, the distance and the central star parameters, the nebular photo-ionization model and the spatial recovery of the...
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We have measured the proper motion (PM) and kinematics of the ansae in NGC 7009 using high dispersion echelle spectra and archive narrow band HST images. Assuming that the ansae are moving at equal and opposite velocities from the central star we obtain a system radial velocity of −53± 2 km.s, the eastern ansa approaching and the western ansa receding at vr = 5.3± 1 km.s −1 with respect to this...
متن کاملOn the nitrogen abundance of FLIERs : the outer knots of the planetary nebula NGC 7009
We have constructed a 3D photoionisation model of a planetary nebula (PN) similar in structure to NGC 7009 with its outer pair of knots (also known as FLIERs –fast, low-ionization emission regions). The work is motivated by the fact that the strong [N ii]λ6583 line emission from FLIERs in many planetary nebulae has been attributed to a significant local overabundance of nitrogen. We explore the...
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A common feature of development in most vertebrate models is the early segregation of the germ line from the soma. For example, in Xenopus and zebrafish embryos primordial germ cells (PGCs) are specified by germ plasm that is inherited from the egg; in mice,Blimp1 expression in the epiblast mediates the commitment of cells to the germ line. How these disparate mechanisms of PGC specification ev...
متن کاملFrom Historical Perspectives to Some Modern Possibilities
A historical perspective on the study of asymmetries in planetary nebulae (PNs) is presented. We also describe our ongoing work in high resolution spectroscopy of planetaries, and discuss some likely future directions for the study of asymmetrical PNs. The first systematic study of planetary nebulae (PNs) was undertaken at Lick Observatory from 1914 to 1917 and is reported in detail in Volume 1...
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 1980
ISSN: 0035-8711,1365-2966
DOI: 10.1093/mnras/193.2.231