Structure and Composition
The bright rim of the planetary nebula has an average thickness of about 10″.1 or about 0.34 light-years. There is a faint halo that extends about 18″ beyond the bright rim giving a complete diameter of around 190″ under the assumption that this emission is uniform around the planetary nebula.
This planetary nebula has been expanding for an estimated 22,100+1700
−1500 years, based on an assumed expansion velocity between 32 and 37 km/s and a 0.78 parsec radius.
Background galaxies are visible near the nebula, and some can be seen through the translucent nebula.
Oxygen is only about half as abundant in the nebula as it is in our own sun.
Read more about this topic: Abell 39
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Famous quotes containing the words structure and, composition and/or structure:
“Science is intimately integrated with the whole social structure and cultural tradition. They mutually support one other—only in certain types of society can science flourish, and conversely without a continuous and healthy development and application of science such a society cannot function properly.”
—Talcott Parsons (1902–1979)
“Those Dutchmen had hardly any imagination or fantasy, but their good taste and their scientific knowledge of composition were enormous.”
—Vincent Van Gogh (1853–1890)
“The philosopher believes that the value of his philosophy lies in its totality, in its structure: posterity discovers it in the stones with which he built and with which other structures are subsequently built that are frequently better—and so, in the fact that that structure can be demolished and yet still possess value as material.”
—Friedrich Nietzsche (1844–1900)