NGC 6741, Phantom Streak Nebula
NGC 6741 is a small planetary nebula in the constellation "Aquila", located about 6,500 light years from Earth. It is also known as the "Phantom Streak Nebula".
With a visual brightness of about 11mag and an apparent size of 7"x5" (arc seconds), it has a high surface brightness and is therefore an easy object even for
smaller telescopes with an aperture of 8". Due to its small size, however, it was not discovered until 1882 by Charles Edward Pickering.
With an age of 1,400 years, the PN is relatively young and has therefore not yet been able to spread very far into interstellar space. The envelope is an ellipsoid with
the dimensions 0.13x0.07x0.06 lightyears and has a density of 7,000- 12,000 molecules per cm³. The total mass of the PN is estimated to be 0.4 solar masses, with 0.2
solar masses accounted for the spherical halo surrounding the inner envelope, which reaches a diameter of 0.26 light years. The complex inner structure is attributed
to the rapid evolution of the central star.
The central star (ZS) is quite massive with 0.68 solar masses and has an extremely high surface temperature of 170,000 Kelvin. The high temperature can be
explained by the fact that the ZS has not yet had much time to cool down. Nevertheless, it shines only about 550 times as brightly as our Sun. The apparent
brightness was determined to be 20.1mag, so it cannot be detected visually even in very large telescopes.
----------------------------------------------------------------------------------------------------------------------------------------------
The PN is a very beautiful object in my 20" f/3.2 Dobsonian. Thanks to its position in the middle of the summer Milky Way, there are many bright field stars in
the vicinity. It appears quite bright even at high magnification and at 270x some structures can be seen. For example, the centre appears slightly darker than the
outskirts of the PN. I also had the impression that the northern and southern edges are a little brighter than the edges in the east and west. As expected, the central
star was not visible.
