NGC 4319 - Galaxy
NGC 4319 is a barred spiral galaxy of Hubble type “SB(r)ab” located ~70 million light-years away in the constellation Draco. It was discovered
by F.W. Herschel on a cold December night in 1797. The galaxy has an apparent magnitude of m= 12.0mag and an apparent size of 2.8x2.1
arcminutes.
The true diameter of NGC 4319 is 60,000 light-years, which makes it only half the size of our Milky Way. In addition to the bar and the tightly
wound spiral arms, the galaxy has also a ring of stars near its core. At the center there is an active galactic nucleus (AGN). The galaxy has
an absolute magnitude of M= -19.7mag, which corresponds to a total luminosity of 6.6 billion suns.
A few arcminutes to the west (right) there is the small galaxy NGC 4291, which appears to interact with NGC 4319. This is supported by the slightly
disturbed appearance of NGC 4319 and X-ray emissions originating from hot gas between the two galaxies. In 1971, astronomer Halton Arp
proposed the controversial theory, that NGC 4319 does not interact with NGC 4291, but rather with the much more distant quasar Mrk 205,
and that the redshift therefore cannot be a measure of distance, but has other causes.
The quasar “Mrk 205” is 970 million light-years away from Earth and has a brightness of m=14.5mag. This results in an absolute magnitude of
M= -22.9mag, which corresponds to a total luminosity of 120 billion suns. Most of the energy comes from a very small area in the center, where
a supermassive black hole with many millions or even billions of solar masses is believed to exist. Incidentally, “Mrk 205” is one of the closest
quasars to us.
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This very interesting trio of objects offers an exciting view in my 20" f/3 telescope and allows for a little excursion into cosmology.
The galaxy NGC 4319 is, of course, very easy to see at a magnification of 270x. The inner region appears significantly brighter and a faint stellar
core is visible in the center. Only the northern of the two curved spiral arms can be seen with averted vision. The quasar “Mrk 205” (blue arrow)
is located directly south of the galaxy and is very easy to spot – but with an apparent brightness of 14.5 mag, that's no big deal for a 20" telescope. ;)
To the west of the nice little star group, NGC 4291 can also be seen, appearing as a bright, round patch of light with a brighter center.
