NGC 6058 PN G064.6+48.2, PK 064+48 1
R.A.: 16h04m26.6s
Dec.: +40°40'56"
Mag 13
Size: 25"
CS mag: 13.9
Although the constellation of Hercules boasts some bright planetary nebulae in NGC 6210 and IC 4563 NGC 6058 is often ignored.
Observers looking for something faint in planetary nebula terms will tend to go chasing after Abell 39, however with a magnitude
at around 13 and a size of 25” NGC 6058 will be a challenge to find with smaller instruments. It was discovered by William Herschel
in 1787 and he described as pretty faint. Deep images suggest that NGC 6058 is member of the class of multipolar planetary nebulae,
here we have several separate jet ejection events that have formed lobes at different orientations. This was followed by another
event which appeared to form an elliptical shell. Recent observations however suggest that this is another jet which has formed
at almost right angles to the others giving this appearance. It is probable that the interaction of this jet with the earlier events
is what is causing the bright arcs on the internal ring. If the lobes are precessing this would indicate some form of binarity for the
progenitor of the planetary nebula. If the distance to the nebula of 3.5 kpc is correct (a rough GAIA parallax for the CS would give
a distance of 3125pc) then all these events happened over a fairly short timescale of 3400-5900 years. It maybe that NGC 6058 is
at the early stages of becoming a starfish type planetary nebula, a form of multipolar nebula. NGC 6058 is thought to be a high excitation
planetary nebula with a central star temperature of perhaps 77000K.The nebula does make an appearance in the Webb Deep
Sky Observers Handbook Vol 2, although it is suggested there that it is challenging in a 20cm. I would think that perhaps a
telescope of 25-30cm aperture with a UHC filter will make the observation easier, especially from the UK. The nebula lies in a
nice triangle of stars. Larger telescopes equipped with either a UHC or OIII filter and high power will show the nebula as having
brighter arcs. The Night Sky Observers Guide volume 2 suggests that you will need a 40cm+ size telescope to see this detail.
My observations of it with my 55cm Dobsonian telescope using a UHC type filter suggests that there is a lot of structure in the disk.
It would have taken more power than I was able to use at the time with an undriven scope. The central star is quite easily seen as
it is of similar brightness to the nebula. NGC 6058 does make the Herschel II observing challenge list. There is a nice amateur image
of it at http://www.capella-observatory.com/I...Ns/NGC6058.htm
ngc6058_Pan.jpg
PanSTARRS image of NGC 6058
Reply With Quote
