NGC 7013 in Cygnus
August 2023 - Galaxy of the Month
Moving into August we are now in the Milky Way season and galaxies are becoming harder to find. For this month I have chosen the little observed galaxy NGC 7013 in Cygnus (near the border with Pegasus) as the galaxy of the month. First discovered by William Herschel in 1784 it was also observed by John Herschel.
It is variously classified as a spiral or lenticular galaxy with NASA/IPAC Extragalactic Database (NED) suggesting a classification of SA(r)0/a which suggests an odd lenticular. The nucleus contains a mild AGN of the LINER type. The galaxy does show the remains of a bar as well as copious amounts of dust.
NGC 7013 is thought to lie at a distance of between 37 and 41 million light-years from us. At this distance it would be perhaps 42000 light-years across.
The GALEX image in the UV suggests there may be a ring of star formation going on around the nuclear region. Radio observations suggest there are two rings of HI gas in the galaxy with little gas in between them. The small bulge-to-disk ratio and the slow rotation velocity suggest that NGC 7013 is a low-mass, low-density galaxy unlike the more luminous, typical lenticular galaxies. The galaxy may thus be a former late-type spiral galaxy which has exhausted most of its interstellar gas, either by star formation or by internal sweeping.
Hubble has observed this galaxy but there appears to be no colour image available only this black and white one. As the galaxy is only two degrees from the Veil nebula it suffers quite a bit of interstellar extinction. I have not been able to find any decent amateur colour images of the galaxy but there is a nice black and white one by Martin Germano. Deep amateur images such as this one by Jim Thommes show some of the dust present in the area.
Although NGC 7013 itself is quite bright for owners of large telescopes there is a faint galaxy just of the southern edge catalogued at about 16th magnitude. It seems to be catalogued as PGC 1881063, although NED only has designations for it from the infra-red WISE and 2MASS surveys. The two galaxies are probably not associated as PGC 1881063 would appear to lie a long way in the background with distances suggested at 285 Mpc.
NGC 7013 does not make it into any of the standard observing guides such as the The Night Sky Observer's Guide (NSOG) and Luginbuhl and Skiff (L&S). It should however be visible at a stretch in 25cm and I suspect easily visible in 35cm from the UK. It does make the Herschel 3 list, although this is mostly faint unremarkable galaxies. It does lie in a rich starfield so this may distract from the galaxy. I would suggest using a medium power when trying to find it.
Owen Brazell - Galaxy Section Director
And as an addition to this month's article, this is a very nice image of NGC 7013 by Denis Janky that I found on Astrobin.