Galaxies Section

Welcome to the Galaxies Section of the Webb Deep-Sky Society. Our role is to promote visual observation and scientific imaging of galaxies by amateur astronomers.

Galaxy of the Month

Below is our current Galaxy of the Month. These are galaxies that we feel are particular worthy of your precious observing time. We have an archive of these articles that stretch back to the beginning of 2011. You can browse them, or search for specific objects and constellations in the Galaxy of the Month archives.

Your observations (sketches, images or observing notes) of any of these objects are very welcome.

For those that use observation planning software

We have plans available for all the Galaxy of the Month pieces from 2011 onwards to make it easier to find the galaxies we have covered so far.

These will be updated as new GOM’s are added.

NGC 7463 in Pegasus

September 2021 - Galaxy of the Month

This interactive image of the NGC 7463 was provided by the Sloan Digital Sky Survey using Aladin Sky Atlas. We also have a finder chart should help you locate these galaxies, as will this link for NGC 7463 on the Stellarium Web planetarium.

Our target this month is the tight triplet of galaxies around NGC 7463 in Pegasus. NGC 7643 itself was discovered by William Herschel in 1784 along with the other brightish galaxy in the group, NGC 7465. The other galaxy in the triplet, NGC 7464, was discovered by d’Arrest in 1864, although it was independently rediscovered by Marth and Vogel later that year.

The WBL has it as part of a small galaxy group listed as WBL 695 which includes the 3 NGC galaxies and UGC 12321. The faint edge on spiral UGC 12313 nearby is not listed as part of the group, however HI observations suggest that it may be connected with the others.

NGC 7463 itself appears to be a barred spiral galaxy with the outer spiral arms distorted by interactions, possibly with NGC 7464. NGC 7464 is itself an interesting system as it is classified as E1pec, although its colours are very blue and it shows emission lines. There are other morphological classifications which suggest it maybe an irregular galaxy however. The NGC 7463/7464 group is also known as Holmberg 802.

The third galaxy in the trio, NGC 7465, is also classified as a distorted form of a barred spiral. The nucleus of NGC 7465 seems to be a LINER, a mild form of AGN and the galaxy contains a lot of dust. It has also been classified as a Seyfert 2 type system. It appears to have a ring of star formation, or a shell of material which may come from interactions within the system or from a merger in the past. It could perhaps also be a polar ring galaxy. The core of the NGC 7465 also appears to have some intense star forming going on.

The main interactions in the group appear to be currently between NGC 7464 and NGC 7465. Interestingly the Lyons Groups of Galaxies (LGG) has NGC 7465 and 7464 as part of the NGC 7448 group as LGG 469. NGC 7463 is not part of that group.

The group is fairly small and faint and thus it is of interest that the Night Sky Observer's Guide (NSOG) Vol 1 suggests it as a target for 12/14 inch telescopes. It does not appear in Luginbuhl and Skiff (L&S). Steve Gottlieb suggests that even in a 18” telescope NGC 7464 was faint. The group is very tight and as such is probably going to require high magnification in order to be able to split all the components, in the range I would think of 250-350x.

Owners of large telescopes may also be able to pick up the two UGC galaxies associated with the core trio, although I expect finding these may require the most transparent nights, although Steve Gottlieb reports that they are faint even in Texas skies with a 48”.

Owen Brazell - Galaxy Section Director