May 2016 - Galaxy of the Month

NGC 4111 in Canes Venatici

As the summer approaches and dark skies end from northern latitudes I thought I would give the bright galaxy NGC 4111 its turn as the galaxy of the month. Completely independently I found that it had already been chosen as object of the week on the Deep Sky Forum and also as the ESO/Hubble picture of the week, obviously a galaxy whose time has come.

On the border of Canes Venatici and Ursa Major, NGC 4111 was first discovered by William Herschel in 1788. NGC 4111 is a near edge on lenticular galaxy showing a boxy central core and tapering spiral arms. The galaxy is thought to be at a distance of about 50 million years.

Deep images from Hubble show a disk of dust and gas orbiting at right angles to the main disk, possibly forming a polar ring galaxy. These are often associated with the mergers of galaxies and this may be all that is left after a merger with a smaller spiral galaxy.

NGC 4111 itself should be visible in telescopes of 20-22cm in aperture but to see much detail will probably require 40cm. Night Sky Observer's Guide (NSOG) reports that with telescopes of 45cm aperture structure can be seen in the disk.

NGC 4111 is part of a group of galaxies but there seems to be some disagreement about how many and which galaxies it is associated with. The WBL catalogue lists it as group number 380 consisting of three galaxies NGC 4111, UGC 7094 and a third galaxy, whilst the LGG catalogue lists NGC 4111 as part of a group of 18 galaxies as group 269 but does not include UGC 7094 as part of the group.

There are also three other NGC galaxies in the immediate area. NGC 4117 was also discovered by William Herschel later in 1788 but the other two are much fainter and were discovered by Stoney in 1851 (NGC 4109) and Mitchell (NGC 4118) in 1854 using Lord Rosse’s 72” reflector at Birr.

If the NGC galaxies are not enough of a challenge then there are two edge on UGC galaxies UGC 7094 and UGC 7089 in the same field but I think these may require large telescopes in the 20” (50cm) category to see, especially from typical UK skies.

All the NGC galaxies will fit in the same field of a high power eyepiece as will NGC 4111 and the two UGC galaxies so before we lose the dark skies for the year try and chase down this small group. For double star fans there is also a nice coloured double star HJ 2596 in the same field.

Owen Brazell - Galaxy Section Director

Observations of NGC 4111 and the surrounding galaxies: Mike Wood and Andrew Robertson use their large reflectors. It appears that the UGC galaxies do require lots of aperture, but Patrick Maloney suggests that might not be as large as you think.