NGC 128 Group in Pisces
October 2020 - Galaxy of the Month
The small group of galaxies around NGC 128 in Pisces, also designated as LGG 6, was first discovered by William Herschel who found NGC 128 itself along with NGC 125 in 1790 using his 18.7” 20 foot reflecting telescope. NGC 126, NGC 127 and NGC 130 had to wait until 1850 when Bindon Stoney discovered them whilst examining the area using Lord Rosse’s 72” telescope.
The LGG 6 group is composed of 11 galaxies including NGC 128, NGC 126, NGC 127 and NGC 130. Nearby MCG +0-2-45 is also associated with the group.
NGC 128 itself appears to be interacting with NGC 127 and there is a tidal tail between the two. NGC 128 itself is an interesting galaxy as, although it is classified as a lenticular, it shows a boxy or peanut shaped nucleus with a strange X form. This could be the result of a previous merger or the ongoing interaction between itself and NGC 127. Although NGC 125 is also a disturbed galaxy it does not appear to be associated with NGC 128.
NGC 125 appears to be a form of shell galaxy. This is shown up well in the image on the CHART32 website. Deep images suggest that NGC 126 also shows some sign of tidal tails so it is also undergoing a gravitational interaction, probably also with NGC 128. It appears that NGC 130 is also interacting with NGC 128 as well.
There were some suggestions that NGC 125 might also be part of the group but its recession velocity is much larger than the others. The possibility remains however that NGC 128 and 125 have interacted in the past. The interaction of NGC 128 with NGC 127 is thought however to be a relatively recent phenomenon and has produced a counter rotating disk of stars in NGC 128 aligned with NGC 127.
The interacting part of the group was also catalogued in the Vorontsov-Velyaminov of interacting galaxies as VV 894. The group also makes it into the WBL catalogue of poor clusters as WBL 10 and that group includes NGC 125 but not some of the others included in LGG 6. The group lies at a distance of perhaps 190 million light years from us.
The group may be a tough one to observe with smaller telescopes. The Night Sky Observer's Guide (NSOG) suggests that only NGC 125 and NGC 128 will be visible in 10-12” scopes whilst the others may need telescopes in the 20” class to see, at least from UK skies. Observations with a 22cm from the UK suggest that NGC 128 was hard and that NGC 125 was not seen. Using a 37cm scope under mediocre skies showed NGC 128 as an edge on and NGC 125 as a circular patch. The other galaxies were not seen.
The group is fairly tight so the use of high power is recommended in order to pick up the fainter members. They should all fit in the field of a modern hyperwide eyepiece at 350x. The fainter MCG member of the group is still close by and will again fit in the same field as the others when using a power around 260x. This is likely to be a challenge however for telescopes in the 20”+ class.
Owen Brazell - Galaxy Section Director