NGC 5614 in Boötes

June 2024 - Galaxy of the Month

Now into June only the brightest galaxies can be seen from the latitude of the UK and I have chosen NGC 5614 in Boötes, also known as part of the Arp 178 triplet, for this GOM.

First discovered by William Herschel in 1785, NGC 5614 is a barred spiral galaxy lying at about 60 Mpc from the earth. The other members of the Arp 178 triplet are NGC 5613 and NGC 5615. NGC 5613 is however an unrelated galaxy lying almost twice as far away as the other two.

NGC 5614 sports a large tidal plume that has come from a gravitational interaction with another galaxy in the past. It is perhaps logical to assume this has come from NGC 5615 which is buried in the arms of NGC 5614. It is interesting to note that it took Bindon Stoney using the 72” at Birr to discover NGC 5615 in 1851. It is likely that NGC 5615 is the remains of a galaxy being torn apart by NGC 5614. Currently however it seems to lie about 3 million light-years from NGC 5614 (further than the Milky Way M31 distance) if so it must be in a long looping orbit.

Given their distances, NGC 5614 maybe about 130,000 light-years across and NGC 5615 only 10,000 light-years across.

One arm of NGC 5614 shows up very prominently in the UV image from GALEX which suggests a lot of star formation going on, and indeed the PanSTARRS image shows a number of clumps in that arm which could be new large young star clusters.

Observationally NGC 5614 should be relatively easy to find. The others given their discovery history will be much more challenging. NGC 5615 lies in the halo of NGC 5614 and will appear almost stellar and is probably going to be a challenge for large telescopes. NGC 5613 should be easier and in the range of 37cm or so. The group is very compact so a high magnification eyepiece will be required to split the group, perhaps of the order of 350x if the seeing conditions and telescope can take it.

The The Night Sky Observer's Guide (NSOG) Vol. 2 suggests that using a 30-35cm scope NGC 5614 is a faint circular patch, but using a 40-45cm scope will show all the galaxies in the group, although here again NGC 5615 is a tough call in the halo of NGC 5614. Steve Gottlieb suggest that NGC 5615 is an averted vision object with 45cm and a faint spot with 55cm, so this is going to be a challenge to find. He also suggests that NGC 5613 is similar in difficulty. There is a fine image of the group by Adam Block and the Mount Lemmon SkyCenter on Wikipedia.

Owen Brazell - Galaxy Section Director