| Description | Messier recorded this object on August 3, 1764, the same date as M31, and attributed discovery to Guillaume-Joseph-Hyacinthe-Jean-Baptiste Le Gentil de la Galazière in 1749. <--> Note: this is the first of 11 Messier Galaxies that Halton Arp selected for his Atlas of Peculiar Galaxies. I developed this description as part of my qualifying for the AL Arp Observing award. This is a very famous galaxy, mostly imaged with its dominant partner, M31. It is extremely bright. I had fun with this, as I've never understood why Arp labelled it "peculiar", and after this "deep dive", I'm still skeptical. The recorded remarks on Arp 168 read as follows: "Faint diffuse plume curved away from M 31 disk." To be clear, M32 looks like a dwarf elliptical galaxy, which might qualify as peculiar by itself. But Arp's category here is defined by "diffuse counter-tails". As I understand it a counter-tail is an asymmetrical dust plume, today understood to be the result of a merger or impending merger. So, to test the "remarks" clarification, I needed to figure out what direction is Andromeda. So I converted my observation to an inverted image, and overlaid it on a personal capture of Andromeda (image 2). I then drew a line from the Center of M32 to M31 on top of my overlay, and cropped out the relevant bits (image 3). Note I left the overlay semi-transparent so you can judge the accuracy of the overlay. Then I took that overlay and placed it back on my original M32 inverted capture... placing an arrow on top of the line indicating towards M31's center (Image 4). -- At this point I removed the overlay to see my inverted capture, knowing the direction to Andromeda (Image 5). Do I think there is a longer plume due south, away from Andromeda? No. Arguably there is an extended plume SW (to lower left corner), but does that count? And is it enough to qualify M32 as peculiar? Just in case there is something about Arp's own capture, I overlaid it on this (image 6). Does it confirm a due south asymmetry? Not to my eye, and the posible SW asymmetry is not confirmed either. So, I continue to be skeptical of this one. |
