Sand and Stars

Poe and A Handful of Dwarf Galaxies

Phoenix Dwarf Galaxy. Image credit ESO

19 Oct 2017

Last night I observed six dwarf galaxies, and the highlight of the evening was seeing for the first time the exceedingly dim and challenging Sculptor Dwarf Galaxy, and it was all thanks to Edgar Allan Poe…

The one thing I did not expect living in my remote dark skies cottage outside a remote village in the vastly remote Kalahari was to enjoy an astonishingly eclectic reading experience! The owners of the charming little hotel in the village are, like myself, incurable readers and they have a small reading room in the hotel… where guests can borrow and, better yet, leave a book.

Because almost all their guests are on holiday, one might be forgiven for thinking that the books left would be airport books… thrillers and romances. Au contraire! All sorts of interesting books pitch up… indeed, one never knows what will turn up.

Edgar Allan Poe (1809-1849)
Edgar Allan Poe (1809-1849)

My recent haul included an engineering history on the steam locomotive (not something I would ever otherwise have read; but it was interesting!), Ian Fleming’s 1957 nonfiction “The Diamond Smugglers” (extremely interesting in light of today’s conflict diamonds – plus, nice to see where James Bond came from!) – and a collection of Edgar Allan Poe’s short stories. I hadn’t read his short stories for decades… and oh my, how I enjoyed his dark, masterful stories with his macabre twists of fate and fascination with science and invention. But what absolutely enchanted me was to discover that Poe was aware of the physiology behind averted vision! In The Murders in the Rue Morgue (the tale with which Poe invented the detective story), he writes…

“…To look at a star by glances – to view it in a side-long way, by turning toward it the exterior portions of the retina (more susceptible of feeble impressions of light than the interior), is to behold the star distinctly – is to have the best appreciation of its lustre – a lustre which grows dim just in proportion as we turn our vision fully upon it. A greater number of rays actually fall upon the eye in the latter case, but in the former, there is the more refined capacity for comprehension.”

(I also discovered to my absolute delight that this was the story in which Poe’s oft-quoted, “to be enamoured of the night for her own sake” comes from. I confess that on nights when clouds have overtaken the sky, I often sit out there in the dark with a cup of tea, entirely enamoured of the night for her own sake.)

Thus it was inevitable that, in search of “the more refined capacity for comprehension” I put the extremely dim and faint Sculptor Dwarf Galaxy at the top of my dwarf galaxy observing list.

Last night was a great night to look at these dim and challenging dwarf galaxies – very dark and very clear. (I also find that the black cloth I put over my head really helps with these low surface brightness objects, not so much because it cuts out any extraneous light – which it does – but because it really sharpens my concentration on what I am seeing in the eyepiece.) 


Observing the dwarf galaxies

16″ f/5 Dobs at magnifications of 46x, 70x, 150x, 228x 

Sculptor Dwarf Galaxy 

RA 01 00 09.3   Dec -33 42 37   Mag 10.0   Dim 30′ x 18′  SB 16.9   PA 110° 

Image credit ESO
Sculptor Dwarf Galaxy. Image credit ESO

You can always figure that a galaxy that was discovered on photographic plates is going to be a tough catch! Harlow Shapley spotted the galaxy in 1937 on photographic plates made with the Harvard 24-inch survey telescope at Boyden Observatory, South Africa. (Interestingly, it was the first dwarf spheroidal galaxy to be discovered.) Luckily, I had done my homework on spotting the Sculptor Dwarf Galaxy, otherwise I certainly would have missed it – not because it is so small but because it is so huge! At 46x, the galaxy is unbelievably diffuse, exceedingly dim, appearing more like a full-moon-sized compression in the star field. There is a handy group of 3 or 4 10th and 11th magnitude stars nearby as a reference point, and I picked it up with averted vision and the black cloth over my head by first noticing a very vague brightening along the western edge compared to the star field. The brightening was more noticeable when I tapped the telescope. Once I had detected the galaxy, I could just hold it steady with direct vision, and only then because of the excellent conditions. And yes, with averted vision there was a more refined capacity for comprehension; it grew in both size and brightness size a little, although even then it is certainly the most ethereal object I have observed, almost insubstantial in the sky. I couldn’t think of a more fitting galaxy to have been inspired to observe by the strange and enigmatic Poe.

Phoenix Dwarf Galaxy 

RA 01 51 06.3   Dec -44 26 41   Mag 12.41   Size 3.4′x3′   SB 14.7   PA 93°      

Phoenix Dwarf Galaxy. Image credit ESO

This dwarf galaxy is a real toughie. My Uranometria Field Guide tells me that the Phoenix Dwarf has the appearance of an open star cluster. I wonder if it doesn’t mean a globular cluster for when it was discovered in 1976 by Hans-Emil Schuster and Richard Martin West it was mistaken for a globular cluster? Regardless, in my telescope it resembles neither an open nor a globular cluster… it appears as a very faint, very small, very slightly oval-shaped ethereal glow, so gossamer I almost felt as if I were seeing through it. As with the Sculptor Dwarf Galaxy, I picked this one up with averted vision, and once I had done so I could hold it steady with direct vision, but only just, it appeared nothing more than a very faint, very small, amorphous glow. A mag 8 star lies 3.5′ SW.

Wolf-Lundmark-Mellote Galaxy 

RA 00 01 58.1   Dec −15  27  39   Mag 10.9   Size 11.5′x4.2′    SB 14.7   PA 15°    

Image credit ESO
Wolf-Lundmark-Mellote. Image credit ESO

This little galaxy with the big name was a delight to observe. It appears as a very faint, large, ethereal oval-shaped glow, elongated N-S. With averted vision it brightens up a little, but remains a gorgeous ghostly glow against the background sky. I tried for WLM 1 – the galaxy’s globular cluster. It would be absolutely awe-inspiring to see a globular cluster roaming the outer limits of a galaxy that lies over 3 million light years away. But alas, I couldn’t pick it up.

NGC 625 Galaxy

RA 01 35 05   Dec -41 26 11   Mag 11.2   Size 5.8′x1.9′ SB 13.6 PA 92°   

DSS image
DSS Image

Here’s an odd coincidence – this galaxy has featured in the last two articles I have written for my blog  – as Phoenix’s brightest galaxy, and as a member of the Sculptor Group of Galaxies… and here it is again on my dwarf galaxy list! Actually, it holds a rather special spot on this list as it, like NGC 253, is a dwarf starburst galaxy! I find it dumbfounding to know that one is observing a galaxy that isn’t plodding along producing a couple of new stars a year, but is producing anything up to a hundred times more than that – a literal starburst. And when it is a dwarf galaxy to boot… observing bliss. The galaxy is a very interesting sight in the telescope because it has a rather unusual appearance – appearing as a bright-ish, large-ish, extended E-W oval that is curiously irregular in both shape and brightness. It is surrounded by a thin fainter halo. Averted vision shows up the irregularity of the central region; the western end seems more blunt than the eastern end, which seems sharper in comparison, and although the glow is by no means mottled or knotty, it has an odd uneven brightness, not quite lumpy looking, but definitely not smooth and even. Very unusual.

IC 5152 Galaxy 

RA 22 02 41.52   Dec -51 17 47.2   Mag 10.6   Size 5.0′x3.2′   SB 13.4   PA 100   

DSS image
IC 5152. DSS image

It is tough to get a really good look at this dwarf galaxy as it has a bright mag 7.7. star superimposed on its NW end that really interferes with observing. Despite the pesky star, it appears as a modestly bright and fairly large oval cloud, roughly elongated E-W that brightens very slightly to a region just SE of the star. With averted vision the galaxy brightens up somewhat (so does the pesky star!) but interestingly, I can see that the galaxy extends a little further west of the star, although this region is very faint and diffuse.

IC 1613 Galaxy 

RA 01 04 49.0   Dec +02 06 49   Mag 9.2   Size 16.2′x14.5′    SB 15.0    PA 50°    

Image credit ESO
IC 1613. Image credit ESO

This dwarf galaxy appears as a faint, large, irregular, very diffuse and ghostly glow, slightly elongated SW-NE. Averted vision certainly does give one a more refined capacity for comprehension as the glow is revealed to consist of two portions: the NE portion of the glow is the smaller of the two but appears more obvious (oddly enough, not brighter but more obvious) while the SW portion is larger but a lot more diffuse and less obvious. The glow between the two patches is extremely faint with averted vision, an ethereal glow that trembles in and out of view on the edge of visibility. Interestingly, with averted vision I can also make out a third portion – an extremely small and extremely faint diaphanous patch lying to the NE that appears detached from the rest of the glow. A 10.5 mag star lies on the western edge of the glow.

Copyright © Susan Young 2017