Sunday, June 19, 2016
Issue #498, The Magic Ring
One of my Facebook friends asked me a question the other day. On the face of it, it was a simple and casual one, “Rod, do you still image the Messiers?” Sometimes the simplest questions turn out to be the most thought-provoking, however. I replied that, yes, I still take pictures of the M objects (and observe them visually as well). After sending my reply, though, there came another—internally generated—question, “Why?”
Because they are just so wonderful. Are there some objects in the NGC and other deep sky catalogs that are better, visually, than some Messiers? Yes. But the preponderance of beauty is in the Ms. Almost—if not quite—every one of them is a gem. Do I get tired of looking at them? That would be like asking whether I get tired of looking at Mona Lisa or reading Hamlet. I have never seriously observed a Messier without seeing something new in it—well maybe except for M40 and M74, but they are the only exceptions.
OK, forward we go…
We start this installment’s bunch with a bang, a real superstar. M57 has been one of my most beloved objects since I first hunted it down many a moon ago with my 4-inch Palomar Junior reflector. Not that I can say it really looked like much back then, not compared to what my telescopes of today will bring home, but, it was easy to find, it was obvious in the eyepiece, and it actually looked a little like the pictures in the astronomy books I checked out of my elementary school’s library.
Certainly M57 is a worthy target for three and four inch telescopes. At magnitude 8.8 and 3’48” across its longest axis, it is easy to see with a small telescope in the suburbs. You can see this corpse of a dead star, yes, but don’t expect too many details with a little telescope. At least you won’t have to worry much about finding it. It’s almost halfway between a line drawn between two of the little summer constellation Lyra’s most prominent stars, Beta and Gamma Lyrae.
In 4-inch and smaller instruments under less than optimum conditions—the inevitable summer haze that affects even Lyra with its nice northerly declination of +30—there is only so much you can expect. M57 will be immediately obvious, even in a fairly low power eyepiece; it’s over twice the average diameter of Jupiter and is not a planetary nebula that will masquerade as a fuzzy star. Unfortunately, all you’ll see easily is just that, that it is not a star. Its ring shape is elusive, even if you pump up the power.
At 6-inches of aperture, things get much better. It will be undeniable that M57 is a smoke ring, not just a disc. When seeing is good, it will also be easy to see that this ring is squished, that it is somewhat elongated. Finally, when you increase the power to 200x or thereabouts, you’ll observe the center is not empty, but hazy; this is a filled donut.
Frankly, the view will be much the same at 8-inches, though all of these things will begin to be easier. You’ll also note on the best nights that the “ends” of the Ring’s oval on its longest axis are not sharp, but diffuse. While, unlike some planetary nebulae, the Ring doesn’t offer strong color, you can still occasionally detect a blue-green tint in it on transparent nights, most easily with 8-inch and larger telescopes.
It’s at 10-inches that you can begin to hope for some lagniappe, including the faint star (magnitude 15 or so) that’s just outside the ring to the northwest. It’s a pretty good accomplishment to bring home that pesky sun, but it is not THE star. The Star is the Ring’s elusive central star, a white dwarf, the remnants of the sun that created the nebula.
Can you see the Ring’s progenitor with a 10-inch? Yes you can. I saw it summer before last with an humble Chinese 10-inch Dobbie. Was it easy? I wouldn’t call it easy, but it was not overly difficult either. A novice observer out there with us on the club field picked it up without much of a fuss when we told him what to look for. That’s the good. The bad is that the central star has regularly eluded me in 30-inch and 42-inch Newtonians.
|M59 and M60...|
How can the central star be easy with a 10-inch one night and impossible with a 42-inch another night? Some people think the star, which is nominally at magnitude 15 or thereabouts, is a variable. That’s possible, but I don’t really think that’s the answer. The problem is the Ring’s filled interior. If the donut hole were dark, the star would be fairly trivial. It is not; the interior is very much a light gray, and the contrast between it and a dim star is minimal.
So how do you see the central star? Really pump up the power, to 500x and higher. In the above mentioned 10, the star wasn’t there at 250x, but with higher magnification it swam right into view. To make use of high power, which spreads out the bright background in the Ring’s donut hole and increases contrast between it and the star, you will of course need good seeing. If the seeing is not good, the star will be invisible even in a very large scope. It will be smeared out of existence. Luckily, even in this day when weather patterns seem to be changing—and not for the better—I get good seeing with fair regularity in the summer and can often at least glimpse that fabled central star.
From the sublime to the ridiculous. Oh, Virgo’s M58, an SAB barred spiral galaxy, ain’t exactly ridiculous, it’s just that it’s in a whole other class compared to objects like M57. Not a bad class, mind you, it’s magnitude 9.66 and 5’54” across so it is fairly prominent for a galaxy. It’s just not liable to put your eye out.
How do you find this galaxy? Easy: push the M button on your goto telescope’s hand control followed by 5 and 8. I am not kidding. Oh, you can find it the old fashioned way with finder and chart even if you are a relative novice, but M58 is right smack in the middle of the cloud of Virgo galaxies at the heart of the constellation, between the arms of the maiden as it were. Best guide to M58? Probably magnitude 5 Rho Virginis, which is about 2-degrees to the southeast of the galaxy in this star poor area. You’ll need a detailed chart, of course, since even in suburban skies you’ll see multiple faint fuzzies in just about every field you land on here.
Once you are there, what will you see? With an 8-inch to 10-inch, you may see at least one more galaxy in the field, NGC 4564, but there is no doubt which one is M58; it is the big one. Is it also bright? I can see it from the backyard with direct vision with my 8-inch, but it is easier with averted vision. Naturally, it is more prominent in a 10. As with many galaxies, bright and dim, what it resembles an unresolved globular cluster: a bright core surrounded by fainter haze.
E5 elliptical Messier galaxy M59 is cool. Not just because it’s bright at 10.6 and shows obvious elongation n/s with dimensions of 5’24” x 3’42”, but because its field is just so beautiful. An 8-inch will turn up at least 3 galaxies here. In addition to M59, there’s M60, another bright M 25.0’ to the southeast, which is graced with a smaller companion galaxy, NGC 4647, 02’41” northwest of its center. M59 itself appears as a noticeably off-round fuzzball with a fairly extensive outer halo.
Once again, goto or digital setting circles are the way to go here. Sometimes, here in the heart of Virgo, it’s still hard to figure out which object is which, however. Luckily, the layout of these three bright galaxies is pretty distinctive, and once you orient yourself as to the way your telescope presents the field as compared to your chart—inverted, mirror reversed—it is easy to ID the fuzzies. Make it easy on yourself and use a computer charting program like Stellarium, which will allow you to flip or invert the field to match what is in the eyepiece.
Is M60 even better than M59? Perhaps. It’s got a brighter magnitude value, 9.8, but this 7’24”x6’0” E2 elliptical galaxy is not as obviously elongated. It trumps M59, however, because it has little buddy NGC 4647 beside it. An 8-inch telescope will have no difficulty picking up a faint nebulous patch beside the main object. Don’t see it? You are likely on M59 rather than M60, then. DSCs or goto are, again, the path to happiness here.
M61 is a face-on SAB spiral galaxy, and face-ons tend to be tough. Luckily, this one is fairly small and bright, 6’30” in diameter and magnitude 9.65, so seeing it is not much of a challenge. Not for a 10-inch in the suburbs. Want to do beyond just seeing it, though? A 10-inch under a dark sky can do well with this one, but a 12-inch is undeniably better.
At least it’s a little easier to find M61 than the run of the mill Virgo galaxy, it being in the western part of the constellation away from the greatest mass of objects. You’ll find M61 5-degrees north of Eta Virginis and about 1-degree 18’ northeast of a prominent 5th magnitude star, 16 Virginis. All in all, finding this one manually was a pleasantly easy surprise.
With the galaxy in the field, what you’ll see with a suburban 10-inch is a round subdued glow with perhaps a hint of a stellar-appearing core. A 12-inch makes the galaxy easier with direct vision but that is about it. Under dark skies with 10-inch and larger telescopes, you’ll see signs of spiral structure, and especially the galaxy’s most prominent, sweeping spiral arm.
Ah…summer’s coming in and that great celestial bug, Scorpius, is on the rise. Our next target, M62, a globular star cluster, looks like it ought to belong to the Scorpion, but it’s actually just over the border in Ophiuchus, in the southern part of that sprawling constellation. At magnitude 7.3 and 15.0’ across, M62 stands out well, or WOULD if it were higher in the sky for most Northern Hemisphere amateurs.
Yes, M62 belongs to Ophiuchus, but if you are finding it The Old Fashioned Way, use two of Scorpius’ stars to pin it down. The glob lies about 4-degrees northeast of the Scorpion’s body, and forms a triangle with two of his stars, Tau and Epsilon Scorpii. Assuming Scorpius is well over the horizon, and the haze and light pollution is not too bad, the M62 may show up in your finder as a wee fuzzy.
It M62 good? It would be if it were higher, but it is not. As is, in an 8-inch under the average summer conditions in the suburbs, you may have to settle for “grainy but not resolved.” A 10-inch at a dark site can bring out a satisfying number of stars in the halo of this somewhat compressed Type IV cluster.
We began on a good one and we end on a good one too, M63, the winsome Sunflower Galaxy. It is still a galaxy, however, despite the fact that it’s a Messier and has a reputation for being spectacular, so don’t expect “blindingly bright.” It is easy enough in a 4-inch, though, and can begin to show its sunflower aspect in a 10-inch under decent conditions given its bright magnitude number, 8.59, and reasonable size, 12’36”.
Finding this Canes Venatici object is easy due to its prominence and to its position about 1/3rd of the way along a line drawn between Canes’ Cor Caroli and the Big Dipper’s Alkaid. The galaxy is actually about 1-degree northeast of this line, but a little scanning with a medium-low power eyepiece should turn it up without much hair pulling.
A 4-inch telescope in the backyard will show you the basic features of this steeply inclined galaxy. It’s a prominent oval with a bright, small, but not stellar center. To see more, you will need a 10-inch and a dark site and a medium-high power ocular. With one, you can hope to glimpse the mottled, patchy, petal-like spiral arms that give rise to M63’s “Sunflower” moniker.
So..? The finish line is not yet in view; it’s a long way off yet, but I smell victory. What say we continue our M-quest next week, too?
O'meara Messier Objects is a great read on this topic, thought your descriptions are certainly better for stay at home viewers. Your "Urban Astronomer" and his book were the basis for me for several years. Both should be in an astro library.
I believe that seeing has to be very steady to see the central star of M57. Since those skies are rare where I live, I have only observed it 3 times and only in larger scopes - twice in a 13.1" and once in a 16". Each time an interesting effect took place; I could see the star and hold it for about 20 seconds, then it would disappear. Stepping away for 30 seconds or so and looking again had the star become visible again only to disappear once more. I suspect that I held my breath or my breathing was more shallow and as O2 blood levels dropped my retina lost sufficient sensitivity. Looking away had me breathing normally again. My observing buddy had the same experience. One other thing I could mention - it is the tiniest speck of a star. This may be why some miss it. I know some have claimed to have seen it in a 4". I must have observed it over 1,000 times in an 8" with no dice. As you state - a ten inch and up improves your chances but it remains elusive. ....DwightPost a Comment