At the northeastern tip of Cassiopeia are two challenging multiple star systems that will quickly draw any dedicated Star Splitter who likes his or her stars closely separated and suffused with subtle color.
Greg mentioned both of them to me a month or so ago, which rattled loose a dim and distant memory of having spent some time on them several years ago. And when I looked up their statistics in the Washington Double Star Catalog, I immediately felt the call and the draw of their regal beauty — after all, this is the domain of Queen Cassiopeia.
A quick look at the map below will show where we are:
Iota (ι) Cassiopeiae (Σ 262) (AB is H I 34) (AC is H II 4)
HIP: 11569 SAO: 12298
RA: 02h 29.1m Dec: +67° 24′
Magnitudes AB: 4.6, 6.9 AC: 4.6, 9.0 AD: 4.6, 8.5
Separation AB: 2.6″ AC: 7.1″ AD: 210.9″
Position Angle AB: 229° (WDS 2012) AC: 116° (WDS 2010) AD: 60° (WDS 1999)
Distance: 141.6 Light Years
Spectral Classification A: A5 B: F5 C: K1
Status: AB is physical, an orbital chart and data can be seen here.
These stars are really a delight to look at in apertures of 60, 80, and 105 millimeters. As Iota (ι) comes into view, you’re greeted with a very tight knot of three stars. A casual glance would fail to catch the tight “B” component, and very likely would miss “C” also because of the 4.4 magnitudes of difference between it and the primary. Unlike some of the wider triples and doubles discussed in other posts, the tight distances between the three stars requires close scrutiny — as Mr. Spock might say, “Captain, this observation will require a performative act of cognition.” And hanging out there in distance, all alone, is frequently ignored 8.5 magnitude “D.”
And the close scrutiny required to pick out “B” and “C” is where the charm of this system lies. I found my vision was drawn directly to the 4.6 magnitude yellow primary and only gradually did the other two stars begin to reveal themselves. In my six inch refractor, though, all three stars leap out from the background of the black sky, and the beauty of the view in that instrument is the rich colors of the primary and secondary.
And there’s more than meets the sharp observing eye here. “A” has a very close companion, designated as “a,” as does “C.” For a view of the closest five stars in this complex system, take a look at this photo taken at Lick Observatory using adaptive optics.
Below are notes from three recent observations:
August 23rd, 2010
I was using a pair of 80mm f/12 refractors on this night, mounted side by side. For a photo of that set up, take a look HERE.
Using a 20mm Plössl (60x), I had to look very closely to see all three stars. The view was much cleaner with a 15mm Plössl (80x), and a bit better with an 11mm Plössl (109x). Still, it was very tight at each of those magnifications, and bright moonlight made it especially difficult to see the ninth magnitude “C” component clearly.
August 25th, 2010
This time, I pulled out the big gun, a six inch f/10 refractor, and the view was so sublime I sat glued to my chair for a good thirty minutes. The “B” component was right up against the primary with a 14mm Radian (109x). Increasing the magnification to 138x with an 11mm Plössl yielded a fantastic view, as did a 9mm Ortho (169x). The primary is a rich yellow, the very close “B” component is white, and “C” was really too faint to show much color, but I could call it gray without too much problem. Haas describes the first two as lemon yellow and blue, and leaves the fainter “C” as a speck.
In the 60mm f/5, I couldn’t detect “B” with an 11mm Plössl (82x) because the diffraction ring hid it. “C” was barely visible. I increased the magnification to 129x with a 7mm Ortho and was able to detect “B,” but at that point “C” became difficult because of the glare from “A” and “B”. Bright moonlight was a factor again during this session.
September 3rd, 2010
Tonight I thought I would take another look at this beautiful triple with a 105mm f/15 refractor, and with a 60mm f/16.7 refractor which is mounted on it. At the time I was looking at Iota (ι), the seeing was erratic — sometimes pretty decent, and at other times, downright horrible. However, unlike the previous two nights, there was no bright moon in the sky.
In the 105mm refractor, all three stars were very obvious in an 18mm Radian (83x). The “B” component was very close to the primary, but when the seeing settled down, it was a beautiful little pinpoint of light. The view in the 60mm scope was very similar with a 15mm Plössl (67x). This time, using the 11mm Plössl (91x), the tight “B” component was visible outside of the diffraction ring, and as before, “C” became lost in the glare of the additional magnification.
And now, if you’ll excuse the poor pun, we’ll take a deep breath, let out a sigh (ψ), and move on to ψ (Psi) Cassiopeiae, which is a short hop away to the northwest. Actually, there was more than one reason to let out a sigh at this point. As I was moving the scope over to Psi (ψ), what sounded like half a dozen coyotes starting howling off to the north of where I was observing. I’ve heard an occasional howl from them before, but this was a chorus. I don’t know who they were singing to, but my four legged observing companion, Klaus, had both ears pointed up as far as they would go.
Psi (ψ) Cassiopeiae HIP: 6692 SAO: 11751
RA: 01h 25.9m Dec: +68° 08′
***** Magnitudes Separation Position Angle WDS Data
AB: (Bu 1101) 4.7, 14.0 2.4″ 38° 1970
AC: (H V 83) 4.7, 9.2 20.3″ 128° 2007
AD: (Bu 1101) 4.7, 10.0 19.1″ 131° 2006
CD: (Σ 117) 9.2, 10.0 2.3″ 250° 2009
Distance: 193 Light Years
Spectral Class: K0
Status: AC is optical; CD is physical; C & D are optical companions of A
This is a complicated star system, to put it mildly. The primary, an orange giant, has a fourteenth magnitude companion (“B”) three arc seconds away — needless to say, I didn’t try for that one. The “C” of the “AC” combination is also a double, consisting of 9.2 magnitude “C” and tenth magnitude “D,” a close 2.3″ away. And if that wasn’t enough, it carries three different designations, as shown in the parentheses in the data line above. If that confuses you, don’t despair — I’m confused, too, and I just described them.
What you’ll see on close examination is a bright primary with two faint and barely separated companions — that is if you’re using enough aperture. On the same night as the previous observation above, September 3rd, the split between the primary and the two companions nineteen and twenty arc seconds away was easy with an 18mm Radian (83x) in the 105mm scope. However, trying to separate those two tenth magnitude companions 2.3″ apart was an exercise in futility. I tried a 14mm Radian (107x), a 12mm Radian (125x), a 10mm Radian (150x), a 9mm Plössl (167x), and 7mm Ortho (214x), but never could really be sure I had both of them in view. Use of averted vision was a must. The best I can say is that one would suspect a double here because they never would quite come into focus as a single star.
In the 60/1000, averted vision was required to pull the the pale dot that was the faint pair out of the glare of the primary in a 15mm Plössl (67x). Using an 11mm Plössl (82x), I could see them with direct vision a bit easier, but averted vision worked much better. There was no hope of splitting the “two of a kind” in that scope, however.
So the question remains: Will one of the two Star Splitters of this series of tremendously interesting double star adventures be able to split the two tenth magnitude companions with more aperture? Will Greg be first? Will John be second? And who’s on third? Will Klaus sing out to the chorusing coyotes when one of us succeeds? Stay tune — we ain’t finished just yet!