Usually when I see a white star I detect a hint of blue or yellow in it – just a hint. Not with 54 Leonis. It is white – really white – or so I thought Until I read the summary in “Double Stars for Small Telescopes” by Sissy Haas. As John says, “Impressions of star colors can vary significantly, sometimes wildly, from one observer to the next.” See “Star Colors” here for more discussion on this. For me, I’ll just say that Haas sees “a bright banana-yellow star” where I see “whiter than white!” Not only that, she says Webb sees it as “greenish white.”
Now this is the sort of thing that would make me want to throw in the towel – decide that I have too vivid an imagination, or that I’m color blind. Except when I look at the scientific data I find that the spectral classification for the primary is A1. The convention is to consider the “A” stars to be white, though the apparent color – what we tend to see – leans towards blue. Being A1 means it’s very close to the blue end of “A” – not the yellow end. An A9 star might have a slight yellow tint. So I’ll conscede that the spectral information doesn’t fully explain why 54 Leonis appears “whiter than white” to me, but “banana-yellow” to Haas. Does this mean I’m right and the other observers quoted are wrong? Of course not. But if you don’t understand why, I suggest you read John’s piece mentioned earlier: “Star Colors.” Meanwhile, let’s look at the relevant facts about 54 Leonis.
RA: 10h 56m Dec: +24° 45′
Magnitudes A: 4.5 B: 6.3
Position Angle 111°
Distance: 290 LY
Spectral Classification: A1V,A2V
Looking in mid-December, 54 Leonis was an early morning object for me and easy to find as it’s 4th magnitude and so visible to the naked eye in my skies. But even if you’re battling light pollution, you should be able to find the bright triangle of second and third magnitude stars that mark the Lion’s rump. Get it in your binoculars or finder than move northwest just six degrees from Zosma and 54 Leonis is marked by a pair of sixth magnitude stars that form a triangle with it. A brief study of these two charts should make it clear.
I first tried to split 54 Leonis with the 50mm Little Rascal, but even with using a 3mm eyepiece on this short-focal-length scope, conditions were too much for it. Under better seeing I think it would split at 68X with this little scope. But this morning I needed to switch t0 s0mething larger, the 60mm Unitron, which has a 900mm focal length, vs. the 205mm focal length of the Little Rascal. There I got a solid split with a 10mm eyepiece. In fact, it split with a 12.5mm (72X) and gave a hint of splitting with an 18mm (50X).
Now here’s the curious thing. With the 60mm my notes says “primary yellow, secondary a puffball.” Uh oh! Notice how those colors pretty much agree with Haas? So where did that pesky “whiter than white” come from? The answer is by using my 8-inch Celestron EdgeHD – a SCT. After looking with the Unitron I had switched to the larger scope because I wanted to check out nearby Porrima. And with it I had written that 54 was “very white” and its companion was “pale blue.” I got a delicate split with a 30mm (66X) – remember, the Little Rascal couldn’t split it with that power, but 8-inches of aperture gives you a lot more resolving power. The split was fine with a 24mm (83X) and delightful with an 18mm (111X).
So is it whiter than white, or banana yellow? Color, as noted, is not only in the eye of the beholder, but also in the amount of light gathered. With 54 Leonis Haas was using a 60mm – and with my 60mm we were in general agreement as to color. It was only when I switched to the larger scope that things changed. Did I mention John has a nice article discussing this sort of thing and more? Go here 😉
Oh- and Porrima? Yes, I got a split with the 8-inch SCT at 266X – but not all that I wanted. As I reported in the voluminous comments section of the Porrima post, “. . . .there was still too much light spilling into the diffraction rings and dancing all around. It was like seeing two pearls caught in a candle flame. I could see the individual stars and black night between them, but there was light shimmering all around – over, under, and mostly beside them.” I want to do better than that – one of these nights conditions will be ideal.