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Over the last couple of nights I've been entertaining myself by observing a few double stars. One problem I'm having is estimating the contrasting colours of some of these beautiful gems. Subtle colour differences in stars such as the Castor pair leave me questioning myself, as to me the primary is pure white, while the secondary is white/pink. I read somewhere only a few days ago that the secondary is white/yellow. ??

Then there are the strongly contrasting but unequally bright doubles, where to me the primary may be White and the secondary a chalky blue. I wore a green suit for a couple of years quite a few years ago, until I was strongly informed it was petrol blue. It seems I can't trust my colour perception, and to make matters worse, both my eyes give a different perception of colour. My left eye is blue biased while my right eye is orange/pink biased. I thought about cancelling each out by using a binoviewer,  but for double stars I really find a single eyepiece works best for me, so far at leased. Does it really matter at the end of the day if I see one star as mild pink while someone else sees a slightly different colour?

 

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Posted (edited)

For Castor, the secondary looks white/pink to me, never seen any hint of yellow in it. 

The different colour bias in each eye is fairly common as far as I'm aware.  I'd suggest using a binoviewer and let the brain work it out.

Also of course the colour casts of some optics and eyepiece can play a part.

Personaly, I dont think it matters if folks have different perceptions of colour - as long as you take this into account when reading other people's descriptions of doubles.

Edited by paulastro
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They’ve both always looked white to me Mike. SkySafari seems to back that up for both of them, very close in colour index. First info is for the brighter star.

Doesn't seem to matter really what colour you see unless for scientific purposes, as long as you are consistently recording the same thing?

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I'm slightly blue right, red left.

I observe with my left so have a high red bias - very noticeable in my variable star observing days. I always see red stars brighter than they are.

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I've only ever seen Castor as white and white.

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Posted (edited)

I've got slightly different colour perceptions in each eye, as well.  I put that down to an eye injury when I was a boy.  I was shot near the eye with an airgun pellet.  Thankfully, it didn't enter the eye, but hit the orbit, if I remember correctly.  To me, Betelgeuse is a lovely yellowish colour and not the red colour as described elsewhere.  It's colour doesn't really change between my left or right eye. 

Edited by merlin100
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I think colour perception will vary person to person and quite possibly change within a person as they age or acquire or loose certain eye conditions.

When doing outreach I've noticed that younger eyes seem to perceive colour differences more readily than older eyes.

 

 

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Colour perception varies from person to person, and although I am very sensitive to slight differences in colour, Castor A & B appear white to me.

Sometimes colour contrast also plays a part. Antares B is often described as 'greenish' in colour although the star actually is blue-white (spectral type B2.5V). Must have something to do with the striking red colour of the primary.

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17 minutes ago, Waddensky said:

Sometimes colour contrast also plays a part. Antares B is often described as 'greenish' in colour although the star actually is blue-white (spectral type B2.5V). Must have something to do with the striking red colour of the primary.

Yes, I can’t recall which star it was, but I have definitely seen a double which appears to have a greenish secondary. I have asked why this is, knowing that there aren’t any green stars so your explanation seems to fit very well, thanks!

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14 minutes ago, Stu said:

Yes, I can’t recall which star it was, but I have definitely seen a double which appears to have a greenish secondary. I have asked why this is, knowing that there aren’t any green stars so your explanation seems to fit very well, thanks!

Is that actually factual Stu? I too have seen green stars, always as less bright companion stars, but I thought they were rare not non-existent.  

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41 minutes ago, mikeDnight said:

Is that actually factual Stu? I too have seen green stars, always as less bright companion stars, but I thought they were rare not non-existent.  

Well I might be wrong, but I don’t know of a mechanism for green stars existing. I’ve asked on the forum a couple of times but never had a response that explains it. The H-R diagram doesn’t have any green on it (labels apart in this instance 🤣) so I assumed they didn’t exist.

71C56123-8FEC-4DCE-A13C-DC23B321B2DB.png

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Thanks Stu, I'm just going to have to come to terms with having odd eyes as regards colour. Perhaps my left eye gives the true colour, as the Castor binary both appear as brilliant white, but its my right eye that's stronger and better suited to detecting ultra-fine detail. Perhaps this colour perception issue is why some see Mars as being yellow orchar, but I've only ever seen it as being varying shades of pink.

I have heard years ago, but can't remember from where, that female astronomers have better true colour perception than us chaps, due to some genetic advantage presumably. Perhaps we could encourage the girls on SGL to check out a few contrasting doubles just to see if there's any truth in that claim?

 

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Posted (edited)
2 hours ago, Stu said:

Well I might be wrong, but I don’t know of a mechanism for green stars existing

What do you know, there's a whole Wikipedia page about it. I read somewhere that there is a reasonable bright star that most people see as being slightly greenish, but I can't remember what star it was.

Edited by Waddensky
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Thanks for everyone's input on this thread. Its made things a little more understandable now I know green stars don't exist in reality, but do exist as a contrast effect. It's also comforting to know I'm not the only one with odd eyes. :icon_eek:

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Posted (edited)

Mike - Castor's stars look white to me.  It's a complex issue - depends on the person, age, which eye, etc., and for close doubles, I believe there is a further perception effect whereby it depends on which star you focus on.  Does the Purkinje Effect (shift towards blue in low light) come in to play with doubles too??  And faint stars reveal colour less.

Doug.

Edited by cloudsweeper

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