Coloured stars

[li'l john]

I am fairly new to all this and realise this might be a strange question. I was observing Castor and Pollux on the 6th, also the Beehive Cluster. Turn Left referred to colours, I think Castor was blue and Pollux yellow. It also said some stars in the Beehive were coloured, the problem is I don't see any colour at all. Is this because I need to "train my eye" or would I need better ep's?

I was using a TAL-1 with the supplied 25mm plossl and a 32mm Celestron Omni.

[Shibby]

Hi John,

It's an interesting question - stars certainly do have different colours, but the problem is that as your eyes become fully dark adapted, your colour perception reduces. I wouldn't say the EP was much of a factor here.

If you don't mind losing some sensitivity, try going inside for a few minutes then back out to the eyepiece and see what difference that makes.

A good test is Betelguese - it has a very distinctive red colour. See if you can make that out!

[Dave Smith]

Slightly defocusing can also help see the colour. Star colour is more obvious when looking at some double stars e.g. albireo or Almach where there is a distinct colour difference.

Dave

[li'l john]

Hi Dave and Shibby, thanks for your help. I'll certainly give your suggestions a go. I have seen colour in Betelguese - though it was more a sandy yellow than red.

Clear skies!

[m_j_lyons]

Most times blue stars will look more white...white obviously looks white. Yellow and orange are hard to distinguish unless they are right next to each other on bright stars. Red often washes out as well. Night vision has a good bit to do with it but more an issue is the small amount of light that we actually get into the eye from each star. Turn Left has several clusters with a single star of a different color that stands out from the rest - that is the best bet for seeing colors. Albireo also stands out in my mind very nicely because of the striking contrast of colors.

[Viv]

Slightly defocusing can also help see the colour. Star colour is more obvious when looking at some double stars e.g. albireo or Almach where there is a distinct colour difference.

Dave

I love looking at Sirius focused & defocused - think it's stunning

[Manok101]

My eyes never focus due to stignatism(sp?) does that affect my observing any?

[li'l john]

Hi Mj, Scarlet and Manok 101, thanks for your replies. Everyone has been very helpful. My optician told me I have a slight astigmatism but it hasn't stopped me focusing. I read somewhere (I wish I could remember where, could have been here on the SGL) that if one has an astigmatism then you will need much better ep's, like Televues, if you use a higher power than 12mm. This wasn't the case the other night and in any case I can't afford Televues and my 9 and 10mm plossl's seem to work ok. Perhaps my astigmatism isn't severe enough. Clear skies to you all.

[brianb]

There's not a lot of saturation in the colours of stars ... there are a few that sort of pop out but the colours are mostly rather pastel. V Cyg is one that always looks like a glowing coal to me, even when it's faint.

Astigmatism affects low power views much more than high power views. You can probably get away without using your glasses when using eyepieces shorter than about 12mm unless your astigmatism is very severe. "Better eps" don't help correct your eyes; you can get an attachment for some TV eyepieces (Dioptrix) that adds astigmatism to the EP to correct your astigmatic sight, enabling you to do without your glasses, but most people either don't need it or find it convenient to keep their glasses on when using low power EPs which usually have masses of eye relief.