A really handy G2V star for calibration.

[RobH]

Hello all,

A while ago, when I first got my colour camera, I was looking for a list of G2V type stars to calibrate my colour balance to.

I did get lists, but all of them had the stars RA/DEC positions but nothing really useful at a glance....nothing saying, this star is in Orion/Cygnus etc.

I'm afraid I can't just look at a co-ordinate and tell what part of the sky it's in....rusty old brain, never any good at that sort of thing :?

Anyway, in this months Sky & Telescope magazine, there is a short article about a star which is the closest match that has been found to the sun. Spectral type G2V.

Apparently it's the best match found so far to the sun in size, mass, temperature and composition.

HIP 56948, MAG 8.65.

220 LY away.

It's in Draco, very close to Lambda Draconis so at the moment, later in the evening it's nearly overhead and is also circumpolar.

(For autostar users, it's not listed. I used Starry night to GOTO it, after using Autostar to centre Lambda Draconis and sync'ing on it)

Hope someone finds this useful

wonder of someone there used the sun to calibrate on last night ??

Cheers

Rob

[Astroman]

I haven't read that article yet, but I heard a talk a few years back about a project to find a match for Sol. They studied several thousand stars, whittling them down in chunks to several dozen. Multiwavelength studies were launched and each prospect dropped by the wayside for one reason or another. Too much UV, not enough, wrong type of X-ray emission, not enough sodium in the atmosphere and so on. It was a fascinating talk, mostly because the researchers all thought it should be fairly easy to find a match. After all, for years scientists have been saying Sol is, "just an ordinary type star", right? Well, guess again. Seems mass and luminosity are not the only criteria for "averegeness". As I recall, if you accepted 3 differences of 1% or less, they came up with three stars close enough to be called "similar". Three out of thousands of G2 stars! The universe never ceases to amaze...

[lunator]

Rob

I read that article as well.

I knew that 18 scorp. was until now the best fit, but had too much lithium.

It would be great if careful analysis started to show a regular wobble in the motion

Cheers

Ian