M31 - Color & Core question

Reg Simpson

Just started with your Horizons training on the weekend. So much fun !

Very little experience with star cluster process and had 2 questions for you.

1) what PI techniques are used to avoid blowing out the M13 core area ?  I saw a recent M13 photo where the core show cluster detail.  How is that done ?

2) question on star color - I see M13 images with a lot of blue color stars in the core and one surrounding bright star,  Is that blue true color or more a color artifact from processing ?  

Just curious on both questions.  Thanks for any tips.

Reg Simpson

first image is my first attempt processing the horizons dataset.

second image is from astrogeo https://t.co/Bv7hTLRaT7

BlockHead

That same article uses one of my images as well.

1. HDRMT is the best tool for managing the core of globular star clusters. This is a tool that takes some understanding and practice to use. HDMRT is even easier to use on the core of M31. But still..there is some practice!

2. Yes, the blue stars are real and not an artifact. Many are blue stragglers (stars that have combined to make larger hotter stars) as well as a real initial mass distribution which still allows for many stars to be at a point along their HR curve (evolution) where they are still bluish (instead of whitish when they were even HOTTER) even though the majority of stars are evolved and old.

-the Blockhead

Reg Simpson

Thanks for the quick reply.  I will give HDRMT a try !

Is there a way inside PI to check individual star colors against the Gaia database.  I need to keep the blue in those stars through my processing

BlockHead

Reg,

Not in the way I imagine you are considering. (I could be wrong of course...)

The GAIA colors are derived from spectra... not color indices. I think you are thinking you would to compare/know a color index of a particular star.

-the Blockhead