NationStates Jolt Archive

What is the relationship between a star's mettalicity and its color? Is size involved? If so, how?

What is the relationship between a star's mettalicity and its color? Is size involved? If so, how?
Disclaimer: I am an amateur, not a chemist or physicist.

AFAIK, Starts produce metals, particularly in the late stages of their lives, and I guess also that large stars would produce more than young ones. But that's an uneducated guess.
I found this website though:
http://www.astro.uiuc.edu/~kaler/sow/spectra.html

O --- ionized and neutral helium, weakened hydrogen --- bluish --- above 31,000 K
B --- neutral helium, stronger hydrogen --- blue-white --- 9750-31,000 K
A --- strong hydrogen, ionized metals --- white --- 7100-9750 K
F --- weaker hydrogen, ionized metals --- yellowish white --- 5950-7100 K
G --- still weaker hydrogen, ionized and neutral metals --- yellowish --- 5250-5950 K
K --- weak hydrogen, neutral metals --- orange --- 3800-5250 K
M --- little or no hydrogen, neutral metals, molecules --- reddish --- 2200-3800 K
L --- no hydrogen, metallic hydrides, alkalai metals --- red-infrared --- 1500-2200 K
T --- methane bands --- infrared --- 1000 K

First the class, then their make-up, then their colour and then their temperature in Kelvin.

Wiki will probably have something too.

Generally, the metal-heavy stars are the ones nearing the end of their lifespan; if I understand stellar astronomy correctly, stars maintain themselves by releasing energy via fusion reactions, using elements up to [but not including] iron [since iron fusion doesn't create energy].

All elements heavier than iron are the result of some or other supernova explosion. I don't know offhand which metals are lighter than iron, or which metals are formed by other means either during [or perhaps after] the supernova.

I would venture to guess as a result of all of this, a star's size is related to its metallacity since the older stars are usually the ones that are getting bigger and redder [and becoming cooler in the process].

But then again I don't know much about astronomy. I'm pretty sure this is accurate, but I wouldn't quote me if I were you.

Thanks. This is just the sort of thing I was looking for (couldn't find anything on wikipedia).

I don't need anything particularly definate, just enough to keep a mod I'm helping with for a space game realistic.

EDIT: and, of course, to satisfy my own curiosity.

http://www.mira.org/fts0/stars/114/txt001w.htm

this has a good explanation, basically the color is the bluer the hotter the star is. because the energy output is greater and the wavelength shorter. the temperature is determined by the size and by the stage in which it is currently burning its fuel (i.e. whether it is burning hydrogen or whether it is in the CNO cycle)

you may also observe absorbance of select wavelength, if the light passes through nebulas with elements, that absorb those.
finally, the whole spectrum will be shifted towards red, depending on how fast the star is moving away from you.
but the two effects described last shouldnt be visible to the naked human eye, just important for research.