Size does matter: The Sun

Hijinx
reply to post by ErosA433

 

Betlegeuse, is a red super giant. It's cooler than our sun, but larger than our solar system's entirety.

Color, goes along with temperature, but it does not go along with size. In fact as our star cools, it will expand, and become less dense.

Indeed though I was speaking of the main sequence and not the giant and sub-giant branch. And Betelgeuse is big, but not THAT big... it extends somewhere between Mars and the Asteroid belt, from the most recent estimates id seen.

Giants are relative rarities because they are short lived in the grand scheme of things. On a HR diagram, the mains sequence stars peel off of the main-sequence and move off into the sub-giants branch. Truly enormous stars of the mains sequence don't live all that long, and spend a short period on the main sequence and then move straight into super-giant territory, some of which don't explode at the end of life, they just blow off all their outer material and fade away. The luminosity and colour of the giant branch is also used to date star clusters, as if all stars are born at around the same time and are of similar size (remember the statement regarding the sun?) then it follows that the older the cluster, the cooler the giant branch. It does reach a limit however because very red and very small stars go on living for what seems like forever, never swelling or expanding, they just slowly fade away.

The lives of stars and all their different types is pretty amazing.

If you are looking at a main sequence star (can be determined by spectral type) and you know the distance, you can use the relative luminosity to calculate an estimated size.

Pretty basic, you look at two red stars that are at the same distance, they appear to be the same temperature, except one is giving you 10x more light. The brighter one is thus larger.

crazyewok
By the way about life in systems with super massive stars.

Theres a big problem, the super massive stars are very short lived. Chances are too short lived for life to develope before the star goes nova.

edit on 10-1-2014 by crazyewok because: (no reason given)

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Aww man, those posts were getting hilarious though.


2nd

ErosA433

Hijinx
reply to post by ErosA433

 

Betlegeuse, is a red super giant. It's cooler than our sun, but larger than our solar system's entirety.

Color, goes along with temperature, but it does not go along with size. In fact as our star cools, it will expand, and become less dense.

Indeed though I was speaking of the main sequence and not the giant and sub-giant branch. And Betelgeuse is big, but not THAT big... it extends somewhere between Mars and the Asteroid belt, from the most recent estimates id seen.

Giants are relative rarities because they are short lived in the grand scheme of things. On a HR diagram, the mains sequence stars peel off of the main-sequence and move off into the sub-giants branch. Truly enormous stars of the mains sequence don't live all that long, and spend a short period on the main sequence and then move straight into super-giant territory, some of which don't explode at the end of life, they just blow off all their outer material and fade away. The luminosity and colour of the giant branch is also used to date star clusters, as if all stars are born at around the same time and are of similar size (remember the statement regarding the sun?) then it follows that the older the cluster, the cooler the giant branch. It does reach a limit however because very red and very small stars go on living for what seems like forever, never swelling or expanding, they just slowly fade away.

The lives of stars and all their different types is pretty amazing.

If you are looking at a main sequence star (can be determined by spectral type) and you know the distance, you can use the relative luminosity to calculate an estimated size.

Pretty basic, you look at two red stars that are at the same distance, they appear to be the same temperature, except one is giving you 10x more light. The brighter one is thus larger.

edit on 10-1-2014 by ErosA433 because: (no reason given)

edit on 10-1-2014 by ErosA433 because: (no reason given)

Thank you for the info.