Another helpful tool is this mini-toc, so you can easily jump around :
Normally when you read non-technical book about Stars you mostly get pretty pictures and may be some explanation, but not much more.
I have been interested for long time about the details of how exactly we know the thing that we know about stars in more detailed way and finally I had some time
to pursue this interest. Let me take you with me in this exploration.
The first article will concentrate on how do we find about the different properties of the Stars, things like mass, distance, temperature etc... then the next
on how exactly normal stars generate energy, how they stay in equilibrium and don't explode for billions of years, then may be we will explore the
evolution of the stars.
This is not meant to be full thesis on Stars, just something more than simple star-overview. Again the idea is to fill a gap I think exists.
Because there is so many interconnections between how you can deduce one property of a star from another,
I want to point your attention toward the flowchart on the right, as you go trough the text below I'm almost sure you will get lost in this maze of information. I know I'm ;)
For this reason I created this shortcut diagram of some of the basic relations, so you can orient yourself of what you can derive from what and by what means.
For more detailed formulas
you can also consult the table at the end of the article.
To give you some idea before we start with the meat of the matter, the things we can infer about stars come mostly from several major places, namely direct
observations for the closest stars using simple geometry, then comes the spectral analysis.
Also knowledge of the Universal law of gravitation and Kepler laws give us glimpse of the mass, periods of rotation, distances in gravitationally bound systems
And finally modeling the interior and exterior of stars from our knowledge of fundamental physics and principles of Quantum mechanics, ideal gases and similar
help us guess how exactly stars work and compare the results with our observations.
Now that you've got general idea what we will be looking for let start ...
I got in alot of trouble mixing data from different sources...so at the end I decided to only consult Wikipedia for source data. Also I'm limiting
myself to three decimal places and this round off in most of the cases causes some small discrepancies with the final values and Wikipedia. Anyway if you find any calculation error please let me
know .. all those numbers give me headache ;)
I'm nowhere near with finishing this article ... as I have time I will try to add some more explanation and other examples.
Some more graphs and images would be good too...
As you can see star characteristics we can glance are many and there is myriad ways of finding them, I hope with this article I was able to show how using basic algebra
you can discover them and possibly gain some understanding of the the mighty furnaces giving us light and life.
|`L ~~ M^3.5`||Mass-luminosity ratio||Average for main sequence stars
|`E = tau T^4`||Stefan-Boltzmann law (flux)||Luminosity-temperature relation (per unit area)
|`L = 4 pi R^2 tau T^4`||Luminosity of a star||Boltzmann law applied to a sphere.
|`R = sqrt(L/(4 pi tau T^4)`||Radius from Temperature and Luminosity||the above formula rearranged
|`F = (G M m)/r^2`||Universal gravitational law||
|`G M T^2 = 4 pi R^3`||Kepler 3rd law||
|`lambda_max = k / T`||Wien law||Find temperature from spectrum.
|`m - M = 5 log d - 5`||Distance from apparent and absolute magnitudes||Distance in parsecs
|`(m_1 + m_2) * T^2 = (d_1 + d_2)^3 = R^3`||Mass of stars in binary system||Kepler 3rd law
|`M = (r*v^2)/G`||Centrifugal force : `F = (mv^2)/r` and G-law||
Next time we will explore how Stars work, the principles involved and some physics rule that stays behind it.