already know to determine the distance to the star, its temperature, composition
, its intrinsic brightness, its size. What are we missing?
But I still I have a question. How should I know the mass of the stars?
mass is what makes the bodies of the universe attract each other. The more mass, the attractiveness is the body in question. Well
. . . Well I guess the biggest stars are the most massive, right? Ale!, Problem solved.
I'm more relaxed. Sure, it makes sense. The largest are the most massive. It must be so. Come, I'm going to relax and take a bath.
I'm in the bathroom little calm. The water is still warm and I have no desire to leave so soon. I'll read a book. Astronomy, of course. Look
coolest photos. This is ... Saturn.
Saturn, the second largest planet in our solar system,
much larger than Earth, it would float in water because of its low density.
Wow! It says here that Saturn would float in water. I can not help looking at my chichas sunk in the water and think that I must be very fat if I
sink into the water and Saturn, which is 10 times larger than Earth, it floats.
Ah! He says that what happens here is that Saturn is less dense than water and it floats. That is, that the matter in Saturn is not as dense and apilotonada in one volume that my belly is more matter than Saturn and therefore sinks. What a depression! I'm going to eat chocolate.
is, that my argument that the larger more massive an object is false. Is not the same take a cork than the same volume, but lead.
So, If I can not trust their size. . . How will I know the mass of the stars?
Mmmm. . . How good is the chocolate! But you should play sports. Anyway ... I can always go to the moon and weigh less. Everyone remembers
the astronauts bouncing on the moon and falling slowly.
were light as a feather.
Wait a minute. . . Why is that? Why do astronauts, who have the same tummy than on Earth, when the moon will weigh less?
The difference between the Earth and Moon is that it is less massive and therefore less strongly attracted to its surface bodies.
Similarly, if a body is orbiting a star much more massive star has the least take the body to circle around him. Faster orbit. It seems logical, right?
Well, we have the problem solved. We watch a double star,
of those that revolve around each other and look how long it takes to return to
same position. That gives us information on the mass of the binary stars. The shorter the time, but mass.
Once we know the mass of stars in a dual system can
stop and analyze how that mass is a function of the light they emit.
When we do this we see that there is a relationship between the light emitted in a star and its mass.
If we determine the dependence of the luminosity of a star of its mass by double stars, this very relationship can be applied to single stars. That is, now we have a law that says that such a shining star
therefore must have a mass equal to both.
There is also another method that starts to be used also to know the mass of single stars. For this we need to talk about our friend
Einstein and relativity. Relativity tells us that light behaves like a
body mass. So, that could happen if an object has some mass
was able to bring a ray of light (or at least make you tickle
).
This means that if a ray of light passes near a star on his way
to Earth, the ray in question is diverted from its original path
taking another direction. We'll see how far the stars are in a slightly different position in the sky. The more different
this position is the star mass is shifting light. And voila, we have the mass of the star. Click
here to see animation of how the background stars change their position over a star in front of them.
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