## Física I Lección 23D

# Binary Stars: A Fascinating Phenomenon in Astronomy

## Understanding Binary Systems

I want to pursue the idea of binary stars. They give us not only the information that we want regarding the orbits, but there is even more that we can get out of it which is even more exciting. So I will remind you what a binary system looks like. Remember the second exam. I’m sure you will never forget that second exam and maybe never forgive me for that. In a binary system, there are two stars – star one with radius r1, mass m1, and velocity v1, and star two going about their common center of mass with mass m2, radius r2, and velocity v2. The center of mass is defined by the equation m1 r1 equals m2 r2.

## Doppler Shift Measurements and Kepler’s Third Law

Imagine that you as an observer are somewhere in the plane of this orbit, and you are observing the system going around. By making Doppler shift measurements of both stars, you can determine the period of rotation, velocities, and radii of the stars. By knowing r1 and r2, you can also calculate r1 plus r2, which is crucial in Kepler’s Third Law. With the knowledge of the periods, you can find the sum of the mass of the two stars in the binary system and ultimately solve for the individual masses of the stars.

## X-ray Binaries: A Fascinating Application in Astronomy

In x-ray astronomy, there are x-ray binaries which involve a star, similar to our sun, in orbit with a neutron star or a black hole. These systems exhibit an inner Lagrangian point where the gravitational pull from both stars is balanced. Material from the donor star can fall towards the neutron star, forming an accretion disk and releasing a tremendous amount of energy. This energy release can be compared to the power of an atomic bomb.

## The Incredible Power of Neutron Stars

When matter crashes onto a neutron star, the kinetic energy released is converted to heat, showcasing the immense power of neutron stars. Even a small object like a ten-gram marshmallow thrown onto a neutron star can release energy comparable to an atomic bomb. The velocity at which objects reach a neutron star can be incredibly high, reaching speeds close to 70% of the speed of light.

In conclusion, binary stars and x-ray binaries provide valuable insights into the dynamics of celestial objects and offer a glimpse into the extraordinary power and energy that exists in our universe.

source