You observe a star orbiting in the outer parts of a galaxy. The distance to this galaxy is known, and you are able to take a spectra of this star and determine its velocity. The star is 22 kpc from the galaxy center and moving in a circular orbit with speed 304 km/s. Compute the total mass of the galaxy internal to the star's orbit. You will get a large number; express it in scientific notation and in units of solar masses [e.g., 4.2e10]. [Hint: there is a Box in Chapter 22 of your textbook that will be of help. See also the course formula sheet.]
Stellar evolution
We may see thousands of stars in the dark sky. Our universe consists of billions of stars. Stars may appear tiny to us but they are huge balls of gasses. Sun is a star of average size. Some stars are even a thousand times larger than the sun. The stars do not exist forever they have a certain lifetime. The life span of the sun is about 10 billion years. The star undergoes various changes during its lifetime, this process is called stellar evolution. The structure of the sun-like star is shown below.
Red Shift
It is an astronomical phenomenon. In this phenomenon, increase in wavelength with corresponding decrease in photon energy and frequency of radiation of light. It is the displacement of spectrum of any kind of astronomical object to the longer wavelengths (red) side.
You observe a star orbiting in the outer parts of a galaxy. The distance to this galaxy is known, and you are able to take a spectra of this star and determine its velocity. The star is 22 kpc from the galaxy center and moving in a circular orbit with speed 304 km/s. Compute the total mass of the galaxy internal to the star's orbit. You will get a large number; express it in scientific notation and in units of solar masses [e.g., 4.2e10].
[Hint: there is a Box in Chapter 22 of your textbook that will be of help. See also the course formula sheet.]
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