The energy source at the center of our galaxy a. is not ...

[newbem]

The energy source at the center of our galaxy
 
  a. is not visible at optical wavelengths.
  b. produces X-rays.
  c. must be less than 10 AU in diameter.
  d. is not visible at optical wavelengths, produces X-rays, and must be less than 10 AU in diameter.
  e. None of the other choices are correct.

Question 2

Describe two methods that could be used to determine the temperature of a star.
 
  What will be an ideal response?

[coreycathey]

Answer to Question 1

d

Answer to Question 2

The Balmer thermometer is a method of determining the temperature of a star. It works because the strength of the Balmer lines depends on the temperature of the star's surface layers. Theoretical calculations can predict how strong the Balmer lines should be for stars of various temperatures. Temperature has a similar effect on the spectral lines of other elements, but the temperature at which the lines reach their maximum strength is different for each element. Another way is to use the temperature-luminosity relationship.

[newbem]

Gracias!

[amcvicar]

Thanks for the timely response, appreciate it