Explain how observations of white-dwarf supernovae provide ...

[cagreen833]

Explain how observations of white-dwarf supernovae provide information on the expansion of the universe when it was younger.
 
  What will be an ideal response?

Question 2

A black hole may be visible because electromagnetic radiation is emitted from an ________ surrounding it, heated up enough to emit X-rays.
 
  Fill in the blank(s) with correct word

[hanadaa]

Answer to Question 1

White-dwarf supernovae attain the same maximum brightness and are therefore good standard candles with which to measure galaxy distances. Therefore, if we see a white-dwarf supernova in a distant galaxy we can measure how far away it is, and thus how old the universe was when the supernova exploded. We can also measure the Doppler shift of spectral lines in the galaxy and find how fast it is moving away from us. This tells us how fast the universe was expanding when it was much younger.

Answer to Question 2

accretion disk

[cagreen833]

Thanks for the timely response, appreciate it

[kishoreddi]

Gracias!