Chapter 20

Here is Chapter 20 – From Young Stars to Black Holes, and its all about stars! Let me know if something looks like it might be wrong! 🙂

1. Construct a Hertzsprung-Russell diagram, putting in the stars given in the table.
H-R Diagram

2. What is a pulsar? Why is its density so high?
A pulsar is a rapidly rotating neutron star. It emits radio waves in two places on the star, giving the radio waves a pulsing effect as the star rotates.

3. What would you take to be the colours of the following stars: (a) Regulus (spectral type B7), (b) Pollox (K0), (c) Arcturus (K2), (d) Alkaid (B3), (e) Chi Cygni (S)?
a)   Regulus would be a white blue coloured star.
b)   Pollox would be an orange star.
c)   Arcturus would be an orange star.
d)   Alkaid would be a bluish coloured star.
e)   Chi Cygni would be a red star.

4. In what way can we hope to detect a black hole?
Because we cannot see a black hole, we need to watch the things we can see. If material is being pulled in a certain direction in a unusual way, and is heated to such a temperature that it can emit X-rays; then it is most likely being affected by a black hole.
Black Hole (Artists Impression)
5. Why can we be confident that our Sun will not suffer a supernova?
We can be reasonably confident because our local star is not large enough to cause a supernova. For a supernova to occur, the Sun would need to be half its weight heavier.


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