Self Assessment Week 11

Question 3 The period-luminosity relationship for Cepheid variables was discovered by

Henrietta Leavitt

Question 1 Which of the following stars is a Cepheid variable?

Polaris

Question 4 Why can astronomers not tell from what direction a particular cosmic ray started toward the Earth?

cosmic rays are charged particles and are thus spiral around the Earth and the Galaxy's magnetic field

Question 5 Astronomers use the term interstellar matter to refer to:

gas and dust that lies between stars

Question 7 Which of the following statements about interstellar matter is FALSE?

if the matter were spread out evenly, it would be about as dense as the Earth's atmosphere

Question 6 Cosmic rays differ from other forms of interstellar matter by

moving much faster, at typical speeds of 90% the speed of light

Question 2 Why do Cepheid variables have that strange name?

the first such variable was discovered in a constellation called Cepheus

Question 10 A star whose temperature is increasing but whose luminosity is roughly constant moves in what direction on the H-R diagram?

to the left

Question 8 A star whose temperature is increasing but whose luminosity is roughly constant moves in what direction on the H-R diagram?

to the left

Question 11 Astronomers identify the "birth" of a real star (as opposed to the activities of a protostar) with what activity in the star?

when nuclear fusion reactions begin inside its core

Question 9 Astronomers identify the "birth" of a real star (as opposed to the activities of a protostar) with what activity in the star?

when nuclear fusion reactions begin inside its core