(E) Topic 13 - Exploring Starlight

Question 1

What is the distance modulus formula?

> What does each of the letters
represent?

Answer 1

M = m + 5 − 5log d

M = Absolute magnitude
m = Apparent magnitude
d = Distance (in Parsecs)

Question 2

What does the term absolute magnitude mean?

Answer 2

How bright a star would appear in space from a certain distance.

Question 3

What does the term apparent magnitude mean?

Answer 3

How bright an object is to us on Earth.

Question 4

What information can be obtained from a stellar spectrum?

Answer 4

• Chemical composition
• Temperature
• Radial velocity

Question 5

How can stars be classified according to their spectral type?

Answer 5

Astronomers categorise stars by temperature and their chemical composition that they obtain from a star’s stellar spectrum.

Question 6

What’s the mnemonic to remember the series of letters to define a spectral type?

Answer 6

Oh Be A Fine Guy Kiss Me

Question 7

Whats the value of 1 pc?

Answer 7

3.1 x 10^13

Question 8

What are the causes of variability in the light curve of eclipsing binary stars?

Answer 8

• One will move in front and behind the other as seen from Earth
• Frequently, one star is brighter than another

Question 9

What is an Eclipsing binary star?

Answer 9

A pair of stars that orbit each other

Question 10

How can the period of an eclipsing binary star can be deduced from its light curve?

Answer 10

By charting the brightness of a binary star you can find its period

e.g. In a graph, the period would be from the ‘dips’ at 24 and 64 leading to a period of 30 hours.