Section II Question 30 from the 2002 HSC Examination
Summary: (a) Describe the observations made by astronomers on Earth to identify a star as an eclipsing binary. Explain how the total mass of a binary star system can be calculated. (b) Use a table showing distance, apparent visible magnitude and colour index; to determine which star is most blue in colour; to calculate the difference in brightness between two stars; and to sketch a labelled diagram indicating the information required to use the trigonometric parallax method to determine the distance to a star. Part (c) is not in the current syllabus. Describe a nuclear reaction taking place in a main sequence star. (d) Discuss how adaptive optics and at least one other development have improved resolution and sensitivity of ground-based astronomy.