SAO 2021, Писмен тур — Задача 9. Galaxies

1. The entire Olympiad lasts for 3.5 hours and is worth a total of 200 marks.
2. Fill in these details on the cover page (after the Contents page), the Summary Answer Sheet and each side of an SAO answer sheet:

   • Year of competition
   • Your participant code
   • The page number – which should be continuous from 1 to N
   • The part of the paper, and the question number
3. Cross out all workings or answers you do not wish to be evaluated.
4. You are allowed to leave the venue early upon submission of your answer script (see Instructions on Cover Page), but only after one hour after the start of the paper and not within 30 minutes to completion of the paper.
5. Please raise your hand to seek assistance from the invigilators (e.g. to visit the restroom, request for more answer sheets, enquire about an ambiguity, etc.)

1. Only the use of scientific calculators is permitted. No graphing or programmable calculators are allowed.
2. Disruptive behaviour, cheating, collusion to cheat or any integrity-related offences are grounds for immediate disqualification.
3. You may opt to retain the question paper and constants sheet for personal use. Return all unused answer sheets to the Organising Team.

1. MS Star Details are derived from: Zombeck, Martin V. (1990). Handbook of Space Astronomy and Astrophysics (2nd ed.). Cambridge University Press
2. Additional MS Star Details are derived from: Vardavas, Ilias M.; et al. (2011), "Chapter 5. Incoming Solar Radiation" Radiation and Climate: Atmospheric Energy Budget from Satellite Remote Sensing.

Astronomy.SG would like to thank the organizing committee and the question setters. This document is typeset in LaTeX.

1. Fill in all required details below, before time is up.
2. Ensure that all materials (answer sheets, graphing paper, practical question paper) you intend to submit for grading have been attached. Amendments to any answer script after it has been collected will not be entertained.
3. Details on each side of answer sheet:

   • Your participant code.
   • Question number.
   • Page number – continuous from 1 to N throughout your answer script.
   • DO NOT WRITE YOUR NAME ON YOUR ANSWER SCRIPT.
4. Order of answer script:

   • Stack 1: i. This cover page.
     ii. Summary Answer Sheet iii. Answer sheets from Part 1 to 3, in continuous order from page 1 to M.
   • Stack 2: i. Answer sheets for Part 4, in continuous order from M to N.
     ii. Graph(s) from Part 4.
   • Stack 3: i. Practical cover page.
     ii. Practical Component from Part 5.

Write all your responses in the summary answer sheet provided.

This section contains a total of 5 short-length questions worth 9 marks each.
You are to choose 4 to do.

This section contains a total of 2 medium-length questions worth 18 marks each.
You are to choose 1 to do.

INSTRUCTIONS TO PARTICIPANTS:

1. Fill in all required details below, before time is up.
2. You are to detach this page and all subsequent pages as part of your response.
3. All detached pages are to be re-stapled and be part of your 3rd stack of your answer script.
4. All responses to this section of the paper are to be written on the question paper itself, in the spaces provided.
5. There will be a star chart provided as part of the question. Responses to the corresponding questions in that section are to be answered on the star chart itself.
6. All final responses shall be written legibly and unambiguously.
7. Details on each page:

   • Your participant code.
   • DO NOT WRITE YOUR NAME ON YOUR ANSWER SCRIPT.

Each question is worth 2 marks.

Summary of answers: