Question 19M.3.HL.TZ1.19
| Date | May 2019 | Marks available | [Maximum mark: 5] | Reference code | 19M.3.HL.TZ1.19 |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Describe, Suggest | Question number | 19 | Adapted from | N/A |
Describe the mechanism of formation of type I a supernovae.
[2]
ALTERNATIVE 1
a white dwarf star in a binary system accretes mass from the companion star ✔
when the white dwarf star mass reaches the Chandrasekhar limit the star explodes «due to fusion reactions»✔
ALTERNATIVE 2
it can be formed in the collision of two white dwarf stars ✔
where shock waves from the collision rip both stars apart ✔
Supernova. The mechanism of the formation of supernovae Ia was well described by many candidates.
Describe the mechanism of formation of type II supernovae.
[1]
a red supergiant star explodes when its core collapses ✔
In (ii), for the description of the mechanism of type II supernovae, many responses lacked detail and did not make mention of core collapse.
Suggest why type I a supernovae were used in the study that led to the conclusion that the expansion of the universe is accelerating.
[2]
«it was necessary» to measure the distance «of very distant objects more accurately» ✔
type I a are standard candles/objects of known luminosity ✔
Part b) was well answered by most of the prepared candidates with a good understanding that these stars behave as “standard candles”.