With plans set to switch members with the second cohort students of YSF, this talk will most likely be the last talk prepared by the first cohort members. The day’s talk is about Stars by an Upper Sixth PTET Student, Batrisyia at Lecture Theater Excellence as our tenth talk. The talk was attended by a large number of students as well as tutors from both departments so we are grateful for your participation. The talk covers about general information on stars, the formation of said stars as well as the events that may occur following the death of a star.
The talk begins with the introduction of stars and briefing about some extra facts about stars. She introduces to us the largest known star, that is the VY Canis Majoris which is so big that when placed side-by-side to our sun, the sun could be as small as a dot. She also talks about that stars do not actually ‘twinkle’ as they appear to be when we look up at the night sky. As explained by her, the light from the stars had to pass through several layers of the atmosphere and is then distorted in order to reach our eyes.
“Do you know the coldest starts are actually red in colour while the hottest stars are blue in colour?”
She proceeds with the formation of stars where clouds of dust, rocks and gases in space called nebula collapsed on itself by gravitational forces, causing temeperature to rise. Rising temperature will eventually bring about nuclear reactions to form stars that we see today. Stars stay alive and stable because of its resources available in its core namely hydrogen which reacts and creates helium and pressure to push the star outwards and preventing it from collapsing back into the core by its gravity.
She explains that stars begin to die when their resources in the core begin to run out. For stars as large as the sun which are considered as the average size of stars in the universe, the stars will become red giants, break apart and eventually turn into a ‘white dwarf’. White dwarves are remains of a sun that can be very small but also very dense – they can have the size of the earth yet having half the mass of the sun.
For much more massive stars, approximately 1.5x larger than the sun, the stars will become red giants with extremely dense cores due to repeated nuclear fusions with high energy. The star with dense cores will collapsed which subsequently is rebounded outwards – unleashing a supernova. After a supernova, two events can happen – the formation of a blackhole or the formation of a neutron star. Neutron stars are similar to white dwarves, having high density at small sizes.
The talk proceeded well with some humour. During the question and answers session, she answered the questions very well as she was very well prepared. There was a student which asked, “Can dead stars, the white dwarves, absorb energy and carry out nuclear fission again?” which Batrisyia replied, “Actually.. yes, if two stars orbiting each other and one of the star dies, the dead star can actually take in materials from the live star and begin nuclear fission and be a live stable star again.”
Our sun is still at a stable state. Its predicted age is to be 10 million years and right now, our sun is 5 million years old.
And with that, we would like to thank for the audience that participated in the talk. We are grateful as well to the teachers and to the Principal for your kind attendance for the talk! We look forward to seeing you in future talks.