• Question: Can you tell me how stars are created or born

    Asked by anon-267538 to Zsolt on 9 Nov 2020.
    • Photo: Zsolt Keszthelyi

      Zsolt Keszthelyi answered on 9 Nov 2020: last edited 9 Nov 2020 12:23 pm

      Thanks for the great question! I will invite Sam Geen, my colleague in Amsterdam, to add some points or different views to my answer.

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      The general picture is that stars form in clouds. These clouds are very large, it would take several years to travel across even with the speed of light. The clouds are also very cold, only a few degrees Kelvin. That’s even colder than liquid nitrogen.

      These “molecular clouds” look quite spectacular. Try searching this term on “Astronomy picture of the day” and you will see many fantastic images of these stellar nurseries.

      The cloud will eventually collapse by its own gravity. It is a complicated process but maybe a little bit similar to adding Lego pieces together one-by-one to build something. There are usually hundreds or thousands of stars forming from one cloud. At some point, there are enough pieces together that the object will be what we call a proto-star. This proto-star is now large enough that it will be able to catch gas more rapidly and grow further.

      Once there is enough mass collected, the very centre of the object will heat up to such high temperatures that hydrogen can fuse into helium. As this fusion begins, the star balances gravity by this new energy and it initiates its life.

      There remains a lot more to understand about this complicated process. One interesting thing though is that stars can also form by merging together. This can happen at various stages, maybe even after stars are born. Of course, you need stars close to each other for this process. It turns out that many stars are actually in systems where they orbit around each other, just like the two stars as can be seen from planet Tatooine in Star Wars.

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Comments

  • Photo: Sam

    Sam commented on :

    _cool wrestler being tagged in sequence_

    _sees Zsolt already surrounded by unconscious wrestlers_

    So sctually that description is pretty good. Galaxies are full of hydrogen and helium gas. Most of it is pretty thin – we’re talking ten million trillion times fewer particles in a cubic metre than the air you’re breathing. But over millions of years, this gas can collapse into denser and denser blobs until it makes stars and planets. Eventually these stars make enough energy to blow away the gas left around the star, and the process starts again somewhere else.

    There are different ways to make these clouds of gas. They can be made in the spiral arms of the Milky Way, or by colliding together with other clouds, or even when galaxies collide together.