This document provides an overview of stars and their life cycles. It begins by explaining ancient peoples' limited understanding of stars and how mythology incorporated them. It then discusses how early science and astronomy developed by observing stars. The document outlines how stars fuse hydrogen and heavier elements over time. It explains that stars with less than 1.44 solar masses become white dwarfs then black dwarfs, those between 1.44-3 solar masses become neutron stars, and more massive stars form black holes. It concludes by thanking the audience for their time.

1. MYSTERY OF
STARS
Welcome to my presentation
Naimul Arif
CSE
0905004

2. Ancient people had no
idea about the size or the
distance of the stars
They thought that the stars were like glittering
pearls attached with the inner surface of the
semispherical sky

3. Greek and Indian mythology
are vastly related with the
stars.
People imagined the clusters
of stars as different
characters

4. Science & research in ancient age
started following the stars:
First calendar of history
Ancient astronomy
Trigonometry

5. Aristotle told about the stars that
they are constant for ever and no
change will happen to them.
People believed it for many
years.
He was proved false in
1572 by Tyco Brahe

6. The sun is also a star.

9. Towards death of the star
After all of the hydrogen has been used, the
small stars turns into red giants.
In case of giant stars, helium starts fusion and
produces carbon, oxygen, silicon, iron and
gradually goes towards lead.
After generating heavy molecules fusion stops and
supernova occurs.

10. What happens after the death of
a star?
The answer was
given by Indian
scientist
Subramanian
Chandrasekhar

11. Chandrashekhar mathematically
proved that, if the mass of the star is:
*Less than 1.44 solar mass:
Black dwarf
*More than 1.44 solar mass and less
than 3 solar mass:
Neutron star
*More than 3 solar mass:
Black hole

12. When the mass of the star is less
than 1.44 solar mass:
*The star cools, expands in size. Called Red Giant.
*The core collapse on itself, turns into a white dwarf
4
containing He2 .
*Then white dwarf gets cooled again and
gradually becomes unable to emit light .
It is now called black dwarf.
The star is completely dead now. No
change will occur to it for ever.

13. If the mass of the star is between 1.44 and 3
solar mass then it turns into a neutron star:
*The core of the star compresses into a very small
volume.
*The protons and electrons in the core forms
neutrons. Ultimately the whole star
turns into a ball of neutrons.
*The neutron star rotates around its axis with a
great angular velocity.
*This star generates electromagnetic wave
continuously.
*As electromagnetic wave is found from it with a
certain frequency, it is called Pulsar.

14. If the mass of the star is more
than 3 solar mass:
*After the explosion, the core of the star starts
to compress because of gravitational
force.
*After compression, it turns into a sphere with
a very small radius and extremely high
density.
*The gravitational pull of the star is then so
high that no matter even light cannot
escape from it.
*Then it is called black hole.

15. Thank you all for
watching my
presentation.
Good bye
NAIMUL ARIF
0905004