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A Star is Born

Explore the fascinating life cycles of stars, from their birth in nebulae to their eventual demise as white dwarfs, neutron stars, or black holes. Understand the different types and characteristics of stars based on mass and temperature, and learn how they evolve over billions of years before meeting their ultimate fate.

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A Star is Born

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  1. A Star is Born By Mona Behrouzian Science 9 Honors December 15, 2014 Presented to Mr. Horton

  2. The Birth of Stars All stars, like the Sun, were formed in a nebula Nebulae are interstellar (meaning between stars) clouds of dust and gas, mostly consisting of hydrogen atoms. These are also known as stellar nurseries, and are filled throughout spiral galaxies

  3. The Birth of Stars cont. Hydrogen atoms are clumped and pressed together by gravity towards the core. As the atoms collide, the temperature rises. The core begins to get denser and denser and the gas pressure increases. Once the gas pressure is equivalent to gravity, atoms stop being added to the center of the proto-star.

  4. The Birth of Stars cont. If the core of the protostar is at the right temperature, a process called nuclear fusion begins. The hydrogen atoms compact and form, converting into helium, a denser element. At this point, the protostar is known as a “main sequence star,” which means it is shining

  5. The Different Types of Stars • The three main types of stars are based on how massive they are. • There are Sun-like, Huge, and Giant stars • Sun-like stars have a mass up to one and a half times of the Sun • Huge stars have a mass from one and a half to three times of the Sun • Giant stars have a mass over three times of the Sun • Each of these types of stars have different lifecycles that they go through • Sun-like: Red Giant  Planetary Nebula  White Dwarf  Black Dwarf • Huge: Red Supergiant  Supernova  Neutron Star • Giant: Red Supergiant  Supernova  Black Hole

  6. The Different Characteristics of Stars Sirius, the brightest star in the night sky Stars can be distinguished by their colors. The color of a star is based on its temperature. Red stars are the coldest, while blue stars are the hottest. The brightness of stars are measured by their magnitude (how heavy it is). The heaviest stars are the brightest stars, having the hottest surfaces. The mass is greatest in these stars, meaning the number of atoms that make it up are the highest.

  7. The Life of a Star: Lifespan Red dwarfstar CHXR 73 • If a star is very massive (e.g. 30-50 times larger than the Sun), its lifespan is a few million years • If a star’s size is similar to the Sun’s, its lifespan is about 10 billion years • If a star is smaller than the Sun, its lifespan is even greater than 10 billion years! • Red dwarfs can live up to trillions of years. Red dwarfs are the smallest stars, with a mass of only 10-50% of the Sun. Due to their size, they burn at a lower temperature, making them very dim compared to other stars. With a lower temperature, they burn up the hydrogen (from the inner and outer core) much slower.

  8. The Death of a Star The Sun is the closest main sequence star to Earth After a star is born, it remains in a stable state (a main sequence star). The state makes up the majority of a star’s life. The life of every star will eventually come to an end. However, depending on how massive the star is, the process of their death varies.

  9. The Death of a Sun-like Star With age, all stars expand. The star’s core begins to lose the hydrogen and helium atoms it is made of. The outer layers of the star cool when it expands, causing the brightness to diminish.The result is known as a red giant While the red giant expands, the core is contracting. The helium atoms in the core are fusing together to form carbon atoms, and as a result, release energy.

  10. The Death of a Sun-like Star cont. Eventually, the outer layers wander out into space, resulting in a planetary nebula. In this phase, the star’s mass is mostly lost.

  11. The Death of a Sun-like Star cont. The star cools and minimizes in size. With no more nuclear fuel, the star becomes a white dwarf. For billions of years, it will radiate any heat that remains Sometime, a white dwarf’s brightness increases by numerous magnitudes, forming a nova In time, all the heat will run out, leaving the once bright shining star into a cold, dead, gloomy black dwarf Black dwarf White dwarf Artistic portrayal of a nova

  12. The Death of a Huge & Giant Star The death of huge and giant stars are the same leading up to their final stage (neutron star vs. black hole) As mentioned before, stars (including huge stars) expand as they age. However, huge stars become into red supergiant's (an even more enormous version of red giants) This life phase lasts millions of years

  13. The Death of a Huge & Giant Star cont. The core of the star experiences a different nuclear process. Atoms fuse into denser elements than carbon. Instantaneously, the core collapses. The crashing of iron atoms causes the temperature in the core to increase to 100 billion degrees! The outer layers of the red supergiant are blown away by a shock wave. This incredible explosion is known as a supernova

  14. The Death of a Huge & Giant Star cont. Animations of a neutron star & a black hole • After the supernova, the star reaches the final stage of its death. This depends on the remaining mass • Huge stars contract into an extremely small and dense star known as a neutron star • Neutron stars have a strong magnetic field and spins rapidly • Giant stars contract to form a black hole • Black holes are extremely dense gravitational fields

  15. Bibliography http://naasbeginners.co.uk/AbsoluteBeginners/Life_of_star.htm http://www.astro.keele.ac.uk/workx/starlife/StarpageS_26M.html http://aspire.cosmic-ray.org/Labs/StarLife/starlife_proto.html http://aspire.cosmic-ray.org/Labs/StarLife/nebula/nebula.html http://www.enchantedlearning.com/subjects/astronomy/stars/lifecycle/stardeath.shtml http://www.enchantedlearning.com/subjects/astronomy/stars/lifecycle/starbirth.shtml http://space.about.com/od/stars/tp/What-Are-The-Different-Types-Of-Stars.htm http://www.space.com/23772-red-dwarf-stars.html http://www.nasa.gov/multimedia/imagegallery/image_feature_1513.html http://en.wikipedia.org/wiki/Nebula http://aspire.cosmic-ray.org/Labs/StarLife/starlife_equilibrium.html http://www.spacetelescope.org/images/opo9313a/ http://epod.usra.edu/blog/2013/01/the-brightest-star.html http://www.crystalinks.com/stars.html http://en.wikipedia.org/wiki/Planetary_nebula http://www.skyandtelescope.com/astronomy-news/novae-surprise-with-gamma-rays-07312014/ http://www.nasa.gov/mission_pages/GLAST/science/neutron_stars.html http://www.nasa.gov/audience/forstudents/k-4/stories/what-is-a-black-hole-k4.html

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