Birth and Death of Stars

Astronomers learn about stars by observing the electromagnetic radiation the stars emit. The most common type of telescope collects and analyzes visible light.

There are other kinds of telescopes that collect the entire range of electromagnetic radiation from radio waves to gamma rays.

Radio Telescope

X-ray Telescope

Stars shine from nuclear fusion for millions or billions of years and change through their life times as the kinds of atoms being fused in the cores change.

Nuclear fusion- The combining of smaller atoms into heavier atoms with the release of tremendous amounts of energy

All stars begin as nebula, clouds of interstellar dust and gas. The smaller stars are the coolest, dimmest, longest living stars and burn red.

nebula Cool red stars

The most massive stars fuse atoms at an intense rate and are very hot and very bright burning with a blue-white color for only a few million years before running out of nuclear fuel.

The most massive stars fuse atoms at an intense rate and are very hot and very bright burning with a blue color for only a few million years before running out of nuclear fuel.

Hot, bright, Fast burning stars Cool, dim, red stars

A main sequence star like the Sun, a yellow star, will fuse hydrogen atoms into helium atoms for 10 billion years before becoming a red giant star, fusing helium into carbon atoms.

Red giants are cool stars but because of their enormous size have immense luminosities. The Sun, at 5 billion years, is about half way through its life time.

Luminosity – how bright a star shines.

The red giant stage lasts for only a few hundred million years at the most. A Sun sized star will die and become a white dwarf after nuclear fusion ceases.

More massive stars will explode as supernova, outshining their galaxy. The cores of stars that go supernova are very dense objects.

Type IA Supernova

Neutron stars are so dense that a teaspoon of neutron star material would weigh hundreds of thousands of tons on Earth.

Some stars collapse into an object so dense that the gravitational field around them is strong enough to prevent light from escaping its grip, a black hole.

1. Which of the following would be an instrument astronomers would use to gather data from stars? a. barometer b. microscope c. radio telescope d. anemometer

1. Which of the following would be an instrument astronomers would use to gather data from stars? a. barometer b. microscope c. radio telescope d. anemometer

2. Stars are formed from accumulations of a. star clusters. b. galaxies. c. solar wind particles. d. dust and gases.

2. Stars are formed from accumulations of a. star clusters. b. galaxies. c. solar wind particles. d. dust and gases.

3. Stars begin their life cycle in a. a black hole. b. a nebula. c. a nova. d. a supernova.

3. Stars begin their life cycle in a. a black hole. b. a nebula. c. a nova. d. a supernova.

4. The surface temperature of a star a. is inferred from it's color. b. is determined using parallax. c. is inferred from it's distance. d. is it's apparent magnitude.

4. The surface temperature of a star a. is inferred from it's color. b. is determined using parallax. c. is inferred from it's distance. d. is it's apparent magnitude.

5. The hottest stars are a. blue in color. b. yellow in color. c. red in color. d. white in color.

5. The hottest stars are a. blue in color. b. yellow in color. c. red in color. d. white in color.

6.The sun is a. a yellow giant star. b. a yellow dwarf star. c. a main sequence star. d. part of a binary star system.

6.The sun is a. a yellow giant star. b. a yellow dwarf star. c. a main sequence star. d. part of a binary star system.

7.The color of a star indicates that its size and temperature is similar to the Suns. What inference can be made about this star?

a. It is older than the Sun. b. The Earth is moving away from this star. c. It will shine for billions of years. d. It is a red giant.

a. It is older than the Sun. b. The Earth is moving away from this star. c. It will shine for billions of years. d. It is a red giant.

8. The Sun will eventually become a. a red giant. b. a massive black hole. c. a supernova. d. a neutron star.

8. The Sun will eventually become a. a red giant. b. a massive black hole. c. a supernova. d. a neutron star.

8. A type of star that is hundreds of thousands of times brighter than the sun but is much cooler a. is a red giant. b. is a supernova. c. is a white dwarf. d. is a blue giant.

8. A type of star that is hundreds of thousands of times brighter than the sun but is much cooler a. is a red giant. b. is a supernova. c. is a white dwarf. d. is a blue giant.

9. Stars collapse and end their lives when a. nuclear fusion ceases in their interiors. b. nuclear fission ceases in their interiors.

c. their supply of oxygen to burn hydrogen fuel is used up. d. the radioactive materials in their interiors have completely decayed.

9. Stars collapse and end their lives when a. nuclear fusion ceases in their interiors. b. nuclear fission ceases in their interiors.

10. Generally, the more massive a star is a. the longer lived it is. b. the less luminous it is. c. the redder in color it is. d. the more luminous it is.

10. Generally, the more massive a star is a. the longer lived it is. b. the less luminous it is. c. the redder in color it is. d. the more luminous it is.

11. Stars many more times more massive than the Sun a. may become supernova or even black holes. b. remain main sequence stars much longer than the Sun does.

c. are not main sequence stars. d. are known as Cepheid variables.

11. Stars many more times more massive than the Sun a. may become supernova or even black holes. b. remain main sequence stars much longer than the Sun does.

12. The sudden appearance of a very bright object in another galaxy usually indicates a a. comet. c. supernova. b. nebula. d. meteor.

12. The sudden appearance of a very bright object in another galaxy usually indicates a a. comet. c. supernova. b. nebula. d. meteor.