Life cycle sci9

• Patterns formed from groups of stars


  Called constellations, discussed in this module
• Characteristics of stars

  • Luminosity
  • Surface temperature
  • Colour
  • Size
  • Mass
• Stars are the most fundamental building blocks of galaxies
• Elements produced in stars are emitted into space when the star dies
• Fusion happens when 2 atoms are forced together to form a heavier atom, creating a lot of energy
• Balance between fusion process outward force and gravity stops the star from collapsing or expanding
• The Sun appears as a yellowish-white star with a surface temperature of approximately 5,500 degrees Celsius
• The Sun constitutes more than 99% of the entire mass of the solar system
• The Sun is a main-sequence star, one of the most common types of stars in the universe
• Proxima Centauri is about 41 million million km away from Earth
• Everything, including humans, is made of "stardust" from elements produced in stars
• Energy in a star is made in its core by nuclear fusion
• Stars are actually massive objects, millions of times larger than the Earth
• All stars are huge spheres of glowing gas mostly made up of hydrogen
• Parallax measurement

  Apparent change in position of an object when viewed from different places
• The energy from nuclear fusion makes stars shine brightly
• Life cycle of stars


  Discussed in this module
• Stars are massive balls of plasma that emit light throughout the universe
• Stars are made of very hot gas, mostly hydrogen and helium
• Energy released from fusion makes a star shine
• Elements heavier than hydrogen and helium in the Universe were made in stars through nuclear fusion
• Light and heat from stars are made by the nuclear fusion process
• Elements move into nearby gas clouds or nebulae and form building blocks for new stars
• Stars look small in the sky because they are very far away
• The Sun is a star around which Earth and the other components of the solar system revolve
• The Sun is the source of energy providing light and heat necessary to support life on Earth
• The Sun is relatively small compared to other stars, with a mass of about 1.989 x 10^30 kilograms
• Astronomers use parallax to measure distances to nearby stars
• Proxima Centauri is the nearest star after the Sun, located 4.3 light years away
• The Sun is an average-brightness star but appears brighter due to its proximity to Earth
• Stars make energy by nuclear fusion
• Parallax shift is used to calculate the distance of a star
• A photometer measures and quantifies the brightness of celestial bodies, depending on luminosity, distance, and obscuring matter
• The sun is an average-brightness star but appears brighter and larger than other stars due to its proximity to Earth
• Brightness

  • Luminosity is the amount of light a star radiates, determined by its size and surface temperature
  • Apparent Magnitude is the perceived brightness factoring in size and distance
  • Absolute Magnitude is the true brightness irrespective of distance from Earth
• Size

  • Stars come in supergiant, giant, medium, and dwarf sizes, distance affects how stars are seen
• Surface Temperature

  • Depends on the star's mass, very massive stars are hottest and glow blue, smaller stars are coolest and glow red
• Characteristics defining a star

  • Brightness
  • Colour
  • Surface temperature
  • Mass
  • Size
• Example star

  • Sirius, also known as the Dog Star or Sirius A, is the brightest star in Earth's night sky
• Stars

  Huge spheres of glowing gas, mostly made up of hydrogen, and make energy by nuclear fusion