12.2 - Galaxies and Stars Flashcards
What are Spiral Galaxies?
Spiral Galaxies are a type of galaxy when viewed directly they look like a pinwheel with spiral arms coming from the galactic core. When viewed from along its edge, a spiral galaxy is a disc shape with a bulge in the centre.
What are Elliptical Galaxies?
Generally, older galaxies without a distinct shape. The stars are spread out more evenly than in a spiral galaxy. We believe they are often the result of merging galaxies!
What are Low Mass Stars?
Mass: smaller than our sun. Typically small red dwarf stars.
Lifespan: Small stars burn their hydrogen fuel very slowly, which means they last for billions and trillions of years for the smallest red dwarfs!
Death: They eventually change into small, hot, dim white dwarfs and quietly burn out over long periods.
What are Intermediate Mass Stars?
Intermediate Mass Stars have three things:
Mass: Similar mass to the Sun.
Life span: Typical “middle mass” star lasts only about 10 billion years. As they run out of fuel, they expand and become red giants.
Death: It ends its life by expanding into a massive red giant star. It then sheds much of its gases into space and collapses in on itself, forming a much smaller white dwarf. After a long time, it cools even more and turns into a black dwarf.
What are High mass stars?
High Mass Stars have three things:
Mass: 12 or more times the mass of the Sun. They are usually large blue stars.
Life span: Short-lived: anywhere from a few million years to about 7 billion years. As they run out of fuel, they expand to an enormous size, becoming supergiants.
Death: These supergiants then end with a supernova and typically become either a black hole or a neutron star.
What are black holes?
Black holes are celestial bodies with such a strong gravitational pull that any light passing too close is pulled into the black hole.
What are the types of black holes?
- Stellar Mass Black Holes
- Supermassive Black Holes
What are Stellar Mass black holes?
Stars between 3 and 10 times the sun’s mass die, they can end their life as a relatively small black holes.
What is a supermassive black hole?
Have a mass anywhere from 100 thousand to billions of solar masses! They are found at the centre of most galaxies and are believed to be formed by collecting large amounts of material as the galaxy was forming.
What are quasars?
The gravity of a supermassive black hole can attract large amounts of gas while a galaxy is still young. As this gas is pulled into the black hole, it begins to circle it, moving faster and faster. Which causes the gas to reach incredibly high temperatures and release an incredible amount of energy into space. They are the brightest objects in the known universe!
