Galaxies and Dark Matter

Flashcards covering key concepts related to galaxies, dark matter, and methods for measuring distance in the universe.

Spiral Galaxy

A type of galaxy characterized by a flat disk and spiral arms, where stars orbit the center in the same direction.

Elliptical Galaxy

A galaxy with an egg-shaped structure and stars that orbit in all directions.

Irregular Galaxy

Galaxies that do not fit into spiral or elliptical classifications, often due to interactions with other galaxies.

Milky Way Galaxy

A barred spiral galaxy approximately 100,000 light-years across, where our solar system is located about 27,000 light-years from its center.

Distance Ladder

A series of methods used by astronomers to determine distances to celestial objects, building upon each other.

Supermassive Black Hole

A massive black hole, often found at the center of galaxies, exhibiting significant gravitational influence.

Active Galactic Nucleus (AGN)

A region at the center of a galaxy that is extremely bright due to gas accreting onto a supermassive black hole.

Dark Matter

A type of matter that does not emit light and can only be detected by its gravitational effects on visible matter.

Luminous Matter

Matter that emits or reflects light, making it detectable through observations.

Gravitational Lensing

A phenomenon where the gravitational field of a massive object distorts the light from a distant object, making it appear brighter.

MACHOs

Massive Compact Halo Objects, a category of potential dark matter candidates, including objects like black holes and neutron stars.

WIMPs

Weakly Interacting Massive Particles, another category of hypothetical dark matter candidates.

Rotation Curve

A plot of the rotation velocity of stars in a galaxy versus their distance from the galactic center.

Standard Candles

Astronomical objects with known luminosities used to gauge distances in the universe.

Globular Clusters

Spherical collections of stars which can be used to measure distances through variable stars.