Dark Matter and Spiral Galaxies

A set of vocabulary flashcards covering key concepts related to dark matter and the structure of the Milky Way as discussed in the lecture notes.

Dark Matter

A form of matter that does not emit light or energy; its presence is inferred from its gravitational effects on visible matter.

Doppler Shift

The change in wavelength of light due to the relative motion of the source; can indicate whether an object is moving toward or away from the observer.

MACHOs

Massive Compact Halo Objects, a category of dark matter candidates that include baryonic objects like brown dwarfs, white dwarfs, and black holes.

WIMPs

Weakly Interacting Massive Particles, a category of hypothetical dark matter particles that interact through weak nuclear forces.

Rotation Curve

A plot of the rotation velocities of objects in a galaxy versus their distance from the galaxy's center; indicates the distribution of mass in the galaxy.

Gravitational Lensing

The bending of light from distant objects around a massive object due to gravity, allowing astronomers to observe the presence of dark matter.

Spiral Density Waves

Regions of higher mass density in the interstellar medium of a galaxy that propagate around the disk, inducing star formation.

Milky Way

The galaxy that contains our Solar System, characterized by its spiral structure and dominated by dark matter.

Flat Rotation Curve

A characteristic of the rotation curve of some galaxies where the rotation velocity remains constant over a distance from the center, suggesting dark matter influence.

Cold Neutral Hydrogen

An abundant form of hydrogen that emits radiation at 21 cm wavelength, used to study the structure and rotation of galaxies.