Astrophysics Concepts

A comprehensive set of flashcards covering key astrophysics concepts, definitions, and differences related to black holes, supernovae, and star formation.

Equivalence Principle

Cannot distinguish between the absence of gravity and free-fall or the presence of gravity and acceleration.

Time Dilation in Strong Gravity

Time slows down in the presence of strong gravity.

Black Hole Formation

A black hole forms when a collapsing core is too massive (over 2.5-3 solar masses) for neutron degeneracy pressure to stop further collapse.

Density of Black Holes

Black holes are extremely dense, packing huge amounts of mass into a tiny volume; at the singularity, density becomes infinite.

Singularity

The center of a black hole where matter is infinitely dense and the laws of physics break down.

General Relativity

Mass and energy bend space and time (spacetime), and this bending is experienced as gravity.

Type Ia Supernova

Occurs when a white dwarf near the Chandrasekhar limit ignites carbon fusion, blowing the star apart.

Difference Between Supernova and Nova

Type Ia supernova destroys the white dwarf completely, while a nova is a surface explosion where the white dwarf survives.

White Dwarf Explosion in Ia Supernova

When it grows close to the Chandrasekhar limit, pressure and temperature become extremely high, triggering runaway carbon fusion.

Eclipse and General Relativity

A 1919 eclipse showed starlight bending around the Sun, confirming Einstein's prediction that gravity curves spacetime.

Light Path and Curved Spacetime

Light follows the curvature of spacetime, bending near mass or energy sources.

Implication of Equivalence Principle on Space and Time

Mass and energy warp spacetime, changing the shape of space and the flow of time.

Mass and Motion in Curved Spacetime

All masses move the same way through curved spacetime; motion in gravity is independent of mass.

First Black Hole Identified

Cygnus X-1, consists of a massive star and an unseen compact object, with X-rays emitted from the accretion disk.

Birth of Protostar and Telescopes

Typically not seen through optical telescopes on Earth because the star is hidden inside a thick cloud of gas and dust.

Duration of Star Formation

The process of a star being born takes 100,000 - 100 million years; more massive stars are born faster.

Jets

Where wind particles escape most effectively in the direction of the star's poles.

Causes of Jets

Material from an accretion disk gets trapped by magnetic fields and is blasted out.

Protostellar Disk

A flat, spinning disk of gas and dust that forms around a newly forming star.

Function of Protostellar Disk

Delivers gas and dust to the young star over time and is where planets can eventually form.

Protostar Definition

Forms during the contraction of a dense core in a giant molecular cloud, before nuclear fusion begins.

Path of Protostars on HR Diagram

Start cool and bright, move downward as they get dimmer and hotter, and reach main sequence once the core is hot enough to start nuclear fusion.