Astrophysics, Cosmology & Relativity
4 terms
Parsec
Astrophysics, Cosmology & Relativity
Parsecs (pc, kpc, Mpc)
An astronomical unit of distance equal to the distance at which a star exhibits a trigonometric parallax angle of exactly one arcsecond (1″).
1 pc = 1 AU / tan(1″) ≈ 3.2616 ly ≈ 3.0857 × 10¹⁶ m
Proper Time
Astrophysics, Cosmology & Relativity
Seconds (Proper Time τ)
The physical time interval measured by a clock moving along a specific worldline through spacetime.
dτ = dt / γ = √(dt² - dx²/c²)
Protostar
Astrophysics, Cosmology & Relativity
Solar Masses & Years
An early evolutionary mass phase of a star formed by the gravitational contraction of an interstellar gas cloud before core hydrogen fusion ignites.
t_collapse ~ t_freefall = √(3π / (32 G ρ))
Pulsar
Astrophysics, Cosmology & Relativity
Milliseconds to Seconds (Rotation Period)
A highly magnetized, rapidly rotating neutron star that emits focused beams of electromagnetic radiation from its magnetic poles.
P_spin ~ 1.4 ms to 10 s, P_dot = dP / dt