AST-29

Escape speed

Sun: 618 km/s.

Reading speed

Astroescape

Governing equation

v_e=\sqrt{2GM/R}

where

M: M (M_\odot)
R: R (R_\odot)
v_e: ve (km/s)

Lecture brief

Historical brief

Hubble expansion, Jeans collapse, Eddington luminosity, Bondi accretion and Stefan–Boltzmann stars are the first astrophysical budgets. The sheets scale a star, a cloud and a horizon. This sheet (AST-29 — Escape speed) is the form associated with escape. Working symbols: $M$ , $R$ $\rightarrow$ $v_e$ . Sun: 618 km/s.

Purpose

Purpose: compute

v_e

from

M

R

in Astrophysics via

v_e=\sqrt{2GM/R}

Sun: 618 km/s. Use it when a real astrophysics question must be answered in SI before a code check.

Live realistic example

In symbols

Live case. Given

M = 1.000\,\mathrm{M_odot}

R = 1.000\,\mathrm{R_odot}

, the governing relation

v_e=\sqrt{2GM/R}

yields

v_e = 617.70\,\mathrm{km/s}

. Sun: 618 km/s. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

M M1 M_\odotR R1 R_\odot

Outputs

ve v_e617.70 km/s

Reading speed

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Narration of this film

Sun: 618 km/s.

Reading speed

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