Equation 20 · A Neutron Star Is a Redshift Standard
What does this equation mean?
Read the formula alongside the article passage below. Each part has a deeper page with its role in the equation, the supporting passage and nearby citations.
This equation gives an approximation: it relates the quantities while allowing an approximation. Read the equation part by part below; each part has a contextual explanation and a link to its mathematical background.
Read it piece by piece
Symbol Δ E
Δ E is part of the quantity the equation computes from the expression on the right.
Symbol E
E is part of the quantity the equation computes from the expression on the right.
Symbol v_eq
q is part of the quantity the equation computes from the expression on the right.
Symbol c
c is part of the quantity the equation computes from the expression on the right.
Symbol pi
pi is one of the signed contributions combined to compute the quantity on the left.
=
The expressions on both sides represent the same quantity under the stated assumptions.
See an illustrated explanation →change
Capital delta attached to a quantity marks a difference between two values of that quantity; the article’s sign convention determines the order.
subscript
The lower label selects a particular version, component, or indexed member of the quantity. For example, x₀ and xₜ can be values at different positions.
superscript
A raised number can be a power. When it is a label or bound, it selects a case or the upper limit of a sum; the formula’s structure distinguishes these uses.
See an illustrated explanation →How to interpret it
Its accuracy depends on the assumptions and range of use described in the article. Read it with the definitions, units, and assumptions supplied by the article.
What the article says around this equation
The mechanism behind that contradiction is simple enough to state in one line, and the paper’s authors compute it carefully because the commonly quoted version understates it by an order of magnitude. Surface rotation Doppler-broadens any spectral line by a fraction of its energy equal to the star’s equatorial velocity over the speed of light, E/E /c = 2 R/c 1.310^{-1}(/500\,)(R/12\,) , where is the star’s spin frequency and R its radius.
Sources cited in the article section
These citations give research context. Read each source to check which claims it supports.
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