Equation 21 · Part 1 · A Neutron Star Is a Redshift Standard

Symbol nu

\nu

\nu

What this part means

the star’s spin frequency.

Its job in the formula

nu is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Full expressionSymbol nuArticle meaning

Where the article explains it

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, $\Delta$ E/E $\approx$ $v_{eq}$ /c = 2 $\pi$ $\nu$ R/c $\approx$ 1.3 $\times$ 10^{-1}( $\nu$ /500\, $\text{Hz}$ )(R/12\, $\text{km}$ ) , where $\nu$ is the star’s spin frequency and R its radius.

The passage around this formula

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, $\Delta$ E/E $\approx$ $v_{eq}$ /c = 2 $\pi$ $\nu$ R/c $\approx$ 1.3 $\times$ 10^{-1}( $\nu$ /500\, $\text{Hz}$ )(R/12\, $\text{km}$ ) , where $\nu$ is the star’s spin frequency and R its radius.

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Learn the underlying idea

A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.

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Sources cited in the article section

[8] Rotational Broadening of Atomic Spectral Features from Neutron Stars ↗

These citations provide research context; check each source for the exact claim it supports.