86 lines
1.9 KiB
JavaScript
86 lines
1.9 KiB
JavaScript
'use strict';
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Object.defineProperty(exports, '__esModule', { value: true });
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/**
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* @copyright 2013 Sonia Keys
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* @copyright 2016 commenthol
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* @license MIT
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* @module stellar
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*/
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/**
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* Stellar: Chapter 56, Stellar Magnitudes.
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*/
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/**
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* Sum returns the combined apparent magnitude of two stars.
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*/
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function sum (m1, m2) { // (m1, m2 float64) float64
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const x = 0.4 * (m2 - m1);
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return m2 - 2.5 * Math.log10(Math.pow(10, x) + 1)
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}
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/**
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* SumN returns the combined apparent magnitude of a number of stars.
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*/
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function sumN (m) { // (m ...float64) float64
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let s = 0;
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for (const mi of m) {
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s += Math.pow(10, -0.4 * mi);
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}
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return -2.5 * Math.log10(s)
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}
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/**
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* Ratio returns the brightness ratio of two stars.
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*
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* Arguments m1, m2 are apparent magnitudes.
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*/
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function ratio (m1, m2) { // (m1, m2 float64) float64
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const x = 0.4 * (m2 - m1);
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return Math.pow(10, x)
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}
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/**
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* Difference returns the difference in apparent magnitude of two stars
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* given their brightness ratio.
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*/
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function difference (ratio) { // (ratio float64) float64
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return 2.5 * Math.log10(ratio)
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}
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/**
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* AbsoluteByParallax returns absolute magnitude given annual parallax.
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*
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* Argument m is apparent magnitude, π is annual parallax in arc seconds.
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*/
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function absoluteByParallax (m, π) { // (m, π float64) float64
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return m + 5 + 5 * Math.log10(π)
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}
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/**
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* AbsoluteByDistance returns absolute magnitude given distance.
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*
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* Argument m is apparent magnitude, d is distance in parsecs.
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*/
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function absoluteByDistance (m, d) { // (m, d float64) float64
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return m + 5 - 5 * Math.log10(d)
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}
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var stellar = {
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sum,
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sumN,
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ratio,
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difference,
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absoluteByParallax,
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absoluteByDistance
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};
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exports.absoluteByDistance = absoluteByDistance;
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exports.absoluteByParallax = absoluteByParallax;
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exports["default"] = stellar;
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exports.difference = difference;
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exports.ratio = ratio;
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exports.sum = sum;
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exports.sumN = sumN;
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