SenrokaiandClaude Opus 5.5
5333be615e
383 695 of the 455 608 stars read "Spectral type Unknown", every Gaia star among them, although 380 884 of them carry a colour. The card now gives those the type of the dwarf whose colour is nearest, in the colour's own system, marked as an estimate: TRAPPIST-1, BP-RP 4.90, reads "Spectral type ~M8, from colour", which is how it was classified (M8 V). A star with neither a type nor a colour gets no subtitle rather than the literal "Unknown". The colours are Pecaut & Mamajek's mean dwarf sequence (2013, ApJS 208, 9, table 5), as Mamajek maintains it online (version 2022.04.16, which carries Gaia BP-RP), from B0 to M8.5. B-V cannot tell O types apart (the whole sequence spans 0.03 of it), and BP-RP turns back past M8.5 and is tabulated only from B9. A colour outside the table gets no estimate: 186 BP-RP and 41 B-V colours, among them the blue Gaia DR3 5612323414549657984 at BP-RP -0.15. 380 657 stars get an estimate: F 97 840, G 144 327, K 105 984, M 29 142, A 3 272, B 92. Checked against catalogued types: - 19 433 HYG dwarfs with a B-V: 74.3 % within two subclasses, 95.5 % within five. - 146 Gaia exoplanet hosts the archive types as dwarfs, from BP-RP: 88.4 % within two subclasses, 98.6 % within five. The estimate assumes a dwarf, so a giant reads later than it is (Pollux, K0 III at B-V 0.99, reads K3). It also ignores reddening. The comment says both. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
96 lines
3.8 KiB
TypeScript
96 lines
3.8 KiB
TypeScript
import { describe, expect, it } from 'vitest';
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import { StarRecord } from '../../shared/models/star.model';
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import { catalogueCensus, describingCatalogue, starReadouts, starSubtitle } from './star-readouts';
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/** Three kinds of star the catalogue holds, each as the decoder gives it back. */
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const HYG_STAR: StarRecord = {
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id: 32263,
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name: 'Sirius',
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x: -0.49,
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y: 2.47,
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z: -0.75,
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magnitude: -1.44,
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magnitudeBand: 'V',
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spectralType: 'A0m',
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colorIndex: 0.009,
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colorSystem: 'B-V',
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distanceError: 0.004,
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distanceFromGaia: false,
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source: 'hyg'
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};
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// A star Gaia alone knows, at 117 pc and good to a tenth.
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const GAIA_STAR: StarRecord = {
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id: 1000000001,
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name: 'Gaia DR3 5612323414549657984',
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x: 117,
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y: 0,
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z: 0,
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magnitude: 11.2,
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magnitudeBand: 'G',
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spectralType: 'Unknown',
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colorIndex: 1.43,
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colorSystem: 'BP-RP',
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distanceError: 0.1,
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distanceFromGaia: true,
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source: 'gaia'
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};
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// HYG's description of Proxima, at the place and distance Gaia measures.
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const PLACED_BY_GAIA: StarRecord = { ...HYG_STAR, name: 'Proxima Centauri', magnitude: 11.01, colorIndex: 1.807, spectralType: 'M5Ve', distanceFromGaia: true, source: 'gaia' };
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function value(readouts: { label: string; value: string }[], label: string): string | undefined {
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return readouts.find((readout) => readout.label === label)?.value;
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}
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describe('starReadouts', () => {
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it('names the band of the magnitude, and which colour the colour index is', () => {
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expect(value(starReadouts(HYG_STAR, null), 'Magnitude')).toBe('V -1.44');
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expect(value(starReadouts(GAIA_STAR, null), 'Magnitude')).toBe('G 11.20');
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expect(value(starReadouts(HYG_STAR, null), 'Colour')).toBe('B−V 0.01');
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expect(value(starReadouts(GAIA_STAR, null), 'Colour')).toBe('BP−RP 1.43');
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});
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it('says a stand-in magnitude was not measured, and leaves out a colour there is none of', () => {
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const unmeasured = starReadouts({ ...GAIA_STAR, magnitude: 12, magnitudeBand: undefined, colorIndex: null, colorSystem: undefined }, null);
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expect(value(unmeasured, 'Magnitude')).toBe('Not measured');
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expect(value(unmeasured, 'Colour')).toBeUndefined();
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});
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it('gives the distance with its uncertainty', () => {
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expect(value(starReadouts(GAIA_STAR, null), 'Distance')).toBe('117 ± 12 pc');
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});
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it('names the catalogue a star comes from, and whose distance it has', () => {
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expect(value(starReadouts(GAIA_STAR, null), 'Source')).toBe('Gaia DR3');
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expect(value(starReadouts(HYG_STAR, null), 'Source')).toBe('HYG');
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expect(value(starReadouts(PLACED_BY_GAIA, null), 'Source')).toBe('HYG, Gaia DR3 distance');
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expect(value(starReadouts({ ...HYG_STAR, source: 'exoplanet-archive' }, null), 'Source')).toBe('NASA Exoplanet Archive');
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});
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it('marks the luminosity as derived', () => {
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expect(starReadouts(HYG_STAR, 25.4).find((readout) => readout.label === 'Luminosity')).toEqual({ label: 'Luminosity', value: '25.40 L☉', derived: true });
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});
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});
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describe('starSubtitle', () => {
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it("prints the catalogue's classification where it has one", () => {
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expect(starSubtitle(HYG_STAR)).toBe('Spectral type A0m');
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});
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it("estimates one from the colour otherwise, in the colour's own system, and says so", () => {
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// 1.43 is a K5 dwarf in BP−RP; read as B−V it would be an M0.
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expect(starSubtitle(GAIA_STAR)).toBe('Spectral type ~K5, from colour');
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});
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it('prints nothing rather than "Unknown" when there is neither', () => {
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expect(starSubtitle({ ...GAIA_STAR, colorIndex: null, colorSystem: undefined })).toBe('');
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});
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});
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describe('catalogueCensus', () => {
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it('counts the stars by the catalogue describing them, not by whose position they have', () => {
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expect(describingCatalogue(PLACED_BY_GAIA)).toBe('HYG');
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expect(catalogueCensus([GAIA_STAR, GAIA_STAR, GAIA_STAR, HYG_STAR, PLACED_BY_GAIA])).toBe('Gaia DR3 3 · HYG 2');
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});
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});
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