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Hoshi Stars星

The stars you can see without a telescope, with names, colours and distances; the 88 constellations with their lines and boundaries; the Messier objects; and seven map projections to draw them on.

Hoshi is the Japanese word 星 for a star. About the name

Contents

Reference · A star's profile: temperature, size, luminosity and disc size with their uncertainty, limb darkening, and the measured shapes of Altair, Regulus and Vega

StarProfiletype

What the catalogue and the published tables say about one star's body.

Import it

import type { StarProfile } from "@johnmorrisdotca/hoshi-stars/profile";

Definition

interface StarProfile {
    hr: number | undefined;
    temperature: (Estimate & {
        basis: TemperatureBasis;
    }) | undefined;
    colour: string | undefined;
    luminosity: Estimate | undefined;
    radius: (Estimate & {
        basis: RadiusBasis;
    }) | undefined;
    angularDiameterMas: Estimate | undefined;
    limbDarkening: number | undefined;
    shape: StarShape | undefined;
    rotation: StarRotation | undefined;
    luminosityClass: LuminosityClass | undefined;
    composite: boolean;
    unknown: Partial<Record<"temperature" | "luminosity" | "radius", Unknown>>;
}

Members

NameTypeDescription
hrnumber | undefined

The Bright Star Catalogue number the profile was made for, or undefined for something else (the Sun).

temperature(Estimate & { basis: TemperatureBasis; }) | undefined

The surface (effective) temperature in kelvin, or undefined where the colour and type give none.

colourstring | undefined

The colour of a black body at that temperature, #rrggbb: for drawing the star. undefined where the temperature is.

luminosityEstimate | undefined

The luminosity in solar luminosities, from the magnitude, the distance and a bolometric correction. undefined where there is no distance.

radius(Estimate & { basis: RadiusBasis; }) | undefined

The radius in solar radii (R = sqrt(L) / T² in solar units), or undefined where neither the distance nor the type gives one.

angularDiameterMasEstimate | undefined

The apparent width of the disc in milliarcseconds (limb-darkened), from the magnitude and temperature alone: it needs no distance, so it is known for every star with a temperature, and it is what an interferometer measures.

limbDarkeningnumber | undefined

The linear limb-darkening coefficient in the V band, 0 (a flat disc) to 1 (the edge is dark): I(μ) = 1 − u(1 − μ). From model atmospheres for the temperature and the class's surface gravity.

shapeStarShape | undefined

Published shape measurements, for the few stars that have them.

rotationStarRotation | undefined

The catalogue's projected rotation speed, for the stars it gives one (about 2,800 of the 5,080).

luminosityClassLuminosityClass | undefined

The luminosity class the figures assumed, which may differ from the catalogue's where it states none.

compositeboolean

The spectral type was a pair (K0III+A0V): the brightness is of both and the figures are the primary's, rough.

unknownPartial<Record<"temperature" | "luminosity" | "radius", Unknown>>

What could not be worked out, and why. Empty for a star with everything.

Examples

import { starByName } from "@johnmorrisdotca/hoshi-stars";
import { starProfile, type StarProfile } from "@johnmorrisdotca/hoshi-stars/profile";

const profile: StarProfile = starProfile(starByName("Vega")!);
console.log(profile.temperature?.value, profile.limbDarkening);
9700 0.48072000000000004

What it prints (run when this page was built)

View sourceEdit on GitHubMade from the source of @johnmorrisdotca/hoshi-stars 0.47.0.