Reference · Nearby stars: Proxima Centauri, Barnard's Star and about 5,600 more, with distance and error

`NearbyStar`type

One nearby star, as the Yale General Catalogue of Trigonometric Stellar Parallaxes gives it, with a 2MASS position where there is one. Positions are J2000 (the ICRS to a fraction of an arc-second).

Import it

import type { NearbyStar } from "@johnmorrisdotca/hoshi-stars/nearby";

Definition

interface NearbyStar {
    id: string;
    name: string | undefined;
    designation: string | undefined;
    aliases: readonly string[];
    gctp: string;
    hd: number | undefined;
    gliese: string | undefined;
    twoMass: string | undefined;
    rightAscension: number;
    declination: number;
    positionSource: NearbyPositionSource;
    positionErrorArcsec: number;
    gctpOffsetArcsec: number | undefined;
    parallaxMas: number;
    parallaxErrorMas: number | undefined;
    lightYears: number | undefined;
    lightYearsError: number | undefined;
    parsecs: number | undefined;
    parsecsError: number | undefined;
    relativeError: number | undefined;
    properMotionRaMas: number;
    properMotionDecMas: number;
    properMotionSource: "GCTP" | undefined;
    magnitude: number | undefined;
    magnitudeKind: NearbyMagnitudeKind | undefined;
    magnitudeSource: "GCTP" | undefined;
    spectralType: string;
    flags: NearbyFlags;
}

Members

Name	Type	Description
`id`	`string`	A key that stays the same: `gctp-` and the catalogue number (`gctp-3278`).
`name`	`string \| undefined`	The common name for the few dozen well-known ones (`Proxima Centauri`), else `undefined`.
`designation`	`string \| undefined`	The Bayer letter or Flamsteed number and constellation (`ι Hor`, `33 Psc`) where the catalogue gives one, else `undefined`.
`aliases`	`readonly string[]`	The catalogue's other names for it: Luyten, Giclas, Ross, variable-star and Durchmusterung names (`G 158-027`, `CD-68 2378`).
`gctp`	`string`	The Yale catalogue number, as a text: `3278` for Proxima, `1810.10` for a component.
`hd`	`number \| undefined`	The Henry Draper number, or `undefined`.
`gliese`	`string \| undefined`	The Gliese-Jahreiss number as `GJ 551`, for the well-known ones, else `undefined`.
`twoMass`	`string \| undefined`	The 2MASS designation (`2MASS J14294291-6240465`) of the source the position comes from, or `undefined`.
`rightAscension`	`number`	Right ascension in degrees at J2000, 0 up to 360.
`declination`	`number`	Declination in degrees at J2000, -90 to 90.
`positionSource`	`NearbyPositionSource`	Where the position comes from.
`positionErrorArcsec`	`number`	The error of the position in arc-seconds: 2MASS's own error plus the motion over the gap to 2000, or the catalogue's digits and a 3% error of its motion over a century.
`gctpOffsetArcsec`	`number \| undefined`	For a 2MASS position, the arc-seconds between it and where the Yale position and motion put the star (the star is where 2MASS says); `undefined` for a Yale position.
`parallaxMas`	`number`	The annual parallax in milliarcseconds; it can be 0 or less, because it is a measurement with an error.
`parallaxErrorMas`	`number \| undefined`	The standard error of the parallax in milliarcseconds, or `undefined`.
`lightYears`	`number \| undefined`	The distance in light-years (`3261.56 / parallax`), or `undefined` for a parallax of 0 or less.
`lightYearsError`	`number \| undefined`	The error of `lightYears`: the distance times the parallax's relative error (a first-order figure, good while that is small), or `undefined`.
`parsecs`	`number \| undefined`	The distance in parsecs, or `undefined`.
`parsecsError`	`number \| undefined`	The error of `parsecs`, or `undefined`.
`relativeError`	`number \| undefined`	The parallax's error divided by the parallax: 0.05 is 5%. `undefined` for a parallax of 0 or less or with no error. Under 0.05 is a good distance, 0.05 to 0.2 a fair one, over 0.2 a rough one.
`properMotionRaMas`	`number`	Proper motion in right ascension, in milliarcseconds a year, already multiplied by cos(declination); 0 where the catalogue has none (`properMotionSource` is then `undefined`). J2000 axes.
`properMotionDecMas`	`number`	Proper motion in declination, in milliarcseconds a year; 0 where the catalogue has none.
`properMotionSource`	`"GCTP" \| undefined`	Where the proper motion is from: `"GCTP"`, or `undefined` where there is none.
`magnitude`	`number \| undefined`	The V magnitude of the Yale catalogue, or `undefined`.
`magnitudeKind`	`NearbyMagnitudeKind \| undefined`	What kind of magnitude it is, or `undefined` with no magnitude.
`magnitudeSource`	`"GCTP" \| undefined`	Where the magnitude is from: `"GCTP"`, or `undefined` with no magnitude.
`spectralType`	`string`	The spectral type as the catalogue gives it (`M5.5eV`), or an empty string.
`flags`	`NearbyFlags`	What to be careful about.

Examples

import { nearbyStarByName, type NearbyStar } from "@johnmorrisdotca/hoshi-stars/nearby";

const proxima: NearbyStar = nearbyStarByName("Proxima Centauri")!;
console.log(proxima.lightYears?.toFixed(2), proxima.lightYearsError?.toFixed(2));

4.24 0.03

What it prints (run when this page was built)

View source Edit on GitHubMade from the source of @johnmorrisdotca/hoshi-stars 0.7.0.

NearbyStartype

Definition

Members

Examples

`NearbyStar`type