Nearby galaxies: the Local Volume (UNGC), the Local Group (McConnachie), and models of M 31, M 33 and the Magellanic Clouds

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見積もり時間
1週間以上
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javascript, three.js

調査の方向性

This is a multi-part planning issue spanning three catalogues and four custom galaxy models, so start by reading MilkyWay.md and the SPARC work in #221/PR #223 to see how galaxy models are mapped today. Galaxies.md is the place where sources and parameter mappings must be documented. Done means M 31, the Magellanic Clouds and M 33 are visible at the stated star limits, and the Local Volume and Local Group galaxies are placed in 3D and searchable on e.

索引モデルが issue の本文から書いたものです。

説明

enhancement track:deep-sky

Part of #117 (deep sky), alongside #40, with SPARC's galaxies (#221, PR #223).

Why

The galaxies visible to the eye aren't in SPARC: Andromeda (M 31, V 3.4), the Triangulum (M 33, 5.7), and the Large and Small Magellanic Clouds. Neither are most of the Local Group's dwarfs.

What

  • The Updated Nearby Galaxy Catalog (UNGC) (Karachentsev, Makarov & Kaisina 2013, AJ 145, 101; VizieR J/AJ/145/101):

    • about 870 galaxies within 11 Mpc;
    • good distances (TRGB, Cepheids), types, B magnitudes, sizes, inclinations, HI masses and K-band luminosities.

    This places the Local Volume in 3D.

  • The Local Group's dwarfs (McConnachie 2012, AJ 144, 4): half-light radius, ellipticity, PA, M_V and distance. That's enough to prime #223's glow model with a Sérsic or exponential spheroid for the dwarf spheroidals.

  • Custom models of the four galaxies seen by eye, as the Milky Way has one (MilkyWay.md). They're large and bright enough that type-driven defaults would look wrong. Starting points:

    • M 31: Courteau et al. 2011 (bulge, disc and halo), and PHAT (Dalcanton et al.) for the dust lanes and ring;
    • M 33: Corbelli et al.;
    • the LMC: van der Marel et al. (bar, disc, inclination and distance);
    • the SMC: published structural fits.

    Check each against photographs at the naked eye's exposure and at a camera's.

Done when

  • From Earth at the default star limit, M 31 and both Magellanic Clouds show where they are and as large as they are, and M 33 shows at a dark sky's limit.
  • The Local Group's dwarfs and the Local Volume's ~870 galaxies are placed in 3D, labelled on e and searchable.
  • Sources and parameter mappings are documented in Galaxies.md.

Where #223 or the S4G issue also has a galaxy, the more detailed model wins, with no duplicates.

Related: SPARC galaxies #221 / PR #223; globulars #228 (Harris, plus Baumgardt); deep-sky objects from OpenNGC #229; nearby galaxies #230; S4G and ATLAS3D #231; large-scale structure #232; catalogues as scene features, analysis as apps #233; galactic dynamics #106; the Milky Way #116.


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