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Research draft

galaxy

vr.tr.galaxy · PHY.SPC

Let an agent describe galaxies by type, distance, size and designation, and handle catalogue cross-identification.

Thing Registry Physical world and living systems

Research draft, second pass

A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.

written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify

Researched by: Claude

Purpose and description

Let an agent describe galaxies by type, distance, size and designation, and handle catalogue cross-identification.

A gravitationally bound system of stars, stellar remnants, gas, dust and dark matter, ranging from dwarf galaxies of millions of stars to giants of trillions.

What it is for: Galaxies are the building blocks of the large-scale universe; studying them explains cosmic history.

It can be observe it, across the spectrum; classify it, by morphology and activity; measure its distance and redshift; catalogue it, with designations.

Distinguishing features

Gravitationally bound with dark matter

Much larger than star clusters

Classified by the Hubble sequence and activity

Our own galaxy is the Milky Way

What it looks like

A fuzzy patch in a telescope; in images, spiral arms, ellipsoids or irregular shapes; the Milky Way is seen from inside as a band of light.

Physical character

stars: 10^6 to 10^13 stars

diameter: 1000-500000+ light years

distance to Andromeda: 2.5 million light years

How it is recognised

Extended, not point-like, sources

Morphology: spiral, elliptical, lenticular, irregular

Designations such as M31, NGC 224, PGC numbers

Related models

is a kind of - large-scale system

astronomical object

contains - components

star and black hole

is part of - larger structures

galaxy cluster

hosts - at the centre of most large galaxies

supermassive black hole

In practice

Families and kinds

spiral, barred spiral, elliptical, lenticular, irregular

dwarf galaxies

active galaxies: radio galaxies, quasars

luminous infrared galaxies

interacting and binary galaxies

Identifiers

Messier and NGC numbers M or NGC plus number classic catalogues

PGC number numeric Principal Galaxies Catalogue

Standards and regulation

IAU nomenclature

Failure modes and hazards

Merging different galaxies with similar designations

Using redshift distances without stating cosmology

Also called

radio galaxyfield galaxydark galaxyluminous infrared galaxypossible galaxybinary galaxyX-shaped radio galaxyLyman-alpha emitterstar-forming galaxyintergalacticbrightest cluster galaxylow-surface-brightness galaxyhypergalaxydead diskblue nuggetquiescent galaxyactive galaxyLittle Red DotsBlueberry galaxydisc galaxyred spiral galaxyGreen Bean Galaxiespolar-ring galaxyelliptical galaxyirregular galaxydwarf galaxypeculiar galaxySeyfert galaxysatellite galaxylow-ionization nuclear emission-line regionjellyfish galaxyFaint blue galaxyPea galaxycompact galaxyactive galactic nucleusred nuggetprotogalaxyinteracting galaxyLyman-break galaxyMarkarian galaxy

+18

Where this came from

wikidata · CC0 1.0

Source repository Registry entry point

Also registered as vr.tr.galaxy-group

Drafted structure

Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.

Identity Which galaxy.

Galaxies carry many designations.

Designations

Catalogue ids.

Designations

Designations and names.

  1. Which designations identify this galaxy? provenance
  2. Is it confirmed or a candidate? boundary

Type

Morphology.

Morphology

Morphological type.

  1. What morphological type is it? definition
  2. Is it active? definition
Distance and size How far and how big.

Distance underpins every physical quantity.

Distance

Method and value.

Distance

Distance and method.

  1. How far away is it, by which method? measurement
  2. Which cosmology was assumed? provenance

Size and mass

Diameter, stars, mass.

Size

Size and mass.

  1. What are its size and mass? measurement
  2. How much is dark matter? measurement
Contents What it contains.

Contents reveal history.

Stars and gas

Populations.

Populations

Stellar populations and gas.

  1. What stellar populations and gas does it contain? measurement
  2. Is it forming stars? measurement

Nucleus

Central black hole.

Nucleus

The central black hole.

  1. Does it have a supermassive black hole, of what mass? measurement
  2. Is the nucleus active? definition
Environment Neighbours and interactions.

Environment shapes galaxies.

Group

Cluster or group.

Membership

Group membership.

  1. Which group or cluster is it part of? definition
  2. Is it interacting with neighbours? definition

Observation

Data sources.

Data

Surveys and archives.

  1. Which surveys have observed it? provenance
  2. How can it be observed by amateurs? action

What the second pass must settle

  • Should named galaxies be instances with cross-identifiers?
  • How should distance methods be recorded?
  • How should uncertain galaxy candidates be marked?
Draft as JSON