spiral galaxy
Let an agent handle spiral galaxies by morphology, orientation, designation and properties.
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 handle spiral galaxies by morphology, orientation, designation and properties.
A galaxy with a flat rotating disc of stars, gas and dust, spiral arms and a central bulge, such as the Milky Way and Andromeda; barred and dwarf spirals are variants.
What it is for: Spiral galaxies include our own and are key to understanding galaxy evolution.
It can be observe and image it; classify its morphology; measure rotation and mass; catalogue it.
Distinguishing features
Disc with spiral arms
Active star formation in arms
Barred and unbarred types
Rotation curves indicate dark matter
What it looks like
A disc with spiral arms seen face-on, or a thin line with a bulge seen edge-on.
How it is recognised
Spiral arms and disc
Face-on and edge-on views
Hubble classes Sa, Sb, Sc, SB
Related models
is a kind of - disc galaxy
contains - components
is evidence for - rotation curves
is confused with - no arms
In practice
Families and kinds
barred and unbarred spirals
grand design and flocculent spirals
dwarf and Magellanic spirals
pure-disc galaxies
Identifiers
NGC, IC and PGC numbers catalogue ids designations
Standards and regulation
IAU nomenclature
Failure modes and hazards
Misclassification from inclination
Confusing catalogue numbers
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.
Morphology Shape.
Morphology defines the class.
Class
Hubble type.
Class
Morphological class.
- What Hubble type is it? definition
- Is it barred? definition
Orientation
Face-on or edge-on.
Orientation
Viewing angle.
- How is it oriented to us? measurement
- Does that affect classification? boundary
Physical Mass and rotation.
Physical data describe it.
Rotation
Rotation curve.
Rotation
Rotation curve.
- What does its rotation curve show? measurement
- What does it imply for dark matter? definition
Star formation
Rate.
Star formation
Star formation rate.
- How fast is it forming stars? measurement
- Where in the disc? definition
Identity Which galaxy.
Identifiers and distance.
Designation
Catalogue ids.
Designation
Designations.
- Which designations identify it? provenance
- What is its common name? definition
Distance
How far.
Distance
Distance.
- How far away is it? measurement
- By which method? provenance
Observation Seeing it.
Some spirals are visible to amateurs.
Visibility
When and where.
Visibility
Visibility.
- When and where is it visible? action
- With what equipment? definition
Images
Colour.
Images
Image interpretation.
- Are images true or false colour? boundary
- Which telescopes took them? provenance
What the second pass must settle
- Should spiral subtypes be separate entries?
- How should morphology classifications be sourced?
- How should orientation be recorded?