Andromeda XXI
E133909
Andromeda XXI is a faint dwarf satellite galaxy of the Andromeda Galaxy located within the Local Group of galaxies.
All labels observed (2)
| Label | Occurrences |
|---|---|
| Andromeda XXI canonical | 7 |
| Andromeda 21 | 1 |
How this entity was disambiguated
This entity first appeared as the object of triple T869176 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.
NED1
Entity disambiguation (via context triple)
gpt-5-mini-2025-08-07
Target entity: Andromeda XXI Context triple: [Local Group, contains, Andromeda XXI]
-
A.
Andromeda II
Andromeda II is a dwarf spheroidal satellite galaxy of the Andromeda Galaxy (M31) located within the Local Group.
-
B.
Andromeda III
Andromeda III is a dwarf spheroidal satellite galaxy of the Andromeda Galaxy located within the Local Group.
-
C.
Andromeda XIX
Andromeda XIX is a faint dwarf spheroidal satellite galaxy of the Andromeda Galaxy within the Local Group.
-
D.
Andromeda XIII
Andromeda XIII is a faint dwarf spheroidal satellite galaxy of the Andromeda Galaxy located within the Local Group.
-
E.
Andromeda XVI
Andromeda XVI is a faint dwarf spheroidal satellite galaxy of the Andromeda Galaxy located within the Local Group.
- F. None of above. chosen
- G. Unsure - the case is ambiguous/there is not enough information to decide.
NED2
Entity disambiguation (via description)
gpt-5-mini-2025-08-07
Target entity: Andromeda XXI Target entity description: Andromeda XXI is a faint dwarf satellite galaxy of the Andromeda Galaxy located within the Local Group of galaxies.
-
A.
Andromeda II
Andromeda II is a dwarf spheroidal satellite galaxy of the Andromeda Galaxy (M31) located within the Local Group.
-
B.
Andromeda III
Andromeda III is a dwarf spheroidal satellite galaxy of the Andromeda Galaxy located within the Local Group.
-
C.
Andromeda XIX
Andromeda XIX is a faint dwarf spheroidal satellite galaxy of the Andromeda Galaxy within the Local Group.
-
D.
Andromeda XIII
Andromeda XIII is a faint dwarf spheroidal satellite galaxy of the Andromeda Galaxy located within the Local Group.
-
E.
Andromeda XVI
Andromeda XVI is a faint dwarf spheroidal satellite galaxy of the Andromeda Galaxy located within the Local Group.
- F. None of above. chosen
Statements (30)
| Predicate | Object |
|---|---|
| instanceOf |
astronomical object
ⓘ
dwarf spheroidal galaxy ⓘ satellite galaxy ⓘ |
| absoluteMagnitudeV | approximately −9.2 ⓘ |
| apparentMagnitudeV | approximately 14.5 ⓘ |
| belongsTo |
Andromeda subgroup of the Local Group
ⓘ
linked to:
Andromeda subgroup
|
| declination | +42° ⓘ |
| discoveredBy | Pan-Andromeda Archaeological Survey ⓘ |
| discoveryMethod | resolved stellar photometry ⓘ |
| discoveryYear | 2011 ⓘ |
| distanceFromEarth |
approximately 2.8 million light-years
ⓘ
approximately 859 kiloparsecs ⓘ |
| galaxyType | dwarf spheroidal ⓘ |
| gasContent | gas-poor ⓘ |
| halfLightRadius | approximately 1.0 kiloparsecs ⓘ |
| hasDarkMatterDominance | yes ⓘ |
| locatedIn | constellation Andromeda ⓘ |
| luminosity | about 3×10^5 times the luminosity of the Sun ⓘ |
| memberOf | Local Group ⓘ |
| metallicity | low ⓘ |
| morphology | spheroidal ⓘ |
| observedInSurvey |
CFHT MegaCam imaging
ⓘ
Pan-STARRS ⓘ
linked to:
Pan-STARRS survey
|
| otherDesignation | And XXI ⓘ |
| partOf | halo of the Andromeda Galaxy ⓘ |
| redshift | approximately −0.001 ⓘ |
| rightAscension | approximately 23h 54m ⓘ |
| satelliteOf | Andromeda Galaxy ⓘ |
| stellarPopulation | predominantly old stars ⓘ |
| surfaceBrightness | very low ⓘ |
How these facts were elicited
The pipeline generated the facts above by prompting gpt-5.1 with this entity's name + description and the instruction below.
Instruction
You are a knowledge base construction expert. Given a subject entity and a description of it, return factual statements that you know for the subject as a JSON list of dictionaries(triples), where keys must be "subject", "predicate" and "object". The number of facts may be very high, between 25 to 50 or more, for very popular subjects. For less popular subjects, the number of facts can be very low, like 5 or 10. # Requirements - If you don't know the subject at all, return an empty list. - If the subject is not a named entity, return an empty list. - Include at least one triple where predicate is "instanceOf". - Do not get too wordy. - Separate several objects into multiple triples with one object.
Input
Subject: Andromeda XXI Description of subject: Andromeda XXI is a faint dwarf satellite galaxy of the Andromeda Galaxy located within the Local Group of galaxies.
Referenced by (8)
Full triples — surface form annotated when it differs from this entity's canonical label.