Population II
E484154
Population II refers to an older, metal-poor class of stars typically found in globular clusters and the galactic halo, formed early in the history of the universe.
Statements (49)
| Predicate | Object |
|---|---|
| instanceOf |
astrophysical concept
ⓘ
stellar population ⓘ |
| alsoKnownAs | Population II stars NERFINISHED ⓘ |
| characteristicAge | old stars ⓘ |
| chemicalAbundancePattern | enhanced alpha-elements relative to iron ⓘ |
| classificationSystem | Baade stellar population classification ⓘ |
| color | generally redder than young massive stars ⓘ |
| contrastWith |
Population I
NERFINISHED
ⓘ
Population III NERFINISHED ⓘ |
| discoveredBy | Walter Baade NERFINISHED ⓘ |
| discoveryContext | resolution of stellar populations in Andromeda ⓘ |
| discoveryEpoch | 1940s ⓘ |
| formationEpoch | early universe ⓘ |
| formedAfter | Population III stars NERFINISHED ⓘ |
| formedFrom | gas enriched by first generations of stars ⓘ |
| foundIn |
bulge of galaxies
ⓘ
dwarf spheroidal galaxies ⓘ galactic halo ⓘ globular clusters ⓘ old stellar halos of galaxies ⓘ |
| heliumContent | lower than in younger populations on average ⓘ |
| hostOf |
blue horizontal branch stars
ⓘ
many RR Lyrae variable stars ⓘ |
| importance | constrains early star formation history ⓘ |
| kinematics |
eccentric orbits
ⓘ
high-velocity orbits ⓘ often highly inclined to galactic disk ⓘ |
| massRange | predominantly low-mass long-lived stars ⓘ |
| metallicity | metal-poor ⓘ |
| metallicityRelativeToSun | lower than solar ⓘ |
| observationalSignature |
dominance in globular cluster color-magnitude diagrams
ⓘ
weak metal absorption lines in spectra ⓘ |
| relativeAgeToPopulationI | older ⓘ |
| relativeMetallicityToPopulationI | lower ⓘ |
| roleInCosmology | tracers of early galaxy formation ⓘ |
| roleInDistanceScale | includes RR Lyrae variables as standard candles ⓘ |
| roleInGalacticAstronomy | used to study galactic halo structure ⓘ |
| spatialDistribution | spheroidal ⓘ |
| starFormationActivity | no ongoing star formation ⓘ |
| typicalAgeRange | ≈ 10–13 billion years ⓘ |
| typicalEnvironment | low gas density regions ⓘ |
| typicalLocationInMilkyWay |
Milky Way globular clusters
ⓘ
Milky Way halo NERFINISHED ⓘ |
| typicalMetallicityRange | [Fe/H] ≈ −1 to −3 ⓘ |
| typicalStellarTypes |
horizontal branch stars
ⓘ
low-mass main-sequence stars ⓘ red giants ⓘ |
| usedToInfer |
age of the Milky Way
ⓘ
chemical evolution of galaxies ⓘ |
Referenced by (2)
Full triples — surface form annotated when it differs from this entity's canonical label.