Star types and compositions

Protostar

Classification: PHabitable zone: Average sizePlanets: Rockballs and asteroidsAtmospheric composition:• 100% hydrogen

Main-sequence star

Classification: O,B,A,G,K,MHabitable zone: varies depending on the size of

the starPlanets: Terrestrial and gas giants, with possible

asteroids and cometsAtmospheric composition:• Mostly hydrogen with a small percentage of

helium

Red giant

Classification: RGHabitable zone: large and widePlanets: Surviving terrestrial Planets and gas

giantsAtmospheric composition:• Mostly helium with some hydrogen

Red supergiant

Classification: SRGHabitable zone: very large and very widePlanets: unknown, mainly no surviving PlanetsAtmospheric composition:• Similar to a red giant with heavier elements up

to iron

Blue supergiant

Classification: SBGHabitable zone: very large and very widePlanets: no surviving PlanetsAtmospheric composition:• Similar to a red supergiant

Supernova

Classification: SHabitable zone: NonePlanets: NoneAtmospheric composition: N/A

Nebula

Classification: NHabitable zone: NonePlanets: NoneAtmospheric composition: N/A

Brown dwarf

Classification: BRDHabitable zone: minimal, reduces as the brown

dwarf coolsPlanets: Carbon worlds lacking waterAtmospheric composition:• Hydrogen• Helium• Methane

White dwarf

Classification: DHabitable zone: smallPlanets: Stripped rocky cores from terrestrial

PlanetsAtmospheric composition:• Traces of hydrogen, helium and carbon

Black dwarf

Classification: BDHabitable zone: NonePlanets: Stripped , frozen rocky cores from

terrestrial PlanetsAtmospheric composition:• Thin layer of helium

Neutron star/Pulsar

Classification: NSHabitable zone: UnknownPlanets: Planets that formed from secondary

accretion diskAtmospheric composition:• Super heated plasma

Quasar

Classification: QHabitable zone: none, may be possible due to

glow from central black holePlanets: NoneAtmospheric composition:• Unknown

Black hole

Classification: BHHabitable zone: None, possible glow from

superheating accretion materialPlanets: captured Planets and/or Planets formed

from accreting material that are in a stable orbit

Atmospheric composition:• None

Hypothetical stars

Iron star

Classification: IHabitable zone: UnknownPlanets: UnknownAtmospheric composition:• Iron only

White hole

Classification: WHHabitable zone: Possible due to light and energy

emitted from the white holePlanets: NoneAtmospheric composition:• None

Strange star

Classification: SSHabitable zone: very thin, almost nonexistentPlanets: Asteroids and Planets composed of

material or strange matterAtmospheric composition:• Strange matter only

Thorne-Zytkow object

Classification: TZOHabitable zone: same as a red giant/red

supergiantPlanets: Dead, molten rockballs or no planets at

allAtmospheric composition:• Same as a red giant/red supergiant