<Table> <Tr> <Th> Star formation </Th> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Th> Object classes </Th> </Tr> <Tr> <Td> Interstellar medium Molecular cloud Bok globule Dark nebula Young stellar object Protostar T Tauri star Pre-main - sequence star Herbig Ae / Be star Herbig--Haro object </Td> </Tr> <Tr> <Th> Theoretical concepts </Th> </Tr> <Tr> <Td> Accretion Initial mass function Jeans instability Kelvin--Helmholtz mechanism Nebular hypothesis Planetary migration </Td> </Tr> <Tr> <Td> Star portal </Td> </Tr> <Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> </Table> <Tr> <Th> Star formation </Th> </Tr>

Why are the majority of stars main sequence stars