Question

Robert is looking at four galaxies:%0D%0A%0D%0Aan irregular galaxy the he calls “Calliope”;%0D%0A%0D%0Aa spiral galaxy that he calls “Medea”;%0D%0A%0D%0Aan elliptical galaxy that he calls “Minerva”;%0D%0A%0D%0Aand a lenticular galaxy that he calls “Ariadne”;%0D%0A%0D%0AWhich of these four is the youngest?%0D%0A%0D%0A(1 point)%0D%0AResponses%0D%0A%0D%0AMedea%0D%0A%0D%0AMedea%0D%0A%0D%0AAriadne%0D%0A%0D%0AAriadne%0D%0A%0D%0AMinerva%0D%0A%0D%0AMinerva%0D%0A%0D%0ACalliope

Answer 1

Calliope — the irregular galaxy. Irregulars are typically gas-rich with ongoing star formation, so they contain the youngest stellar populations compared with ellipticals or lenticulars (and often even spirals).