Hotter stars are O stars and cooler stars are M stars.

较热的恒星是 O 星， 较冷的恒星是 M 星。

The hottest are O stars, then B stars which are slightly cooler, down through A, F, G, K, and with the coolest stars being M.

最热的是 O 恒星，然后是温度稍低的B恒星，一直到 A、F、G、K，最冷的恒星是 M。