The star named Circini has the spectral type and luminosity class of O 8.5 V. Based on this information, which of the following are true?
I. Circini has a surface temperature less than the sun.
II. Circini has a diameter that is greater than that of the sun.
III. Circini is more luminous than the sun.
IV. Circini is located near the upper left hand corner in the HR diagram.

Question

Quizplus · Accepted Answer

I. This statement is false because O-type stars have higher surface temperatures than the sun.
II. This statement is true because O-type stars have larger diameters than the sun.
III. This statement is true because O-type stars are more luminous than the sun.
IV. This statement is true because O-type stars are located in the upper left-hand corner of the HR diagram. I. False - O-type stars have higher surface temperatures than the Sun.
II. True - O-type stars have larger diameters than the Sun.
III. True - O-type stars are more luminous than the Sun.
IV. True - O-type stars are located near the upper left-hand corner in the HR diagram, indicating high luminosity and high temperature.

The Star Named Circini Has the Spectral Type and Luminosity