In the spectral classification of stars,strong absorption lines of which of the following atomic or molecular constituents would indicate very low surface temperature?
A) He II
B) Fe II
C) Mg II
D) TiO

Question

Quizplus · Accepted Answer

TiO (Titanium Oxide) is a molecular constituent that forms in the cooler atmospheres of stars with temperatures below 4000K. Therefore, strong absorption lines of TiO would indicate a very low surface temperature. Absorption lines of He II, Fe II, and Mg II are typically seen in hotter stars.

In the Spectral Classification of Stars,strong Absorption Lines of Which