What feature dominates the spectra of M-type stars?
Answer
Molecular absorption bands, particularly titanium oxide ($ ext{TiO}$)
The spectra of M stars are dominated by molecular absorption bands, such as titanium oxide, which form because their surface temperatures are below $3,700 ext{ K}$.

Related Questions
What physical property is fundamental for astronomers sorting stars into the O, B, A, F, G, K, M sequence?Which sequence correctly lists the main spectral classes from hottest to coolest?What temperature range generally defines O-type stars, the hottest class?What spectral characteristic is a key identifier for A-type stars?Which spectral class includes our Sun, and what is its typical color?What feature dominates the spectra of M-type stars?How are finer distinctions made within the OBAFGKM sequence (e.g., between G0 and G5)?What characteristic spectral signature is observed in B-type stars?What is the primary purpose of the Yerkes luminosity classification system, designated by Roman numerals?What did Annie Jump Cannon originally use as a proxy for temperature when formalizing the spectral classification system?