The spectrum of a star shows the following absorption line characteristics: very strong H,weaker Mg II and Si II,and no He I or Ca II lines.Classify the spectrum of this star,using the absorption line strengths in the spectra of stars as shown in Figure 10-5 and Table 10-1 of Comins,Discovering the Essential Universe,6th ed.
A) B
B) G
C) K
D) A

Question

Quizplus · Accepted Answer

The very strong H lines indicate that the star is a main-sequence star. The absence of He I and Ca II lines suggests that it is not a hot O or B star, ruling out option A. The weaker Mg II and Si II lines suggest a star with a surface temperature between 5200 and 6000 K, which falls within the spectral range of class G, K, and early-M stars. However, the absence of Ca II lines rules out early-K and early-M stars, leaving us with class G as the best option. Thus, the spectrum of this star can be classified as a main-sequence G star.

The Spectrum of a Star Shows the Following Absorption Line