$$\begin{array} { | l | c | c | }
\hline { \text { Star } } & \begin{array} { c }
\text { Parallax } \
\text { (sec of arc) }
\end{array} & \begin{array} { c }
\text { Spectral } \
\text { Type }
\end{array} \
\hline 5 \text { Cen } & 0.026 & \text { B2 IV } \
\hline \text { HR 4758 } & 0.05 & \text { G0 V } \
\hline \text { HD 39801 } & 0.005 & \text { M2 I } \
\hline 9 \mathrm { CMa } & 0.4 & \text { Al V } \
\hline
\end{array}$$
-Which star in the table has the highest surface temperature?

Question

$$\begin{array} { | l | c | c | } 
\hline { \text { Star } } & \begin{array} { c } 
\text { Parallax } \
\text { (sec of arc) }
\end{array} & \begin{array} { c } 
\text { Spectral } \
\text { Type }
\end{array} \
\hline 5 \text { Cen } & 0.026 & \text { B2 IV } \
\hline \text { HR 4758 } & 0.05 & \text { G0 V } \
\hline \text { HD 39801 } & 0.005 & \text { M2 I } \
\hline 9 \mathrm { CMa } & 0.4 & \text { Al V } \
\hline
\end{array}$$
-Which star in the table has the highest surface temperature?

Quizplus · Accepted Answer

The spectral type of a star is directly related to its surface temperature. The spectral types are arranged in order of decreasing temperature as O, B, A, F, G, K, M. Among the given stars, the spectral type of 5 Cen is B2 IV, which is hotter than G0 V (HR 4758), M2 I (HD 39801), and Al V (9 CMa). Therefore, 5 Cen has the highest surface temperature among the given stars.

-Which Star in the Table Has the Highest Surface Temperature