Question

A star emits light with a peak wavelength of 9,750 angstroms. What type of star is this and what is its color? Major stellar spectral types and temperatures Type Color Temperature (K) Comment O Bluish 30,000-80,000 Spectrum with ionized helium and hydrogen but little else; short-lived and rare stars B Bluish 10,000-30,000 Spectrum with neutral helium, none ionized A Bluish 7,500-10,000Spectrum with no helium, strongest hydrogen, some magnesium and calcium F White 6,000-7,500 Spectrum with lonized calcium, magnesium, neutral atoms of iron G Yellow 5,000-6,000 The spectral type of the sun. Spectrum shows 67 elements in the sun K Orange-red 3,500-5,000Spectrum packed with lines from neutral metals M Reddish 2,000-3,500 Band spectrum of molecules e-g, titanium oxide; other related spectral types (R, N, and S) are based on other molecules present in each spectral type Referring to the table above, this would be a (select) star that is (select) in color.

Answer 1

Peak wavelength of light, the star emits, $\lambda peak$ = 9750 Angstroms = 9750 x 10^-10 m

According to Wein's Displacement Law -

$\lambda peak$ *T = 2.898 x 10^-3 m*K

Put the values, we have -

9750 x 10^-10 m * T = 2.898 x 10^-3 m*K

=> T = (2.898 x 10^-3) / (9750 x 10^-10) K = 2972 K

Looking into the table, we find that this temperature comes under the range 2000 - 3500 K.

So, the color of the star is Reddish.

And, type of star is M - Type of star.