Hence, calculate the wavelength at which the peak of the black-body spectrum of this star appears when observed from Earth.

To answer this question, we need more specific information about the star, such as its temperature. However, I can explain how to calculate the wavelength at which the peak of the black-body spectrum of a star appears when observed from Earth.

The peak wavelength of a black-body spectrum is given by Wien's Displacement Law, which states that the wavelength of the peak of the emission of a black body is inversely proportional to its temperature. The formula is:

λ_max = b/T

where:

• λ_max is the peak wavelength,
• b is Wien's displacement constant (approximately 2.898 x 10^-3 m.K),
• T is the absolute temperature of the black body (in Kelvin).

So, if you know the temperature of the star, you can substitute it into this formula to find the peak wavelength.

Please note that the result will be in meters, but it's common to convert it to more practical units like nanometers (nm) or Angstroms (