The apparent magnitude (m) of a celestial object is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere.
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Blue supergiants (BSGs) are hot luminous stars, referred to scientifically as OB supergiants.
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In modern astronomy, a constellation is a specific area of the celestial sphere as defined by the International Astronomical Union (IAU).
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Hydrogen is a chemical element with chemical symbol H and atomic number 1.
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Perseus, named after the Greek mythological hero Perseus, is a constellation in the northern sky.
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A variable star is a star whose brightness as seen from Earth (its apparent magnitude) fluctuates.
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