Monoceros

The constellation of Monoceros (the Unicorn) does not have many bright stars but the brightest star of the constellation is Beta Monoceros which shines at magnitude 3.74 . But Beta Mon is not a single star but a “Triple Star System” composed of three closely spaced magnitude 4 and 5 stars whose combined brightness catapults Beta Mon to the number-one position within the constellation. See the following photo for a close-up view of this intriguing system.
When first discovered by William Herschel in 1781 he described Beta Monoceros as “The most beautiful sight in the Heavens”. To the naked eye it appears as a single mag 3.7 star, but it is actually a triple star system composed of three massive stars (spectral class Be). The primary star is 3,200 times more luminous than our Sun while the other two are ~1,500 times more luminous.
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Close-up view of the GAN 3 system in NGC 2244 shown in the photo above. Located some 6,000 LY away it is unlikely that any of these stars has a true binary connection.
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STF 953 is a physical pair with a subtle but distinct color contrast. In the photo you can see that there are large patches of sky which are devoid of stars which is due to thick clouds of interstellar dust and gas (dark nebula) which obscures the stars shinning from behind. A half-degree to the west is the reflection Nebula NGC 2261 also known as “Hubble’s Variable Nebula”. For a detailed view of NGC 2261 go to the “Nebulas” menu.
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