Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2022 December 26
The featured image shows a star inside a symmetric but complex
and multi-colored nebula which is all surrounded by a faint blue nebula.
Please see the explanation for more detailed information.

NGC 6164: Dragon's Egg Nebula and Halo
Image Credit & Copyright: Russell Croman

Explanation: The star at the center created everything. Known as the Dragon's Egg, this star -- a rare, hot, luminous O-type star some 40 times as massive as the Sun -- created not only the complex nebula (NGC 6164) that immediately surrounds it, but also the encompassing blue halo. Its name is derived, in part, from the region's proximity to the picturesque NGC 6188, known as the fighting Dragons of Ara. In another three to four million years the massive star will likely end its life in a supernova explosion. Spanning around 4 light-years, the nebula itself has a bipolar symmetry making it similar in appearance to more common planetary nebulae - the gaseous shrouds surrounding dying sun-like stars. Also like many planetary nebulae, NGC 6164 has been found to have an extensive, faint halo, revealed in blue in this deep telescopic image of the region. Expanding into the surrounding interstellar medium, the material in the blue halo was likely expelled from an earlier active phase of the O-star. NGC 6164 lies 4,200 light-years away in the southern constellation of the Carpenter's Square (Norma).

Tomorrow's picture: all the way around


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