NGC 6309, also known as the Exclamation Mark Nebula or Box Nebula, is a planetary nebula located in the constellation Ophiuchus. It was discovered by the German astronomer Wilhelm Tempel in 1876. It has a luminosity of about 1800 times that of the Sun. The distance to this nebula is not well known, but it is assumed to be about 6,500 light-years or 2,000 parsecs.
NGC 6309 is a quadrupolar nebula, with two pairs of lobes. Surrounding the pair is a spherical shell. The spherical shell formed before the four lobes. The square-like shape of the nebula gives it the nickname "Box Nebula".
The central star of the planetary nebula is an O-type star with a spectral type of O(He).
See also List of NGC objects (6001–7000)
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