NGC 6309, also known as the Box Nebula, is a
planetary nebula located in the constellation
Ophiuchus. It was discovered by the German astronomer
Wilhelm Tempel in 1876.[4] It has a luminosity of about 1800 times that of the
Sun.[1][2][5] The distance to this nebula is not well known, but it is assumed to be about 6,500 light-years or 2,000 parsecs.[6]
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.[6] The square-like shape of the nebula gives it the nickname "Box Nebula".
^"NGC 6309". Illinois.edu. Retrieved 4 October 2015.
^
abRubio, G.; Vázquez, R.; Ramos-Larios, G.; Guerrero, M. A.; Olguín, L.; Guillén, P. F.; Mata, H. (2015). "NGC 6309, a planetary nebula that shifted from round to multipolar". Monthly Notices of the Royal Astronomical Society. 446 (2): 1931–1938.
arXiv:1410.7060.
Bibcode:
2015MNRAS.446.1931R.
doi:
10.1093/mnras/stu2201.