NGC 6445
NGC 6445, also known as the Little Gem Nebula or Box Nebula, is a planetary nebula in the constellation Sagittarius. It was discovered by William Herschel on May 28, 1786. The distance of NGC 6445 is estimated to be slightly more than 1,000 parsecs based on the parallax measured by Gaia, which was measured at mas.
Characteristics
NGC 6445 has been classified as a bipolar planetary nebula. Its He/H and N/O abundance ratios are consistent with the Type I definition. In optical images, NGC 6445 features a bright, central ring-shaped morphology and open bipolar lobes; the outer envelope emission of NGC 6445 is -dominant.Wide-field optical images obtained by the Nordic Optical Telescope Andalucía Faint Object Spectrograph and Camera show that NGC 6445 has an irregularly shaped central region with a size of ~40"×50", where the emission dominates, while the emission is much more extended and defines an overall bipolar morphology. At distance, NGC 6445 is 4 light years across and is among the largest known.