After 200 years, Webb manages to image the extra-hot central star of Caldwell 69
NGC 6302 is a planetary nebula located 3400 light-years away in the constellation Scorpius. It was discovered in 1826 (nearly 200 years ago) by William Herschel using a small telescope. It has two lobes that look like butterfly wings. The nebula also has a thick dust band in its middle. This band makes it difficult to see the nebula’s central star.
But Webb has used its Mid-Infrared Instrument (MIRI) to provide more details about that complex center. The telescope carried out this observation in integral field unit mode, combining a camera with a spectrograph to get several images in different wavelengths.
Webb’s observation was able to detect the location of the nebula’s central star — something that has not been done before. The star has a temperature of 220,000 Kelvin. This makes it one of the hottest of all the known central stars in a planetary nebula in the Milky Way galaxy.
Webb also unraveled the components of the dust band covering the central star. It revealed that this band contains crystalline silicate like quartz and relatively large dust grains. The dust grains are about a millionth of a meter in size.
The chemical activity outside the central dust band is also interesting. Webb particularly detected jets of iron and nickel streaming outward from the central star in opposite directions. The research team analyzing this observation also detected light emitted from polycyclic aromatic hydrocarbons (PAHs). The detection of PAHs in an oxygen-rich planetary nebula will help scientists better understand how these molecules are formed.
The research team combined Webb’s observation with data from the Atacama Large Millimeter/submillimeter Array to make these discoveries.
