An article in the journal “Galaxies” reports a study of the planetary nebulae NGC 6302, also known as the Butterfly Nebula for its shape, and NGC 7027. A team of researchers used the Hubble Space Telescope in multiple wavelength observations to offer the most complete views ever obtained of these two planetary nebulae. Both of them were already studied with Hubble and many other instruments in the past, but the Wide Field Camera 3 instrument allowed to obtain more details that mean more scientific information on the processes in progress and even more spectacular images.
The Butterfly Nebula has been known for almost a century and a half and is a bipolar planetary nebula since, as can be seen in the images, it has a bilobed symmetry with the two lobes extending from the central area where the progenitor star was to be. In his case, the two lobes have a butterfly-like appearance, hence the nickname. NGC 6302, also known by other designations depending on the catalog, today has at its center an extremely hot white dwarf with over 200,000 Kelvin, which means that it’s the remains of a very large star. That white dwarf was discovered thanks to Hubble after updating its instruments and installing the Wide Field Camera 3.
The planetary nebula NGC 7027 has also been known for a long time and has the peculiarity of being particularly small for this type of formation. Typically, a planetary nebula can extend for a light year and even more, but this extends for one and two tenths in length and width. It’s small, but the X-ray emissions detected indicate very high temperatures, perhaps generated by an accretion disk around the central white dwarf. Its shape reminiscent of an insect with a colored back indicates that it was slowly pushing its mass outwards but recently something happened that generated different and more chaotic shapes.
The planetary nebulae NGC 6302 and NGC 7027 are among the most filled with dust and gas, and this makes their study difficult. Many electromagnetic emissions are blocked by all those materials. Each new campaign of observations with instruments that can better detect the emissions that pass through those materials provide new details. These new observations at different wavelengths made with the Hubble Space Telescope’s Wide Field Camera 3 instrument were successful.
The new observations also allow a comparison with the ones conducted in the past, in particular the movements of the shock waves that are typically generated when stellar winds collide with the previously ejected gas. The history of shock waves helps to reconstruct the history of the nebulae.
It’s possible that these nebulae were born from binary systems and this would explain their bizarre shapes. The interaction between two very close stars could lead to the ejection of gas with the consequent creation of shapes such as the two lobes of the Butterfly Nebula. Another possibility is that two stars merged creating the gas jets.
The new details of the planetary nebulae NGC 6302 and NGC 7027 will continue to be studied to look for further information on their birth and evolution. The Hubble Space Telescope continues to be an extraordinary instrument that offers a lot of scientific data and spectacular images.