A planetary nebula is formed when a star towards the end of its life ejects its outer envelope, leaving behind a hot compact core that becomes a white dwarf.
Fleming 1 is a rather unusual planetary nebula, since observations have revealed the presence of a double white dwarf system with a rotational period of around 2 days. Estimates of the mass of the primary range between 0.5 to 0.86 solar masses, while for the secondary the mass estimates range between 0.7 to 1.0 solar masses. The temperature of the main white dwarf is around 80,000 Kelvin, while the secondary has a temperature of 120,000 Kelvin, thus the binary is responsible for the ionization of the nebula.
Morphologically, there is a pair of symmetrical jets that span more than 10 light years, with numerous knots along them. Both the jets and knots are moving away from the central nebula and it is believed that they were ejected at some point between 10,000-16,000 years ago.
The inner part of the nebula has a shape that resembles a butterfly and it is immersed into a faint halo. The wings of the butterfly point towards the jets and their axis is tilted at an angle of 50° along the line of sight. The main body of the butterfly is surrounded by a torus of hot gas that is expanding forming an inner bright structure. This structure is younger and its age is around 5,000 years.
Image: Composite optical image of Fleming 1 taken with ESO’s Very Large Telescope at Paranal, Chile. The image was created using narrow band filters that are focused on the emission of ionized oxygen ([O II], blue and [O III], green), ionized hydrogen (Hα), and ionized nitrogen ([N II], red).
Image Credit:ESO/H. Boffin
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