The Twin Jet Nebula, or PN M2-9, is a striking example of a bipolar planetary nebula. Bipolar planetary nebulae are formed when the central object is not a single star, but a binary system, Studies have shown that the nebula’s size increases with time, and measurements of this rate of increase suggest that the stellar outburst that formed the lobes occurred just 1200 years ago. Credit: ESA/Hubble & NASA Acknowledgement: Judy Schmidt
The new image highlights nebula PN M2-9 shells and its knots of expanding gas in striking detail via NASA/ESA Hubble Space Telescope. 2 iridescent lobes of material stretch outwards from a central star system. Within these lobes 2 huge jets of gas are streaming from the star system at speeds in >1 million km/ hour.
The M in the name PN M2-9 refers to Rudolph Minkowski, a German-American astronomer who discovered the nebula in 1947. The PN = planetary nebula. The glowing and expanding shells of gas clearly visible in this image represent the final stages of life for an old star of low to intermediate mass. The star has not only ejected its outer layers, but the exposed remnant core is now illuminating these layers – resulting in a spectacular light show. It is a bipolar nebula.
Ordinary planetary nebulae have 1 star at their centre, bipolar nebulae have 2, in a binary star system. Astronomers have found that the 2 stars in this pair each have around the same mass as the Sun, 0.6 – 1.0 solar masses for the smaller star, and 1.0 – 1.4 solar masses for its larger companion. The larger star is approaching the end of its days and has already ejected its outer layers of gas into space, whereas its partner is further evolved, and is a small white dwarf
The characteristic shape of the wings of the Twin Jet Nebula is most likely caused by the motion of the 2 central stars around each other. It is believed that a white dwarf orbits its partner star and thus the ejected gas from the dying star is pulled into 2 lobes rather than expanding as a uniform sphere. However, astronomers are still debating whether all bipolar nebulae are created by binary stars. Meanwhile the nebula’s wings are still growing and, by measuring their expansion, astronomers have calculated that the nebula was created only 1200 years ago.
Within the wings, starting from the star system and extending horizontally outwards like veins are 2 faint blue patches = violent twin jets streaming out into space, a consequence of the binary system. These jets slowly change their orientation, precessing across the lobes as they are pulled by the wayward gravity of the binary system.
The two stars at the heart of the nebula circle one another roughly every 100 years. This rotation not only creates the wings of the butterfly and the 2 jets, it also allows the white dwarf to strip gas from its larger companion, forming a large disc of material around the stars, 15X the orbit of Pluto! This newer version incorporates more recent observations from the telescope’s Space Telescope Imaging Spectrograph (STIS). http://www.spacetelescope.org/news/heic1518/
Recent Comments