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November 10, 2015

Expanding shell of gas and dust around Sakurais Object

This oil painting by Stephen Mack represents what the present expanding shell of gas and dust around the star Sakurais Object (V4334 Sgr) may look like. Mack is a member of the Tohono Oodham Nation, the Native American tribe on whose land Kitt Peak National Observatory, which is managed by the National Optical Astronomy Observatory (NOAO), is located.

Stellar lifetimes are measured in billions of years, so changes in their appearance rarely take place on a human timescale. Thus, the opportunity to observe a star passing from one stage of life to another on a timescale of months to years is very exciting, as there are only a very few examples known. One such star is Sakurai's Object.

In the 1990s, Sakurais Object brightened by a factor of 10000--attributed to a final helium shell flash. In this process the burned out core of the star at the center of the planetary nebula re-ignites. The final helium shell flash is violent, ejecting a cloud of dust and gas that forms a thick cocoon around the star blocking all visible light. By 2000, the dust cloud was so thick that Sakurais Object was not visible even with the Hubble Space Telescope.

Using the Altair adaptive optics system at the Gemini North Telescope on Mauna Kea, Hawaii, to compensate for distortions to starlight caused by the Earths atmosphere, two NOAO astronomers were able to observe the shell of escaping material around the star. This oil painting represents what this may look like.

To learn more, see the NSF News From the Field story NOAO/Gemini: Sakurai's Object: Stellar evolution in real time. (Date image taken: unknown; date originally posted to NSF Multimedia Gallery: Nov. 10, 2015)

Credit: Stephen Mack/NOAO/AURA/NSF

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