Sakurai’s Object: Stellar evolution in real time
TEXT: PHYS.ORG April 2, 2014
Since stellar lifetimes are measured in billions of years, changes in their appearance rarely take place on a human timescale. An opportunity to observe a star passing from one stage of life to another on a human timescale is exciting.
Sakurai's Object (V4334 Sgr) was first reported by a Japanese amateur astronomer in 1996 as a "nova-like object." Only a few years before it had been the faint central star of a planetary nebula.
In the 1990's Sakurai's Object brightened by a factor of 10,000. This brightening has been attributed to a final helium shell flash, a process in which 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 Sakurai's Object was not visible even with the Hubble Space Telescope.
Scientists at the National Optical Astronomy Observatory (NOAO) have been observing the sky in the area of Sakurai's Object waiting for infrared radiation to break through the dust cloud.
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IMAGE: Hydrodynamic picture of flash convection near the luminosity peak of the flash [in Sakurai's object (V4334 Sagittarii)]. FROM: Herwig, Falk et al. Astrophys.J. 727 (2011) 89 arXiv:1002.2241 [astro-ph.SR] LA-UR-10-00630 / via High Energy Physics Info System
IMAGE: Still from a computer simulation done at the Laboratory for Computational Science (U of Minnesota)
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IMAGE: Oil painting by Stephen Mack represents what the present expanding shell of gas and dust around the star may look like. (Mack is a member of the Tohono O’odham Nation, the Native American tribe on whose land the Kitt Peak National Observatory, which is managed by NOAO, is located.) Credit: The National Optical Astronomy Observatory (source)
