Supernova’s companion star spied by UH astronomers
Institute for Astronomy researchers had a once-in-a-lifetime opportunity to study a newly discovered nearby supernova in 2011. The catch: they had had just 10 minutes observing time to gather information on the supernova and little advance notice.
Supernova SN2011fe had been observed for the first time only the night before by University of California, Berkeley scientists using a telescope in California. Discovered relatively close to earth (in Pinwheel Galaxy M101) and early in its lifespan, it afforded an excellent opportunity to better understand the evolution of supernovae.
With the Keck II telescope on Mauna Kea trained on the highly energetic and luminous stellar explosion 21 million light-years from Earth, astronomers Alan Stockton and Hsin-Yi Shih collected data during the precious few minutes after nightfall on August 25, 2011 that the supernova was within Keck’s range.
“It was clearly an opportunity that does not come along very often,” said Stockton, who usually focuses on radio galaxies and active galaxy nuclei.
“It was a thrill to participate in such a momentous study this early in my career,” added Shih, a doctoral candidate who earned his MS in astronomy from UH Mānoa in 2010.
The pair are co-authors on a paper in the December 15 issue of Nature detailing results of the discovery.
Bright and visible across vast cosmic distances, Type 1a supernova observations were key to the discovery that expansion of the universe is accelerating. The origins of the supernovae themselves have remained unclear, however.
Astronomers believe the supernovae are produced by the explosion of a white dwarf composed primarily of carbon and oxygen after it pulls matter from a binary companion, but they have been unable to classify the likely companion stars.
The California researchers used Keck’s high-resolution images to pinpoint the exact location of the new supernova and examined red, green and blue wavelength observations to narrow the list of likely suspects. Excluding a red giant and most types of helium stars, they concluded the companion was most likely a normal star like the sun, a somewhat evolved star called a subgiant or perhaps a white dwarf.
Read the Nature abstract or the following articles:
- Hubble images help pin down identity of August supernova’s companion star (UC Berkeley News Center)
- Astronomers find new clues to supernova origins (Keck Observatory)
- Supernova caught in the act (National Science Foundation)