Spitzer And Hubble Find Five Twins Of Superstar Eta Carinae In Other Galaxies

Posted: Jan 7 2016, 5:53am CST | by , Updated: Jan 7 2016, 5:58am CST, in News | Latest Science News


Spitzer and Hubble Find Five Twins of Superstar Eta Carinae in Other Galaxies
The nearby spiral galaxy M83 is currently the only one known to host two potential Eta Carinae twins. This composite of images from the Hubble Space Telescope's Wide Field Camera 3 instrument shows a galaxy ablaze with newly formed stars. A high rate of star formation increases the chances of finding massive stars that have recently undergone an Eta Carinae-like outburst. Bottom: Insets zoom into Hubble data to show the locations of M83's Eta twins. Credits: NASA, ESA, the Hubble Heritage Team
  • NASA’s Spitzer and Hubble Telescopes find Five Super Stars in other Galaxies

NASA’s Spitzer and Hubble telescopes have found signs of five super stars in other galaxies far away from our own.

Eta Carinae is within 10,000 light years of our galaxy. It is the brightest and largest system close to our solar system. It underwent an eruption that was detected in the midst of the 19th century.

A large plethora of material ten times the size of the sun was ejected into space. This rising plume of gaseous dust still covers most of Eta Carinae. It is a unique supernova.  

But now for the first time, NASA’s Spitzer and Hubble telescopes have found evidence of five similar stars in other galaxies.

While most huge stars are pretty rare, they do have a whole scale effect on the galaxy they inhabit. These big stars explode in the form of supernovae and often spread elements that are necessary to life. 

"The most massive stars are always rare, but they have tremendous impact on the chemical and physical evolution of their host galaxy," said lead scientist Rubab Khan, a postdoctoral researcher at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

Located 7500 light years away, Eta Carinae is five million times as bright as our sun. The binary system comprises two massive stars in a 5.5 year orbit.

The larger of these two weighs as much as 90 times the weight of the sun. As for the smaller one, it weights about 30 times as much as our sun. 

Eta Carinae has been a criterion of sorts for astronomers since its eruption in 1840. However, additional examples were needed for a fuller understanding of the phenomenon.

It takes a high degree of precision to calculate the time when stars explode. And nothing could match Eta Carinae’s level of complexity. The other such star systems were out there somewhere. It was just a matter of time before they were discovered. Twins of Eta Carinae were ultimately detected by the Spitzer and Hubble telescopes.  

Researchers found likely Eta twins in four galaxies by comparing the infrared and optical brightness of each candidate source. Infrared images from NASA's Spitzer Space Telescope revealed the presence of warm dust surrounding the stars. Comparing this information with the brightness of each source at optical and near-infrared wavelengths as measured by instruments on Hubble, the team was able to identify candidate Eta Carinae-like objects. Top: 3.6-micron images of candidate Eta twins from Spitzer's IRAC instrument. Bottom: 800-nanometer images of the same sources from various Hubble instruments. Credits: NASA, ESA, and R. Khan (GSFC and ORAU)

"We knew others were out there," said co-investigator Krzysztof Stanek, a professor of astronomy at Ohio State University in Columbus. "It was really a matter of figuring out what to look for and of being persistent."

Dust is formed when a massive star explodes. This partially blocks the ultraviolet rays and visible light coming from the star. It finally reabsorbs and re-radiates this energy in the form of heat. Seven galaxies were studied from 2012 to 2014.

While they didn’t turn up any Eta Carinae twins, such a series of five stars systems were found closeby. Galaxy M83 had such twin phenomena in them. And NGC 6946, M101 and M51 had such stars in them too.

This is a rare chance of seeing such star systems in foreign areas of the universe. It just goes to show that the universe is stranger than we thought. 

The findings of this study were published in the Dec. 20 edition of The Astrophysical Journal Letters.

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<a href="/latest_stories/all/all/20" rel="author">Sumayah Aamir</a>
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