Hubble Spills Star's Secret: They're Triplets

Nov. 25, 2008 -- Scientists using the Hubble Space Telescope have figured out a massive star that's helping to erode a giant glob of gas in the Carina Nebula is actually a set of triplets.

The star, known as Tr16-244, resides in a cluster in the Carina Nebula, a region rich with gas and dust located about 7,500 light-years from Earth. The nebula is home to some of the youngest, hottest stars in the universe, including Eta Carinae, a massive blue star that is one of the brightest and most luminous stars ever discovered.

Astronomers imaged Tr16-244, along with neighbor star WR 25, as part of a series of studies on star-forming nebulae. They are rare and powerful stars that live relatively short lives, burning through their hydrogen fuel faster than most stars. They radiate brilliantly in ultraviolet wavelengths and appear blue in color.

Newly released images from Hubble show Tr16-244 is made up of three stars, with two stars orbiting so closely around each other that they appeared as a single point of light in previous images. The third star is so far from its siblings that astronomers estimate it needs hundreds or thousands of years to complete a single orbit.

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"Detecting binary or multiple stars can be a difficult business and many are still undiscovered," lead researcher Jesus Maiz Apellaniz with Spain's Instituto de Astrofisica de Andalucia wrote in an email to Discovery News. "The ones with very large separations between the stars are usually easy to detect from ground-based images."

"On the other extreme, the ones with very small separations orbit each other so fast that it is easy to detect their changes in velocity by measuring the Doppler effect in their spectra. However, those with intermediate separations can fall in neither category."

Two years ago, scientists discovered WR 25 actually was at least two stars, a massive Wolf-Rayet star with 50 times the mass of our sun, and a smaller companion that sweeps around it once every 208 days.

"We are interested in massive stars because these objects exert a tremendous influence in their surrounding with their ionizing radiation and their powerful winds," Maiz wrote.

Also, he added, "when they explode as supernovae, they scatter the heavy elements they have produced in their interiors into the interstellar medium.

The stars also have an aesthetic value: Scientists believe radiation from WR 25 and Tr16-244 is sculpting a gas bubble in Carina Nebula into an interesting shape. Earlier pictures from Hubble show what looks like a hand with a finger pointing toward the pair.

Related Links:

European Home Page for the NASA/ESA Hubble Space Telescope

NASA: Hubble Space Telescope

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