Somewhereout there, astronomers knew the sun had another long-lost relative aimlesslydrifting through the Milky Way. Now they've found it.
Although ahappy reunion is unlikely, as the star HIP 56948 is about 200 light-years away,it is now considered to be the best "solar twin" out of four knowncandidates.
The waywardstar challenges the idea that our backyard star has a unique composition, as ithas a similarly low quantity of the element lithium--a lightweight byproduct ofthe fusion reactions that power stars.
AstronomersJorge Melendez of the Australian National University and Ivan Ramirez of the University of Texas at Austin discovered the new star with a telescope at the McDonaldObservatory in Texas. The mid-sized star is one of many in the Draco thedragon constellation and may be a billion years older than the sun, whichis middle-aged at 4.6 billion years.
Three othersolar twins were previously proposed: 18 Scorpius, HD 98618 and HIP 100963. Whilesimilar to the sun in many ways, spectrographic analysis revealed that theirlithium contents are dramatically higher.
Because ofthose observations, astronomers wondered if the sun's lowamount of lithium was unique. The newfound twin now shows that it isn't.
Searchesfor solar twins are important, the astronomers said, because the sun is used asa baseline for many other types of studies. But our own solar power plant istoo close and too bright to study like distant stars.
The solartwins discovered at McDonald should help astronomers study the chemicalcompositions of stars and back theoretical models of our sun's stellar insidesand evolution with real observations.
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