A Stellar Nursery in the Carina nebula: pillars of gas and dust three light years tall (NASA, JPL)

A Stellar Nursery in the Carina nebula: pillars of gas and dust three light years tall (NASA, JPL)

Stars develop in vast nebulae of swirling dust and gas that are light years across. Within these giant molecular clouds (GMCs), gravity gathers matter together into an accretion disk which then further compacts until the density and temperature of the central ball of gas reach the extremes necessary for nuclear fusion to begin. Different stars created in different GMCs thus have different spectrographic characteristics depending on the place of their creation, however GMCs tend to be inconceivably vast and multiple stars form in one stellar nursery at the same time. Such stars share similarities of composition.

The Sun

The Sun

For a long time, astronomers have sought the stars which formed at the same time in the same GMC as our beloved sun (which is approximately four and a half billion years old). Now, at long last, it seems we have found one of the sun’s bigger sisters. A yellow star in the constellation Hercules seems to have the same composition as the sun. Using elaborate computer models of stellar drift, scientists have traced the star (which goes by the unlovely name “HD 162826”) and the sun back to the same place of origin. HD 162826 is 15% larger than the sun (which is why I called it a big sister) and although it does not have any “super Jupiter” type planets, there is a possibility it may have some small rocky inner worlds. The sun has grown somewhat distant from its sibling: during the billions of years since their creation the two stars have drifted 110 light years from each other.

HD 162826

HD 162826

The discovery was made by a team of astronomers from around the world (lead by Ivan Ramirez from the University of Texas). The sun’s sister is not visible to the naked eye, but no doubt many telescopes will be trained on Hercules to discover if there is anything we can learn from our sun’s long sundered nursery mate.