Astronomers have discovered that an aging red giant star has a closely orbiting stellar companion, which could be causing havoc to the star’s processes. The discovery could help researchers better understand what will happen to Earth and the other solar system planets when the sun transforms into a red giant about five billion years from now.<\/p>\n
The red giant<\/a> in question is \u03c01 Gruis, which scientists affectionately refer to as pi-one-Gru, which is located around 530 light-years<\/a> from Earth. This red giant has the same mass as our sun<\/a>, but the fact that it’s in its “puffed out” red giant phase \u2014 also referred to as the asymptotic giant branch (AGB), due to its position on the Hertzsprung-Russell diagram<\/a> of stellar evolution \u2014 means that \u03c01 Gruis is now 350 to 400 times the size of our star.<\/p>\n <\/p>\n \u03c01 Gruis also shines around thousands of times more brightly than the sun, which means spotting potential companions orbiting it, even if they are stars themselves, is extremely difficult. Indeed, companions of AGB stars have been particularly elusive in general. This team tackled that problem by turning to the Atacama Large Millimeter\/submillimeter Array (ALMA<\/a>), an array of 66 radio antennas located in northern Chile.<\/p>\n You may like<\/p>\n “A key part of understanding the orbit of the companion is knowing the mass of the AGB star. Our team helped better constrain this mass by using its observed luminosity and pulsation characteristics to find the best-suited stellar model,” team leader Yoshiya Mori, from Monash University in Australia, said in a statement<\/a>. “This research is especially interesting, as throwing a close companion into the mix could possibly wreak further havoc on the already complicated processes surrounding these stars.”<\/p>\n Stars<\/a> become red giants when they exhaust the hydrogen within their cores and can no longer perform the nuclear fusion process that turns this, the lightest of all elements in the universe<\/a>, to helium. As a result, the cores of stars contract, as they are no longer producing the energy that gives them the outward push to counteract the inward pressure created by their own gravity.<\/p>\n However, in the outer layers of these stars, the fusion of hydrogen to helium is still occurring, and that causes these outer layers to swell out to as much as 1,000 times the original radius of the stars. As red giants age, they undergo pulsations and throw off vast amounts of material.<\/p>\n