The unusual feature of a white dwarf have made astronomers think it went part way through a supernova explosion without go the whole elbow room . If so , it would call forth many questions about how such an event occurs , how common they are , and whether all partial supernovas stop consonant at the same point .
uncommon “ runaway stars ” locomotion either much faster than the usual courtly orbits of those circling the galactic centre or in wildly dissimilar focussing . Their behaviour is attributed to some striking event , most often being part of a close binary system where theircompanion went supernova , with the shockwave giving them an dumbfounding push .
SDSS J1240 + 6710 , a white dwarf 40 percent of the Sun ’s mass , seemed a classic example of such subsister when discovered in 2015 . Its speed of 250 km / s ( 560,000 miles per hour ) is standardised to the Sun ’s but in the opposite direction from almost every other star . However , closer examination has revealed characteristics astronomers have never seen before and are discrepant with any known cause . Professor Boris Gaensickeof the University of Warwick argues the partial supernova hypothesis explain what we see .
When red jumbo star run out of fuel and spill their outer layers , they leave behind blanched dwarfs with aura usually composed of leftover hydrogen and atomic number 2 , the lightest elements . Some have small amounts of slightly heavier elements , carbon or from time to time oxygen , which is impute tomixing with the lead ’s sum .
SDSS J1240 + 6710 is unlike , with an aura of O , neon , magnesium and atomic number 14 , along with minor quantity of elements from standardized parts of the periodic table . We know from keep supernova that all these component are take shape early on in the explosion before the supernova moves on to forging heavier element like branding iron , nickel , and manganese .
InMonthly Notices of the Royal Astronomical Society , Gaeniscke cover that there are no signboard of these heavier supernova residues in SDSS J1240 + 6710 ’s atmosphere .
“ This star is unequalled because it has all the key features of a white dwarf but it has this very high-pitched speed and unusual abundances that make no horse sense when combined with its modest mass , ” Gaeniscke said in astatement . " It has a chemical constitution which is the fingerprint of nuclear burning , a abject mass and a very high speed : all of these facts mean that it must have come from some kind of faithful binary system and it must have undergo thermonuclear lighting . It would have been a type of supernova , but of a form that that we have n’t seen before . "
By astronomical standards , supernovas are very ready events yet still bright for months , giving us plenty of time to get them . However , for most of this time , the volume of the light add up from the radioactive decay of radioactive nickel . If the burst somehow barricade before nickel production , it ’s wink might be so brief we miss it .
SDSS J1240 + 6710 is about 1,430 light - year away – not closemouthed but still in our galactic quadrant . We have no melodic theme if the Milky Way has many such objects as most are probable too far away for us to notice . SDSS J1240 + 6710 ’s “ cooling long time ” evoke the explosion occurred 40 million years ago , but this is based on models create for explosions we are familiar with and may apply poorly to such a distinctive compositor’s case .
