"As in the human case," he noted, "twins are similar but not identical, and can show a few specific differences in their stellar populations." In fact, they're so alike that Ferraro coins them as twins. The researchers drew their novel conclusion by comparing two similar galactic globular clusters, or areas crowded by tons of stars, M3 and M13. "Some stable thermonuclear burning can still occur on a white dwarf's surface." Comparing clusters "This discovery changes the definition, itself, of white dwarfs that we currently teach to students," he said. Thus, contrary to popular belief, not all white dwarfs dim and cool, or age, at the same rate. "This is exactly the accepted model for white dwarfs."įerraro and his team's analysis of Hubble images from the telescope's Wide Field Camera 3 found that some white dwarfs are surrounded by a thin, residual layer of hydrogen that provides a final bump of energy. "Without any source of energy, a star can only cool down and progressively dim its luminosity," Ferraro said. That leaves an exhausted, unenergized, "naked" star-corpse - a white dwarf. © Provided by CNETīy comparing two huge collections of stars, M13 (left) and M3 (right), astrophysicists were able to understand how white dwarfs cool. That's what Hubble regularly captures in its awesome, colorful pictures of magnificent nebulae - stars shedding their outer layers. Once there isn't any hydrogen left, it fuses the helium into even heavier elements.Īs the secondary fusion happens, the stars' outer envelopes of matter are released. Before a star enters the white dwarf realm, it energizes itself by fusing hydrogen into the slightly heavier element, helium. White dwarfs are the last evolutionary stage of low mass stars - like the sun - and are sometimes referred to as the formerly blazing objects' "naked" core. It will retire from blanketing us during our morning coffee and, much like the rest of our cup of joe often forgotten on the dining table, remnants of the old star will slowly cool down. One day, like all the other stars in the universe, our delightfully golden sun will die. He added, "Our discovery suggests using caution in adopting white dwarf cooling sequences as a clock." "Some models for slowly cooling white dwarfs had been computed in the past, this is the very first time that this effect has been observed," explained Francesco Ferraro, an astrophysicist at the University of Bologna who coordinated the study of the stars published Monday in the journal Nature Astronomy. Sirius B, on the right, is a tiny white dwarf star - a corpse of a star about the size of our sun. The stellar bodies' secret is a coating of hydrogen, which slows their postmortem cooling so much that present estimates of their age could be off by up to 1 billion years. NASA's Hubble Space Telescope just detected that some dying stars, or white dwarfs, have an anti-aging regimen effective enough to shelve an intergalactic Sephora.
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