So when a group of Princeton astronomers discovered twin stars, one of which showed signs of having ingested a dozen or more rocky planets, they named them after Kronos and his lesser-known brother Krios. Their official designations are HD and HD , and they are both about light years from Earth. The keys to the discovery were first confirming that the widely separated pair are in fact a binary pair, and secondly observing Kronos' strikingly unusual chemical abundance pattern, explained Semyeong Oh, a graduate student in astrophysical sciences who is lead author on a new paper describing Kronos and Krios.
Oh works with David Spergel, the Charles A.
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Other co-moving star pairs have had different chemistries, Oh explained, but none as dramatic as Kronos and Krios. Most stars that are as metal-rich as Kronos "have all the other elements enhanced at a similar level," she said, "whereas Kronos has volatile elements suppressed, which makes it really weird in the general context of stellar abundance patterns. In other words, Kronos had an unusually high level of rock-forming minerals, including magnesium, aluminum, silicon, iron, chromium and yttrium, without an equally high level of volatile compounds -- those that are most often found in gas form, like oxygen, carbon, nitrogen and potassium.
Kronos is already outside the galactic norm, said Oh, and in addition, "because it has a stellar companion to compare it to, it makes the case a little stronger. Kronos and Krios are far enough apart that some astronomers have questioned whether the two were in fact a binary pair.
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Both are about 4 billion years old, and like our own, slightly older sun, both are yellow G-type stars. They orbit each other infrequently, on the order of every 10, years or so. An earlier researcher, Jean-Louis Halbwachs of the Observatoire Astronomique of Strasbourg, had identified them as co-moving -- moving together -- in his survey, but Oh independently identified them as co-moving based on two-dimensional astrometric information from the European Space Agency's Gaia mission.
During a group research discussion at the Flatiron Institute, a colleague suggested pooling their data sets.
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John Brewer, a postdoctoral researcher from Yale University visiting at Columbia University, had been using data from the Keck Observatory on Mauna Kea, Hawaii, to calculate the spectrographic chemistries and radial velocities of stars. Binary stars should have matching radial velocities, but that information hadn't been available in the Gaia dataset, so seeing their matching velocities in Brewer's data supported the theory that Kronos and Krios, though two light years apart, were a binary set.
Postdoctoral Fellow in Astrophysical Sciences and a co-author on the paper.
Devourer of planets? Researchers dub star 'Kronos'
Oh took more convincing, both scientists recalled. Once simple error had been ruled out, they began entertaining various theories. Maybe Kronos and Krios had accreted their planetary disks at different times during stellar formation. That one can't be tested, said Price-Whelan, but it seems unlikely.
Maybe they only started moving together more recently, after trading partners with another pair of binary stars, a process known as binary exchange. Oh ruled that out with "a simple calculation," she said. Oh's skepticism was finally overcome when she plotted the chemical abundance pattern as a function of condensation temperature -- the temperatures at which volatiles condense into solids.
Condensation temperatures play a key role in planetary formation because rocky planets tend to form where it's warm -- closer to a star -- while gas giants form more easily in the colder regions far from their star. She immediately observed that all of the minerals that solidify below Kelvin were the ones Kronos was low in, while all the minerals that solidify at warmer temperatures were abundant. The fact that there's a trend there hinted towards something related to planet formation rather than galactic chemical evolution.
Devourer Ov Stars | Enlighten
That was her "Aha! Although virtually nothing is known about this entity, what is known is truly terrifying: an enormous dark mass with long, grasping tentacles which it uses to ensnare and consume falling stars. In Earth's prehistory, Ammutseba was worshiped by several now-vanished civilisations, where it was said to be the "daughter" of an entity known as Isfet , which is thought to be either a different name for Azathoth , or perhaps yet another of the being's many avatars on this plane of existence.
Like so many of its kind, Ammutseba now sleeps beneath the Earth, hibernating under the ruined city of some long-dead civilisation deep in Central Africa. There, it is worshiped as a god by a race of albino humans. Sign In Don't have an account?
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