Two black holes merged while spinning in nearly opposite directions, suggesting they were born in different places and met late in life. James R. Riordon reported in “New type of black hole merger found” (SN: 8/27/22, pg. 13).
Reader van snyder wondered if the reason black holes spin in almost opposite directions is that some kind of collision flipped the parent star of one of the black holes.
It is possible, though highly unlikely, that one of the black holes flipped due to an earlier event, Riordon He says. But even then, that event probably wouldn’t have been a collision.
Before a dying star explodes in a supernova to form a black hole, it ejects material. The forces of those ejections could “kick” the dying star, causing it to tilt. That tilt remains even when the star forms a black hole. But the more massive a star is, the harder it is to kick it. a star that it is kicked hard enough to develop a severe tilt would likely have been hit too far from a companion star to easily merge again as a black hole, Riordon He says.
Given that the black holes in the study were spinning in such drastically different directions, one upside down relative to the other, it’s unlikely that the black holes started out as a pair and were thrown out of sync by such a kick. Riordon He says.
Also, black holes are incredibly massive. “The lighter of the two was probably around three times the mass of the sun.” Riordon He says. “Flip it wouldn’t be impossible, but it would be quite difficult to do it by leaving the black holes close enough to merge when they did.”
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The inner ear canals of mammalian ancestors shrank abruptly about 233 million years ago, suggesting that animals became warm-blooded around this time. The change in ear structure may have compensated for the decrease in inner ear fluid as body temperature increased. Carolyn Gramling reported in “Warm blood traced back to the Triassic” (SN: 8/27/22, pg. 9).
Reader van snyder he asked when warm blood, or endothermy, arose in theropods, the ancestors of modern birds. Could a look at birds’ ears also provide clues to that evolutionary timeline?
There’s a lot of debate among researchers about when birds developed endothermy, paleontologist says. Esteban Brussette from the University of Edinburgh.
Some scientists argue that a fast metabolism, which is related to warm blood, evolved early in bird history, brusatte He says. “Others argue that even many Mesozoic birds [from around 252 million to 66 million years ago] it didn’t have a modern avian-style metabolism,” he says, “and that full endothermy evolved late in bird history.”
Instead of developing small, highly curved internal ear canals, birds and their ancestors may have followed a different evolutionary path in response to warm blood, says vertebrate paleontologist. Ricardo Araujo from the University of Lisbon in Portugal.
Previous studies looking at pigeon inner ear fluid, or endolymph, suggest that bird endolymph is much thicker than that of any other tetrapod, vertebrate that has four limbs or that evolved from a four-limbed ancestor . Araujo He says. “While maintaining a more or less primitive character [inner ear] morphology, they changed the chemistry of the endolymph to compensate for the increased body temperature,” he speculates.