Clue to mystery of black holes?
A team of scientists said it found traces of nickel and iron in the powerful jets shooting out of black hole candidate 4U 1630-47, a small black hole just a few times the mass of our sun. It may help solve a scientific puzzle that has lingered for decades.
Astronomers have known that hyper-dense black holes shoot matter into the universe in high-speed streams known as relativistic jets. However, nobody knew exactly what type of material the jets were spewing. "It was one of the unsolved questions about relativistic jets produced in the vicinity of black holes," said Avi Loeb, chair of the department of astronomy at Harvard University, who was not involved with the study. "What is their composition?"
Scientists agreed that the jets would contain electrons, which have a negative charge. But the jets did not have a negative charge overall. That suggested there was something else in there with a positive charge that canceled it out. In addition, some models of the jets suggested they were shooting lightweight electrons and positrons away from the black hole and into the universe. Others thought the jets were made of much heavier normal matter.
"Until now, it wasn't clear whether the positive charge came from positrons, the antimatter 'opposite' of electrons, or positively charged atoms," said James Miller-Jones of the International Center for Radio Astronomy Research and co-author of the Nature study. "Since our results found nickel and iron in these jets, we now know that ordinary matter must be providing the positive charge."
ancient oceans: a saltier time
Seawater retrieved from a crater deep under Chesapeake Bay is 100 million to 145 million years old, researchers say, offering a rare glimpse of ancient ocean conditions in the North Atlantic.
The water, pumped from the 35-million-year-old meteor impact site in 2005 during a deep drilling project, has an average salinity about twice that of the modern ocean, said a study in the journal Nature.
That level of salinity makes sense, given the state of the North Atlantic at the time the water was trapped. During the early Cretaceous period, the North Atlantic was in transition from a closed basin to an open ocean as North America and Africa moved farther apart. "Those are the types of conditions that actually lead to high salinity," said study author Ward Sanford, a research hydrologist with the U.S. Geological Survey. "In places like the Dead Sea, it's completely enclosed and you have elevated salinity."
Chances to study ancient seawater are rare. Sanford says there is probably more preserved water in the Chesapeake site and other deep places along the East Coast, but excavating it is hard and costly. "Until someone decides they want to spend that kind of money again, it's hard to go there to see what else we can learn," he said.
