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      The North Star is much heavier than previously thought

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      The star marking true north is a good deal heavier than we thought.

      The North Star is 5.1 times as massive as the sun, astronomers report in work submitted July 12 to arXiv.org. That value, calculated from the motion of a much fainter star that orbits the luminary, is nearly 50 percent heavier than a recent estimate of 3.45 solar masses.

      Mass profoundly affects stellar life: The more mass a star has, the faster it burns its fuel and the sooner it dies. The earlier mass estimate had suggested that the North Star, also known as Polaris, is roughly 100 million years old (SN/12/2/16). The new estimate means the star formed more recently than this, but no one has yet calculated a revised age. More

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      Sulfur was key to the first water on Earth

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      A chemical element that’s not even in H2O — sulfur — is the reason Earth first got its water, a new study finds, bolstering a similar claim made a year ago. The discovery means our planet was born with all it needed to create its own water and so did not have to receive it from elsewhere.

      Water is essential to terrestrial life, but Earth formed in a region around the newborn sun that was so hot the planet should have been dry (SN: 5/6/15). Now two independent studies of a specific type of meteorite reach the same conclusion: Lots of hydrogen — a key component of water — came to Earth not as H2O but instead bonded with sulfur. This allowed the hydrogen to survive the heat and later join oxygen, the most common element in Earth’s crust, to create water. More

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      A middleweight black hole has been spotted for the first time in our galaxy

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      For the first time, astronomers have spotted a middleweight black hole in the nearby universe. The discovery could help solve the riddle of how even heftier black holes form and grow up with their host galaxies.

      The black hole, which sits about 16,000 light-years from Earth in the center of star cluster Omega Centauri, is at least 8,200 times as massive as the sun, putting it squarely in a rare category of intermediate-mass black holes, researchers report July 10 in Nature. More

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      Strange observations of galaxies challenge ideas about dark matter

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      Head-scratching observations of distant galaxies are challenging cosmologists’ dominant ideas about the universe, potentially leading to the implication that the strange substance called dark matter doesn’t exist.

      That’s one possible conclusion from a new study published June 20 in The Astrophysical Journal Letters. The finding “raises questions of an extraordinarily fundamental nature,” says Richard Brent Tully, an astronomer at the University of Hawaii at Manoa who was not involved in the work.

      Astronomers suspect dark matter exists because of the way stars and other visible material at a galaxy’s visible edge rotate. The rotation speeds of objects far from a galactic center are much higher than they should be given the amount of luminous stuff seen in telescopes. Under physicists’ current understanding of gravity, this implies that a massive reservoir of invisible matter must be tugging on those stars. More

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      A stellar explosion may add a temporary ‘new star’ to the night sky this summer

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      Keep your eyes on the night sky this summer, scanning for the constellation Corona Borealis, and if you are lucky, you may glimpse what appears to be a new star winking on in the dark.

      The brightening point of light will not be a new star, but a nova eruption about 3,000 light-years from Earth. There, a white dwarf star orbiting a red giant tears material from its larger companion. When enough mass collects on the white dwarf’s surface, the rising pressure and temperature will trigger a blast that can be seen from Earth with the naked eye — but for only a few days to a week. More

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      We may finally know the source of mysterious high-energy neutrinos

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      Supermassive black holes at the hearts of active galaxies may be churning out a lot of the universe’s high-energy neutrinos.

      Two teams using data from IceCube, the world’s premier neutrino observatory located in Antarctica, have independently identified a common type of these active galaxies, called Seyfert galaxies, as likely neutrino producers. These findings, reported in Physical Review Letters and arXiv.org, bolster some astronomers’ view that the cores of such active galaxies could churn out the majority of the cosmic neutrinos seen streaming across the universe. More

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      Venus might be as volcanically active as Earth

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      Present-day volcanism on Venus might be far more pervasive than previously believed.

      A new analysis of decades-old data from NASA’s Magellan spacecraft finds signs of fresh lava flows occurring on the Venusian surface between 1990 and 1992, researchers report May 27 in Nature Astronomy.

      “This definitely is another step in the path to understanding Venus as a living, breathing world,” says planetary scientist Paul Byrne of Washington University in St. Louis, who was not involved in the work. More

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      The universe may have a complex geometry — like a doughnut

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      The cosmos may have something in common with a doughnut.

      In addition to their fried, sugary goodness, doughnuts are known for their shape, or in mathematical terms, their topology. In a universe with an analogous, complex topology, you could travel across the cosmos and end up back where you started. Such a cosmos hasn’t yet been ruled out, physicists report in the April 26 Physical Review Letters. 

      On a shape with boring, or trivial topology, any closed path you draw can be shrunk down to a point. For example, consider traveling around Earth. If you were to go all the way around the equator, that’s a closed loop, but you could squish that down by shifting your trip up to the North Pole. But the surface of a doughnut has complex, or nontrivial, topology (SN: 10/4/16). A loop that encircles the doughnut’s hole, for example, can’t be shrunk down, because the hole limits how far you can squish it.  More