2. Dark Energy Is Acting Up
The universe is expanding more quickly than it should, and no one knows why. Astronomers have been using Hubble for the past six years to improve the accuracy of expansion parameters. They calculated that the universe is expanding at a rate of 73 kilometers (45 mi) per second per megaparsec. So two galaxies separated by 3.3 million light-years, or one megaparsec, are flying apart at 73 kilometers (45 mi) per second.
That’s an irreconcilable 9 percent discrepancy compared to Planck satellite predictions, with only a 1-in-5,000 chance of error.
The study implies that dark energy is even more confounding that previously thought. Maybe it’s growing stronger. Or maybe it’s more “sociable” than thought and is interacting with the universe in a novel way. Or an entirely new type of particle could be at fault.
1. All Sunlike Stars Have Siblings
Lots of stars have companions, potentially even the Sun. A new study says that it does because all Sunlike stars are born binary.
Astronomers surveyed young single stars and binaries in the Perseus constellation 600 light-years away, but the math makes the most sense when all Sunlike stars are born as “wide binaries” approximately 500 astronomical units apart (1 AU = 150 million kilometers (93 million mi)).
But the partnerships either shrink or break apart early in their lifetime, after only about a million years. And a long-lost sibling could better explain the current state of our own solar system.
Though the universe is still an overwhelmingly lonely place and the model suggests that 60 percent of these pairs eventually split up, the remaining stars shrink into “tight binaries.” Meanwhile, our Sun’s theoretical companion, Nemesis, may be lost among the other stars in our galaxy.