Next Week’s Night Sky:
Wednesday is the first quarter moon. The evenings surrounding the first quarter are the best for seeing the lunar terrain when it is dramatically lit by low-angle sunlight.
Planet Nine
An exoplanet circling two stars 336 light-years away may provide clues about where a long-sought world may be hiding in our own solar system.
This strange exoplanet, HD106906 b, was first discovered in 2013 with the Magellan Telescopes at the Las Campanas Observatory in Chile’s Atacama Desert. But in order to determine its orbit, astronomers needed the Hubble Space Telescope’s clarity and precision to track the planet for 14 years. Eleven times the mass of Jupiter, HD106906 b lies incredibly far from its host stars, taking 15,000 years to complete one orbit at a distance more than 730 times that between Earth and the Sun. Not only is HD106906 b far-flung for an exoplanet, but it also sits 30 degrees off the orbital plane of the dusty disk surrounding its host stars.
It’s possible that HD106906 b formed much closer to its twin host stars, but as it traveled through the debris disk surrounding the stars, its orbit decayed. The whirling twin stars then kicked the planet further out into the system when it migrated too close. The planet was almost entirely ejected from the system, but astronomers think a passing star might have stabilized the planet’s distant orbit. Candidates for such a passing star have previously been identified using the European Space Agency’s Gaia survey satellite.
Some astronomers suspect a similar scenario may have played out in our own solar system, paving the way for the hypothetical planet dubbed Planet Nine. Proposed in 2015, the gravitational influence of Planet Nine could explain the strange orbits of a unique group of Kuiper Belt objects beyond Neptune.
Planet Nine has yet to be discovered (or even proven to exist), but HD106906 b’s strange orbit provides a compelling parallel to what researchers predict Planet Nine’s orbit would look like. Using the upcoming James Webb Space Telescope, astronomers hope to gather more data on HD106906 b to understand the planet in detail and hope to find other planets in similar orbits around other stars.
Most Distant Quasar
Astronomers have found the most distant quasar yet discovered, a powerhouse seen shining just 670 million years after the Big Bang. The quasar’s supermassive black hole, some 1.6 billion times as massive as the Sun, is the youngest on record, posing a challenge to theorists trying to explain how black holes could have grown so massive so early in cosmic history.
One theory about early black hole evolution holds that massive first-generation consisting mostly of hydrogen explode in supernova blasts, leaving behind already massive black holes that consume surrounding material and growing rapidly in the process. Another model suggests supermassive black holes can be formed when dense star clusters collapse, directly forming a massive black hole.
But the newly discovered quasar, known as J0313-1806, features a black hole that’s too young and too massive to be explained by earlier theories. If the quasar’s black hole formed as early as 100 million years after the Big Bang and then grew as fast as possible, it would have had to start out with a mass of 10,000 suns to reach its current size.
Because that mechanism does not require mature stars for raw material, team members say it’s the only model that can explain a 1.6-billion-solar-mass black hole when the universe was just 5 percent of its current age.
Age of Supernovae
Astronomers are winding back the clock on the expanding remains of a nearby, exploded star. By using NASA’s Hubble Space Telescope, they retraced the speedy shrapnel from the blast to calculate a more accurate estimate of the location and time of the stellar detonation.
The victim is a star that exploded long ago in the Small Magellanic Cloud, a satellite galaxy to our Milky Way. The doomed star left behind an expanding, gaseous corpse, a supernova remnant named 1E 0102.2-7219, which NASA’s Einstein Observatory first discovered in X-rays. Like detectives, researchers sifted through archival images taken by Hubble, analyzing visible-light observations made 10 years apart.
To calculate an accurate explosion age, the astronomers picked the 22 fastest moving ejecta clumps, or knots. The researchers determined that these targets were the least likely to have been slowed down by passage through interstellar material. They then traced the knots’ motion backward until the ejecta coalesced at one point, identifying the explosion site. Once that was known, they could calculate how long it took the speedy knots to travel from the explosion center to their current location.
Hubble also clocked the speed of a suspected neutron star—the crushed core of the doomed star—that was ejected from the blast. Based on their estimates, the neutron star must be moving at more than 2 million miles per hour from the center of the explosion to have arrived at its current position. The suspected neutron star was identified in observations with the European Southern Observatory’s Very Large Telescope in Chile, in combination with data from NASA’s Chandra X-ray Observatory.
Do you have any cool astronomy research news from this week? Share it in the comments below!