Astronomy Stories are Cosmic!
Each year about this time, I go stand under a firehose of astronomy information. It’s actually called the American Astronomical Society winter meeting, and it brings together several thousand of the world’s astronomers (not just Americans) to share the latest and greatest in astronomy research.
So, what do we learn at this meeting? Let’s take just take two examples of things I heard about on this first day.
To Pluto…
It began with a Kavli Award talk given by Alan Stern, PI of the New Horizons mission. The view of this distant world as seen by the spacecraft is getting better with each data dump as it sends back mission data across billions of miles as it speeds toward a January 2019 encounter with the Kuiper Belt object 2014 MU69.
Alan’s overview showed that Pluto is an unexpectedly amazing world. For example, the large, heart-shaped Sputnik Planum is distinctly younger than the rest of Pluto’s surface — around only a million years old. This region is, as Alan stated, about the size of Texas and ringed by mountains made of water ice. There is also nitrogen and other ices, but even as cold as it is at Pluto, these ices are about the consistence of cold toothpaste — not something you can build mountains from. Water ice, yes — and the flyby data revealed water ice in amounts the team didn’t expect. Yet, there it is, in towering mountains the height of the Rockies in Colorado.
Sputnik Planum is brighter than the rest of the surface of Pluto, and has absolutely NO craters on it — which means that this region is constantly being resurfaced from below. That also implies something is supplying a heat source that melts and softens the ices flowing into the Planum, glacier-like.
The New Horizons team has also found evidence of ice volcanoes on Pluto, something that most of us thought might be there, but with no proof until the mission sent back high-resolution imaqes of intriguing features that do look like volcanic calderas made of ice, and evidence of volatiles (gases) near the vents.
The mission also mapped the Pluto atmosphere, which has distinct haze layers in it; and charted Charon (Pluto’s binary companion), and the smaller moons Nyx, Styx, Kerberos and Hydra. At least two of the smaller moons appear to be smashed-together objects and they spin very rapidly on their axes.
Want to learn more about Pluto? Visit the New Horizons Web page for more images and info releases.
Astronomy Beyond the Galaxy
Now, the second story that intrigued me takes us far out of our own solar system and galaxy.
imagine if you will that you are an astronomer and you’re looking at, oh, say a galaxy called SDSS J1126+2944 using the Hubble Space Telescope and the Chandra X-ray Telescope. Hubble gives you a fine visible-light and near-infrared view of the galaxy, but Chandra reveals something kind of interesting and much more energetic: a pair of black holes at the galaxy’s heart.
One of the black holes is surrounded by stars (as supermassive black holes often are), but the other one is not. In fact, it’s strangely deprived of a stellar “coma”.
Why would that be?
That’s the question that Dr. Julia Comerford of the University of Colorado wants to answer. She’s the one who found the halfway-nekkid black hole, and she described it for us today.
“One black hole is starved of stars, and has 500 times fewer stars associated with it than the other black hole,” she said. “The question is why there’s such a discrepancy.”
One possibility she described is that the galaxy experienced a merger. As the merger went on, the galaxy was subjected to extreme gravitational and tidal forces that stripped away most of the stars from one of the black holes.
The other possibility, however, leads to a rare type of object called an “intermediate” mass black hole. That’s one with a mass of between 100 and 1 million times that of the Sun. Intermediate-mass black holes are predicted to exist at the centers of dwarf galaxies and would have a lower number of associated stars. These intermediate-mass black holes can grow and one day become supermassive black holes. If that’s what happened here, then Comerford has uncovered an object still somewhat rare in the pantheon of galaxy-class black holes.
“Theory predicts that intermediate black holes should exist, but they are difficult to pinpoint because we don’t know exactly where to look,” said Scott Barrows, a postdoctoral researcher at CU-Boulder who co-authored the study. “This unusual galaxy may provide a rare glimpse of one of these intermediate mass black holes.”
If this galaxy does indeed contain an intermediate black hole, it would provide researchers with an opportunity to test the theory that supermassive black holes evolve from these lower-mass ‘seed’ black holes.
There are many more astronomy stories being told at AAS! Stay tuned!
