Scientists use models to investigate how solar activity begins and persists over time. // NASA/SDO/GSFC
When you bring people from many different time zones together for a conference, it's a good idea to begin the day with a presentation about "the largest energy-release events in the solar system." These events are, of course, solar eruptions, and today at the American Astronomical Society (AAS) meeting, Tibor Török of Predictive Science, Inc., updated us on the latest questions and the models attempting to answer them.
These models are computer simulations (not Heidi Klum), and they show that solar activity appears to be "sympathetic," meaning that if one part of the Sun experiences instability, another part can — as a result — respond with its own instability and eruption.
"One eruption could feed our energy needs for several tens of thousands of years," said Török. Because of that enormous power, solar events can be dangerous to life and technology on and above Earth. Török's group's main research goal is to forecast the occurrence and impact of the solar activity that could destroy satellites and power grids and harm astronauts. But the Sun, like politics and quantum theory and you, is complicated, and taking its nuances into account is no easy task. "We aim, of course, to model observed events and not just ideal events," he said, but he also emphasized that the computer power necessary only now is becoming possible, as processors become faster and scientists zoom in on the Sun's coronal details.
Török won the Karen Harvey prize, an award to recognize and encourage new talent in solar physics as well as to highlight Harvey's work in understanding our star.
The Atacama Large Millimeter/submillimeter Array in Chile was inaugurated last March. ALMA/ESO/NRAO/NAOJ/J. Guarda
Another plenary talk I attended was about the newly inaugurated Atacama Large Millimeter/submillimeter Array (ALMA
) in Chile. This monster radio telescope has 66 antennas that can be placed on 238 pads, leading to configurations ranging in size from 492 feet (150 meters) to 9.3 miles (15 kilometers). When the antennas are 15 kilometers apart, they act like a single telescope that is 15 kilometers wide (luckily, since building a 15-kilometer telescope is not exactly feasible).
Despite the telescope's formidability, National Radio Astronomy Observatory Director Toney Beasley wanted astronomers to know that "you don't have to be a hairy, four-armed, black-belt radio astronomer to use ALMA" (although I saw on Twitter that someone else interpreted his words as "hairy-forearmed," which is an equally compelling image).
Beasley called ALMA a "generational task" because it took so long to complete, partly because a volcano initially caused construction problems, "until [they] threw a few postdocs in it."
Although ALMA science has just begun, 22 scientific papers already have come out. Discoveries range from potential planet formation around brown dwarfs to images of gas flowing inside a protoplanetary disk to "more gravitational lenses than [Toney Beasley knew] existed in the universe."
In other news, scientists highlighted high-mass objects and their end states today:
- Sean Couch of the University of Chicago was excited to report that his team's 3-D simulations of supernovae didn't result in ... well ... supernovae. His 2-D models ended in explosions, but his 3-D models mostly sloshed around. He was not disappointed, though, because when "results imply that we are missing key physics or getting the physics wrong," new, unexpected physics awaits discovery.
Scientists detected a 'light echo' from the recurrent nova T Pyxidis. // NASA/ESA/Hubble
- Teams led by Dino Drozdov and Peter Garnvich of Clemson University and the University of Notre Dame, respectively, witnessed and tracked "light echoes" from supernovae. When the light from a supernova bounces off dust, that light reaches us after the light we initially receive from an explosion. The researchers witnessed these echoes in SN 2007af and SN 2009ig. Light echoes are 10,000 (or more) times fainter than their supernova parents, making these new phenomena part of a small group of known echoes.
- Stephen Lawrence of Hofstra University in Long Island reported on a recurrent nova — a nova that repeats with a period of 100 years or fewer — called T Pyxidis, which had an outburst in 2011. That outburst is echoing off the material left from four of its previous outbursts, allowing astronomers to learn about those ejections and the area around the star. It's almost meta.
- Guenther Hasinger of the University of Hawaii discussed scientists' near-total success in resolving the X-ray background into individual sources like star-forming galaxies and the supermassive black holes that power active galactic nuclei. The X-ray background is the high-energy "glow" that permeates the sky, and scientists want to understand how the sources contributing to it have changed over cosmic time.
On the exoplanet frontier, we had a few shake-ups:
- First, Karen Collins of the University of Louisville reported the discovery of Saturn-sized KELT-6b, a planet low on metals (where metals are everything heavier than hydrogen and helium, which is astronomers' favorite joke and also is true). The Kilodegree Extremely Little Telescope (KELT), whose name and newsworthy results laugh in the face of convention, found this 6-billion-year-old world 700 light-years from Earth. It's just 50 percent as metallic as Earth. Because scientists can compare this planet directly to the similar, but more well-studied and metallic, planet HD209458b, they can learn how different environments lead to different compositions. FYI, KELT is located at Winer Observatory in Arizona, is diminutive, and has a 16 MP camera. This is its fourth planetary discovery. To learn more about KELT, visit http://arxiv.org/abs/0704.0460.
- Next, Steve Howell of the NASA Ames Research Center in California broke some extremely big (EB) news: Most of the Sun-like stars that NASA's Kepler telescope has been observing appear to be bigger than scientists thought. And a quarter of those are 35 percent larger. Before you say, "Big whoop," consider that astronomers calculate a planet's radius by how long its passage across the star takes, and their determination of the star's habitable zone depends on the star's size. If Howell's team's results, which are based on 258 stars in the Kepler field, are correct, 87 percent of Kepler's Sun-like star systems have farther-out habitable zones, and scientists will need to search for planets with longer orbits in order to find ones that could host water-loving life.
- Derek Buzasi of Florida Gulf Coast University in Fort Myers gave a presentation entitled "Flying Toasters." The smaller text just below that headline read, "Heating exoplanets via the stellar wind." Buzasi spoke about research into what makes hot Jupiters so hot. In a time when searching for Earth's elusive twin(s) is the focus, these large, strange planets have fallen from the headlines. But not so long ago, they were the only ones scientists could find. They're easier to detect, being, you know, hot and Jupiter-sized. Buzasi reported that these planets are "puffed up" to a size larger than predicted (theme?), suggesting that theories thus must account for more heating. Buzasi posited that the planets' magnetospheres capture the incoming solar wind and channel it through the planet via the north and south poles. This creates a "global electric circuit" with a current in the billions of amps. This external and electric (like a toaster?) heating mechanism likely is one of several ways the planets become so scorching.
With these last two items in mind, I'll leave you with a thought expressed in one of the day's later sessions, which was about bridging the gap between the lab and space itself. Fausto Cattaneo of the University of Chicago said, "Typically, if you get something wrong in astrophysics, nobody gets hurt." So while Kepler stars need revised sizes, hot Jupiters need more heat, and scientists can't make supernovae explode, these issues simply mean we have as many discoveries ahead of us as we do behind us.