Stars in the early stages of life are surrounded by dust clouds that thin out and dissipate as the star reaches maturity, becoming rings in their final stages. One star, however, has a dust ring that has long puzzled astronomers because it is not centered around the star as usual. Instead, the ring is elliptical, with the parent star off to one side.
"We wanted to know why this ring was off-center," says Alice C. Quillen, Associate Professor of Astronomy and author of the study. "People guessed there might be a planet in there, but nobody knew where it might be, or how big it might be. Now we've got a very good idea."
Roughly 250 planets have been discovered so far around stars other than our Sun. Most have been revealed by the way the planets influence their parent stars, but Quillen has been working for years on understanding the delicate interaction between stellar dust disks and the planets that shape them. She is now one of the world's experts in predicting planet size and position from the features of a star's dust ring.
Quillen used new images from the Hubble Space Telescope that caught the star, Fomalhaut, and its surrounding ring almost edge-on and in more detail than ever before. Fomalhaut, 25 light-years away, is the brightest star in the autumn sky. Using a device called a coronagraph that blocks out a star's light so dimmer objects near it can be seen, the Hubble revealed that Fomalhaut was indeed off-center within its ring. The images were also clear enough to show that the ring itself had a surprisingly sharp edge.
That sharp edge was the clue Quillen was looking for. Since ascertaining one of the first extra-solar planets using dust-ring analysis in 2002, Quillen has greatly strengthened her planet-ring interaction models. Treating the ring like a hydrodynamic structure, for instance, is necessary for younger stars whose dust is relatively fine and acts more like a fluid—while the physics of dust collision become dominant in older ring systems where the dust has begun clumping into larger bodies.
The sharp inside edge of Fomalhaut, Quillen calculated, demanded that a relatively small, Neptune-size planet was tucked right up against the inner side of the ring, using its gravity to toss dust in the area out of orbit.
According to Quillen's calculations, the ring is elliptical because the Neptunian planet's own orbit around Fomalhaut is elliptical—a curiosity in such a young system. When stars form from a giant cloud of gas and dust, the angular momentum of the cloud carries over to all the objects that form from the cloud, including new planets. Those new planets should, initially at least, orbit in nice, circular paths—not elliptical ones. Fomalhaut's ring is offset by 1.4 billion miles, more than 15 times the distance from the Earth to the Sun, suggesting the hidden planet's orbit is also tremendously skewed.
"Something had to skew that planet, and that's what we're working on now," says Quillen. "There may have been fantastic planetary collisions early on that changed their orbits. We're working on figuring out how many more planets of what size you'd need to account for that elliptical orbit, and to account for why there is no other dust inside that ring."
Quillen's model will remain just a theory until a new generation of telescopes can actually see the Formalhaut planets in question. These telescopes will be equipped with sophisticated coronagraphs that can block out Formalhaut's light enough to let the planets themselves shine through.
This research was funded by the National Institutes of Science and NASA.
Jonathan Sherwood | EurekAlert!
Move over, lasers: Scientists can now create holograms from neutrons, too
21.10.2016 | National Institute of Standards and Technology (NIST)
Finding the lightest superdeformed triaxial atomic nucleus
20.10.2016 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences