UF-led team uses new observatory to characterize low-mass planets orbiting nearby star

Twice as massive as the sun and 20 times brighter, Fomalhaut is surrounded by a ring of dust and debris, making it a favorite system for astronomers to study and a natural laboratory for testing planet formation theories.

In 2008, images of Fomalhaut taken by the Hubble Space Telescope led to the discovery of “Fomalhaut b,” the first extra solar planet to be directly detected in visible light. At the time, astronomers believed it to be a giant planet, akin to Jupiter or Saturn, but later infrared images failed to detect the planet, meaning that it had to be smaller than Saturn.

UF astronomers, along with scientists from the new Atacama Large Millimeter Array in Chile, known as ALMA, and the National Radio Astronomy Observatory, used ALMA’s superior resolution and sensitivity to study the system in unprecedented detail. Their results indicate that there are not one, but two planets, with masses between that of Mars and a few times larger than Earth, working together to shape the ring of dust.
The new study reveals that the ring is sharply truncated in the inner and outer edges and is only about 16 astronomical units, or AU, wide, or about 16 times the distance between the Earth and the sun. That may seem large, but the center of the ring is about 140 AU, making the ring relatively very narrow. It also finds that the ring is vertically thin, about one-seventh as tall as it is wide. Those properties give important clues to explain the planetary system of Fomalhaut.

The results are described in a paper to appear this month in the Astrophysical Journal Letters.

“Combining ALMA observations of the ring’s shape with computer models, we can place very tight limits on the mass and orbit of any planet near the ring.” said Aaron Boley, a Sagan Postdoctoral Fellow at UF and leader of the study. “The masses of the planets must be small so they do not destroy the ring, but their masses cannot be too low or they would not shape the ring.”

Although Fomalhaut is a much hotter star than the sun, the planets are so far from their host star that they are among the coldest planets known around a normal star. They are thought to be low-mass bodies, but astronomers do not have enough data to tell whether they have a significant amount of hydrogen gas or are mostly rock and ice.

“ALMA observations show that Fomalhaut’s ring is even more narrow and thinner than previously known,” said Matthew Payne, an astronomer at the University of Florida who contributed to the study. “Fomalhaut b alone only explains the ring’s sharp inner edge. Our analysis suggests that two planets, one interior and one exterior, are shepherding the ring, analogous to how Uranus’ moons Cordelia and Ophelia confine Uranus’ brightest ring.”

The Atacama Large Millimeter/submillimeter Array, located in the Atacama Desert of northern Chile at an altitude of 16,400 feet is the largest astronomical project in existence. Still under construction, ALMA began scientific operations in September.

“ALMA may still be under construction, but it has already proved to be the world’s most powerful telescope for observing the universe at millimeter and submillimeter wavelengths of light.” said Stuartt Corder, an astronomer at the National Radio Astronomy Observatory and co-author of the study.

“Once ALMA is completed, we will be able to study systems like Fomalhaut with even greater detail, and see through the veil of dust that hides the early stages of planet formation,” said co-author Bill Dent, an astronomer at ALMA.

This research was supported by the NASA Sagan Fellowship Program, the National Radio Astronomy Student Observing Support Program and the University of Florida’s College of Liberal Arts and Sciences. The Joint ALMA Observatory is a partnership of the European Organization for Astronomical Research in the Southern Hemisphere, the National Astronomical Observatory of Japan (on behalf of the National Institutes of Natural Sciences and Academia Sinica), and the NRAO (managed by Associated Universities, Inc. on behalf of the NSF and the National Research Council of Canada) in cooperation with the Republic of Chile.
Credits
Writer Javier Barbuzano, jbarbuzano@astro.ufl.edu
Source Aaron Boley, aaron.boley@astro.ufl.edu

Media Contact

Aaron Boley EurekAlert!

More Information:

http://www.ufl.edu

All latest news from the category: Physics and Astronomy

This area deals with the fundamental laws and building blocks of nature and how they interact, the properties and the behavior of matter, and research into space and time and their structures.

innovations-report provides in-depth reports and articles on subjects such as astrophysics, laser technologies, nuclear, quantum, particle and solid-state physics, nanotechnologies, planetary research and findings (Mars, Venus) and developments related to the Hubble Telescope.

Back to home

Comments (0)

Write a comment

Newest articles

The Sound of the Perfect Coating

Fraunhofer IWS Transfers Laser-based Sound Analysis of Surfaces into Industrial Practice with “LAwave”. Sound waves can reveal surface properties. Parameters such as surface or coating quality of components can be…

Customized silicon chips

…from Saxony for material characterization of printed electronics. How efficient are new materials? Does changing the properties lead to better conductivity? The Fraunhofer Institute for Photonic Microsystems IPMS develops and…

Acetylation: a Time-Keeper of glucocorticoid Sensitivity

Understanding the regulatory mechanism paves the way to enhance the effectiveness of anti-inflammatory therapies and to develop strategies to counteract the negative effects of stress- and age-related cortisol excess. The…

Partners & Sponsors