"Over the last 12 years or so nearly 400 planets have been found, and the vast majority of them have been very large¯Jupiter mass or even larger," says researcher Paul Butler of the Carnegie Institution's Department of Terrestrial Magnetism. "These latest planets are part of a new trend of finding much smaller planets – planets that are more comparable to Earth."
The international team of researchers, co-led by Butler and Steven Vogt of the University of California, Santa Cruz, was able to detect the new planetary systems by combining data from observations spanning several years at the W. M. Keck Observatory in Hawaii and the Anglo-Australian Telescope in New South Wales, Australia. The researchers used the subtle "wobbling" of the stars caused by the planets' gravitational pull to determine the planets' size and orbits. Greg Henry at Tennessee State University independently monitored the brightness of the stars to rule out stellar "jitter"¯roiling of gases on a star's surface that can be confused with a planet-induced wobble.
The bright star 61 Virginis, visible with the naked eye in the constellation Virgo, is only 28 light-years from Earth and closely resembles the Sun in size, age and other properties. Earlier studies had eliminated the possibility of a Jupiter-sized planet orbiting 61 Virginis. In this study, the researchers found evidence of three low-mass planets, the smallest of which is five times the mass of Earth and speeds around the star once every four days.
Butler points out that the signal produced by this planet was one of the smallest ever detected. "One has to be very cautious when you claim a discovery," he says. "What gives us confidence is that we see the signal from two separate telescopes, and the two signals match up perfectly."
The other newly-discovered system orbits the star HD 1461, located 76 light-years from Earth. HD 1461 also closely resembles the Sun and is visible in the constellation Cetus. The researchers found clear evidence for one planet 7.5 times the mass of Earth and possible indications of two others. The 7.5-Earth-mass planet, designated HD 1461b, is intermediate in size between Earth and Uranus. It orbits its star once every six days.
These planets have orbits close to their stars and so they would be too hot to support life or liquid water. But Butler says that they point the way toward finding similar planets in similar orbits around nearby M-dwarfs, stars that are typically less than half the mass of the Sun and typically put out less than two percent the Sun's energy. "These sorts of planets around M dwarfs actually would be in a liquid water zone," he says. "So we are knocking on the door right now of being able to find habitable planets."
The discoveries are reported in two papers accepted for publication in the Astrophysical Journal. In addition to Vogt and Butler, the coauthors of the two papers include Eugenio Rivera, Greg Laughlin, and Stefano Meschiari of the University of California, Santa Cruz; Greg Henry at Tennessee State University; Chris Tinney, Rob Wittenmyer, and Jeremy Bailey of the University of New South Wales, Australia; Simon O'Toole of the Anglo-Australian Observatory, Australia; Hugh Jones of the University of Hertfordshire, U.K.; Brad Carter of the University of Southern Queensland, Australia; and Konstantin Batygin of the California Institute of Technology.
The research was supported by the National Science Foundation, and NASA's Office of Space Science, the NASA Keck PI program, the Carnegie Institution for Science, and the NASA Astrobiology Institute.
The Carnegie Institution (www.CIW.edu) has been a pioneering force in basic scientific research since 1902. It is a private, nonprofit organization with six research departments throughout the U.S. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.
The NASA Astrobiology Institute (NAI), founded in 1998, is a partnership between NASA, 16 U.S. teams, and five international consortia. NAI's goal is to promote, conduct, and lead interdisciplinary astrobiology research and to train a new generation of astrobiology researchers. For more information, see http://astrobiology.nasa.gov/nai.
Paul Butler | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
23.07.2018 | Science Education
23.07.2018 | Health and Medicine
23.07.2018 | Life Sciences