The star system harboring the new planet contains only one star, as do the other three systems with extrasolar planets analyzed by Kane, an assistant professor of physics and astronomy, and his colleagues. It is a surprising finding, given the high rate of multiple-star systems in our solar neighborhood.
"There is a great interest in these stars that are known to host planets," Kane explained, since astronomers suspect that planet formation in a multi-star system would be very different from planet formation in a single-star system like our own. Kane presented his findings today at the annual conference of the American Astronomical Society.
A multiple-star system "might have not one but two planetary disks" where planets form, he said. "Or it could be that having an extra star would be disruptive, and its gravity could cause any protoplanets to pull apart."
Relatively few extrasolar planets have been found in multiple-star systems, "but we know that they are there," Kane said.
In the four systems studied by the researchers, using optical imaging data collected at the Gemini North observatory in Hawaii, there were some intriguing signs that perhaps a second star -- or something else -- was present.
In each system, the extrasolar planets were discovered by the radial velocity technique, pioneered at SF State by astronomer Geoffrey Marcy, now at the University of California, Berkeley. The radial velocity technique measures variations in the speed at which a star moves away and toward Earth, perturbed or "wobbled" by the gravitational pull of a nearby cosmic body. Depending on the radial velocity signature, astronomers can calculate whether the wobble is coming from a planet or star.
In the star systems studied by Kane and his colleagues, there was a part of the radial velocity data that couldn't be explained entirely by the pull of an orbiting planet. And at the same time, the planets that had already been discovered in these systems followed eccentric orbits, swinging away from their stars in a less circular and more elliptical fashion, "more like that of a comet," Kane said.
With these two clues, the researchers wondered if the radial velocity and eccentric orbits might be explained by the presence of another star in the system. But when they took a closer look at the systems, they were able to rule out the possibility that another star was perturbing the system.
"I thought we were likely to find stellar companions, and when all four didn't have a binary star, that did surprise me," Kane said.
But in the case of one star, Pisces' HD 4230, the unexplained radial velocity appears to be coming from the pull of a previously undiscovered giant planet, the researchers report. They confirmed the planet's presence with additional radial velocity data collected at Hawaii's Keck observatory.
Given that the researchers did not find any stellar companions, Kane says it is very likely that the leftover radial velocity is instead a signal that there are additional planets to be found in all four systems. The researchers feel this is especially true for the system called HD 168443, where their ability to detect a companion star was very strong.
Kane is one of the few astronomers to use a variety of planet-hunting techniques, including radial velocity and imaging. He said that the new findings had motivated him to look at other extrasolar systems with similar kinds of unexplained radial velocity data, to see if other stars or planets may be lurking there.
"Limits on Stellar Companions to Exoplanet Host Stars with Eccentric Planets" is in press at Astrophysical Journal. Kane co-authored the study with SF State Postdoctoral Fellow Natalie R. Hinkel; Steve B. Howell of NASA Ames Research Center; Elliott P. Horch of Southern Connecticut State University; Ying Feng and Jason T. Wright of Pennsylvania State University; David R. Ciardi of NASA Exoplanet Science Institute; Mark E. Everett of National Optical Astronomy Observatory and Andrew W. Howard of the University of Hawaii.
SF State is the only master's level public university serving the counties of San Francisco, San Mateo and Marin. The university enrolls more than 30,000 students each year. With nationally acclaimed programs in a range of fields -- from creative writing, cinema and biology to history, broadcast and electronic communications arts, theatre arts and ethnic studies -- the University's more than 219,000 graduates have contributed to the economic cultural and civic fabric of San Francisco and beyond.
Nan Broadbent | EurekAlert!
Quantum Logical Operations Realized with Single Photons
03.05.2016 | Max-Planck-Institut für Quantenoptik
Cavitation aggressive intensity greatly enhanced using pressure at bubble collapse region
03.05.2016 | Tohoku University
Using an ultra fast-scanning atomic force microscope, a team of researchers from the University of Basel has filmed “living” nuclear pore complexes at work for the first time. Nuclear pores are molecular machines that control the traffic entering or exiting the cell nucleus. In their article published in Nature Nanotechnology, the researchers explain how the passage of unwanted molecules is prevented by rapidly moving molecular “tentacles” inside the pore.
Using high-speed AFM, Roderick Lim, Argovia Professor at the Biozentrum and the Swiss Nanoscience Institute of the University of Basel, has not only directly...
If a person pushes a broken-down car alone, there is a certain effect. If another person helps, the result is the sum of their efforts. If two micro-particles are pushing another microparticle, however, the resulting effect may not necessarily be the sum their efforts. A recent study published in Nature Communications, measured this odd effect that scientists call “many body.”
In the microscopic world, where the modern miniaturized machines at the new frontiers of technology operate, as long as we are in the presence of two...
Researchers from the Max Planck Institute Stuttgart have developed self-propelled tiny ‘microbots’ that can remove lead or organic pollution from contaminated water.
Working with colleagues in Barcelona and Singapore, Samuel Sánchez’s group used graphene oxide to make their microscale motors, which are able to adsorb lead...
Neutron scattering and computational modeling have revealed unique and unexpected behavior of water molecules under extreme confinement that is unmatched by any known gas, liquid or solid states.
In a paper published in Physical Review Letters, researchers at the Department of Energy's Oak Ridge National Laboratory describe a new tunneling state of...
Honeycomb structures as the basic building block for industrial applications presented using holo pyramid
Researchers of the Alfred Wegener Institute (AWI) will introduce their latest developments in the field of bionic lightweight design at Hannover Messe from 25...
27.04.2016 | Event News
15.04.2016 | Event News
12.04.2016 | Event News
03.05.2016 | Physics and Astronomy
03.05.2016 | Life Sciences
03.05.2016 | Physics and Astronomy