The report, to be published in the Feb. 15 issue of the journal Science, describes the series of observations that began March 28, 2006, when a collaboration known as Optical Gravitational Microlensing Equipment (OGLE) detected a signal, possibly due to a planet in microlensing event OGLE-2006-BLG-109, that the researchers had discovered and announced two days earlier.
After the OGLE group announced this possible detection of a planetary system via e-mail, other astronomers from the Microlensing Follow-Up Network (MicroFUN), Microlensing Observations in Astrophysics (MOA) and Probing Lensing Anomalies NETwork (PLANET) collaborations also began intensive, round-the-clock observations of this event. The combined data from these four groups revealed a series of brightness variations over the ensuing 11 days that indicated that two planets orbit a star half the mass of the sun located 5,000 light years from Earth. This star, called OGLE-2006-BLG-109L, and its planets were discovered using a technique known as gravitational microlensing.
Early calculations by the report’s lead author, Scott Gaudi of Ohio State University, and the MicroFUN group indicated that most of the telltale brightness variations were due to a planet with a mass similar to that of Saturn, but that there was a brief additional brightening observed from Israel and Chile that could only be explained by an additional planet with nearly the mass of Jupiter. However, Gaudi’s calculations did not provide a perfect fit to the data and involved several approximations.
Subsequently, Bennett performed more sophisticated calculations in his office at Notre Dame using his own advanced computer program that included an important additional feature: the orbital motion of the Saturn-mass planet.
“Even though we observed the micolensing effect of the Saturn for less than 0.3 percent of its orbit, the observations simply could not be explained without accounting for the orbit,” Bennett said.
Critical assistance with these calculations was provided by Sergei Nikolaev at Lawrence Livermore National Laboratory, who devoted much supercomputer time to the calculations.
The result was one of the most complicated calculations of a star-planet system using the gravitational microlensing method.
Gravitational microlensing takes advantage of the fact that light is bent as the rays pass close to a massive object, like a star. The gravity from the mass of the intervening object, or lens star, warps surrounding space and acts like a giant magnifying glass. As predicted by Albert Einstein and later confirmed, this phenomena causes an apparent brightening of the light from the background “source” star. The effect is seen only if the astronomer’s telescope lies in almost perfect alignment with the source star and the lens star. Astronomers are then able to detect planets orbiting the lens star if the light from the background star also is warped by the planets.
The discovery of the double planet system was a triumph for astronomers who use this method, which is of such high sensitivity that it can detect planets similar to those in our own solar system, with the exception of Mercury.
“These planets could not have been detected without any other technique,” Bennett said.
“The light curve of this event revealed an unprecedented amount of information about the planetary host star and the planets,” he continued.
The effect of the orbital motion of the Earth can be detected in the light curve, and this reveals that the mass of the host star is half the mass of the sun. This mass estimate was confirmed by subsequent observations of the planetary host star with the Keck telescope.
The light curve also reveals the orbital motion of the Saturn-mass planet during the 11 days when the planetary signal was visible.
To date, only 25 multiple planet systems have been observed. A majority are very dissimilar to our solar system and that of OGLE-2006-BLG-109L.
The Jupiter- and Saturn-sized planets orbiting OGLE-2006-BLG-109L are only the fifth and sixth planets that have been detected using the gravitational lensing method. Gaudi and Bennett conclude that if the OGLE-2006-BLG-109L planetary system is typical, then it is possible that they would have similar planets as our own solar system.
William Gilroy | EurekAlert!
Basque researchers turn light upside down
23.02.2018 | Elhuyar Fundazioa
Attoseconds break into atomic interior
23.02.2018 | Max-Planck-Institut für Quantenoptik
A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.
In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...
A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.
By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
23.02.2018 | Physics and Astronomy
23.02.2018 | Health and Medicine
23.02.2018 | Physics and Astronomy