The challenge was the observation of effect occurred during the transit of Venus across the Sun on June 6th, dubbed "Rossiter-McLaughlin effect". This is a phenomenon that occurs when a celestial body passes in front of a star, hiding a part of its rotating surface and that produces a temporary distortion in the profiles of the spectral lines of light coming from the eclipsed star.
Astronomers led by Paolo Molaro, from INAF Astronomical Observatory of Trieste succeeded in this ambitious task, observing and measurirng the magnitude of this tiny effect. Their findings are published online today in a paper of the journal Monthly Notices of the Royal Astronomical Society Letters, published by Oxford University Press.
The Rossiter-McLaughlin effect has already been observed in systems composed of two stars that eclipse each other, but it becomes more and more difficult to observe when the celestial body is the size of a planet, and moreover not so great as Jupiter but rather similar in size to the Earth, just as it is during the transit of Venus.
Measuring the extent of this weak effect on the light from other planetary systems through telescopes of the next generation such as E-ELT (the European Extremely Large Telescope) will be a useful tool for the search and study of exoplanets. Astronomers will be able to learn important orbital parameters in these systems and thus improve our understanding of the history of their formation.
"Critical to the success of this mission was the use of the HARPS spectrograph at ESO that now, along with his 'twin brother' installed at the Telescopio Nazionale Galileo (TNG) operated by INAF on Canary Islands, represents the state of the art for measuring radial velocities of celestial objects and the best hunter of planetary systems around other stars. The measured magnitude of the effect is comparable to being able to track the speed of a person walking at a slow pace at a distance of 150 million kilometers, the space that separates us from the Sun. Nowadays there is no other instrument capable of recording so tiny changes, especially if you only have a few hours to measure them" said Lorenzo Monaco, an Italian astronomer working at ESO.
But the mere use of HARPS would not be sufficient to achieve this result. The observations of the integrated light of the sun at high resolution are in fact extremely difficult to conduct and to overcome this problem, astronomers pointed their instruments to the Moon to capture the sunlight reflected from it. For this reason, the transit was observed by astronomers in Chile when in fact it would be impossible to do so, since in that region of the world it was night. This unusual strategy has imposed special calculations to achieve the desired results. "The transit of Venus seen from the Moon has a slightly different schedule than what has been observed on Earth," said Simone Zaggia from INAF Astronomical Observatory of Padua, who participated in the mission. "The Moon was in fact 8 degrees ahead of the Earth and Venus reaches alignment with the Sun and the Moon about two hours later. The transit was also slightly longer than that observed on Earth because the Moon was above the plane of rotation of the Earth around the Sun".
Observations show that the partial eclipse on the solar disc produced by the transit of Venus has generated a modulation in the radial velocity of the Sun of less than one meter per second, which is just 3 km/h. "The agreement with the theoretical models is around a few centimetres per second and is an amazing result ever reached before" says Mauro Barbieri, from University of Padua, who is also a member of the team. "Among other things, this change in velocity is comparable with that due to the natural expansion and contraction of our star. However, our observations have allowed us to clearly see the Rossiter-McLaughlin effect during transit".
The results obtained from these observations - the only ones with purely scientific purposes that have been carried out on the Earth during the last transit of Venus - will be of great help to astronomers, who in the next decade will be able measure this phenomenon in extrasolar systems, unleashing the full potential of new generation of telescopes such as the E-ELT. "This measurement - says Paolo Molaro - foretells the sensational results that in a few years will be able to get thanks to the advent of the 40-meter class telescopes equipped with high-resolution spectrographs. This mammoth astronomical instruments will open for sure a new horizon in the study of orbital properties of other Earth-like planets that are found around other stars in our galaxy".
Paolo Molaro | EurekAlert!
Hope to discover sure signs of life on Mars? New research says look for the element vanadium
22.09.2017 | University of Kansas
22.09.2017 | Forschungszentrum MATHEON ECMath
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy