The authors, lead by Rosine Lallement, research scientist at the GEPI-CNRS/Paris Observatory (GEPI¨CCNRS/Observatoire de Paris/Universit¨¦ Paris Diderot)) base their study on an analysis of data from NASA¡¯s Voyager 1 and Voyager 2 space probes. As a result of these findings, it now will be possible to test locally (within the Milky Way galaxy) models designed to measure of the same types of emissions that are observed in distant galaxies.
Lyman alpha emissions, with a wavelength of 121.6 nanometers, are the principal signature of hydrogen atoms in the universe and are used as indicators of the formation of stars in galaxies shortly after the Big Bang (the primordial universe). However, because these emissions are at the ultraviolet end of the spectrum, they are completely obscured by the earth¡¯s atmosphere and the proximity of the Sun, which is composed primarily of hydrogen and produces an intense flux of ultraviolet photons. As the two Voyager probes moved farther and farther from the Sun¡ªfrom 1993 to 2003, they travelled between six and 13 billion kilometers (40 to 90 Astronomical Units) from the Sun¡ªthe glow of local Lyman alpha emissions in the vicinity of the probes has become easier to detect, growing 20 times more intense than if observed from Earth orbit.
Lallement¡¯s team of researchers used the residual ultraviolet light detected by the Voyager probes to develop a theoretical model of the interplanetary glow observable in the sky. The model makes it possible to measure the slight excess radiance in the direction of the Milky Way, which correlates with the ¡°red¡± radiance (H alpha with a wavelength of 656.3 nanometers) that is characteristic of the regions that surround young, hot stars. As a result, astronomers on Earth will be able to test models that have been developed to interpret observations of the Lyman alpha emission from very distant galaxies, where the emission is associated with the first bursts of forming stars.
Much of what is known about the distant universe is based on measurements of the Lyman alpha emission from distant galaxies, and some of these distant galaxies are detected only from this emission. This new model should help astronomers formulate a better understanding of the behavior of distant galaxies.
About Boston University¡ªFounded in 1839, Boston University is an internationally recognized private research university with more than 30,000 students participating in undergraduate, graduate, and professional programs. As Boston University¡¯s largest academic division, the College and Graduate School of Arts & Sciences is the heart of the BU experience with a global reach that enhances the University¡¯s reputation for teaching and research.
Contact information for the authors:
In the USA:Jean-Loup Bertaux
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
Theorists publish highest-precision prediction of muon magnetic anomaly
16.07.2018 | DOE/Brookhaven National Laboratory
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....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences