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
NASA detects solar flare pulses at Sun and Earth
17.11.2017 | NASA/Goddard Space Flight Center
Pluto's hydrocarbon haze keeps dwarf planet colder than expected
16.11.2017 | University of California - Santa Cruz
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses