NASA spies Earth-sized exoplanet orbiting Sun-like star
Nature 523, 7562 (2015). http://www.nature.com/doifinder/10.1038/nature.2015.18048
Author: Alexandra Witze
Potentially rocky world spotted by Kepler spacecraft offers glimpse at Earth's future.
‘Half-pipe’ telescope will probe dark energy in teen Universe
Nature 523, 7562 (2015). http://www.nature.com/doifinder/10.1038/523514a
Author: Davide Castelvecchi
Canadian observatory aims to chart cosmic expansion rate between 10 billion and 8 billion years ago.
Astronomy: Telescope spies early galaxy's birth
Nature 523, 7562 (2015). doi:10.1038/523505a
Astronomers have spotted the glow from one of the most distant galaxies ever seen in the early Universe.Roberto Maiolino at the University of Cambridge, UK, and his colleagues used the high-resolution Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile to observe three faint galaxies
Magnetospherically driven optical and radio aurorae at the end of the stellar main sequence
Nature 523, 7562 (2015). doi:10.1038/nature14619
Authors: G. Hallinan, S. P. Littlefair, G. Cotter, S. Bourke, L. K. Harding, J. S. Pineda, R. P. Butler, A. Golden, G. Basri, J. G. Doyle, M. M. Kao, S. V. Berdyugina, A. Kuznetsov, M. P. Rupen & A. Antonova
Aurorae are detected from all the magnetized planets in our Solar System, including Earth. They are powered by magnetospheric current systems that lead to the precipitation of energetic electrons into the high-latitude regions of the upper atmosphere. In the case of the gas-giant planets, these aurorae include highly polarized radio emission at kilohertz and megahertz frequencies produced by the precipitating electrons, as well as continuum and line emission in the infrared, optical, ultraviolet and X-ray parts of the spectrum, associated with the collisional excitation and heating of the hydrogen-dominated atmosphere. Here we report simultaneous radio and optical spectroscopic observations of an object at the end of the stellar main sequence, located right at the boundary between stars and brown dwarfs, from which we have detected radio and optical auroral emissions both powered by magnetospheric currents. Whereas the magnetic activity of stars like our Sun is powered by processes that occur in their lower atmospheres, these aurorae are powered by processes originating much further out in the magnetosphere of the dwarf star that couple energy into the lower atmosphere. The dissipated power is at least four orders of magnitude larger than what is produced in the Jovian magnetosphere, revealing aurorae to be a potentially ubiquitous signature of large-scale magnetospheres that can scale to luminosities far greater than those observed in our Solar System. These magnetospheric current systems may also play a part in powering some of the weather phenomena reported on brown dwarfs.
When the first galaxies started to form a few hundred million years after the Big Bang, the Universe was full of a fog of hydrogen gas. But as more and more brilliant sources — both stars and quasars powered by huge black holes — started to shine they cleared away the mist and made the Universe transparent to ultraviolet light. Astronomers call this the epoch of reionisation, but little is known about these first galaxies, and up to now they have just been seen as very faint blobs. But now new observations using the Atacama Large Millimetre/submillimetre Array (ALMA) are starting to change this.
A team of astronomers led by Roberto Maiolino from the University’s Cavendish Laboratory and Kavli Institute for Cosmology trained ALMA on galaxies that were known to be seen only about 800 million years after the Big Bang. The astronomers were not looking for the light from stars, but instead for the faint glow of ionised carbon coming from the clouds of gas from which the stars were forming. They wanted to study the interaction between a young generation of stars and the cold clumps that were assembling into these first galaxies.
They were also not looking for the extremely brilliant rare objects — such as quasars and galaxies with very high rates of star formation — that had been seen up to now. Instead they concentrated on rather less dramatic, but much more common, galaxies that reionised the Universe and went on to turn into the bulk of the galaxies that we see around us now.
From one of the galaxies — given the label BDF 3299 — ALMA could pick up a faint but clear signal from the glowing carbon. However, this glow wasn’t coming from the centre of the galaxy, but rather from one side.
“These observations enable an unprecedented understanding of the assembly process of the first galaxies formed in the Universe – for the first time we can observe and disentangle the different components contributing to the earliest phases of galaxy formation,” said Maiolino. “These observations have enabled us to test with unprecedented detail theories of galaxy formation in the early Universe.”
The astronomers think that the off-centre location of the glow is because the central clouds are being disrupted by the harsh environment created by the newly formed stars — both their intense radiation and the effects of supernova explosions — while the carbon glow is tracing fresh cold gas that is being accreted from the intergalactic medium.
By combining the new ALMA observations with computer simulations, it has been possible to understand in detail key processes occurring within the first galaxies. The effects of the radiation from stars, the survival of molecular clouds, the escape of ionising radiation and the complex structure of the interstellar medium can now be calculated and compared with observation. BDF 3299 is likely to be a typical example of the galaxies responsible for reionisation.
“We have been trying to understand the interstellar medium and the formation of the reionisation sources for many years. Finally to be able to test predictions and hypotheses on real data from ALMA is an exciting moment and opens up a new set of questions. This type of observation will clarify many of the thorny problems we have with the formation of the first stars and galaxies in the Universe,” said co-author Andrea Ferrara, from the Scuola Normale Superiore in Pisa, Italy.
“This study would have simply been impossible without ALMA, as no other instrument could reach the sensitivity and spatial resolution required,” said Maiolino. “Although this is one of the deepest ALMA observations so far it is still far from achieving its ultimate capabilities. In future ALMA will image the fine structure of primordial galaxies and trace in detail the build-up of the very first galaxies.”
The results are reported in the journal Monthly Notices of the Royal Astronomical Society.
R. Maiolino et al., “The assembly of “normal” galaxies at z∼7 probed by ALMA,” Monthly Notices of the Royal Astronomical Society (2015).
Adapted from an ESO press release.
An international team of astronomers led by the University of Cambridge have detected the most distant clouds of star-forming gas yet found in normal galaxies in the early Universe – less than one billion years after the Big Bang. The new observations will allow astronomers to start to see how the first galaxies were built up and how they cleared the cosmic fog during the era of reionisation. This is the first time that such galaxies have been seen as more than just faint blobs.For the first time we can observe and disentangle the different components contributing to the earliest phases of galaxy formationRoberto MaiolinoESO/R. MaiolinoThe central object is a very distant galaxy, labelled BDF 3299. The bright red cloud just to the lower left is the ALMA detection of a vast cloud of material that is in the process of assembling the very young galaxy
YesRelated Links: Atacama Large Millimeter/submillimeter Array (ALMA)
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