Fleishman G.D.,New Jersey Institute of Technology |
Fleishman G.D.,RAS Ioffe Physical - Technical Institute |
Kuznetsov A.A.,Armagh Observatory |
Kuznetsov A.A.,Institute of Solar Terrestrial Physics
Astrophysical Journal | Year: 2010
Radiation produced by charged particles gyrating in a magnetic field is highly significant in the astrophysics context. Persistently increasing resolution of astrophysical observations calls for corresponding three-dimensional modeling of the radiation. However, available exact equations are prohibitively slow in computing a comprehensive table of high-resolution models required for many practical applications. To remedy this situation, we develop approximate gyrosynchrotron (GS) codes capable of quickly calculating the GS emission (in non-quantum regime) from both isotropic and anisotropic electron distributions in non-relativistic, mildly relativistic, and ultrarelativistic energy domains applicable throughout a broad range of source parameters including dense or tenuous plasmas and weak or strong magnetic fields. The computation time is reduced by several orders of magnitude compared with the exact GS algorithm. The new algorithm performance can gradually be adjusted to the user's needs depending on whether precision or computation speed is to be optimized for a given model. The codes are made available for users as a supplement to this paper. © 2010. The American Astronomical Society. All rights reserved.
Agency: GTR | Branch: STFC | Program: | Phase: Research Grant | Award Amount: 42.20K | Year: 2014
In recent years, a wealth of observational data from a range of (highly successful) ground- and satellite-based solar facilities has revealed the perplexing and complex nature of the Suns atmospheric structure and dynamics. This tremendous complexity is a result of the continuous interaction of the plasma motions with the magnetic field. To understand these interactions, we need to observe, model and interpret solar phenomena over a wide range of spatial and temporal scales, and in particular establish the links between the small-scale processes and the large-scale phenomena. Solar physics research is very strong in the UK and an area of high priority in the STFC Roadmap. The commissioning of the Rapid Oscillations in Solar Atmosphere imager in 2009 allowed the UK community to expand both its user base of ground-based solar facilities and its exploitation of data from such facilities, which can provide higher spatial and temporal resolution that their satellite-based counterparts. For the future, the Advanced Technology Solar Telescope (ATST), under construction by the US National Solar Observatory with first-light expected in 2019, will be a truly revolutionary facility for ground-based solar physics. It will operate in the optical and near-infrared and be the pre-eminent ground-based solar telescope for the foreseeable future. Key advances in its instrumentation over that currently available include ultra-high spatial (25 km on the solar surface) and temporal (millisecond) resolution, high resolution imaging spectroscopy and coronal magnetometry. The first-light science objectives of the ATST are at the core of UK solar physics research programmes, and it is clearly important for the UK community to have access to the facility to remain competitive. Current UK-led technology has been highlighted as the best option for detectors meeting the science requirements of the ATST. In this proposal we aim to secure UK participation in the ATST and maximise the science return for the UK community at the time of first-light. This will be achieved by a joint programme, funded by STFC, a consortium of UK universities/research institute and industry (Andor Technology plc), on the development of new state-of-the-art detectors for the ATST, plus a set of software tools that will allow the optimal planning of ATST observations and the processing of the resultant datasets. The main academic benefit for the UK will be dedicated observing time on the world-leading ATST facility, which our solar physics community will be in an excellent position to exploit. In terms of non-academic benefit, the proposed detector development will have a significant socio-economic impact and is therefore in line with the STFC strategy for economic growth through innovation. It will open new technological markets and provide growth and diversity in existing detector markets.
Agency: GTR | Branch: STFC | Program: | Phase: Training Grant | Award Amount: 139.28K | Year: 2013
Doctoral Training Partnerships: a range of postgraduate training is funded by the Research Councils. For information on current funding routes, see the common terminology at www.rcuk.ac.uk/StudentshipTerminology. Training grants may be to one organisation or to a consortia of research organisations. This portal will show the lead organisation only.
Agency: GTR | Branch: STFC | Program: | Phase: Research Grant | Award Amount: 306.05K | Year: 2012
This research programme combines projects in Solar Physics, Planetary Science and Stellar and Galactic Astrophysics. These fields encompass studies of our Sun and Solar System, and Stars (including the evolution of both single and binary systems, i.e. two stars orbiting around one another) and the role played by stars as tracers for our understanding of the wider Universe. A key uncertainty in our knowledge is the role of binarity in the evolution of stars, and the interactions of one star with another during their evolution. In this case, at different times, material from one star can flow onto the other (and sometimes vice versa), and more rarely two stars may collide to produce a single more massive object or sometimes a gigantic explosion called a supernova. Such stellar collisions are called mergers, and they lead to objects with unusual chemical composition which contain a fossil record of the two stars joint history or (in the case of a supernova) to an object with short-lived properties that can be used to probe the most distant parts of the Universe. A second area of our research on stars concerns the measurement of stellar magnetic fields, and the impact of magnetic fields on a stars evolution. The reason why some stars are magnetic, and others less so, remains a mystery, and our work aims to provide reliable data with which to compare the different ideas. A third is the origin, evolution and fate of the most massive stars in the Universe. Their evolution is dominated by powerful stellar winds. Do such stars explode disruptively at the end of their lives, or do they ultimately collapse to produce black holes; and, in either case, what is the effect of the stellar wind on neighbouring stars and the nearby star-forming regions? This work will significantly advance our understanding of stars. Our work on the Sun - our nearest Star - has implications not just for understanding stars generally but also for how processes in our Suns visible atmosphere produce the observed phenomena that ultimately leads to heating of its million-degree Corona and the formation of the Solar Wind. The Sun is a variable star showing a dominant roughly 11-year cycle of magnetic activity between episodes of sunspot maximum and minimum. It is currently observed continuously by a fleet of spacecraft, and our detailed observations from instruments onboard these spacecraft (which cover a very wide range of wavelengths) are designed to improve our understanding of the physics of the Suns atmosphere and the mechanisms by which it produces occasional massive outbursts of mass and energy. Some of these outbursts have huge power, and can lead not just to the visible appearance of aurorae in the Earths upper atmosphere but to potentially damaging effects on spacecraft and large-scale power systems on Earth. The variable magnetic activity of the Sun has broad implications for Earths place in the near-space environment. Lastly, we seek to understand the origin of our planetary system, and the evolution of the small bodies - comets and asteroids (and their debris) - within it. We will study the newly discovered populations of small satellites orbiting the giant planets, for example Jupiter and Saturn, to test theories of the origin of our Solar System. We will also investigate the detailed processes by which comets decay into meteoroid streams, debris from which may occasionally cross Earths orbit to produce the well-known phenomenon of a meteor shower - the burning up of small pieces of cometary material in the Earths atmosphere. Not only are there interesting scientific reasons to study such objects and their interrelationships with each other in the Solar System, but the study of Earths near-space astronomical environment has important practical benefits, leading to better understanding of the distribution of small bodies on near-Earth orbits and the time-variable risk of collisions with the Earth.
News Article | January 3, 2016
The ancient Romans may have been on to something when they hailed Jupiter as the supreme god because, according to scientists in the present time, Jupiter - the planet this time, not the god - has a big influence over how life on Earth began and why humans have to adapt to the ever-changing climate. According to several studies, Jupiter has a part in supporting life on Earth and possibly even jump-started it billions of years ago. When the whole universe was still in a hot dense state, Jupiter didn't seem to like its company so it hurled them into the sun and straight out of existence. Yes, we're still talking about the planet, not the god. For decades it's been believed that our biggest neighboring planet, along with fellow giant, Saturn, has been protecting our solar system from rogue asteroids and massive comets called centaurs. However, studies done by various researchers seem to show that, unlike our earlier belief that Jupiter plays the hero, the Earth is actually in a possibly fatal interplanetary dodgeball game against the giant planet. Dodgeball With Jupiter It's not that Jupiter is aiming at Earth and seeking to destroy our planet. It's just that, unlike the earlier idea that Jupiter and the other outer planets have been protecting the inner planets from rogue celestial bodies, the truth is the opposite. According to a study, Jupiter's gravitational field is actually the reason why some centaurs get hurled towards Earth and the Earth is just lucky that none of the centaurs have had deadly effects to human life. Gregory Laughlin, professor of astronomy and astrophysics at the University of California, Santa Cruz and Konstantin Batygin from the Division of Geological and Planetary Sciences at the California Institute of Technology proposed that our solar system was actually composed of planets larger than Earth in its early stages but that Jupiter was responsible for sending those planets towards the sun. A bit scary, but astronomers have yet to find evidence that Jupiter is discreetly pushing the Earth toward the sun so that may be a good sign. "Jupiter may prove to be a questionable shield, a jovian planet may be useful, instead, to deliver necessary life-enabling volatile compounds to the inner solar system," Kevin R. Grazier wrote. This brings us to the next Jupiter hypothesis. Jupiter: Earth, I Am Your Father In accordance with the University of Buckingham and Armagh Observatory study published on Dec. 22 in the Royal Astronomical Society's journal Astronomy & Geophysics and the proposal above, Jupiter's act of sending centaurs towards the Earth's orbit was also one of the ways how life on Earth began. According to Grazier's study published in the journal Astrobiology, a Jupiter-Saturn team exists and it is the work of these two planets which led to the formation of our solar system as it is today. Grazier performed a series of simulations with different computations to determine whether Jupiter really acts as a shield for the inner planets or a bouncer. His computations showed that Jupiter did throw celestial objects out of the solar system. However, it was also responsible for hurtling centaurs towards Earth. Likewise, the simulations showed that Saturn played an active role with regard to the purging of life-threatening celestial bodies. "Without Jupiter, far fewer objects were ejected from the solar system; without Saturn, far fewer objects were perturbed into Jupiter's path. Though Jupiter has primarily been credited with clearing of the outer solar system, Saturn was an important accomplice," Grazier concluded. Jupiter's Effect On Earth's Climate This part is mostly hypothetical since the simulations that Jonathan Horner, Dave Waltham and F. Elliot Koch did involve repositioning Jupiter. Specifically, the team wanted to determine what would happen if Jupiter had an eccentric orbit, or an orbit that is more like a circle than an ellipse. The result is that the position of Jupiter had little effect over Earth's Milankovitch cycles, or the variations in Earth's orbit and tilt that result in changes in climate. However, the limitations they set for their research, that is, charting results at 100-year intervals for only a span of a million years, may have affected the outcome. The team believes that a longer time period for the simulation may indicate more accurate results. Waltham is looking forward to patching up the discrepancy that was formed between his old research and the new results. So What Does It Mean For The Earth? Well, for one thing, it gives our solar system a huge boost in morale to know that we're really quite unique. For another, it gives us a clearer idea of how our solar system actually works. Sure, we know that Mars is red, Saturn clearly isn't single because someone or something put a ring on it and that planets can also be bullied just like what scientists did to Pluto, but what these studies about Jupiter show us is that our solar system isn't just a bunch of giant rocks in space and that, one way or another, each has a purpose for the other.