Evidence of Non-Thermal Particles in Coronal Loops Heated Impulsively by Nanoflares

The physical processes causing energy exchange between the Sun's hot corona and its cool lower atmosphere remain poorly understood. The chromosphere and transition region (TR) form an interface region between the surface and the corona that is highly sensitive to the coronal heating mechanism. High resolution observations with the Interface Region Imaging Spectrograph (IRIS) reveal rapid variability (about 20 to 60 seconds) of intensity and velocity on small spatial scales at the footpoints of hot dynamic coronal loops. The observations are consistent with numerical simulations of heating by beams of non-thermal electrons, which are generated in small impulsive heating events called "coronal nanoflares". The accelerated electrons deposit a sizable fraction of their energy in the chromosphere and TR. Our analysis provides tight constraints on the properties of such electron beams and new diagnostics for their presence in the nonflaring corona.Comment: Published in Science on October 17: http://www.sciencemag.org/content/346/6207/1255724 . 26 pages, 10 figures. Movies are available at: http://www.lmsal.com/~ptesta/iris_science_mov

2012 Boise State MiniBaja

Background: The SAE MiniBaja is an international competition amongst engineering colleges, sponsored by the Society of Automotive Engineers, to develop and compete with a high performance, yet cost effective off-road vehicle. Boise State University has had a MiniBaja team since 2004 and every year the team is striving to produce the optimal vehicle. In 2005 the team used a trailing arm rear suspension that gave them substantial suspension travel as well as CNC machined front spindles that proved to be a light weight and durable feature to the car. In 2009 the car was built with durability in mind and all though nothing failed on the car it was too heavy and large to be competitive. Lastly in 2011 the MiniBaja had trouble with maneuverability due to a small cockpit and unsatisfactory steering geometry. One thing that has remained unchanged throughout several years was the use of a multi-speed gear box. The multi-speed gear box has been a major hindrance due to having a gear ratio that was not optimal for power transfer from the motor to wheels. The 2012 Boise State MiniBaja team proposes to build the most advanced vehicle to date by addressing each of the advantages and disadvantages of the previous cars. Purpose: The team will use the vehicle in a competition that stresses the need for a fast, lightweight vehicle that is capable of conquering any terrain. To this end, the following criterion will be addressed during the development of the vehicle: Weight Safety Max speed 42 MPH Well handling suspension Drive train function Aggressive steering Solution: The critical areas of design will be the suspension, drive train, and frame. Each of these subcategories must be designed in a way to achieve the fastest most maneuverable MiniBaja. These goals will be attained through a light frame, well designed drive train, and precision suspension geometry; all of which will be designed and optimized using the computer program SolidWorks and Microsoft Excel.To save weight, items on the car that were previously made out of steel will be replaced by aluminum or a composite material. Safety will be regulated by strictly following the SAE rules for designing a MiniBaja race vehicle. To obtain a max speed of 42 miles per hour a gear box has been designed and will be machined here at BSU, which will give a top speed of 42 MPH while also reducing the rotating mass in the gear box by 30%. In addition, the drive chain has been removed from the system, which will increase efficiency by about 15%. The last criterion to be addressed is the need for improved steering which will be accomplished by using a custom designed steering quickener. The quickener will increase the amount of front wheel deflection per revolution of the steering wheel by 1:2. These changes will make the car more agile and increase the cars overall performance giving Boise State an advantage over other competitors

The High-Resolution Coronal Imager (Hi-C)

The High-Resolution Coronal Imager (Hi-C) was flown on a NASA sounding rocket on 11 July 2012. The goal of the Hi-C mission was to obtain high-resolution (≈ 0.3 - 0.4′′), high-cadence (≈ 5 seconds) images of a solar active region to investigate the dynamics of solar coronal structures at small spatial scales. The instrument consists of a normal-incidence telescope with the optics coated with multilayers to reflect a narrow wavelength range around 19.3 nm (including the Fe xii 19.5-nm spectral line) and a 4096×4096 camera with a plate scale of 0.1′′ pixel-1. The target of the Hi-C rocket flight was Active Region 11520. Hi-C obtained 37 full-frame images and 86 partial-frame images during the rocket flight. Analysis of the Hi-C data indicates the corona is structured on scales smaller than currently resolved by existing satellite missions. © 2014 Springer Science+Business Media Dordrecht (outside the USA)