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Physics posts

• March 14, 2017
• 08:05 AM
• 122 views

Solar Science with the Atacama Large Millimeter/Submillimeter Array — A New View of Our Sun by S. Wedemeyer

The Atacama Large Millimeter/submillimeter Array (ALMA), which consists of 66 antennas placed on the Chajnantor plateau in the Chilean Andes, has already produced impressive results for a large range of astronomical objects. Regular observations of the Sun have been carried out for the first time in December 2016 and exciting results can be expected soon. ALMA combines high spatial, temporal, and spectral resolution with the diagnostic advantages of radiation at [...]... Read more »

Wedemeyer, S., Bastian, T., Brajša, R., Hudson, H., Fleishman, G., Loukitcheva, M., Fleck, B., Kontar, E., De Pontieu, B., Yagoubov, P.... (2015) Solar Science with the Atacama Large Millimeter/Submillimeter Array—A New View of Our Sun. Space Science Reviews, 200(1-4), 1-73. DOI: 10.1007/s11214-015-0229-9

• February 28, 2017
• 07:03 AM
• 119 views

Quasi-periodic acceleration of electrons in the flare on 2012 July 19 by Jing Huang et al.*

We study the quasi-periodic pulsations (QPPs) of nonthermal emission in an M7.7 class flare on 2012 July 19 with spatially resolved observations at microwave and HXR bands and with spectral observations at decimetric, metric waves. Microwave emission at 17 GHz of two footpoints, HXR emission at 20–50 keV of the north footpoint and loop top, and type III bursts at 0.7–3 GHz show prominent in-phase oscillations at 270$\,$s. Through the [...]... Read more »

Huang, J., Kontar, E., Nakariakov, V., & Gao, G. (2016) QUASI-PERIODIC ACCELERATION OF ELECTRONS IN THE FLARE ON 2012 JULY 19. The Astrophysical Journal, 831(2), 119. DOI: 10.3847/0004-637X/831/2/119

• February 24, 2017
• 11:06 AM
• 198 views

What if black holes were not... holes? A Los Alamos physicist explains his alternative theory behind these mysterious objects.

© Elena E. GiorgiThe concept of a “black hole” — a celestial body so dense and massive that not even light can escape its gravitational field — dates back to the 18th century, with the theoretical work of Pierre-Simon Laplace and John Michell. But it wasn’t until the early 20th century that these mysterious dark objects were first described mathematically by German physicist Karl Schwarzschild. Schwarzschild’s work predicted the existence of a finite distance around the black hole (........ Read more »

Mazur, P., & Mottola, E. (2004) Gravitational vacuum condensate stars. Proceedings of the National Academy of Sciences, 101(26), 9545-9550. DOI: 10.1073/pnas.0402717101

Emil Mottola. (2010) New Horizons in Gravity: The Trace Anomaly, Dark Energy and Condensate Stars. Acta Physica Polonica B (2010) Vol.41, iss.9, p.2031-2162. arXiv: 1008.5006v1

• February 20, 2017
• 02:30 PM
• 63 views

This Squid Gives Better Side-Eye Than You

Yes, this cephalopod is looking at you funny. It's a kind of cockeyed squid—an animal that looks like some jokester misassembled a Mr. Potato Head. One of the cockeyed squid's eyes is big, bulging and yellow. The other is flat and beady. After studying more than 25 years' worth of undersea video footage, scientists think they know why.

The Monterey Bay Aquarium Research Institute (MBARI) in California has been dropping robotic submarines into the ocean for decades. The footage from th........ Read more »

• February 14, 2017
• 07:02 AM
• 257 views

Large-scale simulations of Langmuir Wave Distributions Induced by Electron Beams by H. Reid and E. Kontar

Langmuir waves that generate type III radio bursts are excited by high-energy electron beams streaming out from the corona through interplanetary space. Despite a smooth temporal distribution of electrons, the Langmuir waves are measured to occur in discrete clumps, commonly attributed to the turbulent nature of the solar wind electron density (e.g. Smith and Sime 1979, Melrose et al 1986). But how do fluctuations in the background plasma shape the [...]... Read more »

• January 31, 2017
• 07:06 AM
• 491 views

Emission of radiation by plasmas with counter-streaming electron beams by L. F. Ziebell et al.*

The phenomena of emission of radiation by the Sun, which are known as type II and type III solar radio bursts, have been known and investigated for more than sixty years. The bursts of radiation occur at a frequency corresponding to the plasma frequency at the source region, and harmonics [...]... Read more »

Ziebell, L., Petruzzellis, L., Yoon, P., Gaelzer, R., & Pavan, J. (2016) PLASMA EMISSION BY COUNTER-STREAMING ELECTRON BEAMS. The Astrophysical Journal, 818(1), 61. DOI: 10.3847/0004-637X/818/1/61

• January 17, 2017
• 07:03 AM
• 272 views

Simultaneous near-Sun observations of a moving type IV radio burst and the associated white-light CME by K. Hariharan et al.*

Quasi-continuum radio emissions of duration ~10-60 min that occur along with flares and coronal mass ejections (CMEs) in the solar atmosphere are termed as type IV bursts. The bursts are non-thermal in nature and can be classified into two categories, i.e. moving type IV (type IVm) bursts and stationary type [...]... Read more »

• January 3, 2017
• 07:01 AM
• 292 views

Observation of quasi-periodic solar radio bursts associated with propagating fast-mode waves by C. R. Goddard et al.*

Flaring activity on the Sun triggers waves and oscillations in the solar corona. The study of these waves and oscillations allows comparisons to magnetohydrodynamic (MHD) theory and modelling to be made, and seismological inversions based on this comparison allow local plasma parameters to be measured indirectly (e.g. De Moortel & [...]... Read more »

• December 30, 2016
• 12:20 PM
• 312 views

Yang-Mills theory paper gets published!

Exact solutions of quantum field theories are very rare and, normally, refer to toy models and pathological cases. Quite recently, I put on arxiv a pair of papers presenting exact solutions both of the Higgs sector of the Standard Model and the Yang-Mills theory made just of gluons. The former appeared a few month ago […]... Read more »

Marco Frasca. (2015) A theorem on the Higgs sector of the Standard Model. Eur. Phys. J. Plus (2016) 131: 199. arXiv: 1504.02299v3

Marco Frasca. (2015) Quantum Yang-Mills field theory. arXiv. arXiv: 1509.05292v1

Carl M. Bender, Kimball A. Milton, & Van M. Savage. (1999) Solution of Schwinger-Dyson Equations for ${\cal PT}$-Symmetric Quantum Field Theory. Phys.Rev.D62:085001,2000. arXiv: hep-th/9907045v1

• December 27, 2016
• 02:04 PM
• 486 views

Why we have not met Aliens yet?

A huge of number of people keeps on thinking about the existence of some other intelligent beings in the universe but still we have not met any aliens. Why?

Earth is rare

Earth is special planet

One of the reasons that we have not met aliens is that Earth is rare and there is nothing just like Earth in the universe. In this regard, Paleontologist Peter Ward and astronomer Donald Brownlee presented the Rare Earth Hypothesis about 17 years ago.

According to the Rare Earth Hypothesis, t........ Read more »

Heller, R., & Armstrong, J. (2014) Superhabitable Worlds. Astrobiology, 14(1), 50-66. DOI: 10.1089/ast.2013.1088

• December 20, 2016
• 07:02 AM
• 373 views

Diagnosing the Source Region of a Solar Burst on 26 September 2011 by Using Microwave Type-III Pairs by Tan B. L. et al.*

Accelerated electron beams are believed to be responsible for both hard X-ray (HXR) and strong coherent radio emission during solar flares. However, so far the location of the electron acceleration and its physical parameters are poorly known. The solar microwave Type-III pair burst is possibly the most sensitive signature of [...]... Read more »

• December 13, 2016
• 08:23 AM
• 409 views

Acceleration of electrons in the solar wind by Langmuir waves produced by a decay cascade by Catherine Krafft and Alexander Volokitin

It was recently reported that a significant part of the Langmuir waveforms observed by the STEREO satellite (Graham and Cairns, 2013) during type III solar radio bursts are likely consistent with the occurrence of electrostatic decay instabilities, when a Langmuir wave $$\mathcal{L}$$ resonantly interacts with another Langmuir wave $$\mathcal{L}^{\prime}$$ and [...]... Read more »

• December 9, 2016
• 07:18 PM
• 411 views

The Most Interesting Stellar System Of All?

Researchers at the Carnegie Institution of Washington re-examined the Kepler data and determined that it had also been steadily dimming over the course of those four years, on top of its sporadic dips in brightness. For 1,000 days, the rate of dimming observed was constant; then, for 200 days after, its dimming rate suddenly increased by some order of magnitude; finally, for the remaining 200 days, its brightness had remained largely unchanged.... Read more »

Boyajian, T., LaCourse, D., Rappaport, S., & et al. (2016) Planet Hunters IX. KIC 8462852 – where's the flux?. Monthly Notices of the Royal Astronomical Society, 457(4), 3988-4004. DOI: 10.1093/mnras/stw218

Montet, B., & Simon, J. (2016) KIC 8462852 FADED THROUGHOUT THE MISSION . The Astrophysical Journal, 830(2). DOI: 10.3847/2041-8205/830/2/L39

• December 6, 2016
• 02:29 PM
• 437 views

Does non-ionizing radiation pose a health risk? Everyone knows that ionizing radiation, like gamma rays, can cause cancer by damaging DNA. But the scientific consensus is that there is no such risk from non-ionizing radiation such as radiowaves or Wi-Fi.

Yet according to a remarkable new paper from Magda Havas, the risk is real: it's called When theory and observation collide: Can non-ionizing radiation cause cancer?

• December 6, 2016
• 07:08 AM
• 333 views

Source regions of the type II radio burst observed during a CME–CME interaction on 2013 May 22 by P. Mäkelä et al.*

Occasionally the Sun ejects a pair of magnetized plasma clouds, called coronal mass ejections (CMEs), roughly into the same propagation direction in closely timed sequence. If the second CME is faster than the first one, the CMEs could either just slip through each other or they could collide and interact, [...]... Read more »

• November 29, 2016
• 07:02 AM
• 374 views

Simultaneous Submillimeter and Hard X-Ray Intermittent Processes during Flares by Guillermo Giménez de Castro et al.*

Intermittency is a disruptive characteristic of a process, which can be associated, in many cases, with a sudden energy release. Intermittency is a key characteristic of flares that should become evident in the flux time evolution at many different wavelengths. We investigate the similarities and differences of the intermittency during [...]... Read more »

• November 22, 2016
• 07:03 AM
• 401 views

Energetic electrons generated during solar flares by Gottfried Mann

The Sun is an active star. It manifests not only in everybody’s well-known Sun spots with the related 11-year cycle. This activity manifests not only as the well-known sun spot phenomenon with a related 11-year cycle, but also in flares, coronal mass ejections (CMEs), and solar energetic particle (SEP) events. Thus, [...]... Read more »

Gottfried Mann. (2016) Energetic electrons generated during solar flares. Journal of Plasma Physics. info:/

• November 15, 2016
• 07:05 AM
• 367 views

Solar Type III Radio Bursts: Directivity Characteristics by G. Thejappa and R. J. MacDowall

Type III radio bursts are a group of fast drifting radio emissions associated with solar flares [see also previous CESRA highlights on type III bursts here and here]. These radio emissions are believed to be excited at the fundamental and second harmonic of the electron plasma frequency, by the electron beam excited Langmuir waves [...]... Read more »

G. Thejappa and R. J. MacDowall. (2015) Solar Type III Radio Bursts: Directivity Characteristics . Journal of Physics: Conference Series. info:/

• November 1, 2016
• 09:01 AM
• 464 views

Multiwavelength study of 20 jets that emanate from the periphery of active regions by Sargam M. Mulay et al.*

Solar jets are transient phenomena observed in the solar atmosphere. They appear as sharp-edged, impulsive, and collimated flows of plasma that move outwards with a bright spot at the footpoint, which forms an ‘inverted-Y’ topology of magnetic field lines. They are observed throughout the atmosphere i.e. in the photosphere (Hα, Ca II K [...]... Read more »

Mulay et al. (2006) Multiwavelength study of 20 jets that emanate from the periphery of active regions. Astronomy . info:/

• October 18, 2016
• 09:02 AM
• 487 views

Decameter type III bursts with changing frequency drift-rate signs by V. Melnik et al.*

We discuss properties of type III bursts that change the sign of their drift rate from negative to positive and vice versa. Moreover, these bursts may change the sign of their drift rates more than once. These particular type III bursts were observed simultaneously by the radio telescopes UTR-2, URAN-2, [...]... Read more »

V. Melnik et al. (2015) Decameter type III bursts with changing frequency drift-rate signs . Solar Physics. info:/