• May 9, 2017
• 07:07 AM
• 163 views

# Microwave emission as a proxy of CME speed in ICME forecasting by Carolina Salas Matamoros, Ludwig Klein and Gerard Trottet

Coronal Mass Ejections (CMEs) are one type of interplanetary structure that mostly affect the geomagnetic field (e.g. Gonzalez and Tsurutani, 1987; Zhang et al, 2007). These structures are observed and studied through coronagraphic images. The basic limitation of the coronagraph is that it shows the corona only in the plane of the sky, and blocks by necessity the view on the solar disk. Thus, the projection effect in the kinematic [...]... Read more »

• May 8, 2017
• 11:54 PM
• 138 views

# Quick Look: The Thermal Structure of the Venus Atmosphere

SummaryFor two years beginning in 2013, a large team led by Sanjay Limaye set out to combine and compare the following:Venusian atmospheric data collected by probes in the 1970s and 1980s (used to create the Venus International Reference Atmosphere, or VIRA)Venus Express data on the vertical and horizontal structure of the atmosphereEarth-based observations of the upper atmosphere temperature structure of Venus made since VIRAFigure 1a: Vertical coverage of post-VIRA atmospheric structure experi........ Read more »

• April 26, 2017
• 11:33 PM
• 55 views

# Recently Active Lava Flows on Idunn Mons

OverviewCombined VIRTIS emissivity and Magellan SAR image of Idunn MonsIn Idunn Mons on Venus: Location and extent of recently active lava flows, Piero D'Incecco and his colleagues looked closer at 1 µm thermal emissivity anomalies on the eastern flank of Idunn Mons, as observed by the VIRTIS instrument on Venus Express. Hypothesizing that recent lava flows were responsible, they overlayed the VIRTIS emissivity data with SAR images from the Magellan mission to look for lava flows that may have ........ Read more »

D'Incecco, P., Müller, N., Helbert, J., & D'Amore, M. (2017) Idunn Mons on Venus: Location and extent of recently active lava flows. Planetary and Space Science, 25-33. DOI: 10.1016/j.pss.2016.12.002

• April 25, 2017
• 07:02 AM
• 194 views

# The Brightness Temperature of the Quiet Solar Chromosphere at 2.6 mm by Kazumasa Iwai et al

The brightness temperature of the Sun constitutes a basic property of the solar atmosphere. The main emission mechanism of the Sun at millimeter and submillimeter wavelengths is thermal free–free emission from the chromosphere, which is an atmospheric layer with a temperature ranging between 6000 to 20,000 K. The opacity of thermal free–free emission depends on the temperature and density in the emission region. In addition, the Rayleigh– Jeans law is applicable [...]... Read more »

Iwai, K., Shimojo, M., Asayama, S., Minamidani, T., White, S., Bastian, T., & Saito, M. (2017) The Brightness Temperature of the Quiet Solar Chromosphere at 2.6 mm. Solar Physics, 292(1). DOI: 10.1007/s11207-016-1044-5

• April 21, 2017
• 12:02 PM
• 56 views

# Spectral Guide for Earth-based Observers to Complement Akatsuki Mission

OverviewMeant as a guide for Earth-based observers of Venus (professional and amateur), Overview of useful spectral regions for Venus: An update to encourage observations complementary to the Akatsuki mission provides detailed information regarding the wavelengths at which observations should be made to complement the Akatsuki mission at Venus.Two tables (one for day side observing, the other for night side) provide opportunities across a "spectrum" of wavelengths, indicating what products are l........ Read more »

• April 18, 2017
• 12:43 PM
• 50 views

# Bright highlands in equatorial Venus likely ferro-electric. What's up with the high-latitude highlands?

OverviewA lot of papers have been written about the highly reflective highlands (in radar) on Venus, with several different hypotheses (e.g. high porosity, metal frost).  Allan Treiman, Elise Harrington, and Virgil Sharpton look specifically at high-latitude highlands in comparison to highlands in the equatorial regions.  Both areas feature high reflectivity, but the reflectance patterns are distinct, as they describe in Venus' radar-bright highlands: Different signatures and mate........ Read more »

• April 17, 2017
• 12:20 AM
• 42 views

# Discovery of a 150 day period in the Venus condensational clouds

OverviewUsing near infrared (NIR) data from the VIRTIS instrument that once traveled aboard the Venus Express spacecraft, Kevin McGouldrick and Constantine C. C. Tsang found a periodic variation in radiance, most intense at the mid-latitudes.  The paper is here.What Did They Find?They identified A 150-day periodic variation in radiance within the 1.74 µm and 2.30 µm windows, which is most pronounced between 30° and 60° latitude.  They also found that in these mid-latitudes, ra........ Read more »

• April 11, 2017
• 09:00 AM
• 324 views

# Looking for clues for past life on Mars

NASA's Curiosity Mars. Credits: NASA/JPL-Caltech/MSSSOn August 6, 2012, the NASA Curiosity rover landed on Mars at the base of Mount Sharp, a mountain the size of Kilimanjaro (~19,000 feet) in the middle of Gale Crater. Nina Lanza, space scientist at the Los Alamos National Laboratory, remembers the day well. As part of the team that built ChemCam, one of the ten instruments on the rover, she spent three months at the Jet Propulsion Laboratory in California, living on “Mars time” to fol........ Read more »

Ricardo, A. (2004) Borate Minerals Stabilize Ribose. Science, 303(5655), 196-196. DOI: 10.1126/science.1092464

Stephenson, J., Hallis, L., Nagashima, K., & Freeland, S. (2013) Boron Enrichment in Martian Clay. PLoS ONE, 8(6). DOI: 10.1371/journal.pone.0064624

• April 11, 2017
• 06:34 AM
• 283 views

# How Electron Beams Produce Continuous Coherent Plasma Emission by H. Che, M. Goldstein, P. Diamond, and R. Sagdeev

It is commonly accepted that energetic electron beams can produce drift frequency radio emission or Type III bursts since Ginzburg and Zhelezniakov first proposed the idea in 1958. However, the electron two-stream instability time (see reference 2) in the corona is fraction of a second, while the duration of coronal Type III bursts lasts several orders of magnitude longer. This problem is called the “Sturrock Dilemma” and remains a subject [...]... Read more »

• March 28, 2017
• 08:04 AM
• 248 views

# Radio Diagnostics of Electron Acceleration Sites During the Eruption of a Flux Rope in the Solar Corona by Eoin Carley et al.*

Flares and coronal mass ejections (CMEs) are thought to result from magnetic energy release in the solar corona, often involving the destabilisation of a twisted magnetic structure known as a flux rope (Chen et al. 2011, Webb et al. 2012). This activity may be accompanied by the acceleration of electrons (Kahler 2007, Lin et al. 2011). However, there is ongoing debate on exactly where, when and how this particle acceleration occurs [...]... Read more »

• March 14, 2017
• 08:05 AM
• 316 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
• 263 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 14, 2017
• 07:02 AM
• 422 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
• 626 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
• 423 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
• 442 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 27, 2016
• 02:04 PM
• 674 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
• 505 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
• 542 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
• 535 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