Archive for February 21st, 2013

21 February

Understanding Our Powerful Sun & Its CME (Coronal Mass Ejection)

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Dear Friends, Visitors/Viewers/Readers,

(Please click on red links below)

As a result of posting The Unexpected Atmospheric Intruder on Feb. 16, 2013, I’ve received multiple  questions/concerns expressed by our viewers toward the space and our Sun.  Therefore, I’ve prepared this particular session on “Understanding Our Powerful Sun & Its CME(coronal mass ejection)” for your viewing pleasure, to further our appreciation of our Sun, and to kindle our curiosity and wonder for exploration into the space.  With the help from NASA Heliophysics (meaning Physics of the Sun),  I’d like to present to you this composite of 2 footage about the Sun, the star at the center of our Solar System, and its CME (coronal mass ejection), the massive burst of solar wind and magnetic fields rising above the solar corona or being released into space.  Be sure to stay long enough to also view the activities of CME.

 

Can you feel the light and intense warmth projected from the screen…from this giant active star ?

Our Sun, with a diamter-1,392,684 km (109 x that of Earth) (NASA)

While the origin and sustenance of life here on Earth are intimately connected to this active star of over 4.6 billion years, our fate in the next 4+ billion years will depend much on our ability to understand and predict Sun’s variability in producing streams of high energy particles and radiation that can help/harm life on Earth or alter its evolution.  Better understanding of the connections between the Sun, solar wind, planetary space environments, and our place in the Galaxy would enable us to uncover the fundamental physical processes occurring throughout the Universe and allow us to predict the impacts of solar variability on humans, our technological systems, and the presence of life here on Earth. Since heliophysics is simply too vast a field to cover in one post, we will be concentrating in some basic understanding of the Sun and its coronal mass ejection (CME) in this one.

The almost perfectly spherical Sun consists of hot plasma

Sun’s plasma  trapped by magnetic fields shows up as thin lines in extreme UV light (NASA)

interwoven with magnetic fields,

with a diameter of about 1,392,684 km (about 109 x that of earth) and a mass about 2 x 10^30 kilograms (about 330,000 x that of earth). It accounts for almost 99.86% of the total mass of the Solar System.  Chemically, about three quarters of the Sun’s mass consists of hydrogen while the rest is mostly helium…and the remainder (about 1.69%) consists of heavier elements such as oxygencarbonneoniron, etc.  The Sun formed from the gravitational collapse of a region within a large molecular cloud. Most of the matter gathered in the center, while the rest flattened into an orbiting disk that would become the Solar System. The central mass became increasingly hot and dense, eventually initiating thermonuclear fusion in its core. It is thought that almost all other stars form by this process. The Sun’s stellar classification, based on spectral class, is G2V, and is informally designated as a yellow dwarf, because its visible radiation is most intense in the yellow-green portion of the spectrum and although its color is white, from the surface of the Earth it may appear yellow because of atmospheric scattering of blue light. In the spectral class label, G2 indicates its surface temperature of approximately 5778 K (5505 °C), and V indicates that the Sun, like most stars, is a main-sequence star, and thus generates its energy by nuclear fusion of hydrogen nuclei into helium. In its core, the Sun fuses 620 million metric tons of hydrogen each second.  The Sun (the star closest to Earth, approximately 149.6 million kilometers away or the distance that light travels in 8 minutes and 19 seconds) is brighter than about 85% of the stars in the Milky Way galaxy.

The Milky Way

Star Formatioin

Its hot corona continuously expands in space, creating the solar wind,  a stream of charged particles that extends to the heliopause at roughly 100 astronomical units. (Source: wikipedia)

Coronal mass ejections (CMEs) release huge quantities of matter and  electromagnetic radiation into space above the sun’s surface, either near the corona (sometimes called a solar prominence), or farther into the planet system, or beyond (interplanetary CME).

Sun’s CME (interplanetary)

The ejected material is a plasma consisting primarily of electrons and protons, but may contain small quantities of heavier elements such as helium, oxygen, and even iron. The theory of heavier element emissions during a CME is speculative information and requires further verification. It is highly unlikely that a CME contains any substantial amount of heavier elements, especially considering that the sun has not yet arrived at the point of helium flash and thus cannot begin to fuse elements heavier than helium. Coronal mass ejections are associated with enormous changes and disturbances in the coronal magnetic field. They are usually observed with a white-light coronagraph. Recent scientific research has shown that the phenomenon of magnetic reconnection is responsible for CME and solar flares. Magnetic reconnection is the name given to the rearrangement of magnetic field lines when two oppositely directed magnetic fields are brought together. This rearrangement is accompanied with a sudden release of energy stored in the original oppositely directed fields. Most ejections originate from active regions on the Sun’s surface, such as groupings of sunspots associated with frequent flares. Near solar maxima the Sun produces about three CMEs every day, whereas near solar minima there is about one CME every five days.

As magnetic fields of the sun rearrange and realign, sunspots can appear on its surface. From Feb.19-20, 2013, scientists watched a giant sunspot form in under 48 hours. The sunspot shown in this image from the SDO (Solar Dynamics Observatory) has grown to over six Earth diameters across, but its full extent is hard to judge since the spot lies on a sphere not a flat disk. (NASA)

NASA-Another CME from Sunspot, via coronograph spectrometers

 

 

 

 

 

 

 

 

On the sun, magnetic reconnection may happen on solar arcades—a series of closely occurring ropes of magnetic lines of force. These lines of force quickly reconnect into a low arcade of ropes,

Sun’s CME flux ropes

Sun’s CME flux ropes in figure 8

leaving a helix of magnetic field unconnected to the rest of the arcade. The sudden release of energy in this reconnection causes the solar flare. The unconnected magnetic helical field and the material that it contains may violently expand outwards forming a CME.This also explains why CMEs and solar flares typically erupt from what are known as the active regions on the sun where magnetic fields are much stronger on average.

Sun’s CME flux ropes seen from different angles

NASA SDO (Solar Dynamics Observatory) telescope (NASA)

 

 

 

 

 

 

 

 

I hope you enjoyed viewing/reading this piece as much as I had in researching and composing this piece.

~have a bright and sunny day~

Gathered, written, and posted by sunisthefuture-Susan Sun Nunamaker

Any of your comments/suggestions/questions are welcomed at sunisthefuture@gmail.com

Homepage:  http://www.sunisthefuture.net


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