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Posts Tagged ‘Sun’

Eastern U.S. To See Partial Solar Eclipse Nov. 3

October 31, 2013 1 comment

For people in the eastern United States, the sun will rise half covered by the moon on Sunday morning, November 3, and the partial eclipse will last about 3/4 of an hour. Jay Pasachoff, Field Memorial Professor of Astronomy at Williams College and chair of the International Astronomical Union’s Working Group on Eclipses, advises that people able to see very low on the eastern horizon and having suitable filters in hand would enjoy the event.

A total solar eclipse will sweep across Africa about two hours later on that Sunday, when it will be afternoon, six hours later, in west Africa. After starting in the Atlantic, the shadow of the moon will reach Gabon, where Pasachoff and colleagues will observe totality, with the support of a research grant from the Committee for Research and Exploration of the National Geographic Society.

Link To Full Story

Changes in Comet Rotation May Be Predicted With Greater Accuracy

September 6, 2013 Leave a comment

Credit: NASA / JPL-Calthech / UMD

Credit: NASA / JPL-Calthech / UMD

Planetary Science Institute researchers have discovered a way to predict the changes in the rotational states of comets that could help scientists learn more about the approaching Comet C/2012 S1 (ISON), which will pass by the Sun on Thanksgiving Day and has attracted worldwide interest because it may become sufficiently bright to be seen by the naked eye.

PSI Senior Scientists Nalin H. Samarasinha and Beatrice E.A. Mueller have determined such changes are a function of a comet’s size, period and solar energy it receives, but surprisingly not a function of the fraction of a comet’s surface that is active according to a paper published in the Astrophysical Journal Letters.

“You get more change if there is more solar energy and less change if it is spinning more rapidly to begin with or if it is a larger comet. Larger, rapidly rotating comets are not going to change their spin status very much,” Samarasinha said. “We expected that the fraction of the surface of the comet that is active would also be a controlling factor, but that proved not to be the case.”

Full Story: http://www.psi.edu/news/cometrotation.html

A&A Press Release – No Evidence Of Planetary Influence On Solar Activity

September 6, 2013 Leave a comment

Image Credit: Swedish Solar Telescope at the Roque de los Muchachos Observatory

Image Credit: Swedish Solar Telescope at the Roque de los Muchachos Observatory

In 2012, Astronomy & Astrophysics published a statistical study of the isotopic records of solar activity, in which Abreu et al. claimed that there is evidence of planetary influence on solar activity. A&A is publishing a new analysis of these isotopic data by Cameron and Schüssler. It corrects technical errors in the statistical tests performed by Abreu et al. They find no evidence of any planetary effect on solar activity.

The Sun is a magnetically active star. Its activity manifests itself as dark sunspots and bright faculae on its visible surface, as well as violent mass ejections and the acceleration of high-energy particles resulting from the release of magnetic energy in its outer atmosphere. The frequency with which these phenomena occur varies in a somewhat irregular activity cycle of about 11 years, during which the global magnetic field of the Sun reverses. The solar magnetic field and the activity cycle originate in a self-excited dynamo mechanism based upon convective flows and rotation in the outer third of the solar radius.

Systematic observations of sunspots since the beginning of the 17th century indicate that solar activity also varies on longer timescales, including periods of very low activity, such as the so-called Maunder minimum between 1640 and 1700.

Full Story: http://www.aanda.org/index.php?option=com_content&task=view&id=966&Itemid=277

Stanford Solar Scientists Solve One Of The Sun’s Mysteries

August 28, 2013 Leave a comment

Credit: NASA SDO / HMI

Credit: NASA SDO / HMI

Stanford solar scientists have solved one of the few remaining fundamental mysteries of how the sun works.

The mechanism, known as meridional flow, works something like a conveyor belt. Magnetic plasma migrates north to south on the sun’s surface, from the equator to the poles, and then cycles into the sun’s interior on its way back to the equator.

The rate and depth beneath the surface of the sun at which this process occurs is critical for predicting the sun’s magnetic and flare activity, but has remained largely unknown until now.

Full Story: http://news.stanford.edu/pr/2013/pr-solar-magnetic-field-082913.html

Oldest Solar Twin Identified

August 28, 2013 Leave a comment

Astronomers have only been observing the Sun with telescopes for 400 years — a tiny fraction of the Sun’s age of 4.6 billion years. It is very hard to study the history and future evolution of our star, but we can do this by hunting for rare stars that are almost exactly like our own, but at different stages of their lives. Now astronomers have identified a star that is essentially an identical twin to our Sun, but 4 billion years older — almost like seeing a real version of the twin paradox in action.

Jorge Melendez (Universidade de São Paulo, Brazil), the leader of the team and co-author of the new paper explains: “For decades, astronomers have been searching for solar twins in order to know our own life-giving Sun better. But very few have been found since the first one was discovered in 1997. We have now obtained superb-quality spectra from the VLT and can scrutinise solar twins with extreme precision, to answer the question of whether the Sun is special.”

Full Story: http://www.eso.org/public/news/eso1337/

CfA-Built Telescope On IRIS Sees First Light


Credit: NASA

Credit: NASA

NASA’s Interface Region Imaging Spectrograph (IRIS) observatory has produced its first images and spectra of a little understood region of the Sun through which the energy that supports the Sun’s hot corona is transported. IRIS was launched on June 27, 2013, and the front cover of the IRIS telescope was opened on July 17.

“Already, we’re finding that IRIS has the capability to reveal a very dynamic and highly structured chromosphere and transition region,” says astrophysicist Hui Tian of the Harvard-Smithsonian Center for Astrophysics (CfA). “Thin and elongated structures are clearly present in these first-light images, and they evolve quickly in time.”

Important goals of the IRIS mission are to understand how the Sun’s million degree corona is heated and to reveal the genesis of the solar wind.

Full Story: http://www.cfa.harvard.edu/news/2013/pr201321.html

Sun’s Loops Are Displaying An Optical Illusion


Credit: NASA/SDO

Credit: NASA/SDO

The Sun’s outer atmosphere, or corona, has posed an enduring mystery. Why is it so hot? The Sun’s visible surface is only 10,000 degrees Fahrenheit, but as you move outward the temperature shoots up to millions of degrees. It’s like a campfire that feels hotter the farther away you stand.

To understand how the corona is heated, some astronomers study coronal loops. These structures are shaped like an upside-down U and show where magnetic field lines are funneling solar gases or plasma.

Our best photos of the Sun suggest that these loops are a constant width, like strands of rope. However, new work shows that this is an optical illusion; the loops are actually tapered, wider at the top and narrower at the ends. This finding has important implications for coronal heating.

“You need less energy to heat the corona if the loops have a tapered geometry, which is exactly what we found,” says lead author Henry Winter of the Harvard-Smithsonian Center for Astrophysics (CfA).

Full Story: http://www.cfa.harvard.edu/news/2013/pr201318.html

Using The Sun To Illuminate A Basic Mystery Of Matter


While antiparticles can be created and then detected with costly and complex particle-accelerator experiments, such particles are otherwise very difficult to study. However, Fleishman and the two co-researchers have reported the first remote detection of relativistic antiparticles — positrons — produced in nuclear interactions of accelerated ions in solar flares through the analysis of readily available microwave and magnetic-field data obtained from solar-dedicated facilities and spacecraft. That such particles are created in solar flares is not a surprise, but this is the first time their immediate effects have been detected.

The results of this research have far-reaching implications for gaining valuable knowledge through remote detection of relativistic antiparticles at the Sun and, potentially, other astrophysical objects by means of radio-telescope observations. The ability to detect these antiparticles in an astrophysical source promises to enhance our understanding of the basic structure of matter and high-energy processes such as solar flares, which regularly have a widespread and disruptive terrestrial impact, but also offer a natural laboratory to address the most fundamental mysteries of the universe we live in.

Full Story: http://www.njit.edu/news/2013/2013-228.php

Solar Dynamic Loops Reveal A Simultaneous Explosion And Implosion, Plus Evidence For Magnetic Reconnection


Credit: NASA / SDO / University of Glasgow

Credit: NASA / SDO / University of Glasgow

Movies of giant loops projecting from the surface of the Sun are giving new insights into the complex mechanisms that drive solar flares and Coronal Mass Ejections (CMEs). These eruptions release vast energy and electrically charged particles that can affect the Earth through space weather. Imagery from NASA’s Solar Dynamics Observatory (SDO), used in two separate studies, shows the dynamics of loops before, during and after eruptions. Results have been presented at the National Astronomy Meeting in St Andrews.

Coronal loops are giant magnetic arches filled with hot plasma at temperatures of over a million degrees Celsius. The structures are anchored in the dense photosphere, the visible surface of the Sun. The loops form the building blocks of the corona, the halo surrounding the Sun that can be seen during a total eclipse. They are dynamic structures that oscillate back and forth after explosive events such as solar flares.

Researchers from the University of Glasgow observed four groups of loops that contracted rapidly during a flare on 9 March 2012. The loops had a ‘staggered start’ to their collapse, showing delays of 60–80 seconds from the inner to the outer loops.

“This event is a great example of a simultaneous implosion and explosion,” said Dr Paulo Simões. “Our interpretation is that energy is transferred from the magnetic field to power the flare, leaving a pocket of reduced magnetic support that causes an implosion. The staggering between the loop contractions is caused by the time delay needed for the ‘information’ about the loss of support to travel outwards.”

Full Story: http://www.ras.org.uk/news-and-press/224-news-2013/2313-solar-dynamic-loops-reveal-a-simultaneous-explosion-and-implosion-plus-evidence-for-magnetic-reconnection
Full Video: http://www.astro.gla.ac.uk/users/paulo/implosion.avi

Solar Prominences Put On Strange And Beautiful Show In The Sun’s Sky


Rotating disc in solar prominence. Credit: NASA / SDO / Li / Smith / Aberystwyth University

Rotating disc in solar prominence. Credit: NASA / SDO / Li / Smith / Aberystwyth University

Cloud spotting seems to be growing in popularity as a hobby here on Earth. Now scientists studying the solar atmosphere are building their own collection of fascinating moving features that they’ve spotted in the Sun’s sky. The unusual solar prominences include a giant disc that rotates for several hours, feathery streamers as long as fifty Earths, a super-heated jet striking the top of a prominence and twisted ribbons flowing in opposite directions at a million kilometres per hour.

The features were discovered by Dr Xing Li and PhD student, Jeff Smith, of Aberystwyth University using the Atmospheric Imaging Assembly (AIA) telescope on board the Solar Dynamics Observatory (SDO) satellite. The findings have been presented at the RAS National Astronomy Meeting in St Andrews.

Prominences are – relatively – cold gaseous features, with temperatures around 5000 degrees Celsius compared to the surrounding the hot solar atmosphere of about 1-2 million degrees. They can be seen as towering features extending outwards from the Sun’s surface, often in the shape of a loop. They are called filaments when viewed against the solar disc, appearing as dark stripes because the cold gases they contain absorb the light emitted from below. Solar prominences and filaments supply most of the material released in coronal mass ejections, vast eruptions from the Sun’s atmosphere that can cause space weather and create geomagnetic storms on Earth.

Full Story: http://www.ras.org.uk/news-and-press/224-news-2013/2315-solar-prominences-put-on-strange-and-beautiful-show-in-the-suns-sky