dna.org.es

Una espectacular imagen del Sol muestra cambios en su corona que pueden ser peligrosos para nuestro planeta

Desde hace unos meses, los científicos vienen advirtiendo de que el Sol ha despertado de un largo letargo y de que se prepara para una fase de intensa actividad jamás conocida hasta la fecha. Estos movimientos solares provocan explosiones que, si llegan al suficiente grado de violencia, pueden dejar frita nuestra red eléctrica y desbaratar los sistemas de comunicaciones y de navegación por satélite. Ya se han registrado algunas de estas erupciones con una fuerza inusitada, aunque sólo han sido una advertencia. Ahora, una nueva e impresionante imagen del astro rey obtenida por la sonda de la NASA denominada Observatorio de Dinámica Solar (SDO, por siglas en inglés), muestra algo muy poco tranquilizador, un agujero en la corona solar, una zona donde el campo magnético se abre y permite que el viento solar se escape. Este agujero está girando hacia la Tierra, lo que podría producir una tormenta geomagnética que llegue a afectarnos.

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NASA’s Solar Dynamics Observatory (SDO), launched in February of 2010, has started to send back data. The instruments are giving solar scientists an unprecedented look at the sun, says Dean Pesnell, SDO project scientist. The hope is to better understand how solar activity–solar flares, coronal mass ejections, coronal holes–is linked to the sun’s magnetic field.

Thank you www.sciencefriday.com

48 Hour MPEGs

Tue, 24 Aug 2010

The latest 48 hour mpegs have been released on the website. They are available for all 10 AIA channels.

• Latest AIA 094
• Latest AIA 131
• Latest AIA 171
• Latest AIA 193
• Latest AIA 211
• Latest AIA 304
• Latest AIA 335
• Latest AIA 1600
• Latest AIA 1700
• Latest AIA 4500

Esta nueva imagen del Sol fue obtenida el pasado 20 de agosto mediante un instrumento para obtener imágenes heliosísmicas magnéticas (HMI) con el que está equipado la sonda SDO. Las líneas de campo magnético están codificadas por colores: las blancas muestran los campos magnéticos que están cerrados -es decir, que no sueltan viento solar- y las líneas doradas los campos abiertos, aquellos que sí lo dejan escapar. Para los científicos, la comprensión de este mecanismo resulta muy importante, ya que creen que las tormentas solares están provocadas por los cambios en la estructura y las conexiones de estos campos.
Los agujeros de la corona son vastas regiones menos densas y más frías que las áreas que las rodean. El agujero permite un flujo constante de alta densidad del plasma y se provoca un aumento en la intensidad de los efectos del viento solar en la Tierra cuando un agujero de este tipo de enfrenta a nuestro planeta.

www.abc.es

NASA STEREO – August 14-15, 2010; Popping Out All Over

As the STEREO (Behind) spacecraft observed in extreme UV light, the Sun popped off no fewer than six eruptions over just two days (Aug. 14-15, 2010). At one point, three were occurring events at the same time. Most these were eruptive prominences in which cooler clouds of gases above the surface break away from the Sun. The most powerful of these events, a coronal mass ejection, began around 6:30 UT on Aug. 15. It was harder to see from this spacecraft’s angle since it blasted out from the whiter active region in the lower center, so it had the Sun as its backdrop.

http://sdo.gsfc.nasa.gov/

http://hmi.stanford.edu/

Como viene siendo habitual aprovechamos el post para dar un repaso a las ultimas noticias y videos de los diferentes eventos y misiones de las agencias espaciales internacionales. NASA, ESA, JAXA….etc

Astronomers working with the super planet finding HARPS instrument at the La Silla Observatory in Chile, have discovered a remarkable extrasolar planetary system that has some striking similarities to our own Solar System. At least five planets are orbiting the Sun-like star HD 10180, and the regular pattern of their orbits is similar to that observed for our neighbouring planets. One of the new extrasolar worlds could be only 1.4 times the mass of the Earth, making it the least massive exoplanet ever found.

Astronomers using ESO’s world-leading HARPS instrument have discovered a planetary system containing at least five planets, orbiting the Sun-like star HD 10180. The researchers also believe the system has two other planets, one of which would have the lowest mass ever found, making the system similar to our own Solar System in terms of the number of planets. Furthermore, the scientists find that the location of the planets follows a regular pattern, as also seen in our own Solar System

The team of astronomers used the HARPS spectrograph, attached to ESO’s 3.6-metre telescope at La Silla, Chile. HARPS is an instrument with unrivalled stability and great precision, and the world’s most successful exoplanet hunter. The astronomers, led by Christophe Lovis from the Geneva Observatory, studied the Sun-like star HD 10180 over a period of six years! This star is located 127 light-years away in the southern constellation Hydrus (“the Male Water Snake”).

Thanks to the 190 individual HARPS measurements, the astronomers detected the wobbles of the star caused by five or more planets. The five strongest signals correspond to planets with Neptune-like masses — between 13 and 25 Earth masses — which orbit the star in between 6 to 600 days. The astronomers have also strong reason to believe that two other planets are present. One would be a Saturn-like planet orbiting in 2200 days. The other, having a mass of only about 1.4 times that of the Earth would be the least massive exoplanet ever discovered. This suspected planet is very close to its host star and so it is likely to be very hot. One ‘year’ on this planet lasts only 1.18 Earth-days!

The newly discovered Solar System is unique in several respects. First of all, with at least five Neptune-like planets lying within a distance equivalent to the orbit of Mars, this system is more populated than our own Solar System in its inner region, and has many more massive planets there. Furthermore, the system probably has no Jupiter-like gas giant. In addition, all the planets seem to have almost circular orbits. Dynamical studies of the new system reveal complex interactions between planets and give us insights into its long-term evolution.

Using the new discovery as well as data for other planetary systems, the astronomers discovered that the locations of the planets seem to follow a regular pattern — similar to the “Titius-Bode” law that exists in our Solar System. This could be a general signature of how planetary systems form. Another important result is that all very massive planetary systems are found around massive and metal-rich stars, while the four lowest-mass systems are found around lower-mass and metal-poor stars. These properties confirm current theoretical models.

There is no doubt that this remarkable discovery highlights the fact that we are now entering a new era in exoplanet science: the study of complex planetary systems and not just of individual planets!!
And with HARPS, European astronomers will be a driving force behind this transition.

ESOcast is produced by ESO, the European Southern Observatory. ESO, the European Southern Observatory, is the pre-eminent intergovernmental science and technology organisation in astronomy designing, constructing and operating the world’s most advanced ground-based telescopes.

• http://www.eso.org/
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CH Cyg

‘Deep within this optical image lies an intriguing system known as CH Cyg. CH Cyg is a binary star system containing a white dwarf that feeds from the wind of a red giant star.’

http://chandra.harvard.edu/resources/podcasts/

Global Warming Reduces Plant Productivity

The past decade is the warmest on record since instrumental measurements began in the 1880s. Previous research suggested that in the ’80s and ’90s, warmer global temperatures and higher levels of precipitation – factors associated with climate change – were generally good for plant productivity. An updated analysis published this week in Science indicates that as temperatures have continued to rise, the benefits to plants are now overwhelmed by longer and more frequent droughts. High-resolution data from the Moderate Resolution Imaging Spectroradiometer, or MODIS, indicate a net decrease in NPP from 2000-2009, as compared to the previous two decades.

NASA: Climate Change – Plant Productivity in a Warming World

Earth has done an ecological about-face: Global plant productivity that once flourished under warming temperatures and a lengthened growing season is now on the decline, struck by the stress of drought.

NASA-funded researchers Maosheng Zhao and Steven Running, of the University of Montana in Missoula, discovered the global shift during an analysis of NASA satellite data. Compared with a six-percent increase spanning two earlier decades, the recent ten-year decline is slight — just one percent. The shift, however, could impact food security, biofuels, and the global carbon cycle.

“We see this as a bit of a surprise, and potentially significant on a policy level because previous interpretations suggested that global warming might actually help plant growth around the world,” Running said.

“These results are extraordinarily significant because they show that the global net effect of climatic warming on the productivity of terrestrial vegetation need not be positive — as was documented for the 1980′s and 1990′s,” said Diane Wickland, of NASA Headquarters and manager of NASA’s Terrestrial Ecology research program.

Conventional wisdom based on previous research held that land plant productivity was on the rise. A 2003 paper in Science led by then University of Montana scientist Ramakrishna Nemani (now at NASA Ames Research Center, Moffett Field, Calif.) showed that global terrestrial plant productivity increased as much as six percent between 1982 and 1999. That’s because for nearly two decades, temperature, solar radiation and water availability — influenced by climate change — were favorable for growth.

Setting out to update that analysis, Zhao and Running expected to see similar results as global average temperatures have continued to climb. Instead, they found that the impact of regional drought overwhelmed the positive influence of a longer growing season, driving down global plant productivity between 2000 and 2009. The team published their findings Aug. 20 in Science.

“This is a pretty serious warning that warmer temperatures are not going to endlessly improve plant growth,” Running said.

The discovery comes from an analysis of plant productivity data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite, combined with growing season climate variables including temperature, solar radiation and water. The plant and climate data are factored into an algorithm that describes constraints on plant growth at different geographical locations.

For example, growth is generally limited in high latitudes by temperature and in deserts by water. But regional limitations can very in their degree of impact on growth throughout the growing season.

Zhao and Running’s analysis showed that since 2000, high-latitude northern hemisphere ecosystems have continued to benefit from warmer temperatures and a longer growing season. But that effect was offset by warming-associated drought that limited growth in the southern hemisphere, resulting in a net global loss of land productivity.

“This past decade’s net decline in terrestrial productivity illustrates that a complex interplay between temperature, rainfall, cloudiness, and carbon dioxide, probably in combination with other factors such as nutrients and land management, will determine future patterns and trends in productivity,” Wickland said.

“Even if the declining trend of the past decade does not continue, managing forests and croplands for multiple benefits to include food production, biofuel harvest, and carbon storage may become exceedingly challenging in light of the possible impacts of such decadal-scale changes,” Wickland said.

http://www.nasa.gov/centers/goddard/home/index.html
http://eospso.gsfc.nasa.gov/newsroom/viewStory.php?id=1657

http://svs.gsfc.nasa.gov/vis/iTunes/f0004_index.html

‘The past decade is the warmest on record since instrumental measurements began in the 1880s. Previous research suggested that in the ’80s and ’90s, warmer global temperatures and higher levels of precipitation factors associated with climate change – were generally good for plant productivity. An updated analysis published this week in Science indicates that as temperatures have continued to rise, the benefits to plants are now overwhelmed by longer and more frequent droughts. High-resolution satellite data indicates a net decrease in plant productivity from 2000-2009, as compared to the previous two decades.’