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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

NASA Spacecraft Revealing More Details About Planet Mercury

September 29, 2011 Leave a comment

Credit: Courtesy of Science/AAAS

Credit: Courtesy of Science/AAAS

After only six months in orbit around Mercury, NASA’s MESSENGER spacecraft is sending back information that has revolutionized the way scientists think about the innermost planet. Analyses of new data from the spacecraft show, among other things, new evidence that flood volcanism has been widespread on Mercury, the first close-up views of Mercury’s “hollows,” the first direct measurements of the chemical composition of Mercury’s surface, and the first global inventory of plasma ions within Mercury’s space environment.

The results are reported in a set of seven papers published in a special section of Science magazine on September 30, 2011.

“MESSENGER’s instruments are capturing data that can be obtained only from orbit,” says MESSENGER Principal Investigator Sean Solomon, of the Carnegie Institution of Washington. “We have imaged many areas of the surface at unprecedented resolution, we have viewed the polar regions clearly for the first time, we have built up global coverage with our images and other data sets, we are mapping the elemental composition of Mercury’s surface, we are conducting a continuous inventory of the planet’s neutral and ionized exosphere, and we are sorting out the geometry of Mercury’s magnetic field and magnetosphere. And we’ve only just begun. Mercury has many more surprises in store for us as our mission progresses.”

Full Story: http://www.nasa.gov/mission_pages/messenger/media/Telecon20110929.html

NASA Gives Public New Internet Tool To Explore The Solar System

September 5, 2011 Leave a comment

NASA is giving the public the power to journey through the solar system using a new interactive Web-based tool.

The “Eyes on the Solar System” interface combines video game technology and NASA data to create an environment for users to ride along with agency spacecraft and explore the cosmos. Screen graphics and information such as planet locations and spacecraft maneuvers use actual space mission data.

Full Story: http://www.nasa.gov/home/hqnews/2011/sep/HQ_11-288_System_Eyes.html

A Planet Made of Diamond

August 25, 2011 Leave a comment

An artist's visualisation of the pulsar and its orbiting planet. Image credit – Swinburne Astronomy Productions

An artist's visualisation of the pulsar and its orbiting planet. Image credit – Swinburne Astronomy Productions

A once-massive star that’s been transformed into a small planet made of diamond: that’s what astronomers think they’ve found in our Milky Way.

The discovery has been made by an international research team, led by Professor Matthew Bailes of Swinburne University of Technology in Melbourne, Australia, and is reported in today’s [Thursday August 25, 2011] issue of the journal Science.

Although bizarre, the “diamond planet” is in accord with our current picture of how certain binary star systems form.

The researchers, from Australia, Germany, Italy, the UK and the USA first detected an unusual star called a pulsar using the 64-m Parkes radio telescope of the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) and followed up their discovery with the Lovell radio telescope in the UK and one of the Keck telescopes in Hawaii.

Pulsars are small spinning stars about 20 km in diameter — the size of a small city — that emit a beam of radio waves. As the star spins and the radio beam sweeps repeatedly over Earth, radio telescopes detect a regular pattern of radio pulses.

For the newly discovered pulsar, known as PSR J1719-1438, the astronomers noticed that the arrival times of the pulses were systematically modulated. They concluded that this was due to the gravitational pull of a small companion planet, orbiting the pulsar in a binary system.

The pulsar and its planet are part of the Milky Way’s plane of stars and lie 4,000 light-years away in the constellation of Serpens (the Snake). The system is about an eighth of the way towards the galactic center from the Earth.

The modulations in the radio pulses tell astronomers several things about the planet.

First, it orbits the pulsar in just two hours and ten minutes, and the distance between the two objects is 600,000 km — a little less than the radius of our Sun.

Second, the companion must be small, less than 60,000 km (that’s about five times the Earth’s diameter). The planet is so close to the pulsar that, if it were any bigger, it would be ripped apart by the pulsar’s gravity.

But despite its small size, the planet has slightly more mass than Jupiter.

“This high density of the planet provides a clue to its origin”, said Professor Bailes.

A Star Is Torn

The team thinks that the “diamond planet” is all that remains of aonce-massive star, most of whose matter was siphoned off towards the pulsar.

Pulsar J1719-1438 is a very fast-spinning pulsar — what’s called a millisecond pulsar. Amazingly, it rotates more than 10,000 times per minute, and has a mass of about 1.4 times that of our Sun, but is only 20 km in diameter. About 70 per cent of millisecond pulsars have companions of some kind. Astronomers think it is the companion that, in its star form, transforms an old, dead pulsar into a millisecond pulsar by transferring matter and spinning it up to a very high speed. The result is a fast-spinning millisecond pulsar with a shrunken companion — most often a so-called white dwarf.

“We know of a few other systems, called ultra-compact low-mass X-ray binaries, that are likely to be evolving according to the scenario above and may likely represent the progenitors of a pulsar like J1719-1438,” said team member Dr. Andrea Possenti, Director at INAF-Osservatorio Astronomico di Cagliari.

But pulsar J1719-1438 and its companion are so close together that the companion can only be a very stripped-down white dwarf, one that has lost its outer layers and over 99.9 per cent of its original mass.

“This remnant is likely to be largely carbon and oxygen, because a star made of lighter elements like hydrogen and helium would be too big to fit the measured orbit,” said Dr. Michael Keith (CSIRO), one of the research team members.

The density means that this material is certain to be crystalline: that is, a large part of the star may be similar to a diamond.

“The ultimate fate of the binary is determined by the mass and orbital period of the donor star at the time of mass transfer. The rarity of millisecond pulsars with planet-mass companions means that producing such exotic planets is the exception rather than the rule, and requires special circumstances,” said Dr. Benjamin Stappers from the University of Manchester.

The team found pulsar J1719-1438 among almost 200,000 gigabytes of data using special codes on supercomputers at Swinburne University of Technology in Australia, The University of Manchester in the UK, and the INAF-Osservatorio Astronomico di Cagliari, Italy.

The discovery was made during a systematic search for pulsars over the whole sky that also involves the 100 meter Effelsberg radio telescope of the Max-Planck-Institute for Radio Astronomy (MPIfR) in Germany. “This is the largest and most sensitive survey of this type ever conducted. We expected to find exciting things, and it is great to see it happening. There is more to come!,” said Professor Michael Kramer, Director at the MPIfR.

Professor Matthew Bailes leads the “Dynamic Universe” theme in a new wide-field astronomy initiative in Australia, the Centre of Excellence for All-sky Astrophysics (CAASTRO).

The discovery of the new binary system is of special significance for him and fellow team member Professor Andrew Lyne, who jointly ignited the whole pulsar-planet field in 1991 with what proved to an erroneous claim of the first extra-solar planet. The next year though the first extra-solar planetary system was discovered around the pulsar PSR B1257+12.

More info: http://www.scienceimage.csiro.au/mediarelease/mr11-diamond.html

Astronomers Find Ice and Possibly Methane on Snow White, a Distant Dwarf Planet

August 22, 2011 Leave a comment

An artist's conception of 2007 OR10, nicknamed Snow White. Astronomers suspect that its rosy color is due to the presence of irradiated methane. Credit: NASA

An artist's conception of 2007 OR10, nicknamed Snow White. Astronomers suspect that its rosy color is due to the presence of irradiated methane. Credit: NASA

Astronomers at the California Institute of Technology (Caltech) have discovered that the dwarf planet 2007 OR10—nicknamed Snow White—is an icy world, with about half its surface covered in water ice that once flowed from ancient, slush-spewing volcanoes. The new findings also suggest that the red-tinged dwarf planet may be covered in a thin layer of methane, the remnants of an atmosphere that’s slowly being lost into space.

Full Story: http://news.caltech.edu/press_releases/13445