Planets and their sun grow together

Some 450 light-years from Earth, embryonic planets may be feeding tendrils of gas to the newborn star they orbit. The discovery helps explain how a young star can grow even as budding planets suck up much of the gas and dust around it. Without the tendrils replenishing it, the star’s supply of gas would disappear in less than a year.

 

Jupiter and Saturn may have done something similar for the sun in its early days, 4.5 billion years ago. “This is one of the nearest examples of the birth of a solar system,” says Simon Casassus, an astronomer at the University of Chile. He and his colleagues describe the finding online January 2 in Nature.

The star in question is named HD 142527, in the southern constellation Lupus. It’s about twice the mass of the sun but far younger, only about 2 million years old. Astronomers knew it was surrounded by a swirling disk of gas and dust, which has a big clearing in it from about 10 times to 140 times the Earth-sun distance. They think a big budding planet — something like Jupiter in its very early days — might orbit its star at about 90 times the Earth-sun distance, clearing out a gap like a snowplow shoveling roads.

Casassus’ team looked at this gap using the ALMA array of radio telescopes in Chile, which can detect faint emissions from gases such as carbon monoxide. The team found some of this gas drifting through the gap — probably leftover stuff that the protoplanet hadn’t cleared away, Casassus says.

More intriguingly, denser gas formed several filaments stretching across the gap. These streamers are almost certainly guided and shaped by protoplanets embedded within them, Casassus says.

The filaments are faint, says University of Hawaii astronomer Jonathan Williams, but “my gut reaction is that their interpretation is probably correct and that this is an exciting result.”

Simulations of how the gas might flow suggest not one but at least two big protoplanets surround the star. One, of around 10 Jupiter masses, probably orbits at the expected 90 times the Earth-sun distance. A second, of around 4 Jupiter masses, may orbit closer in, at around 40 times the Earth-sun distance. “At this point, we can’t tell how many objects orbit the star,” cautions Sally Dodson-Robinson, an astronomer at the University of Texas at Austin.

Astronomers haven’t yet directly spotted any protoplanets around HD 142527, but they keep looking. The Nature paper relies on one hour’s worth of observations from ALMA; Casassus has six more hours of data that should be arriving on his desk within the next few weeks. “There’s lots more to come,” he says.

Science News Magazine

M.W

 

Climate Warming Unlikely to Cause Near-Term Extinction of Ancient Amazon Trees

The authors of a new study warn that extreme drought and forest fires will impact Amazonia as temperatures rise, and the over-exploitation of the region's resources continues to be a major threat to its future. Conservation policy for the Amazon should remain focused on reducing global greenhouse-gas emissions and preventing deforestation, they said.

The study by University of Michigan evolutionary biologist Christopher Dick and his colleagues demonstrates the surprising age of some Amazonian tree species -- more than 8 million years -- and thereby shows that they have survived previous periods as warm as many of the global warming scenarios forecast for the year 2100.

The paper is scheduled for online publication Dec. 13 in the journal Ecology and Evolution. The new study is at odds with earlier papers, based on ecological niche-modeling scenarios, which predicted tree species extinctions in response to relatively small increases in global average air temperatures.

"Our paper provides evidence that common Amazon tree species endured climates warmer than the present, implying that -- in the absence of other major environmental changes -- they could tolerate near-term future warming under climate change," said Dick, an associate professor of ecology and evolutionary biology and acting director of the U-M Herbarium.

But study co-author Simon Lewis of University College London and the University of Leeds cautioned that "the past cannot be compared directly with the future."

"While tree species seem likely to tolerate higher air temperatures than today, the Amazon forest is being converted for agriculture and mining, and what remains is being degraded by logging and increasingly fragmented by fields and roads," Lewis said. "Species will not move as freely in today's Amazon as they did in previous warm periods, when there was no human influence. Similarly, today's climate change is extremely fast, making comparisons with the past difficult.

"With a clearer understanding of the relative risks to the Amazon forest, we conclude that direct human impacts, such as forest clearance for agriculture or mining, should remain a focus of conservation policy," Lewis said. "We also need more aggressive action to reduce greenhouse gas emissions in order to minimize the risk of drought and fire impacts to secure the future of most Amazon tree species."

Dick and his colleagues used a molecular clock approach to determine the ages of 12 widespread Amazon tree species, including the kapok and the balsa. Then they looked at climatic events that have occurred since those tree species emerged. In general, they inferred that the older the age of the tree species, the warmer the climate it has previously survived.

The researchers determined that nine of the tree species have been around for at least 2.6 million years, seven have been present for at least 5.6 million years, and three have existed in the Amazon for more than 8 million years.

"These are surprisingly old ages," Dick said. "Previous studies have suggested that a majority of Amazon tree species may have originated during the Quaternary Period, from 2.6 million years ago to the present."

The 12 tree species used in the study are broadly representative of the Amazon tree flora. Primary forest collection sites were in central Panama, western Ecuador and Amazonian Ecuador. Additional collections were made in Brazil, Peru, French Guiana and Bolivia. Other plant samples were obtained from herbarium specimens.

 

Science Daily

M.W

Physicist Calculates Field Strengths in the Early Universe

Magnets have practically become everyday objects. Earlier on, however, the universe consisted only of nonmagnetic elements and particles. Just how the magnetic forces came into existence has been researched by Prof. Dr. Reinhard Schlickeiser at the Institute of Theoretical Physics of the Ruhr-Universität Bochum. In the journal Physical Review Letters, he describes a new mechanism for the magnetisation of the universe even before the emergence of the first stars.

No permanent magnets in the early universe

Before the formation of the first stars, the luminous matter consisted only of a fully ionised gas of protons, electrons, helium nuclei and lithium nuclei which were produced during the Big Bang. "All higher metals, for example, magnetic iron could, according to today's conception, only be formed in the inside of stars," says Reinhard Schlickeiser. "In early times therefore, there were no permanent magnets in the Universe." The parameters that describe the state of a gas are, however, not constant. Density and pressure, as well as electric and magnetic fields fluctuate around certain mean values. As a result of this fluctuation, at certain points in the plasma weak magnetic fields formed -- so-called random fields. How strong these fields are in a fully ionised plasma of protons and electrons, has now been calculated by Prof. Schlickeiser, specifically for the gas densities and temperatures that occurred in the plasmas of the early universe.

Weak magnetic fields with large volumes

The result: the magnetic fields fluctuate depending on their position in the plasma, however, regardless of time -- unlike, for example, electromagnetic waves such as light waves, which fluctuate over time. Everywhere in the luminous gas of the early universe there was a magnetic field with a strength of 10^-20 Tesla, i.e. 10 sextillionth of a Tesla. By comparison, the earth's magnetic field has a strength of 30 millionths of a Tesla. In MRI scanners, field strengths of three Tesla are now usual. The magnetic field in the plasma of the early universe was thus very weak, but it covered almost 100 percent of the plasma volume.

Interaction of thermal shock waves and magnetic fields

Stellar winds or supernova explosions of the first massive stars generated shock waves that compressed the magnetic random fields in certain areas. In this way, the fields were strengthened and aligned on a wide-scale. Ultimately, the magnetic force was so strong that it in turn influenced the shock waves. "This explains the balance often observed between magnetic forces and thermal gas pressure in cosmic objects," says Prof. Schlickeiser. The calculations show that all fully ionised gases in the early universe were weakly magnetised. Magnetic fields therefore existed even before the first stars. Next, the Bochum physicist is set to examine how the weak magnetic fields affect temperature fluctuations in the cosmic background radiation.

Source :Science Daily

M.Wassouf

 

Hubble Eyes the Needle Galaxy: IC 2233, One of the Flattest Galaxies Known

Like finding a silver needle in the haystack of space, the NASA/ESA Hubble Space Telescope has produced a beautiful image of the spiral galaxy IC 2233, one of the flattest galaxies known.

Typical spiral galaxies like the Milky Way are usually made up of three principal visible components: the disk where the spiral arms and most of the gas and dust is concentrated; the halo, a rough and sparse sphere around the disk that contains little gas, dust or star formation; and the central bulge at the heart of the disk, which is formed by a large concentration of ancient stars surrounding the Galactic Center.

However, IC 2233 is far from being typical. This object is a prime example of a super-thin galaxy, where the galaxy's diameter is at least ten times larger than the thickness. These galaxies consist of a simple disk of stars when seen edge on. This orientation makes them fascinating to study, giving another perspective on spiral galaxies. An important characteristic of this type of objects is that they have a low brightness and almost all of them have no bulge at all.

The bluish color that can be seen along the disk gives evidence of the spiral nature of the galaxy, indicating the presence of hot, luminous, young stars, born out of clouds of interstellar gas. In addition, unlike typical spirals, IC 2233 shows no well-defined dust lane. Only a few small patchy regions can be identified in the inner regions both above and below the galaxy's mid-plane.

Lying in the constellation of Lynx, IC 2233 is located about 40 million light-years away from Earth. This galaxy was discovered by British astronomer Isaac Roberts in 1894.

This image was taken with the Hubble's Advanced Camera for Surveys, combining visible and infrared exposures. The field of view in this image is approximately 3.4 by 3.4 arcminutes.

Source:Science Daily

M.W

'Liquid That Thinks:' Swarm of Ping-Pong-Ball-Sized Robots Created

Correll and his computer science research team, including research associate Dustin Reishus and professional research assistant Nick Farrow, have developed a basic robotic building block, which he hopes to reproduce in large quantities to develop increasingly complex systems.

Recently the team created a swarm of 20 robots, each the size of a Ping Pong ball, which they call "droplets." When the droplets swarm together, Correll said, they form a "liquid that thinks."

To accelerate the pace of innovation, he has created a lab where students can explore and develop new applications of robotics with basic, inexpensive tools.

Similar to the fictional "nanomorphs" depicted in the "Terminator" films, large swarms of intelligent robotic devices could be used for a range of tasks. Swarms of robots could be unleashed to contain an oil spill or to self-assemble into a piece of hardware after being launched separately into space, Correll said.

Correll plans to use the droplets to demonstrate self-assembly and swarm-intelligent behaviors such as pattern recognition, sensor-based motion and adaptive shape change. These behaviors could then be transferred to large swarms for water- or air-based tasks.

Correll hopes to create a design methodology for aggregating the droplets into more complex behaviors such as assembling parts of a large space telescope or an aircraft.

In the fall, Correll received the National Science Foundation's Faculty Early Career Development award known as "CAREER." In addition, he has received support from NSF's Early Concept Grants for Exploratory Research program, as well as NASA.

He also is continuing work on robotic garden technology he developed at the Massachusetts Institute of Technology in 2009. Correll has been working with Joseph Tanner in CU-Boulder's aerospace engineering sciences department to further develop the technology, involving autonomous sensors and robots that can tend gardens, in conjunction with a model of a long-term space habitat being built by students.

Correll says there is virtually no limit to what might be created through distributed intelligence systems.

"Every living organism is made from a swarm of collaborating cells," he said. "Perhaps someday, our swarms will colonize space where they will assemble habitats and lush gardens for future space explorers."

Science Daily

M.W