Based on results from the first year of the Kepler mission, researchers have learned a way to distinguish two different groups of red giant stars: the giants, and the truly giant giants. The findings appear this week in Nature.
Red giants, having exhausted the supply of hydrogen in their cores, burn hydrogen in a surrounding shell. Once a red giant is sufficiently evolved, the helium in the core also undergoes fusion. Until now, the very different stages looked roughly the same.
Lead author Timothy Bedding, from the University of Sydney in Australia, and his colleagues used high-precision photometry obtained by the Kepler spacecraft over
more than a year to measure oscillations in several hundred red giants.
Using a technique called asteroseismology, the researchers were able to place the stars into two clear groups, “allowing us to distinguish unambiguously between hydrogen-shell-burning stars (period spacing mostly 50 seconds) and those that are also burning helium (period spacing 100 to 300 seconds),” they write. The latter population lend to the star an oscillation pattern dominated by gravity-mode period spacings.
In a related News and Views article, Travis Metcalfe of the Boulder, Colo.-based National Center for Atmospheric Research explains that like the sun, “the surface of a red giant seems to boil as convection brings heat up from the interior and radiates it into the coldness of outer space. These turbulent motions act like continuous starquakes, creating sound waves that travel down through the interior and back to the surface.” Some of the sounds, he writes, have just the right tone — a million times lower than what people can hear — to set up standing waves known as oscillations that cause the entire star to change its brightness regularly over hours and days, depending on its size. Asteroseismology is a method to measure those oscillations.
Metcalfe goes on to explain that a red giant’s life story depends not only on its age but also on its mass, with stars smaller than about twice the mass of the sun undergoing a sudden ignition called a helium flash.
“In more massive stars, the transition to helium core burning is gradual, so the stars exhibit a wider range of core sizes and never experience a helium flash. Bedding and colleagues show how these two populations can be distinguished observationally using their oscillation modes, providing new data to validate a previously untested prediction of stellar evolution theory,” he writes.
The study authors conclude that their new measurement of gravity-mode period spacings “is an extremely reliable parameter for distinguishing between stars in these two evolutionary stages, which are known to have very different core densities but are otherwise very similar in their fundamental properties (mass, luminosity and radius). We note that other asteroseismic observables, such as the small p-mode separations, are not able to do this.”
The Sun continues to be active! This movie from the Solar Dynamics Observatory starts at 11:35 UT on March 24, 2011 and goes through midnight. It shows the active area 1176 – and active it was. Several flares are visible — according to the SDO website, there are B, C and M class flares all seen in this 20 second video. See below for another movie from March 19 of a looping solar prominence eruption on the limb of the Sun. Continue reading “Fireworks on the Sun”
Amateur astronomer Catalin Fus from Poland has captured one of the most amazing images I’ve ever seen – and his timing was impeccable. On March 7th at 13:05:49 UTC, just after space shuttle Discovery had undocked from the International Space Station, the two ships flew in formation directly in front of the Sun, as seen from Fus’ location just outside of Krakow. With his solar-filtered telescope focused on active sunspot region 1166, he found there were a couple extra spots in his image – Discovery and the ISS. Given that this was Discovery’s final mission in space and final visit to the ISS, this image has historical significance, as well as just being absolutely fantastic. Keep in mind that transits like this last just over a half a second.
He used the following equipment:
Telescope : 102mm f6.3 GPU oilspaced apochromat
self-made Herschel Prism + Meade TeleXtender 2x 1.25”
Mount: Losmandy G11
Camera: Canon EOS 550D
1frame @ ISO 100, 1/1000s
With just a touch of post processing done in PixInsight and PS CS5
You can see more Fus’ handiwork at his website, www.catalinfus.ro. Our thanks to Catalin for allowing Universe Today to post his incredible image.
Feast your eyes on some of the solar system’s earliest materials: the pink core comprises melilite, spinel and perovskite. The multi-colored rim contains hibonite, perovskite, spinel, melilite/sodalite, pyroxene, and olivine. This close-up reveals part of a pea-sized chunk of meteorite, a calcium-aluminum rich inclusion, formed when the planets in our solar system were still dust grains swirling around the sun — and it can tell an early part of the story about what happened next.
Meteorites have puzzled space scientists for more than 100 years because they contain minerals that could only form in cold environments, as well as minerals that have been altered by hot environments. Carbonaceous chondrites, in particular, contain millimeter-sized chondrules and up to centimeter-sized calcium-aluminum-rich inclusions, like the one shown above, that were once heated to the melting point and later welded together with cold space dust.
“These primitive meteorites are like time capsules, containing the most primitive materials in our solar system,” said Justin Simon, an astromaterials researcher at NASA’s Johnson Space Center in Houston, who led the new study. “CAIs are some of the most interesting meteorite components. They recorded the history of the solar system before any of the planets formed, and were the first solids to condense out of the gaseous nebula surrounding our protosun.”
For the new paper, which appears in Science today, Simon and his colleagues performed a micro-probe analysis to measure oxygen isotope variations in micrometer-scale layers of the core and outer layers of the ancient grain, estimated to be 4.57 billion years old.
All of these calcium-aluminum-rich inclusions, or CAIs, are thought to have originated near the protosun, which enriched the nebular gas with the isotope oxygen-16. In the inclusion analyzed for the new study, the abundance of oxygen-16 was found to decrease outward from the center of the core, suggesting that it formed in the inner solar system, where oxygen-16 was more abundant, but later moved farther from the sun and lost oxygen-16 to the surrounding 16O-poor gas.
Simon and his colleagues propose that initial rim formation could have occurred as inclusions fell back into the midplane of the disk, indicated by the dashed path A above; as they migrated outward within the plane of the disk, shown as path B; and/ or as they entered high density waves (i.e., shockwaves). Shockwaves would be a reasonable source for the implied 16O-poor gas, increased dust abundance and thermal heating. The first mineral layer outside the core had more oxygen-16, implying that the grain had subsequently returned to the inner solar system. Outer rim layers had varying isotope compositions, but in general indicate that they also formed closer to the sun, and/or in regions where they had lower exposure to the 16O-poor gas from which the terrestrial planets formed.
The researchers interpret these findings as evidence that dust grains traveled over large distances as the swirling protoplanetary nebula condensed into planets. The single dust grain they studied appears to have formed in the hot environment of the sun, may have been thrown out of the plane of the solar system to fall back into the asteroid belt, and eventually recirculated back to the sun.
This odyssey is consistent with some theories about how dust grains formed in the early protoplanetary nebula, or propylid, eventually seeding the formation of planets.
Perhaps the most popular theory explaining the composition of chrondrules and CAIs is the so-called X-wind theory propounded by former UC Berkeley astronomer Frank Shu. Shu depicted the early protoplanetary disk as a washing machine, with the sun’s powerful magnetic fields churning the gas and dust and tossing dust grains formed near the sun out of the disk.
Once expelled from the disk, the grains were pushed outward to fall like rain into the outer solar system. These grains, both flash-heated chondrules and slowly heated CAIs, were eventually incorporated along with unheated dust into asteroids and planets.
“There are problems with the details of this model, but it is a useful framework for trying to understand how material originally formed near the sun can end up out in the asteroid belt,” said coauthor Ian Hutcheon, deputy director of Lawrence Livermore National Laboratory’s Glenn T. Seaborg Institute.
In terms of today’s planets, the grain probably formed within the orbit of Mercury, moved outward through the region of planet formation to the asteroid belt between Mars and Jupiter, and then traveled back toward the sun again.
“It may have followed a trajectory similar to that suggested in the X-wind model,” Hutcheon said. “Though after the dust grain went out to the asteroid belt or beyond, it had to find its way back in. That’s something the X-wind model doesn’t talk about at all.”
Simon plans to crack open and probe other CAIs to determine whether this particular CAI (referred to as A37) is unique or typical.
Source: Science and a press release from the University of California at Berkeley.
The long lull in sunspots at the end of Solar Cycle 23 wasn’t just fodder for global cooling predictions — it gave solar physicists plenty to study. And a new computer analysis may have come up with a fairly simple explanation for the sun’s odd quiet. Lead author Dibyendu Nandy, of the Indian Institute of Science Education and Research in Kolkata, and his colleagues report in Nature today that the long string of sunspot-free days between solar cycles 23 and 24 may directly correlate with the speed of north-south flow of plasma toward the sun’s equator. Their collage, above, shows magnetic fields in the interior of the Sun simulated using a solar dynamo model (center) and the observed solar corona at two different phases of solar activity: A quiescent phase during the recent, unusually long minimum, at right, and a comparatively active phase following the minimum, at left.
The sun’s magnetic activity varies periodically, exhibiting an ~11-year cycle that can be monitored by observing the frequency and location of sunspots. Sunspots are strongly magnetized regions generated by the sun’s internal magnetic field and are the seats of solar storms that generate beautiful auroras but also pose hazards to satellites, navigation technologies like GPS and communications infrastructures.
Towards the end of solar cycle 23, which peaked in 2001 and wound down in 2008, the Sun’s activity entered a prolonged minimum, characterized by a very weak polar magnetic field and an unusually large number of days without sunspots: 780 days between 2008 and 2010. In a typical solar minimum, the sun goes spot-free for about 300 days, making the last minimum the longest since 1913.
The study authors conducted magnetic dynamo simulations of 210 sunspot cycles spanning some 2,000 years while varying the speed of the solar internal meridional (north-south) plasma flow. The sun’s plasma flows much like Earth’s ocean currents: rising at the equator, streaming toward the poles, then sinking and flowing back to the equator. At a typical speed of 40 miles per hour, it takes about 11 years to make one loop.
Nandy and his colleagues discovered that the Sun’s plasma rivers speed up and slow down like a malfunctioning conveyor belt, probably due to complicated feedback between the plasma flow and solar magnetic fields.
“It’s like a production line – a slowdown puts distance between the end of the last solar cycle and the start of the new one,” said study co-author Andres Munoz-Jaramillo, a visiting research fellow at the Harvard-Smithsonian Center for Astrophysics.
Specifically, the authors write, a fast meridional flow in the first half of a cycle, followed by a slower flow in the second half, leads to a deep sunspot minimum — and can reproduce the observed characteristics of the cycle 23 minimum.
Nandy and his colleagues say continued solar observations will be key to confirming and elaborating on the modeling results.
“We anticipate that NASA’s recently launched Solar Dynamics Observatory will provide more precise constraints on the structure of the plasma flows deep in the solar interior, which could be useful for complementing these simulations,” they write.
The Sun continues to be active! A large-sized (M 3.6 class) flare occurred near the edge of the Sun on February 24, 2011, and it blew out a gorgeous, waving mass of erupting plasma that swirled and twisted over a 90-minute period. This event was captured in extreme ultraviolet light by NASA’s Solar Dynamics Observatory spacecraft. Some of the material blew out into space and other portions fell back to the surface. Because SDO images are super-HD, the scienctists can zoom in on the action and still see exquisite details. The video above was created using a cadence of a frame taken every 24 seconds; still, the sense of motion is, by all appearances, seamless. Sit back and enjoy the jaw-dropping solar show. See one of the images, below.
Spaceweather.com reports that Earth was little affected by this blast, as plasma clouds produced by the blast did not come our way.
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The latest active sunspot — #1163 — is currently behind the Sun’s eastern limb, but be turning toward Earth in the days ahead, setting the stage for more activity if the eruptions continue.
According to SpaceWeather: “Fast-growing active region 1161 erupted this morning, producing an M6.6-class solar flare at 1011 UT. The almost-X category blast was one of the strongest flares in years and continued the week-long trend of high solar activity.” Just how awesome is that? Then take a look at these white light solar images done by John Chumack…
While today’s activity isn’t supposed to impact Earth in a negative manner, who knows what it might produce in the days ahead? Just ask NOAA!
“A G1 (minor) geomagnetic storm continues. What might have been three hits of shocks/CMEs seems to have merged to be just one interplanetary shock/CME structure. Look for about another day’s worth of geomagnetic activity, pending additional treats in the solar wind. Elsewhere Region 1158 had another R2 (moderate) radio blackout, and fast-growing new Region 1162 likely generated an R1 (minor) event.”
With 1158 nearing the limb and wonderfully active, now is the time for solar observers to try and catch the “Wilson Effect” – an effect in which the penumbra of a sunspot appears narrower in the direction toward the Sun’s center.
While you’re at it, it doesn’t hurt to keep watch for auroral activity tonight and in the days ahead – despite the lunar interference. With satellite communications impacted in my area, I’m anxious to see what the nights – and days – bring!
On February 13, 2011, sunspot 1158 let loose the strongest solar flare of the current solar cycle, a blast of radiation across the electromagnetic spectrum, from radio waves to x-rays and gamma-rays. NASA’s Solar Dynamics Observatory recorded an intense flash of extreme ultraviolet radiation, as seen above, and located in approximately the middle of the Sun’s disk in the image below. The eruption also produced a loud blast of radio waves, and coronagraph data from STEREO-A and SOHO agree that the explosion produced a fast but not particularly bright coronal mass ejection. Spaceweather.com predicts a CME cloud will likely hit Earth’s magnetic field on or about Feb. 15th, and high-latitude sky watchers should be alert for auroras.
Jason Major from Lights in the Dark created the video below of magnetic activity around a sunspot 1158, from data region from SDO spacecraft, during February 12-13, 2011.
Super Bowl SUNday XLV marks a watershed moment in observing our Sun. Today, February 6, 2011, NASA’s twin STEREO solar observatories will reach locations on exact opposite sides of the Sun, called opposition, and they are beaming back uninterrupted images from both the entire front and rear side hemispheres of Earths star in three dimensions and 360 degrees for the first time.
“For the first time in history we can see the entire Sun at one time – both the far side and the near side,” said Joe Gurman, in an interview for Universe Today. Gurman is the Project Scientist for NASA’s STEREO mission at the NASA Goddard Spaceflight Center in Greenbelt, MD. This will significant aid space weather forecasting.
To mark this historic milestone, NASA today released images captured by STEREO on Feb. 2 – slightly prior to opposition – which gives humankind our first ever global look at the whole sphere of our Suns surface and atmosphere in extreme ultraviolet light (EUV). The probes were over 179 degrees apart. See location maps and images below
This article features even newer EUV images – compared to NASA’s press release – that were taken even closer to opposition by STEREO on Feb. 3 and today on Feb. 6 and which I downloaded from the STEREO website. The newer EUV images show an ever so slightly more complete solar view as the probes orbit reaches further to the suns far side.
Coincidentally, the STEREO duo may reach opposition – exactly 180 degrees apart – while the Super Bowl XLV half time show is ongoing, at roughly 7:30 p.m. EST in the evening of Sunday, Feb. 6.
There is a tiny sliver of unseen solar surface on the far side of the sun at the extreme fringes of the far side EUV images that will fill in over the new few days to give an even better view. As of today that wedge is less than 1 degree. See the solar image collections above and below.
“The currently unseen far side wedge will disappear around February 12,” Gurman told me. “There might still be some small areas at high latitudes we won’t be able to see, but the view from the ecliptic is always limited. It takes about 3 days to get back the high resolution data.”
“On either side of the wedge, the features are smeared out because they’re from the “limbs” (edges) of the Sun as seen from each STEREO spacecraft.”
“The far side resolution will increase as the STEREO twins proceed around the sun.”
“On the near side, we can substitute the much higher resolution SDO AIA image data along the nearside “seam”, said Gurman.
SDO is in Earth orbit on the earth-facing side of the sun and will fill in the gap.
“For the next 8 years we will have a 360 degree view of the Sun by combining STEREO and SDO data,” said Gurman. “We will have that whole sun view until the STEREO spacecraft swing back to the earth side of the Sun.”
Why is it important to image the far side of the sun?
Because scientists can now immediately detect active regions on the far side of the sun which were hidden from our view up until now.
“No active region can hide from us anymore because we will now have this 360 degree view.”
The new far side data will allow much faster detection of solar storms which in turn will enable faster predictions of space weather which potentially can severely impact sensitive technological infrastructure on Earth and throughout the solar system.
Until now, we had to wait about two weeks until the rear side active regions of the sun rotated into our view on the front side. But no longer. On average the sun rotates in about 27 days – faster at the equator and slower at the poles.
“We will now be able to detect the coronal mass ejections, or CMEs as they happen on the far side instead of waiting until they rotate around with no forewarning. The magnetic storms with energetic particles blast out at varying speeds of about 700 to 1000 km/sec and can reach Earth in one to three days,” said Gurman.
These magnetic storms are a threat to air traffic control of airliners, can disrupt the power grip, damage communications systems, space satellites in Earth orbit and around the solar system, effect other sensitive electronics systems and also harm astronauts working aboard the International Space Station.
STEREO is comprised of two nearly identical STEREO spacecraft – dubbed STEREO Ahead and STEREO Behind –orbiting around our Sun. One probe – B – trails Earth around the sun and moves a bit slower; the other one – A – leads the Earth traveling slightly faster.
Each probe images half of the suns sphere and broadcasts the data back to Earth continuously, 24 hours each day. STEREO’s solar telescopes are tuned to four different wavelengths of extreme ultraviolet radiation (171, 195, 284, 304 Å) selected to trace key aspects of solar activity such as flares, tsunamis and magnetic filaments.
“The images are converted into a spherical projection by researchers on the science teams,” said Gurman. An international group of scientific institutions and governments from the U.S., UK, France, Germany, Belgium, Netherlands and Switzerland designed and built STEREO’s science imaging and particle detecting instruments.
The two probes have been slowly separating in opposite directions at about 45 degrees per year ever since they were launched together aboard a Delta II rocket on October 25, 2006 from Cape Canaveral Air Force Station (CCAFS) in Florida.
After hurtling past the moon, the solar powered spacecraft – weighing some 600 kg – were flung into solar orbit on opposite sides of the Earth and have been moving away from Earth and apart from each other. In this way the wedge of unseen solar territory has been diminishing as the probes gain more complete coverage of the sun, thus enabling us to formulate a more complete understanding of the solar environment.
STEREO stands for Solar TErrestrial RElations Observatory. Their mission is to provide the very first, 3-D “stereo” images of the sun to study the nature of coronal mass ejections.
The STEREO mission is currently funded until 2013.
“The probes have enough fuel to last 100 years,” said Gurman. “The lifetime limiting factor is the spacecraft electronics and funding. The solar arrays will only gradually degrade over decades.”
NASA/STEREO Reveals the Entire Sun
Launched in October 2006, STEREO traces the flow of energy and matter from the sun to Earth. It also provides unique and revolutionary views of the sun-Earth system. STEREO, when paired with SDO, can now give us the first complete view of the sun’s entire surface and atmosphere
What do NASA, Robots, the Sun and the NFL have in common ?
Well … its Super SUNday … for Super Bowl XLV on Feb. 6, 2011
The unlikely pairing of Football and Science face off head to head on Super Bowl SUNday. Millions of television viewers will see NASA’s Robonaut 2, or R2, share the the limelight with the Steelers and the Packers of the NFL. The twin brother of R2 is destined for the International Space Station (ISS) and will become the first humanoid robot in space. It will work side by side as an astronaut’s assistant aboard the space station.
The fearsome looking R2 is set to make a first ever special guest appearance during the FOX Networks Super Bowl pre-game show with FOX sports analyst Howie Long. The pre-game show will air starting at 2 p.m. EST on Feb. 6.
And there’s more.
On Super SUNday Feb. 6, NASA will publish Humankinds first ever image of the ‘Entire Sun’ courtesy of NASA’s twin STEREO spacecraft. And given the stunningly cold and snowy weather in Dallas, the arrival of our Sun can’t come soon enough for the ice covered stadium and football fans. See photos above and below.
The two STEREO spacecraft will reach positions on opposite sides of the Sun on Sunday, Feb. 6 at about 7:30 p.m. in the evening, possibly coinciding with the Super Bowl half time show.
At opposition, the STEREO duo will observe the entire 360 degrees sphere of the Sun’s surface and atmosphere for the first time in the history of humankind.
The nearly identical twin brother of R2 is packed aboard Space Shuttle Discovery and awaiting an out of this world adventure from Launch Pad 39 A at NASA’s Kennedy Space Center (KSC) in Florida. Blast off of the first humanoid robot is currently slated for Feb. 24.
R2 is the most dextrously advanced humanoid robot in the world and the culmination of five decades of wide-ranging robotics research at NASA and General Motors (GM).
This newest generation of Robonauts are an engineering marvel and can accomplish real work with exceptionally dexterous hands and an opposable thumb. R2 will contribute to the assembly, maintenance and scientific output of the ISS
“R2 is the most sophisticated robot in the world,” says Rob Ambrose, Chief of NASA’s Johnson Space Center’s (JSC) Robotics Division.
“We hope R2 should help to motivate kids to study science and space,” Ron Diftler told me in an interview at KSC. Diftler is NASA’s R2 project manager at JSC.
The amazingly dexterity of the jointed arms and hands enables R2 to use exactly the same tools as the astronauts and thereby eliminates the need for constructing specialized tools for the robots –saving valuable time, money and weight.
The robot is loaded with advanced technology including an optimized overlapping dual arm dexterous workspace, series elastic joint technology, extended finger and thumb travel, miniaturized 6-axis load cells, redundant force sensing, ultra-high speed joint controllers, extreme neck travel, and high resolution camera and IR systems.
R2 weighs some 300 pounds and was manufactured from nickel-plated carbon fiber and aluminum. It is equipped with two human like arms and two hands as well as four visible light cameras that provide stereo vision with twice the resolution of high definition TV.
“With R2 we will demonstrate ground breaking and innovative robotics technology which is beyond anything else out there and that will also have real world applications as GM works to build better, smarter and safer cars,” according to Susan Smyth, GM Director of Research and Development.
“Crash avoidance technology with advanced sensors is a prime example of robonaut technology that will be integrated into GM vehicles and manufacturing processes.”
Robonaut 2 flight unit poses with the NASA/GM development team inside the Space Station Processing Facility at KSC in this 360 degree panorama from nasatech.net
I was fortunate to meet R2 and the Robonaut team at KSC. R2 is incredibly life like and imposing and I’ll never forget the chance to shake hands. Although its motions, sounds, illuminated hands and muscular chest gives the unmistakable impression of standing next to a lively and powerful 300 pound gorilla, it firmly but gently grasped my hand in friendship – unlike a Terminator.
So its going to make for a mighty match up some day between the fearsome looking R2 and the NFL players.
Well apparently, R2 and Howie will be making some predictions on which player will win the MVP award and a GM Chevrolet. Stay tuned.
So come back on SUNday Feb. 6 for NASA’s release of the first ever images of our entire Sun from the STEREO twins.