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Star Ate My Planet

May 20

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“The Star That Ate My Planet” may sound like a B-grade science fiction movie title, but this is really happening 600 light-years away. Like a moth in a candle flame, a doomed Jupiter-sized planet has moved so close to its sunlike parent star that it is spilling its atmosphere onto the star.

This happens because the planet gets so hot that its atmosphere puffs up to the point where the star’s gravity pulls it in. The planet will likely be completely devoured in 10,000 years. Observations by Hubble’s new Cosmic Origins Spectrograph measured a variety of elements in the planet’s bloated atmosphere as the planet passed in front of its star.

The planet, called WASP-12b, is the hottest known world ever discovered, with an atmosphere seething at 2,800 degrees Fahrenheit.

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Runaway Star!

May 11

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Doradus RunawayA heavy runaway star is rushing away from a nearby stellar nursery at more than 250,000 miles an hour, a speed that will get you to the Moon and back in two hours. The runaway is the most extreme case of a very massive star that has been kicked out of its home by a group of even heftier siblings.

The homeless star is on the outskirts of the 30 Doradus nebula, a raucous stellar breeding ground in the nearby Large Magellanic Cloud. The finding bolsters evidence that the most massive stars in the local universe reside in 30 Doradus, making it a unique laboratory for studying heavyweight stars. 30 Doradus, also called the Tarantula Nebula, is roughly 170,000 light-years from Earth.

Tantalizing clues from three observatories, including the Hubble Space Telescope’s newly installed Cosmic Origins Spectrograph (COS), and some old-fashioned detective work, suggest that the star may have traveled about 375 light-years from its suspected home, a giant star cluster called R136. Nestled in the core of 30 Doradus, R136 contains several stars topping 100 solar masses each.

The observations offer insights into how massive star clusters behave.

“These results are of great interest because such dynamical processes in very dense, massive clusters have been predicted theoretically for some time, but this is the first direct observation of the process in such a region,” says Nolan Walborn of the Space Telescope Science Institute in Baltimore and a member of the COS team that observed the misfit star. “Less massive runaway stars from the much smaller Orion Nebula Cluster were first found over half a century ago, but this is the first potential confirmation of more recent predictions applying to the most massive young clusters.”

Runaway stars can be made in a couple of ways. A star may encounter one or two heavier siblings in a massive, dense cluster and get booted out through a stellar game of pinball. Or, a star may get a ‘kick’ from a supernova explosion in a binary system, with the more massive star exploding first.

“It is generally accepted, however, that R136 is sufficiently young, 1 million to 2 million years old, that the cluster’s most massive stars have not yet exploded as supernovae,” says COS team member Danny Lennon of the Space Telescope Science Institute. “This implies that the star must have been ejected through dynamical interaction.”

The runaway star research team, led by Chris Evans of the Royal Observatory Edinburgh, published the study’s results May 5 in the online edition of The Astrophysical Journal Letters.

Astronomers have been on the trail of this rogue star since 2006 when a team led by Ian Howarth of University College London spotted it with the Anglo-Australian Telescope at Siding Spring Observatory. The observation revealed that the stellar misfit was an exceptionally hot, massive, blue-white star and relatively far from any cluster in which such stars are usually found.

Hubble astronomers unexpectedly picked up another clue when they used the star as a target to calibrate the COS instrument, installed in May 2009 during Servicing Mission 4. Those ultraviolet spectroscopic observations, made in July 2009, showed that the wayward star is unleashing a fury of charged particles in one of the most powerful stellar winds known, a clear sign that it is extremely massive, perhaps as much as 90 times heavier than the Sun. The star, therefore, also must be very young, about 1 million to 2 million years old, because extremely massive stars live only a few million years.

Sifting through Hubble’s archive of images, astronomers found another important piece of evidence. An optical image of the star taken by the Wide Field Planetary Camera 2 in 1995 revealed that it is at one end of an egg-shaped cavity. The cavity’s glowing edges stretch behind the star and point in the direction of its home in 30 Doradus.

Another spectroscopic study from the European Southern Observatory’s Very Large Telescope (VLT) at the Paranal Observatory in Chile revealed that the star’s velocity is constant and not a result of orbital motion in a binary system. Its velocity corresponds to an unusual motion relative to the star’s surroundings, evidence that it is a runaway star.

The study also confirmed that the light from the runaway is from a single massive star rather than the combined light of two lower-mass stars. In addition, the observation established that the star is about 10 times hotter than the Sun, a temperature that is consistent with a high-mass object.

The VLT observations are part of a legacy program called the FLAMES (VLT multi-object spectrograph) Tarantula Survey. The survey, conducted by an international team led by Evans of the Royal Observatory, comprises more than 900 stars in the 30 Doradus region. Like the COS observations of the star, the FLAMES results also were serendipitous. The star’s location is far from the nebula’s central region, placing it at the edge of the FLAMES survey field.

The renegade star may not be the only runaway in the region. Two other extremely hot, massive stars have been spotted beyond the edges of 30 Doradus. Astronomers suspect that these stars, too, may have been ejected from their home. They plan to analyze the stars in detail to determine whether 30 Doradus might be unleashing a barrage of massive stellar runaways into the surrounding neighborhood.

The wayward star will continue to streak across space, says team member Paul Crowther of the University of Sheffield in England, and will eventually end its life in a titanic supernova explosion, likely leaving behind a remnant black hole.

http://hubblesite.org/newscenter/archive/releases/2010/14/full/

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Happy Birthday Hubble

Apr 23

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Carina NebulaNASA’s best-recognized, longest-lived, and most prolific space observatory zooms past a threshold of 20 years of operation this month. On April 24, 1990, the space shuttle and crew of STS-31 were launched to deploy the Hubble Space Telescope into a low Earth orbit. What followed was one of the most remarkable sagas of the space age.

Hubble’s unprecedented capabilities made it one of the most powerful science instruments ever conceived by humans, and certainly the one most embraced by the public. Hubble discoveries revolutionized nearly all areas of current astronomical research, from planetary science to cosmology. And, its pictures were unmistakably out of this world. This brand new Hubble photo is of a small portion of one of the largest seen star-birth regions in the galaxy, the Carina Nebula. Towers of cool hydrogen laced with dust rise from the wall of the nebula.

The scene is reminiscent of Hubble’s classic “Pillars of Creation” photo from 1995, but is even more striking in appearance. The image captures the top of a three-light-year-tall pillar of gas and dust that is being eaten away by the brilliant light from nearby bright stars. The pillar is also being pushed apart from within, as infant stars buried inside it fire off jets of gas that can be seen streaming from towering peaks like arrows sailing through the air.

http://hubblesite.org/newscenter/archive/releases/2010/13/

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Other Planets

Apr 6

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As our telescopes grow more powerful, astronomers are uncovering objects that defy conventional wisdom. This latest example is the discovery of a planet-like object circling a brown dwarf. It’s the right size for a planet, estimated to be 5-10 times the mass of Jupiter. There has been a lot of discussion in the context of the Pluto debate over how small an object can be and still be called a planet. This new observation addresses the question at the other end of the size spectrum: How small can an object be and still be a brown dwarf rather than a planet? This new companion is within the range of masses observed for planets around stars — less than 15 Jupiter masses. But should it be called a planet? The answer is strongly connected to the mechanism by which the companion most likely formed. What’s even more puzzling is that the object formed in just 1 million years, a very short time to make a planet according to conventional theory.

http://hubblesite.org/newscenter/archive/releases/2010/03/

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Space Junk

Feb 25

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The already untidy mass of orbital debris that litters low Earth orbit nearly got nastier last month. A head-on collision was averted between a spent upper stage from a Chinese rocket and the European Space Agency’s (ESA) huge Envisat Earth remote-sensing spacecraft.Space junk tracking information supplied by the U.S. military, as well as confirming German radar data, showed that the two space objects would speed by each other at a nail-biting distance of roughly 160 feet (50 meters).

ESA’s Envisat tips the scales at 8 tons, with China’s discarded rocket body weighing some 3.8 tons. A couple of tweaks of maneuvering propellant were used to nudge the large ESA spacecraft to a more comfortable miss distance. But what if the two objects had tangled?

Such a space collision would have caused mayhem in the heavens, adding clutter to an orbit altitude where there are big problems already, said Heiner Klinkrad, head of the European Space Agency’s Space Debris Office in Darmstadt, Germany.

It turns out, Klinkrad told SPACE.com, that 50 percent of all the close conjunctions that Envisat faces are due to the lethal leftovers from China’s January 2007 anti-satellite test, as well as chunks of junk resulting from last year’s smashup between an active U.S. Iridium satellite and a defunct Russian Cosmos spacecraft.

Klinkrad joined several orbital debris experts that took part in the 33rd Annual Guidance and Control Conference organized by the Rocky Mountain Section of the American Astronautical Society. The five-day meeting began Feb. 5.

Avoidance maneuvers

Significant progress has been made by the U.S. and the international aerospace communities in recognizing the hazards of orbital debris, reported Nicholas Johnson, chief scientist for orbital debris at the NASA Johnson Space Center in Houston, Texas.

Johnson added that steps are being taken to reduce or eliminate the potential for the creation of new debris. However, “the future environment is expected to worsen without additional corrective measures,” he noted.
During 2009, Johnson reported, five different NASA robotic spacecraft carried out collision avoidance maneuvers: a Tracking and Data Relay Satellite (TDRS-3), Cloudsat, Earth Observing Mission 1, Aqua, and Landsat 7. Also, the space shuttle and the International Space Station took collision avoidance actions, he said.

The worst thing that could happen, according to ESA’s Klinkrad, is the International Space Station (ISS) receiving a fatal hit. The space station is currently home to five astronauts representing the U.S., Russia and Japan. “A penetrating object hitting the ISS, and possibly causing a casualty onboard . . . I think that would be the most dramatic case we could have,” Klinkrad suggested. Such an incident might turn public opinion against human spaceflight, he said.

Collaboration on the increase

One bit of good news in all this orbital riff-raff. Due to last year’s satellite crash between the Iridium and Cosmos spacecraft, Johnson explained that the Joint Space Operations Center (JSpOC) of the U.S. Strategic Command now conducts conjunction assessments for all operational spacecraft in Earth orbit, regardless of ownership nationality. “To be honest, a year ago, we couldn’t even have hoped to have done this,” Johnson told SPACE.com.

“It’s really a consequence of the collision last year. People have been talking about this for years. But now we’ve made the commitment . . . that this is something that needs to be done and can be done relatively easily,” Johnson said. Klinkrad concurred. “The collaboration is getting even closer now,” he said.

Duck or pluck?

Playing dodge ball with high-speed space debris is one tactic. But there is also a growing interest in removing the most troublesome objects — perhaps an annual quota of some sort.Targeted would be specific inclination bands and altitude regimes, Klinkrad said. But prior to implementing debris remediation measures on a global scale, technical, operational, legal and economic problems must be overcome. Klinkrad and NASA’s Johnson provided a wearisome appraisal of the future.

Even with an immediate halt of launch activities, spacefaring nations will be dealing with an unstable low-Earth orbit environment in some altitude and inclination bands. This would be a consequence of about 20 catastrophic collisions within the next 200 years, the two orbital debris experts explained. Some orbit altitudes already have critical mass concentrations that will trigger “collisional cascading” within a few decades, unless debris environment remediation measures are introduced.

The Kessler Syndrome

The idea of debris creating debris was put in motion by Donald Kessler, along with fellow NASA researcher, Burton Cour-Palais, back in 1978. Their research suggested that, as the number of artificial satellites in Earth orbit increases, the probability of collisions between satellites also increases. Satellite collisions would produce orbiting fragments, each of which would increase the probability of further collisions, leading to the growth of a belt of debris around the Earth.Now, decades later, that prophecy has been dubbed the Kessler Syndrome.

Kessler told SPACE.com that the disorder fits into much more complex natural laws that include the evolution of the solar system, as well as meteoroids, meteorites, and climate-changing asteroids. Kessler is now an orbital debris and meteoroid consultant in Asheville, North Carolina.”There is nothing complex about what is called the ‘Kessler Syndrome’ . . . it is just the way nature may have converted a disorderly group of orbiting rocks into an orderly solar system . . . although nature reminds us with a large asteroid or comet collision every few million years that it isn’t quite finished yet. “In the case of orbital debris, this collision process is just starting,” Kessler explained. Consequently, nobody should be surprised that as orbital debris models became more complex — and as more data is obtained — the same conclusion holds, Kessler said.

“The future debris environment will be dominated by fragments resulting from random collisions between objects in orbit, and that environment will continue to increase, even if we do not launch any new objects into orbit,” Kessler concluded.


http://www.space.com/missionlaunches…er-100223.html

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The Moon Is Leaving

Feb 20

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When scientists first began doing laser range finding with the laser mirrors left on the lunar surface by the Apollo astronauts, they soon began to note a slight change in distances. The moon is actually leaving the orbit of the Earth and one day will simply shrug off the gravitational pull of the Earth and become a solar roaming free agent. Most likely scenario is that it may well, eventually, become caught in the gravitational field of Jupiter, the solar system’s vast vacuum cleaner, and either become a Jovian satellite or be destroyed in a titanic collision. Another possibility is that it may stay in the same orbit as Earth and eventually catch it up and collide.

Last night (Feb 19th 2010), on Discovery tv, I watched a program which enforced that which I already knew. It showed us, in some quite spectacular graphics, that a Mars sized object hit the virgin Earth at approx 45 dgrees causing a mass ejection of material into surrounding space. Most of this coagulated together to form the Moon and the heavier iron elements fell back to Earth.

When the moon originally formed, it was 15 times nearer the Earth, therefore 15 times as large. Must have been some sight, moonrise!

Sci Fi addicts may well recall the UK Sci Fi sceries, Space 1999, in which the moon was blown clear of Earth by a nuclear accident. But, what that fictional series did not show was the effect this would have on Earth. The tides will cease for a start, when the seas level out, cities like New York and Rio would become uninhabitable as a 4 metre rise would occur.

The last time the Earth ‘wobbled’ was back when the Sahara was a lush, tropical giant forest. The result of that ‘wobble’ is as we see the Sahara now. The moonless Earth will experience wobbles of more severity. The Earth’s angle to the sun (23 deg) is maintained by the Moon, without this steadying effect, weather patterns would be severely more extreme and changes to the surface was more markedly differing in style. The Moon leaving would cause the Earth to become unstable and fluctuations occur. The polar caps could become the new equator for example! The northern hemisphere enjoys its ‘winter’ even though the Earth is actually nearest to the Sun, and vice versa due to this 23 degree angle. Which is why summers down under are notably hotter than our own, when the Earth is furthest from the Sun. Anyway, hopefully by this time, we may have actually evolved enough to have the ability and knowledge to ‘move house’?

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Your Mobile Is Cracked

Dec 31

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The encryption system used to protect 80 per cent of the world’s mobile phone calls has been cracked, claim a group of computer scientists who have published their findings online. Karsten Nohl told a conference of computer hackers in Berlin that he and his colleagues were trying to expose weaknesses in mobile communication security and hoped their findings would encourage wireless operators to improve their security.

He told the conference: “This shows that existing GSM security is inadequate.” The GSM association, the industry body that manages the GSM standard, said that although Mr Nohl’s findings made it theoretically possible to eavesdrop on a call, in practice such eavesdropping would be unlikely.

However, Simon Bransfield-Garth, chief executive of mobile encryption firm Cellcrypt, said that Mr Nohl’s work would make it far easier for criminals to intercept calls. “This will reduce the time to break a GSM call from weeks to hours,” he told the New York Times.

Most mobile phone calls worldwide are made using the GSM standard. GSM calls are protected by a 22-year-old encryption algorithm, known as A5/1. The algorithm, which is designed to prevent mobile phone calls from being intercepted by eavesdroppers, works by forcing mobile phones and bas stations to continually change frequencies. A typical phone conversation changes frequencies around 60 times.

The GSM Association has had a stronger algorithm, called A5/3, available since 2007 but few mobile network providers have made the upgrade.

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Water Planet Discovered

Dec 17

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A rocky and water-rich planet, not much heftier than our own, has been discovered so close to our solar system that astronomers one day may be able to study its atmosphere. And though astronomers are pretty certain the water exists, they don’t know its state, with speculations ranging from liquid water to water ice and an exotic state called a superfluid. The extrasolar planet, now named GJ 1214b, is about 40 light-years away. It orbits a red dwarf star. It is the only known “Super-Earth” exoplanet — worlds that have masses between Earth and Neptune — with a confirmed atmosphere. “Astronomically speaking, this [planet] is on our block,” meaning it’s in our cosmic neighborhood, said study leader David Charbonneau of the Harvard-Smithsonian Center for Astrophysics in Mass. “For perspective, our own TV signals have already passed beyond the distance of this star.” The planet is about three times the size of Earth and about 6.5 times as massive. It is the second smallest planet discovered outside of our solar system to date, trailing behind only CoRoT-7b, which is 1.7 times Earth’s size and about five times as massive.

GJ 1214b is rare among known rocky exoplanets because it partially eclipses, or transits, its star as seen from Earth. This fortunate alignment allows astronomers to calculate the size and density of the planet, and Charbonneau’s team thinks GJ 1214b is likely a water world with a solid center. Moreover, the planet has a thick surrounding atmosphere of hydrogen and helium.

Normally, a planet located at that distance from this particular type of star would be so hot that any water on its surface would be in a vapor form. But scientists think the thick atmosphere of GJ 1214b creates a high pressure environment that keeps water on the surface in a liquid state. That’s just speculation, however.

Read the rest of this entry »

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‘Tiny’ Kuiper Belt Object Detected

Dec 16

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NASA’s Hubble Space Telescope has discovered the smallest object ever seen in visible light in the Kuiper Belt, a vast ring of icy debris that is encircling the outer rim of the solar system just beyond Neptune. The needle-in-a-haystack object found by Hubble is only 3,200 feet across and a whopping 4.2 billion miles away. The smallest Kuiper Belt Object (KBO) seen previously in reflected light is roughly 30 miles across, or 50 times larger. This is the first observational evidence for a population of comet-sized bodies in the Kuiper Belt that are being ground down through collisions. The Kuiper Belt is therefore collisionally evolving, meaning that the region’s icy content has been modified over the past 4.5 billion years.

The object detected by Hubble is so faint — at 35th magnitude — it is 100 times dimmer than what Hubble can see directly.

So then how did the space telescope uncover such a small body? In a paper published in the December 17th issue of the journal Nature, Hilke Schlichting of the California Institute of Technology in Pasadena, Calif., and her collaborators are reporting that the telltale signature of the small vagabond was extracted from Hubble’s pointing data, not by direct imaging.

Hubble has three optical instruments called Fine Guidance Sensors (FGS). The FGSs provide high-precision navigational information to the space observatory’s attitude control systems by looking at select guide stars for pointing. The sensors exploit the wavelike nature of light to make precise measurement of the location of stars. Schlichting and her co-investigators determined that the FGS instruments are so good that they can see the effects of a small object passing in front of a star. This would cause a brief occultation and diffraction signature in the FGS data as the light from the background guide star was bent around the intervening foreground KBO.

They selected 4.5 years of FGS observations for analysis. Hubble spent a total of 12,000 hours during this period looking along a strip of sky within 20 degrees of the solar system’s ecliptic plane, where the majority of KBOs should dwell. The team analyzed the FGS observations of 50,000 guide stars in total. Scouring the huge database, Schlichting and her team found a single 0.3-second-long occultation event. This was only possible because the FGS instruments sample changes in starlight 40 times a second. The duration of the occultation was short largely because of the Earth’s orbital motion around the Sun.

They assumed the KBO was in a circular orbit and inclined 14 degrees to the ecliptic. The KBO’s distance was estimated from the duration of the occultation, and the amount of dimming was used to calculate the size of the object. “I was very thrilled to find this in the data,” says Schlichting. Hubble observations of nearby stars show that a number of them have Kuiper Belt–like disks of icy debris encircling them. These disks are the remnants of planetary formation. The prediction is that over billions of years the debris should collide, grinding the KBO-type objects down to ever smaller pieces that were not part of the original Kuiper Belt population.

The finding is a powerful illustration of the capability of archived Hubble data to produce important new discoveries. In an effort to uncover additional small KBOs, the team plans to analyze the remaining FGS data for nearly the full duration of Hubble operations since its launch in 1990.

http://hubblesite.org/newscenter/archive/releases/2009/33/full/

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Happy Christmas – From Hubble

Dec 16

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And all of creation was contained therein

And all of creation was contained therein

December 15, 2009: Just in time for the holidays: a Hubble Space Telescope picture postcard of hundreds of brilliant blue stars wreathed by warm, glowing clouds. The festive portrait is the most detailed view of the largest stellar nursery in our local galactic neighborhood. The massive, young stellar grouping, called R136, is only a few million years old and resides in the 30 Doradus Nebula, a turbulent star-birth region in the Large Magellanic Cloud (LMC), a satellite galaxy of our Milky Way. There is no known star-forming region in our galaxy as large or as prolific as 30 Doradus. Many of the diamond-like icy blue stars are among the most massive stars known. Several of them are over 100 times more massive than our Sun. These hefty stars are destined to pop off, like a string of firecrackers, as supernovas in a few million years.

The image, taken in ultraviolet, visible, and red light by Hubble’s Wide Field Camera 3, spans about 100 light-years. The nebula is close enough to Earth that Hubble can resolve individual stars, giving astronomers important information about the birth and evolution of stars in the universe. The Hubble observations were taken Oct. 20-27, 2009. The blue color is light from the hottest, most massive stars; the green from the glow of oxygen; and the red from fluorescing hydrogen.

http://hubblesite.org/newscenter/archive/releases/2009/32

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