Posted on by Ian O'Neill

Feeding Time at the Stellar Zoo: Infant Stars Generate Lots of Gas

Artist's impression of a young star with surrounding disk of dust (ESO/L. Calçada)

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Understanding how stars form is critical to astronomers. If we can gain a better understanding of how intermediate-size infant stars grow, we can begin to answer some of the most perplexing questions hanging over the evolution of our own Solar System. Unfortunately, the nearest star forming regions are about 500 light years away, meaning that astronomers cannot simply use traditional optical telescopes to peer into star-forming disks of gas and dust. So, researchers working with the European Southern Observatory (ESO) are combining high resolution spectroscopic and interferometry observations to give the most detailed view yet of infant stars eating away at their proto-planetary disk, blasting out violent stellar winds as they do so…

It sounds like baby stars are very much like their human counterparts. They need a conveyor belt of food supplying their development and they blast huge amounts of waste back out in the form of gas. These findings come from researchers using the ESO’s Very Large Telescope Interferometer (VLTI), giving us milli-arcsecond resolution when focusing on these star-forming regions. The detail this provides is equivalent to studying the period (‘full stop’ as I prefer to call it) at the end of this sentence at a distance of 50 km (31 miles).

This high resolution is achieved by combining the light from two or more telescopes separated by a certain distance. This distance is known as the “baseline,” and interferometers such as the VLTI have a large baseline (of up to 200 metres), simulating a telescope diameter equivalent to this distance. However, the VLTI now has another trick up its sleeve. The AMBER spectrometer can be used in conjunction with the interferometer observations to give a more complete view of these feeding stars, probing deep into the spectrum of light being emitted from the region.

“So far interferometry has mostly been used to probe the dust that closely surrounds young stars. But dust is only one percent of the total mass of the discs. Their main component is gas, and its distribution may define the final architecture of planetary systems that are still forming.” – Eric Tatulli, co-leader of the VLTI international collaboration from Grenoble, France.

The Herbig Ae/Be star R Coronae Australis, a young intermediate-size star (2MASS)
The Herbig Ae/Be star R Coronae Australis, a young intermediate-size star (2MASS)
Using the combined power of the VLTI and AMBER instrument, astronomers have been able to map this gas surrounding six stars belonging to the Herbig Ae/Be family. These particular stars are typically less than 10 million years old and a few times the mass of our Sun. They are very active stars in the process of forming, dragging huge amounts of material from a surrounding disk of dust.

Until now, astronomers have not been able to detect gas emission from young stars feeding on their stellar disks, thereby keeping the physical processes acting close to the star a mystery.

“Astronomers had very different ideas about the physical processes that have been traced by the gas. By combining spectroscopy and interferometry, the VLTI has given us the opportunity to distinguish between the physical mechanisms responsible for the observed gas emission,” says co-leader Stefan Kraus from Bonn in Germany. In two of the Herbig Ae/Be stars, there is evidence for a large quantity of dust falling into them, thereby increasing their masses. In four cases, there is evidence for a strong stellar wind, forming an extended stellar gas outflow.

The VLTI observations also reveal dust from the surrounding disk is much closer than one would expect. Usually there is a cut-off distance for dust location as the stars heat will cause it to vaporize. However, it would appear in one case that gas between the star and dusty disk shields the dust from evaporating; the gas acts as a radiation-block, allowing the dust to extend closer to the star.

“Future observations using VLTI spectro-interferometry will allow us to determine both the spatial distribution and motion of the gas, and might reveal whether the observed line emission is caused by a jet launched from the disc or by a stellar wind“, Kraus added.

These phenomenal observations of star-forming dust disks and gas emission, 500 light years away, open up a new kind of high-resolution astronomy. This will help us understand how our Sun fed off its surrounding disk of dust, eventually forming the planets and, ultimately, how life on Earth was possible…

Source: ESO

Posted on by Nancy Atkinson

NASA Confirms ISS Crew Will Expand to Six in 2009

The ISS had a full house during the STS-124 mission. Credit:NASA

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A Russian official misspoke last weekend when he said the number of crew members on board the International Space Station probably wouldn’t increase next year as planned. On Saturday, Roscosmos head Anatoly Perminov said, “I doubt that the ISS crew will be increased to six people from next year because the final decision has not been taken yet. All countries participating in the ISS program have to decide it.” But today NASA spokesman Kelly Humphries said Perminov made a mistake. “There are no impediments for going forward with expanding the crew size from three to six,” Humphries told Universe Today. The issue was also discussed during a press conference with the space station crew, including the newly arrived crew of three that launched on a Soyuz rocket on Sunday: U.S. astronaut Mike Fincke, Russian cosmonaut Yury Lonchakov and U.S. space tourist Richard Garriott.

NASA and the international partners working together to construct the ISS want to increase the crew size in order to expand the capability to conduct research. But in order to boost the crew size, the station must be able to recycle condensation, cooling water and even urine to provide enough potable water for the astronauts, their experiments and the station’s U.S. oxygen generator. Additional astronaut sleep stations, a second toilet (and repairing the one already on board) and a second galley also must be delivered, installed and checked out.

Fincke said the main mission during his Expedition 18 is to get the space station, currently sized for three people, up and running and ready to go for six people. “It’s going to take a lot of work, but it’s the next step in getting the space station fully operational. We’ve got the right team for it,” he said. Fincke will take over as commander of the station on Oct. 22.

Sources: UPI, SpaceflightNow.com,

Posted on by Ian O'Neill

Hottest Ever Exoplanet Discovered: WASP-12b

WASP-12b orbits so close to its star that it is heated to a record-breaking 2250°C (ESA/C Carreau)

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Planets approximately the size of Jupiter orbiting close to their star in other systems are often referred to as “Hot Jupiters.” It would appear that a new classification is required: Very Hot and Very Fast Jupiters. WASP-12b is an exoplanet, about 50% more massive than Jupiter, orbiting a star (imaginatively called WASP-12) over 800 light years away, but it isn’t any ordinary exoplanet. It orbits its host star 1/40th of the distance at which the Earth orbits the Sun and it takes a breathtaking one day to complete one orbit. As a consequence, its host star heats WASP-12b to record-breaking temperatures; the planet is being toasted up to 2250 °C. For an exoplanet of this size, to be orbiting so close to a star has caused a stir amongst planet hunters. WASP-12b is and oddity, there’s nothing else like it… so far.

This new discovery originates from the UK’s Wide Area Search for Planets, a.k.a. “SuperWASP”. SuperWASP is a robotic system surveying both hemispheres, consisting of two observatories (one in the Canary Islands, off the coast of Africa, called SuperWASP-North; one in South Africa called SuperWASP-South) with eight cameras in both. The north and south observatories are on the look out for extrasolar planets, but rather than focusing on one star and seeing whether it wobbles (thereby giving away the presence of the gravitational pull of an orbiting planet), SuperWASP looks out for the periodic dimming of stars as their companion planets pass in front of them. Since it began operations in 2004, the two observatories have found 15 transiting exoplanets (as of April 2008).

Artist illustration of the planet orbiting the sun-like star HD 149026 (U.C. Santa Cruz)
Artist illustration of the planet orbiting the sun-like star HD 149026 (U.C. Santa Cruz)
Now, astronomers have focused their attentions on one rather strange exoplanet. When WASP-12b was first seen by the robotic planet spotters, researchers knew they were on to something special. The speed at which WASP-12b was transiting its host star (WASP-12) indicated that it had an orbital period of only 1.1 (Earth) days. This therefore meant that it had to be located very close to the star. This meant that it was going to be hot. Very, very hot in fact. Early estimates put WASP-12b’s surface temperature into the record-breaking range, possibly challenging the calculated temperature of HD 149026b, an exoplanet some 257 light-years away in the constellation of Hercules, with an estimated temperature of 2050°C. WASP-12b has an estimated surface temperature of 2250°C – that’s half as hot as the temperature of our Sun’s photosphere, and approximately the same temperature as many Class M stars.

Although impressive, there may be hotter “Hot Jupiters” out there, but the orbital velocity of WASP-12b will be a tougher record to beat. To date, most Jupiter-sized exoplanets have orbital periods of a few days, which led astronomers to believe there was some planetary mechanism preventing these planets from migrating very close to their host stars. Although Jupiter-like planets will have formed further away from their stars, they drift closer as they evolve until they settle into a stable orbit. Usually these orbits are located far away from the star, but WASP-12b obviously didn’t read the rule book before it set up home in its stellar oven.

“When the planets form and migrate inward, something is causing them to stop and preferentially stop with a period of three days,” said Leslie Hebb of the University of St Andrews, UK. “I was surprised that the period could be so much shorter.”

So WASP-12b has a strange orbit, making it orbit very fast, causing it to be heated to astounding temperatures. But the strangeness doesn’t stop there. It has a diameter 1.8 times that of Jupiter, far bigger than gas giants are thought to grow. However, the extreme temperatures WASP-12b is experiencing may explain its obesity problem – the star could be causing the planet to “puff up,” making the gas giant less dense, but blowing it 80% larger than Jupiter proportions.

Now, SuperWASP researchers hope to probe the planetary system for UV light radiating from the exoplanet, possibly showing evidence that WASP-12b’s atmosphere is undergoing aggressive stripping or evaporation at such close proximity to the host star.

Source: New Scientist

Posted on by Nancy Atkinson

Where In The Universe Challenge — With a New Twist

Here’s the image for this week’s “Where In The Universe” challenge. But we’re going to try something different this time. Several readers have suggested (and maybe even begged) that we don’t reveal the answer right away, but allow everyone a chance to mull over the image and provide their answer in the comment section. Then tomorrow, I’ll post the answer and you can see how you did. So here you go: Take a look at the image above and try to determine where in the universe this image was taken. Give yourself extra points if you can name the spacecraft responsible for taking this image. Post your answers in the comments (if you’re brave enough!) and check back tomorrow for the answer. Good luck!

Posted on by Nancy Atkinson

The Violent Variations of Black Holes

Artist impression of a black hole. Credit: ESO/L. Calçada

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What is the environment around a black hole really like? Astronomers are getting a better idea by observing the light coming from the accretion disk surrounding black holes. The light is not constant — it flares, sputters and sparkles – and this flickering provides new and surprising insights into the colossal amount of energy emanating from around black holes. By mapping out how well the variations in visible light match those in X-rays on very short timescales, astronomers have shown that magnetic fields must play a crucial role in the way black holes swallow matter.

“The rapid flickering of light from a black hole is most commonly observed at X-ray wavelengths,” says Poshak Gandhi, who led the international team that reports these results. “This new study is one of only a handful to date that also explore the fast variations in visible light, and, most importantly how these fluctuations relate to those in X-rays.”

The observations tracked the flickering of the black holes simultaneously using two different instruments, one on the ground and one in space. The X-ray data were taken using NASA’s Rossi X-ray Timing Explorer satellite. The visible light was collected with the high speed camera ULTRACAM, a visiting instrument at ESO’s Very Large Telescope (VLT), recording up to 20 images a second. ULTRACAM was developed by team members Vik Dhillon and Tom Marsh. “These are among the fastest observations of a black hole ever obtained with a large optical telescope,” says Dhillon.

To their surprise, astronomers discovered that the brightness fluctuations in the visible light were even more rapid than those seen in X-rays. In addition, the visible-light and X-ray variations were found not to be simultaneous, but to follow a repeated and remarkable pattern: just before an X-ray flare the visible light dims, and then surges to a bright flash for a tiny fraction of a second before rapidly decreasing again.

Watch a movie of the fluctuations.

None of this radiation emerges directly from the black hole, but from the intense energy flows of electrically charged matter in its vicinity. The environment of a black hole is constantly being reshaped by a competing forces such as gravity, magnetism and explosive pressure. As a result, light emitted by the hot flows of matter varies in brightness in a muddled and haphazard way. “But the pattern found in this new study possesses a stable structure that stands out amidst an otherwise chaotic variability, and so, it can yield vital clues about the dominant underlying physical processes in action,” says team member Andy Fabian.

The visible-light emission from the neighborhoods of black holes was widely thought to be a secondary effect, with a primary X-ray outburst illuminating the surrounding gas that subsequently shone in the visible range. But if this were so, any visible-light variations would lag behind the X-ray variability, and would be much slower to peak and fade away. “The rapid visible-light flickering now discovered immediately rules out this scenario for both systems studied,” asserts Gandhi. “Instead the variations in the X-ray and visible light output must have some common origin, and one very close to the black hole itself.”

Strong magnetic fields represent the best candidate for the dominant physical process. Acting as a reservoir, they can soak up the energy released close to the black hole, storing it until it can be discharged either as hot (multi-million degree) X-ray emitting plasma, or as streams of charged particles travelling at close to the speed of light. The division of energy into these two components can result in the characteristic pattern of X-ray and visible-light variability.

Papers on this research: Here and Here

Source: ESO

Posted on by Nancy Atkinson

18-Year-Old Rocket Motor Found in Australian Outback

A solid rocket motor casing from a commercial U.S. Delta 2 launch vehicle was found inAustralia, nearly 18 years after it reentered. Picture by Michael White

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This just in from ‘The Sky is Falling’ Department: NASA’s Orbital Debris Newsletter reports that a launch vehicle rocket motor casing was found by ranchers in the Australian Outback during a cattle round-up on a three million-acre pasture property. It was first spotted by Mr. Arthur Taylor who was flying a Cessna aircraft to look for stray cattle. The casing appeared in relatively good condition (see picture above) and did not seem to be very old. Mr. Michael White forwarded numerous photos of the object to the NASA Orbital Debris Program Office, including one with a clear serial number next to the nozzle attachment point. Using the serial number, NASA Kennedy Space Center personnel were able to trace the motor casing to a a specific mission.

The casing came from a Delta 2 rocket used on June 2, 1990 to launch the Indian INSAT-1D geosynchronous spacecraft from the Cape Canaveral Air Force Station, Florida. This solid rocket motor served as the launch vehicle’s third stage which carried the payload from a low altitude parking orbit into a geosynchronous transfer orbit. (If you want to trace it yourself, here are the particulars: U.S. Satellite Number 20645, International Designator 1990-051C), Reentry of the stage occurred a few months later.

This isn’t the first time rocket casings have been found in Australia, and this object joins similar solid rocket motor casings found in Saudi Arabia, Thailand, and Argentina during the past several years.

Yikes!

Sources: CollectSpace, NASA’s Orbital Debris Program

Posted on by Ian O'Neill

Space Tourist Garriott Docks with Station (Videos)

The Soyuz TMA-13 approaches the Space Station alongside another Soyuz spaceship, set to return Garriott in 10 days (NASA)

[/caption]The Soyuz TMA-13 carrying Expedition 18 to the International Space Station (ISS) has successfully docked, delivering astronaut Mike Fincke, cosmonaut Yuri Lonchakov and space tourist Richard Garriott. The Soyuz spaceship docked with the Zarya module ahead of schedule over breathtaking views of southern Asia. Richard Garriott, a 47 year-old computer games entrepreneur and son of retired US astronaut Owen Garriott, spent $30 million for the privilege of spending ten days travelling to, and living on the orbital outpost. To appreciate how the Earth has changed in the 35 years since his father first looked down on Earth from the US Skylab space station, Garriott Jr. will spend some of his time taking photos of our planet so the images can be compared…

It looked like a flawless docking procedure between the Soyuz spacecraft and the ISS over the scenic backdrop of the Earth. Soyuz gently floated toward its dock with the Russian-built Zarya module along side the Soyuz TMA-12 that carried Expedition 17 to the station back in April. The already parked Soyuz will be the return vehicle in eight days time (on October 23rd) for cosmonauts Sergei Volkov and Oleg Kononenko who will chaperone Richard Garriott back to solid ground at the end of his space “vacation.” Volkov and Kononenko, members of Expedition 17 have spent six months in space.

View the Soyuz TMA-13 dock with the space station »

'Running the lockers' inside Skylab. (NASA)
'Running the lockers' inside Skylab. (NASA)
Now that Garriott is getting settled in his temporary orbital home, he only has a short time to complete all the tasks he has set. As the sixth space tourist to visit the space station, he will obviously enjoy the views, but Garriott is also keen to follow in his father’s footsteps. Owen Garriott lived and worked on Skylab in 1973 for 59 days and he found that by running around the circumference of the station, that he was able to build up enough centrifugal force to remain in contact with the sides. Although Garriott Jr. is keen to try this zero-gravity activity out for himself, the International Space Station doesn’t have a large enough volume.

“I have been trying to figure out where on the International Space Station could this best be performed,” Richard said. “One of the great things about Skylab is that it had this massive internal volume and this nice ring of lockers that gave you a relatively smooth surface to make that attempt and a reasonable diameter so that at a nice jog pace, the centrifugal force would do a reasonable job of holding you to the outside wall. The ISS’s diameter is much smaller.” So it would appear that “running the lockers” as Owen called it, will not be possible on board the ISS. I guess they don’t make space stations like they used to…

View the Expedition 18 crew arrive on the space station, being welcomed by Sergei Volkov and Oleg Kononenko »

Jogging inside the space station to one side, the Expedition 18 crew will begin to supervise the start-up of new life-support equipment for the station. This is one of the steps to ensure that the station can accommodate six full-time crewmembers as from the planned expansion in May 2009.

Sources: BBC [1] [2], collectSPACE

Posted on by Nancy Atkinson

Martian Dust Storm Hampers Phoenix Lander’s Activities

Dust storm on Mars. Credit: MARCI Science Team

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The science team for the Phoenix Lander was forced to curtail many of their activities over the weekend because of a regional dust storm that temporarily lowered the lander’s solar power. But Phoenix weathered the storm well, and the team is back investigating the Red Planet’s northern plains. The 37,000 square-kilometer storm (nearly 23,000 miles) moved west to east, and weakened considerably by the time it reached the lander on Saturday, Oct. 11. The science team was expecting the worst, so this tamer storm put the spacecraft in a better than expected situation, said Ray Arvidson of Washington University in St. Louis, the lead scientist for Phoenix’s Robotic Arm.

The lander is now back to busily collecting samples and weather data, analyzing the soil samples, and conducting other activities before fall and winter stop Phoenix cold.

“Energy is becoming an issue, so we have to carefully budget our activities,” Arvidson said.

The Phoenix team tracked the dust storm last week through images provided by the Mars Reconnaissance Orbiter’s Mars Color Imager. The imager’s team estimated that after the dust storm passed through Phoenix’s landing site on Saturday, the dust would gradually decrease this week.

This dust storm is a harbinger of more wintry and volatile weather to come. As Martian late summer turns into fall, the Phoenix team anticipates more dust storms, frost in trenches, and water-ice clouds. They look forward to collecting data and documenting this “most interesting season,” Arvidson said.

Source: Phoenix News Site

Posted on by Nancy Atkinson

Procedure to Repair Hubble Begins Wednesday

The Hubble Space Telescope. Credit: NASA

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The procedure to begin “brain surgery” on the Hubble Space Telescope will begin at 6:00 am EDT (10:00 GMT) on October 15. The venerable space telescope will be put into electronic hibernation; then engineering teams will work from the ground around the clock for two days to reconfigure a data handler system which failed two weeks ago. If the procedure is successful, science operations could resume as early as Friday, October 17. The Control Unit/Science Data Formatter, which relays science data to Earth, is a redundant system, with two sides. Side A has been used exclusively since the telescope’s launch over 18 years ago in 1990. Side B hasn’t been powered on since well before launch. “It is obviously a possibility that things will not come up,” said Art Whipple, manager of the Hubble Space Telescope Systems Management office at the Goddard Spaceflight Center in Greenbelt, Md. “We have very good confidence this will work. In addition, we have contingency plans built in at each step of the transition where if something does not go the way we expect it to, we’ll be able to back out and go down an alternate path.”

Whipple said there is very little aging that goes on with an unpowered component in space. “It’s actually a very benign storage environment,” he said.

In addition six associated components have to be switched over to a redundant side as well. “Five of the six redundant components in this data management system that will be brought on line have also not been powered since 1990,” said Whipple. “The command procedures to accomplish this transition have been thoroughly tested.”

Engineers and mission managers have been working the past two weeks, devising a plan and testing procedures. NASA headquarters gave approval for the activation on Tuesday.

The planned Hubble Servicing Mission 4, shuttle mission STS-125, would have launched today (Oct. 14) if the data handler had not gone off line. NASA has re-set a tentative launch date for mid-February. The seven member crew, commanded by veteran Scott Altman, will perform five back-to-back spacewalks to add new cameras, (the Wide Field Camera 3 (WFC3) and the Cosmic Origins Spectrograph), replace old batteries and gyroscopes, add docking equipment and upgrade the telescope’s guidance system. The astronauts will also attempt to fix the Space Telescope Imaging Spectrograph (STIS) and the Advanced Camera for Surveys (ACS). Those two were never designed to be repaired in orbit. In addition, a spare data handler system will brought up, after engineers test and certify the unit. That unit has not been turned on since 1992.

It has yet to be determined if the spare data handler will be ready by mid-February, and if the astronauts can be trained ready for the additional work required for the unit switch-out.

“We think in the first week or two in November we will have a much better handle on the actual state of the hardware,” Whipple said. “The paperwork says February should be supportable, but we should have much higher confidence (in November).”

Sources: NASA press release, NASA news conference

Posted on by Fraser Cain

Mass of the Moon

NASA's image of the Moon

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The mass of the Moon is 7.347 x 1022 kg.

That sounds like a large number, and I suppose it is compared to the mass of a single person, a car or even a building. But you’ve got to keep it in context. The mass of the Moon is only 1.2% the mass of the Earth. In other words, you would need 81 objects with the mass of the Moon to match the mass of the Earth.

The diameter of the Moon is only about 1/4 the diameter of the Earth, so it might seem like the mass of the Moon is strangely low. And you would be right. The key is the Moon’s low density. It has a density of only 3.3 g/cm3. This is almost half the density of Earth.

Astronomers think that a Mars-sized object crashed into the Earth about 100 million years after the Earth formed. The huge cloud of ejected debris coalesced into the Moon, which still orbits us today. The Moon has a lower density because the impact gouged out the outer crust and mantle, and didn’t eject so much of the Earth’s iron core.

Want more information about the mass of the Earth? Or what about the mass of Mars?

The Physics Factbook has more information about the mass of the Moon. And here’s an article that explains how you would go about weighing the Moon.

You can listen to a very interesting podcast about the formation of the Moon from Astronomy Cast, Episode 17: Where Did the Moon Come From?

Reference:
NASA Moon Facts