High School Student Discovers Strange Pulsar-Like Object

When Lucas Bolyard looked at the bottom plot, he noticed the thick, black blob left of the center. He saw that this signal was positioned on the graph where it indicated a non-zero "dispersion measure," or DM. Dispersion measure is used by astronomers as an indicator of cosmic distances. The non-zero DM value of this pulse is a clue that the signal came from space, not from Earth. The other blobs on the bottom of the graph are signals at a distance of zero-- that is from here on Earth. CREDIT: NRAO/AUI/NSF

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A high-school student from West Virginia has discovered a new astronomical object, a strange type of neutron star called a rotating radio transient. Lucas Bolyard, a sophomore at South Harrison High School in Clarksburg, WV, made the discovery while participating in a project in which students are trained to search through data from the Robert C. Byrd Green Bank Telescope (GBT). Bolyard made the discovery in March, after he already had studied more than 2,000 data plots from the GBT and found nothing.

The project is the Pulsar Search Collaboratory (PSC), which allows students to do real scientific research by looking at data from the GBT, the largest radio telescope in the US.

Lucas Bolyard CREDIT: NRAO/AUI/NSF
Lucas Bolyard CREDIT: NRAO/AUI/NSF

“Lucas is one of the most enthusiastic students involved in the project,” said Duncan Lorimer, astronomer from West Virginia University. “He’s one of these youngsters that never gives up, he’s very persistent and he has all the attributes that a scientist should have.”

Rotating radio transients are thought to be similar to pulsars, superdense neutron stars that are the corpses of massive stars that exploded as supernovae. Pulsars are known for their lighthouse-like beams of radio waves that sweep through space as the neutron star rotates, creating a pulse as the beam sweeps by a radio telescope. While pulsars emit these radio waves continuously, rotating radio transients emit only sporadically, one burst at a time, with as much as several hours between bursts. Because of this, they are difficult to discover and observe, with the first one only discovered in 2006.

“This neutron star is rotating very rapidly, so you have something the size of city with the mass of the sun, spinning incredibly rapidly,” said Lorimer “which also has an incredibly large magnetic field which is how we detect it with radio telescopes.”

“These objects are very interesting, both by themselves and for what they tell us about neutron stars and supernovae,” said Maura McLaughlin, also from WVU. “We don’t know what makes them different from pulsars — why they turn on and off. If we answer that question, it’s likely to tell us something new about the environments of pulsars and how their radio waves are generated.”

“They also tell us there are more neutron stars than we knew about before, and that means there are more supernova explosions. In fact, we now almost have more neutron stars than can be accounted for by the supernovae we can detect,” she added.

Robert C. Byrd Green Bank Telescope CREDIT: NRAO/AUI/NSF
Robert C. Byrd Green Bank Telescope CREDIT: NRAO/AUI/NSF

“I was home on a weekend and had nothing to do, so I decided to look at some more plots from the GBT,” Bolyard said. “I saw a plot with a pulse, but there was a lot of radio interference, too. The pulse almost got dismissed as interference,” he added.

Nonetheless, he reported it, and it went on a list of candidates for McLaughlin and Lorimer to re-examine, scheduling new observations of the region of sky from which the pulse came. Disappointingly, the follow-up observations showed nothing, indicating that the object was not a normal pulsar. However, the astronomers explained to Bolyard that his pulse still might have come from a rotating radio transient.

Confirmation didn’t come until July. Bolyard was at the NRAO’s Green Bank Observatory with fellow PSC students. The night before, the group had been observing with the GBT in the wee hours, and all were very tired. Then Lorimer showed Bolyard a new plot of his pulse, reprocessed from raw data, indicating that it is real, not interference, and that Bolyard is likely the discoverer of one of only about 30 rotating radio transients known.

Suddenly, Bolyard said, he wasn’t tired anymore. “That news made me full of energy,” he exclaimed. “My friends were really excited because they think I’m going to be famous!”

As of a year ago, Bolyard said he wouldn’t have thought of becoming astronomer, but this has given him second thoughts. “Making this discovery has made me very excited to get into a scientific field,” he said. “It’s a lot of hard work, but it’s worth it.”

The PSC, led by NRAO Education Officer Sue Ann Heatherly and Project Director Rachel Rosen, includes training for teachers and student leaders, and provides parcels of data from the GBT to student teams. The project involves teachers and students in helping astronomers analyze data from 1500 hours of observing with the GBT. The 120 terabytes of data were produced by 70,000 individual pointings of the giant, 17-million-pound telescope. Some 300 hours of the observing data were reserved for analysis by student teams.

Learn more about the PSC and Bolyard’s discovery on the Sept. 18 edition of 365 Days of Astronomy.

NRAO has a video about the discovery.

The student teams use analysis software to reveal evidence of pulsars. Each portion of the data is analyzed by multiple teams. In addition to learning to use the analysis software, the student teams also must learn to recognize man-made radio interference that contaminates the data. The project will continue through 2011.

“The students get to actually look through data that has never been looked through before,” Rosen said. From the training, she added, “the students get a wonderful grasp of what they’re looking at, and they understand the science behind the plots that they’re looking at.”

Source: NRAO

Battlestar Photoshopica: Otto Travels to Pluto

Otto the Dachshund traveling through the Hubble Deep Field. Created by Ralph Petrozello

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Our “Astro Art” feature needs a catchier name, and frankly we need more people to read this feature or it will be toast. So here’s the new name: Battlestar Photoshopica, suggested by UT reader Dave Finton. And spread the word about these very cool posts which showcase our readers’ prowess with digital image editing software. Here’s this week’s edition, which is probably the cutest image we’ve ever received. This is Otto the Dachshund, created by Ralph Petrozello. Otto is on his way to Pluto. Really. This image was chosen by The Planetary Society to be part of the New Horizons Digital Time Capsule, on board the New Horizons spacecraft on its way to Pluto. The time capsule consists of photographs of things in 2006 that people expect will be transformed by 2015, when the spacecraft arrives at Pluto. Only fifty photos were selected, and this is one of them.

Ralph told us more about this image:

“I took a photo of my Dachshund, Otto, reflected in a car’s rear view mirror while he was looking out the window with his sun glasses on. (…he really wore them,) Ralph said. “I replaced the background of the photo with the Hubble Deep Field image, and the reflection in his sun glasses so it appeared as though he was traveling through space towards Pluto, looking out towards the “Andromeda Galaxy” going by. The photo also captured the words on the mirror, “Objects In Mirror Are Closer Than They Appear”…which Otto was to me.”

“Otto is gone now, …but I know his memory will live on.”

Ralph is a member of the I forgot to mention that I am also a member of the San Diego Astronomy Association.

For more info on the New Horizons Digital Time Capsule, see the Planetary Society’s website.

Earth’s Circumference

Blue marble Earth. Image credit: NASA

The Earth’s circumference – the distance around the equator – is 40,075 kilometers around. That’s sounded nice and simple, but the question is actually more complicated than that. The circumference changes depending on where you measure it. The Earth’s meridional circumference is 40,008 km, and its average circumference is 40,041 km.

Why are there different numbers for the Earth’s circumference? It happens because the Earth is spinning. Think about what happens when you spin around holding a ball on a string. Your rotation creates a force that holds the ball out on the end of the string. And if the string broke, the ball would fly away. Even though the Earth is a solid ball of rock and metal, its rotation causes it to flatten out slightly, bulging at the equator.

That bulge isn’t very much, but when you subtract the meridional circumference (the equator when you pass through both poles), and the equatorial circumference, you see that it’s a difference of 67 km. In other words, if you drove your car around the equator of the Earth, you would drive an extra 67 km than you would if you drove from pole to pole to pole.

And that’s why the average circumference of Earth is 40,041 km. Which answer is correct? It depends on how accurate you want to be with your calculation.

We have written many articles about the Earth for Universe Today. Here’s an article about how fast the Earth rotates, and here’s an article about how round the Earth is.

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.

New Chandra Deep X-ray Image of the Galactic Center

•A deep new image of the center of the Milky Way by the Chandra X-ray Observatory. NASA/CXC/UMass/D. Wang et al.

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Chandra has done it again in creating some of the most visually stunning images of our Universe. This time, Chandra’s X-ray eyes show a dramatic new vista of the center of the Milky Way galaxy. This mosaic from 88 different images exposes new levels of the complexity and intrigue in the Galactic center, providing a look at stellar evolution, from bright young stars to black holes, in a crowded, hostile environment dominated by a central, supermassive black hole.

Permeating the region is a diffuse haze of X-ray light from gas that has been heated to millions of degrees by winds from massive young stars – which appear to form more frequently here than elsewhere in the Galaxy – explosions of dying stars, and outflows powered by the supermassive black hole – known as Sagittarius A* (Sgr A*). Data from Chandra and other X-ray telescopes suggest that giant X-ray flares from this black hole occurred about 50 and about 300 years earlier.

See this link for an animation that provides greater detail of the galactic center.

The area around Sgr A* also contains several mysterious X-ray filaments. Some of these likely represent huge magnetic structures interacting with streams of very energetic electrons produced by rapidly spinning neutron stars or perhaps by a gigantic analog of a solar flare.

Scattered throughout the region are thousands of point-like X-ray sources. These are produced by normal stars feeding material onto the compact, dense remains of stars that have reached the end of their evolutionary trail – white dwarfs, neutron stars and black holes.

Because X-rays penetrate the gas and dust that blocks optical light coming from the center of the galaxy, Chandra is a powerful tool for studying the Galactic Center. This image combines low energy X-rays (colored red), intermediate energy X-rays (green) and high energy X-rays (blue).

The image is being released at the beginning of the “Chandra’s First Decade of Discovery” symposium being held in Boston, Mass. This four-day conference will celebrate the great science Chandra has uncovered in its first ten years of operations. To help commemorate this event, several of the astronauts who were onboard the Space Shuttle Columbia – including Commander Eileen Collins – that launched Chandra on July 23, 1999, will be in attendance.

Source: Chandra

Carnival of Space #121

This week’s Carnival of Space is hosted by Brian Wang over at Next Big Future.

Click here to read the Carnival of Space #121.

And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, let Fraser know if you can be a host, and he’ll schedule you into the calendar.

Finally, if you run a space-related blog, please post a link to the Carnival of Space. Help us get the word out.

New Equinox Stunners From Cassini

Saturn at Equinox. credit: NASA/JPL/Space Science Institute

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Every 14.8 Earth years, equinox occurs at Saturn. But this is the first time there has been a spacecraft in situ to watch what happens when the sun is directly overhead at the equator, illuminating the rings directly edge-on. New images compiled from the Cassini spacecraft show a rare and breathtaking display of nature: the setting of the sun on Saturn’s rings. The image above — a mosaic of 75 different images — shows the beauty of this ringed world, but the most surprising revelation from these new images are that newly discovered lumps and bumps in the rings are as high as the Rocky Mountains.

Saturn's rings reaching new heights.  Credit: NASA/Space Science Institute
Saturn's rings reaching new heights. Credit: NASA/Space Science Institute

The shadows in this image have lengths as long as 500 kilometers (310 miles), meaning the structures casting the shadows reach heights of almost 4 kilometers (2.5 miles) above the ringplane. These heights are much greater than those previously observed for the Daphnis edge waves, and are very likely caused by the distance between Daphnis and the inner edge of its gap getting unusually small at certain times

“We thought the plane of the rings was no taller than two stories of a modern-day building and instead we’ve come across walls more than 2 miles [3 kilometers] high,” said Carolyn Porco, Cassini imaging team leader at the Space Science Institute in Boulder, Colo. “Isn’t that the most outrageous thing you could imagine? It truly is like something out of science fiction.”

“The biggest surprise was to see so many places of vertical relief above and below the otherwise paper-thin rings,” said Linda Spilker, deputy project scientist at JPL. “To understand what we are seeing will take more time, but the images and data will help develop a more complete understanding of how old the rings might be and how they are evolving.”

Propeller feature in the rings.  Credit: NASA/Space Science Institute
Propeller feature in the rings. Credit: NASA/Space Science Institute

An unusually large propeller feature has been detected just beyond the Encke Gap in this Cassini image of Saturn’s outer A ring, taken a couple days after the planet’s August 2009 equinox. Propeller-like features, a few kilometers long, centered on and created by the action of small embedded moonlets only about 330 feet (100 meters) across, were discovered early in the mission. These findings constituted the first recognition that bodies smaller than the 8-kilometer-wide ring moon, Daphnis, in the outer A ring and bigger than the largest ring particles (about 30 feet, or 10 meters, across) were present in Saturn’s rings.
New insights into the nature of Saturn's rings are revealed in this panoramic mosaic of 15 images taken during the planet's August 2009 equinox.
New insights into the nature of Saturn's rings are revealed in this panoramic mosaic of 15 images taken during the planet's August 2009 equinox.

Waves in the inner B ring, first seen in Saturn orbit insertion images, are now more obvious and distinct. This mosaic combines 15 separate images. Also visible are bright spokes, consisting of tiny particles elevated above the ring plane and surrounded by the dark outer B ring, can also be seen near the middle of the mosaic.
ring impacts
These two Cassini images, taken four years before Saturn’s August 2009 equinox, have taken on a new significance as data gathered at equinox indicate the streaks in these images are likely evidence of impacts into the planet’s rings.

In one unexpected equinox discovery, imaging scientists have uncovered evidence for present-day impacts onto the rings. Bright, and hence elevated, clouds of tiny particles, sheared out by orbital motion into streaks, up to 3,000 miles (5,000 kilometers) long, have been sighted in the A and C rings. These clouds — very likely thrown up by impacts — rising above the dark ring plane are more directly catching the sun’s rays during equinox, and are hence well lit and easily visible by contrast.

By the brightness and dimensions of the streaks, scientists estimate the impactor sizes at roughly one meter, and the time since impact at one to two days. These equinox data now lend more confidence to the impact interpretation of earlier Cassini images, taken in 2005, showing similar streaks in the C ring. In the 2005 images, the impactors are likely much smaller than one meter, and yet have left a visible ejecta cloud. All together, these observations are heralded as the first visual confirmation of a long-held belief that bits of interplanetary debris continually rain down on Saturn’s rings and contribute to their erosion and evolution.

Summing up the past several months of Cassini’s exploration of Saturn during this unusual celestial event, imaging team leader Carolyn Porco in Boulder, Colo., said, “This has been a moving spectacle to behold, and one that has left us with far greater insight into the workings of Saturn’s rings than any of us could have imagined. We always knew it would be good. Instead, it’s been extraordinary.”

For more images and information see CICLOPS.

Spectacular Videos of Shuttle Piggyback Flight


With the shuttle retirement looming, you never know if or how often you’re going to see this sight again. So enjoy these two videos of the shuttle hitching a piggyback ride back to Kennedy Space Center atop a modified 747. Space shuttle Discovery left Edwards Air Force Base in California on Sunday, Sept. 20 and arrived at KSC today, the 21st. Top, is the 747/shuttle landing at KSC (it gets good about 1:20 in) and below is really pretty footage of the duo getting ready to leave Edwards just at dawn, and the lighting is just plain gorgeous.
Continue reading “Spectacular Videos of Shuttle Piggyback Flight”

Reaching Near Space For Less Than $150

Earth from 93,000 feet. Long Island in the background. Credit: The 1337Arts Group


A group of MIT students have launched a low-budget satellite to near space, taking images of the curvature of Earth and the blackness of space. Their approach was to use low tech, off the shelf equipment, which included a Styrofoam beer cooler, a camera from eBay, open source software and an inexpensive helium balloon as the launch vehicle in order to do their complete mission launch for less than $150. Total cost? $148. The experience? Priceless, including getting interviewed on CNN and Fox News about their achievement. The best news for the rest of us? They’ll soon be sharing an illustrated step-by-step guide on how to launch your own low-budget satellite.

The team, led by Justin Lee and Oliver Yeh had the goal of seeing Earth from space, but didn’t have a lot of money to do it. They knew they’d have to gather all the materials for less than $150.
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Their satellite was a huge success. It reached 93,000 feet (calculated from the linear ascent rate at the beginning of the launch), took several images of Earth from space (see their gallery here) and was retrieved using an inexpensive GPS system.

They say the time lapse video above isn’t all that great because the cooler wasn’t stabilized. But the images are incredible.

Many people have launched balloons (see some of our previous articles, here and here) but this is the lowest price to space anyone has ever accomplished. The students say they hope to be an inspiration to others.

The balloon falling back to Earth after bursting.  Credit:  1337arts team.
The balloon falling back to Earth after bursting. Credit: 1337arts team.

Lee and Yeh caution about making sure future explorers contact the FAA about launching a balloon, and to launch from a safe place so the balloon and equipment doesn’t land in a highly populated area.

Next, they want to do it again, but add a rocket to the balloon to launch their payload even higher.

Check out their website for more info and the great images.

Hawking Radiation

Zero Gravity Flight
Stephen Hawking, weightless (courtesy Zero Gravity Corporation)

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When humans starve, they grow thin and eventually die; when a black hole starves, it too grows thin and dies … but it does so very spectacularly, in a burst of Hawking radiation.

At least that’s the way we understand it today (no black-hole-pining-away has yet been observed), and the theory may be wrong too.

Cosmologist, astrophysicist, and physicist Stephen Hawking showed, in 1974, that black holes should emit electromagnetic radiation with a black body spectrum; this process is also called black hole evaporation. In brief, this theoretical process works like this: particle-antiparticle pairs are constantly being produced and rapidly disappear (through annihilation); these pairs are virtual pairs, and their existence (if something virtual can be said to exist!) is a certain consequence of the Uncertainty Principle. Normally, we don’t ever see either the particle or antiparticle of these pairs, and only know of their existence through effects like the Casimir effect. However, if one such virtual pair pops into existence near the event horizon of a black hole, one may cross it while the other escapes; and the black hole thus loses mass. A long way away from the event horizon, this looks just like black body radiation.

It turns out that the smaller the mass a black hole has, the faster it will lose mass due to Hawking radiation; right at the end, the black hole disappears in an intense burst of gamma radiation (because the black hole’s temperature rises as it gets smaller). We won’t see any of the black holes in the Milky Way explode any time soon though … not only are they likely still gaining mass (from the cosmic microwave background, at least), but a one sol black hole would take over 10^67 years to evaporate (the universe is only 13 billion years old)!

There are many puzzles concerning black holes and Hawking radiation; for example, black hole evaporation via Hawking radiation seems to mean information is lost forever. The root cause of these puzzles is that quantum mechanics and General Relativity – the two most successful theories in physics, period – are incompatible, and we have no experiments or observations to help us work out how to resolve this incompatibility.

Colorado University’s Andrew Hamilton has a good introduction to this topic, as does Usenet Physics FAQ (often recognized by John Baez’ association with it).

Some Universe Today stories which include Hawking radiation are Synthetic Black Hole Event Horizon Created in UK Laboratory, How to Escape from a Black Hole, and When Black Holes Explode: Measuring the Emission from the Fifth Dimension.

Black Holes Big and Small, and The Large Hadron Collider and the Search for the Higgs-Boson are two Astronomy Casts relevant to Hawking radiation.

Sources:
Colorado University
ThinkQuest
University of California – Riverside

Chandrasekhar Limit

Subrahmanyan Chandrasekhar (credit: University of Chicago Press)

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When a human puts on too much weight, there is an increased risk of heart attack; when a white dwarf star puts on too much weight (i.e. adds mass), there is the mother of all fatal heart attacks, a supernova explosion. The greatest mass a white dwarf star can have before it goes supernova is called the Chandrasekhar limit, after astrophysicist Subrahmanyan Chandrasekhar, who worked it out in the 1930s. Its value is approx 1.4 sols, or 1.4 times the mass of our Sun (the exact value depends somewhat on the white dwarf’s composition how fast it’s spinning, etc).

White dwarfs are the end of the road for most stars; once they have used up all their available hydrogen ‘fuel’, low mass stars shed their outermost shells to form planetary nebulae, leaving a high density core of carbon, oxygen, and nitrogen (that’s a summary, it’s actually a bit more complicated). The star can’t collapse further because of electron degeneracy pressure, a quantum effect that comes from the fact that electrons are fermions (technically, only two fermions can occupy a given energy state, one spin up and one spin down).

So what happens in the core of a massive star, one whose core weighs in at more than 1.4 sols? As long as the star is still ‘burning’ nuclear fuel – helium, then carbon etc, then neon, then … – the core will not collapse because it is very hot (electron degeneracy pressure won’t hold it up ’cause it’s too massive). But once the core gets to iron, no more burning is possible, and the core will collapse, spectacularly, producing a core collapse supernova.

There is a way a white dwarf can go out with a bang rather than a whimper; by getting a little help from a friend. If the white dwarf has a close binary companion, and if that companion is a giant star, some of the hydrogen in its outer shell may end up on the white dwarf’s surface (there are several ways this can happen). The white dwarf thus adds mass, and every so often the thin hydrogen envelope blows up, and we see a nova. One day, though, the extra mass may put it over the limit, the Chandrasekhar limit … the temperature in its center gets high enough that the carbon ‘ignites’, the ‘flame’ spreads throughout the star, and it becomes a special kind of supernova, a Ia supernova.

For more technical details of the Chandrasekhar limit, Richard Fitzpatrick of the University of Texas at Austin has an online Thermodynamics & Statistical Mechanics course, which includes a page on the Chandrasekhar limit.

Supernovae are very important to astronomy, so you won’t be surprised to learn that there are lots of Universe Today stories on the Chandrasekhar limit! Some examples: White Dwarf Theories Get More Proof, White Dwarf “Close” to Exploding as Supernova, and Colliding White Dwarfs Caused a Powerful Supernova.

Astronomy Cast Episode 90 (The Scientific Method) includes a look at how Chandrasekhar worked out the limit that now bears his name, and Where Do Stars Go When They Die? also covers this topic.

References:
Wikipedia
http://www.bluffton.edu/~bergerd/NSC_111/stars.html