Astronomy Archives

August 20, 2007December 26, 2015 by Fraser Cain

Closest Neutron Star Discovered

Canadian and US astronomers have located what is thought to be the closest neutron star ever seen. The exotic object, nicknamed Calvera after the villain in the movie “The Magnificent Seven”, is located in the constellation Ursa Minor, somewhere between 250 and 1,000 light-years away. It’s a member of a rare group of isolated neutron stars – they lack binary companions – and could be just the tip of the iceberg.

The discovering astronomers pored over a gigantic catalog of 18,000 X-ray sources captured by the German-American ROSAT satellite, which was operational between 1990 and 1999. They compared these X-ray sources to objects visible other wavelengths of light, such as infrared, visible light, and radio waves. One object, 1RXS J141256.0+792204, stood out as being visible only in X-rays.

Then they targeted the object with NASA’s Swift satellite, and performed more detailed observations. Swift was able to find the source, and confirmed that it was putting out as much X-ray energy today as had been captured by ROSAT. Then they pointed one of the most powerful telescopes on Earth, the 8.1 Gemini North Telescope in Hawaii, and couldn’t find a single optical light object down to the faintest magnitudes. It was only shining in X-rays.

According to the researchers, there are no widely accepted alternate theories for objects like Calvera, which are bright in X-rays, but faint in visible light. Either it’s an unusual example of a neutron star, or it might be a completely new kind of object. Another mystery: it’s high above the plane of the Milky Way Galaxy. It must have formed in the plane, but then somehow migrated up to its current position.

With the discovery of Calvera, astronomers think there could be many objects like this. It’s close enough that astronomers will be able to perform detailed observations with many instruments. It should yield interesting results for years to come.

Original Source: PSU News Release

August 17, 2007December 26, 2015 by Fraser Cain

Dead Star Found Polluted By Earthlike Planet

Astronomers have found a burned out white dwarf star with the remants of an Earthlike planet orbiting it. This chemical fingerprint gives hope that terrestrial planets, like the ones in our Solar System, could be common across the Universe. Now we just need to find some that havn’t been pulverized into planet powder.

The white dwarf star surrounded by planetary remains is called GD 362, and it’s located about 150 light-years from Earth. Although it’s a dying star, it has a ringlike structure around it like Saturn. During their observations, astronomers from UCLA captured the distinct signature of a rocky asteroid interacting with the white dwarf.

At some point in the recent past, an asteroid was torn apart by the powerful gravitational forces around the compact object, and the dust has polluted the white dwarf’s atmosphere. The relative abundances of elements match the chemical constituents of the planets in the inner Solar System.

Here’s a comment from Michael Jura, a UCLA professor and co-author of the research:

“What we have here is a composition of the white dwarf that is fairly similar to that of the inner planets of our solar system. Are there other terrestrial planets like Earth in other solar systems? This white dwarf’s fingerprint is a significant advance in demonstrating that something like terrestrial planet formation occurred around this other star and probably occurred around other stars as well, because it suggests the Earth’s composition is not unique.”

With this discovery, astronomers have evidence that the kinds of forces that made the Earth and planets in our Solar System happened around GD 362, back when it was a newly forming star. And it gives us a glimpse into the future fate of our planet.

In approximately 5 billion years, when our Sun starts to run out of hydrogen fuel, it will expand out enormously, consuming the inner planets, and maybe even the Earth. The change in the Sun’s density will affect the orbits of all the remaining planets. Some may spiral inward and be consumed by the Sun. Others may spiral outward into interstellar space. Others may collide into smaller and smaller objects. Eventually, our Sun may have its own ring of leftover planetary material. And one of those chunks might be a piece of the Earth.

Original Source: UCLA News Release

August 16, 2007December 26, 2015 by Fraser Cain

Galaxy Cluster Collision Creates a Dark Matter Core

This strange photograph is a composite image of Abell 520, a massive cluster of galaxies in the process of colliding with one another – it’s one of the most massive structures in the Universe. Several different instruments and observatories came together to produce the image, and the final result gave astronomers a big mystery: its dark matter is behaving strangely.

When galaxies collide, three ingredients come into play: individual galaxies and their billions of stars, hot gas in between the galaxies, and the mysterious dark matter that actually makes up the bulk of the mass. Optical telescopes can see the light from the stars in the galaxies, and X-ray observatories, like Chandra can see the radiation pouring out of the superheated gas. But the presence of dark matter has to be calculated by the way it warps light from more distant objects.

During gigantic collisions like this, astronomers believed that the dark matter and galaxies should stay together, even during the most violent collisions. And this was seen in another galaxy collision: the so-called Bullet Cluster. But in the collision of Abell 520, something surprising was seen.

They found a dark matter core, containing hot gas, but no galaxies. For some reason, the galaxies were stripped away from the densest part of the dark matter. Here’s what Dr. Hendrik Hoekstra, from the University of Victoria had to say:

“It blew us away that it looks like the galaxies are removed from the densest core of dark matter. This would be the first time we’ve seen such a thing and could be a huge test of our knowledge of how dark matter behaves.”

In addition to this core, they also found a corresponding “light region”, which had galaxies, but little or no dark matter. Somehow this collision separated the dark matter from the regular matter.

So what could have stripped these two apart? One possibility is that the galaxies and dark matter were torn apart by a series of gravitational slingshots. Unfortunately, the researchers weren’t able to come up with a realistic computer simulation that had gravitational interactions powerful enough to do this.

Here’s the stranger possibility: we know that dark matter is affected by gravity, but maybe there’s also some kind of unknown interaction between particles of dark matter. This would be extremely difficult to detect since we can’t even see the stuff.

The astronomers have secured time with the Hubble Space Telescope, and will come back and take another look with its powerful gaze. This should help answer some of the mysteries they’ve unearthed.

Original Source: Chandra News Release

August 15, 2007December 26, 2015 by Fraser Cain

Self Organizing Space Dust Could Be a Precursor to Life

As if searching for life wasn’t already difficult enough, physicists now think that clouds of particles in space could mimic the behaviour of life: dividing, replicating and even evolving. This discovery could help scientists understand how life got started here on Earth, and offers intriguing possibilities for life that could evolve in the interstellar clouds of outer space.

This discovery comes from European and Australian researchers, and their work is published in today’s issue of the New Journal of Physics. They developed computer simulations that showed how clouds of molecules naturally organize themselves into complex helix-like structures that resemble DNA.

Over time, an electrical process called polarization organizes the molecules into more and more complex structures. According to the researchers, this suggests a mechanism where organic molecules could assemble faster than in previous models. This shorter time frame means that complex life could be prevalent across the Universe – they get part of the way in space, and then finish off when they reach a planet. Astronomers have already observed vast clouds of these particles out in space with radio telescopes.

Life on Earth requires water, and these molecules wouldn’t have access to the liquid in the near absolute zero temperatures of interstellar space; however, they are able to interact through this polarization process. So there might be a limit, where the structures can’t become complex enough to seed life on young planets. But this process could begin the formation of life, from a random collection of atoms to more complex molecules, and eventually the precursors of life. Evolution could then take over.

Original Source: Science Now

August 15, 2007December 26, 2015 by Fraser Cain

That’s Not a Comet, that’s a Star

If you take a quick look at the photograph with this story you’d think you’re looking at a comet. I’ve actually got it cut down the image a little to fit the website. To really see the full-sized version, check out this link. Well, that’s not a comet, it’s actually the star Mira, moving so fast through interstellar space that it’s leaving a tail behind.

Mira is an older, red giant star shedding massive amounts of material into space. As the star moves quickly through interstellar space, the particles slow down, and remain as a long tail stretching behind. In fact, this tail is 13 light-years long, or 20,000 times the average distance of Pluto from the Sun.

The image was captured by NASA’s Galaxy Evolution Explorer satellite, and the researchers announced their findings during a NASA press conference today. Their research will be published in the latest issue of the journal Nature.

Billions of years ago, Mira was probably quite similar to our own Sun. As it ran out of hydrogen fuel, the star swelled up, becoming an enormous red giant. It’s known as a variable red giant, and pulsates on a regular basis, puffing up its outer layers and brightening enough to be visible with the unaided eye. Eventually the star will run out of material, and settle down as a white dwarf star.

Since it’s traveling at 130 km/s (80 miles/s), all this material cast off by Mira builds up on the leading side; it creates a bow shock in the front, where sloughed off gas is compressed as it encounters the interstellar winds. The compression causes the gas to heat up and blaze in the ultraviolet spectrum. This material then swirls around behind the star, creating a turbulent, tail-like wake. Since the tail is only visible in the ultraviolet spectrum, it took NASA’s Galaxy Evolution Explorer -which mainly observes in ultraviolet – to find it.

Original Source: Nasa News

August 14, 2007December 26, 2015 by Fraser Cain

Hidden Galaxies Ablaze with Star Formation

We have a few pockets of star formation here in the Milky Way. But new galaxies have been discovered, 12 billion light years away, with 1000 times as much star formation. These galaxies are seen just a few billion years after the Big Bang, and they should be incredibly bright. But they aren’t; they’re hiding.

The galaxies were discovered using the AzTEC imaging camera on the James Clerk Maxwell Telescope. Under visible light, these galaxies have shrouded themselves completely in gas and dust. This camera observes in the infrared spectrum, where radiation isn’t completely obscured by dust.

The discovering astronomers first turned up several hundred candidate galaxies in the infrared and submillimeter wavelengths as part of a large survey. Then they did follow-on observations of the 7 brightest candidates using the Smithsonian’s Submillimeter array to pinpoint the exact location of each galaxy. This let them confirm that the bright candidates were indeed individual galaxies, and not clusters of galaxies blurring together.

Once they had the precise locations, they used even more powerful instruments, like Hubble, the Spitzer Space Telescope, and the Very Large Array of radio telescopes. The galaxies were hidden to Hubble, but detectable by Spitzer, which could pierce through the dust in the infrared spectrum to see the stars in the galaxy. The Very Large Array could only see two of the brightest galaxies.

Astronomers believe these galaxies have such huge levels of star formation because they have recently undergone mergers and collisions. The source of the infrared radiation is actually very compact, and the galaxies could be evolving into quasars.

Original Source: CfA News Release

August 9, 2007December 26, 2015 by Fraser Cain

The Galaxy Zoo is Busy

I introduced you to the Galaxy Zoo a few weeks ago. You know, the online site where you use your powerful human brain to help catalog galaxies for science. As I predicted in my article, the response was overwhelming.

According to a recent press release from the Galaxy Zoo project:

“The response has been breathtaking,” said Alex Szalay from Johns Hopkins University, a member of the Galaxy Zoo team. “The traffic was 20 times higher than what we hoped for. This shows the public is really interested in science if they feel they can contribute in a meaningful way.”

The public wants to make a meaningful contribution to science. I could have told them that.

Anyway, right after launch, their website was buried by visitors. In fact, the demand was so great that they blew a circuit breaker in their computer room. The team has been catching up quickly. They’ve upgraded their computer hardware, just to keep ahead of demand, and they’re already hard at work analyzing the fountains of data generated.

Here’s the funny part. At its peak, humans were classifying more than 60,000 galaxies an hour. Since their stated goal is 1 million galaxies, that should have taken them the better part of a single day to wrap up the project.

I hope someone else out there appreciates the power and enthusiasm of the public to perform this kind of service. The gap between professional and amateur is closing, and the contributions made by the public can be nothing short of awe-inspiring.

People love to help out.

Original Source:Sloan Digital Sky Survey

August 8, 2007December 26, 2015 by Fraser Cain

Hidden Cluster Seen For the First Time

This newly released photograph taken by the Spitzer Space Telescope is of a previously hidden star cluster, revealed now in the infrared spectrum. At visible wavelengths, this cluster, located in the southern portion of the Serpens cloud would be totally obscured by dust. But now, thanks to Spitzer, we can see it for the first time.

The cluster was discovered by Robert Gutermuth and Tyler Bourke, from the Harvard-Smithsonian Center for Astrophysics. They originally uncovered it using the Spitzer Space Telescope, but they weren’t able to determine whether they were forming a new “family unit”, or whether they were part of an existing cluster. Follow on observations with the Smithsonian’s Submillimeter Array (SMA) let them measure its velocity; the newly discovered clouds are drifting at the same velocity as the rest of the Serpens star-forming cloud.

In the Spitzer image, the newly discovered Serpens South stars are the green, yellow and orange points of light. That black line that runs through the image is actually a dense patch of gas and dust which is currently condensing to form stars. The green areas are hot hydrogen gas. And the wisps of red indicate regions where there are large quantities of organic molecules called polycyclic aromatic hydrocarbons. You might find similar particles on your barbecue grill, or coming out your car’s exhaust pipe.

The discovery was made as part of the Gould’s Belt Survey. This is a study of all the prominent star-forming regions located within 1,600 light-years of Earth. Photographs from Spitzer as well as several other ground-based telescopes will be merged together into a large data set that astronomers can study for years to come.

Original Source:Centre for Astrophysics

August 7, 2007December 26, 2015 by Fraser Cain

Four Galaxies in a Cosmic Collision

Galaxies aren’t born, they evolve, getting built up through a succession of mergers over billions of years. In most cases, this process is slow and steady, with galaxies tearing apart their satellite neighbours and gaining mass. But in one cosmic collision seen by NASA’s Spitzer Space Telescope, 4 extremely massive galaxies are coming together at the same time in a cosmic pileup.

These merging galaxies aren’t small either. No, when this collision is all wrapped up, the remaining monster galaxy will have 10 times the mass of our Milky Way – one of the largest galaxies in the entire Universe. We’ll have a taste of this in about 5 billion years, when the Milky Way merges with Andromeda.

Regular mergers are very common across the Universe; it’s how galaxies grow. But this is different. Bigger, more massive, more destructive. Here’s a cool quote from one of the discovering scientists:

“Most of the galaxy mergers we already knew about are like compact cars crashing together,” said Kenneth Rines of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. “What we have here is like four sand trucks smashing together, flinging sand everywhere.”

It’s inevitable that the most massive galaxies in the Universe will collide and merge too, they’ve just never been seen before.

Galaxy collisions are one of the events that can ignite star formation. The gravitational interaction between galaxies causes clouds of gas and dust to collapse, creating new stellar nurseries. But that won’t happen here. Spitzer didn’t see large quantities of gas, and hot, young star formation; only old stars.

Original Source:NASA News Release

August 6, 2007December 26, 2015 by Fraser Cain

Some Variable Stars Cloak Themselves from View

Most stars shine with a brilliant light, barely changing for billions of years. Others vary in brightness dramatically, dimming and brightening in a period of days, weeks or months. One class, called R Coronae Borealis are erratic in their cycles of brightening and dimming, and now astronomers think they know why: they’re hiding behind a dusty blanket.

An international team of astronomers from France and Brazil has detected a huge cloud of dust around an R Coronae Borealis star called RY Sagittarii, lending evidence to the theory that these stars are actually enshrouding themselves in dust, and hiding from view.

The theory goes that these stars, which can be 50 times larger than our Sun, puff out an envelope of dust around themselves. As this cloud moves into our line of sight from the Earth, it eclipses the star. From our point of view, the star dims in brightness. Then as the solar radiation blasts the dust particles away, the star brightens again.

The researchers used ESO’s Very Large Telescope Interferometer to clearly detect the presence of clouds around a variable star called RY Sagittarii. This was the first time these dust clouds were ever directly detected. The brightest dust cloud was detected several hundred stellar radii away from the centre of the star, so it had clearly drifted away. They discovered that a huge envelope surrounds the star in an area 120 times as big as RY Sagittarii itself.

The cloud is traveling at a speed of 300 km/s, so the astronomers calculated that it was probably ejected about 6 months before it was discovered. They’re planning to perform follow up observations on RY Sagittarii to understand how these dust clouds are formed, and how they dissipate.

Original Source: ESO News Release