Fraser Cain, Author at Universe Today

November 1, 2007December 26, 2015 by Fraser Cain

Supermassive Black Holes Shape Their Galaxies

Astronomers are now understanding the connection between supermassive black holes and the galaxies they inhabit better and better. In fact, it now looks like the powerful winds that blow out of these monsters can have a significant effect on the galaxies they inhabit, helping determine their growth.

In a recent study, published in the journal Nature, a group of scientists from the Rochester Institute of Technology report on their study of the rotating winds the rise up above the accretion disks surrounding supermassive black holes in distant galaxies.

With millions of times the mass of the Sun, supermassive black holes pull strongly at the material in their host galaxy. Just like water going down a drain, this material backs up into a swirling accretion disk. The material heats up, and blazes with radiation visible clear across the Universe – this is a quasar.

Astronomers from RIT and the University of Hertfordshire in England studied one quasar, PG 1700+518, located about 3 billion light-years from Earth. They were able to detect winds of gas coming off the accretion disk for the first time, both moving vertically away from the disk, but also rotating at the same speed.

This helps solve the long-standing mystery of how the accretion disk rids itself of angular momentum. It turns out, this wind needs to happen. If gas wasn’t being removed this way, material would stop falling in, and the quasar would turn off as the supermassive black hole was starved for fuel.

This wind both helps manage the growth of the black hole, but it also regulates the evolution of the galaxy. As the wind moves out into more distant regions of the galaxy, it helps collapse pockets of cold hydrogen, leading to regions of star formation.

Original Source: RIT News Release

November 1, 2007December 26, 2015 by Fraser Cain

Colliding White Dwarfs Caused a Powerful Supernova

There are a few ways that stars can go kaboom, and each variant is different enough that astronomers can figure out what kind of object detonated as a supernova. But when a bizarre explosion was detected last year, it left astronomers puzzled. Now, it looks like SN 2006gz might have been caused by two white dwarfs colliding together.

Millions of years ago, there were two regular stars in a binary system, orbiting one another. Over time, one, and then the other ran out of hydrogen fuel, bulged up as red giants, and then settled down to live out their futures as slowly cooling white dwarfs. But instead of billions of years of quiet cooling, the two stars had decaying orbits. They spiraled inward, and finally collided, detonating as supernova 2006gz.

When SN 2006gz was first discovered last year, astronomers thought they were dealing with a type Ia event. This is where a white dwarf is in a binary system with another star. Like a vampire, the white dwarf feeds on material from the companion star until it reaches 1.4 times the mass of the Sun. This magic point, called the Chandrasekhar limit, is the upper limit of mass a white dwarf can have. And when that limit is reached, the white dwarf detonates as a supernova, visible for billions of light years.

The problem is that SN 2006gz seemed to be too bright. In other words, it must have gotten more mass than the Chandrasekhar limit before detonating. It also had the strongest spectral signature of unburned carbon ever seen.

And that was the key. Mathematical models suggested that colliding white dwarfs would generate this specific signature of unburned carbon. They also suggested that an explosion should contain evidence of compressed layers of silicon, created during the explosion and then compressed during the shockwave that rebounded from the surrounding layers of carbon and oxygen – this too was seen.

Thanks to good observations, SN 2006gz was relatively easy to recognize as a collision between white dwarfs. But this event might be more common in the Universe, and astronomers will need to go back and carefully analyze supernovae on record to see if they’ve been wrongly categorized.

Original Source: CfA News Release

November 1, 2007December 26, 2015 by Fraser Cain

Carnival of Space #27 – and an Announcement

I’m happy once again to be the host of the Carnival of Space, here at Universe Today. I also wanted to announce that I’m going to be taking over the reins of the carnival from the founder, Henry Cate, who’s getting a little spread too thin with everything he’s working on. A big thanks to Henry for putting the time to get things to this point, and I hope I’m able to live up to the high standards he created. If you have any questions, just drop me an email at [email protected].

Now, onto the carnival.

Space Files writes about a little known amateur-built satellite bound for Mars.

Have you ever wondered what the Milky Way would look like if you could get outside it? astropixie takes us on a tour out of the galaxy, step by step.

Maybe there isn’t any such thing as dark matter. Centauri Dreams looks at an alternative theory to Newtonian gravity that might just solve the problem.

Surfin English shows the tricks, tools and techniques you need to photograph the planets.

As the media focuses its attention on the troubles with torn solar arrays and stuck joints affecting the latest shuttle/ISS mission, Stuart Atkinson, is frustrated by the lack of attention paid to a very special and historic meeting that took place at the start of the mission.

Once it was thought that moons could not exist within the Roche Limit. Now there is evidence of moons and possibly other massive objects. Since Saturn’s Rings contain conditions similar to the Solar System’s formation, they may shed light on how our Earth was formed. From A Babe in the Universe.

And finally, from my own Universe Today, I humbly offer up this article about the search for the origins of the Tunguska impactor.

October 31, 2007January 24, 2021 by Fraser Cain

Astrosphere for October 31st, 2007

Happy Halloween everyone. First up, enjoy a triple view of Comet Holmes, captured by ngc3314.

Of course, Halloween is an excuse to write spooky flavoured press releases. Here’s one from NASA’s Cassini mission about the spooky sounds of the Saturnian system. And this chilling tale of a meteorite… IT Came From Vesta. Astronomy Picture of the Day focuses on the “Ghost Head Nebula“. Cosmic Log’s Alan Boyle looks at the science of spooks. And finally, Phil Plait has a terrifying image of, of… well, you’ll just have to see for yourself.

Thomas Marquart from Apparent Brightness suggests a trick you can use to pare down your RSS feeds to just get the ones you want. I actually do this to just focus on space-related news.

Have you noticed a bright star in the mornings? That’s not a star, that’s Venus.

Centauri Dreams reconsiders Gliese 581. It’s looking less and less Earthlike every day.

October 31, 2007December 26, 2015 by Fraser Cain

Three New Jupiter-Sized Planets Discovered

You know the science of planet hunting is getting mainstream when there’s very little fanfare for the discovery of 3 new extrasolar planets with the size of Jupiter. 3 new planets people! They’re named WASP-3, WASP-4, WASP-5, and were discovered by a European team of astronomers using observatories in South Africa and the Canary Islands.

The new planets were discovered using the SuperWASP instruments. These are high speed cameras affixed to two telescopes: SuperWASP-North at Roque de los Muchachos Observatory on the island of La Palma in the Canaries and SuperWASP-South at the South African Astronomical Observatory, South Africa. Both instruments are equipped with a detailed CCD camera array capable of monitoring up to 400,000 stars every minute.

They’re watching to see if any of those stars vary in brightness. If a star does get brighter and dimmer over a regular period, the astronomers can then determine if a planet is passing in front – an event known as a transit (or eclipse). Just by measuring the dimming, astronomers can then determine the size of the planet, and even some of its chemical constituents.

With this latest discovery, the three new planets all contain roughly the mass of Jupiter, but orbit much closer into their parent stars. They complete an orbit every 2 two days.

According to one of the discoverers, Dr Don Pollacco of Queenâ€™s Astrophysics Research Centre, “these are among the shortest orbital periods yet discovered. Being so close to their star, the surface temperatures of the planets will be more than 2000 C, so it is unlikely that life as we know it could survive there. However, the finding of Jupiter-mass planets around other stars supports the idea that there are also many Earth-sized planets waiting to be discovered as the technology employed by astronomers improves.â€?

Even a relatively tiny planet the size of the Earth should visibly dim the light from a star as it passes in front. This is an exciting technique that should just get better and better over time.

Original Source: University of St. Andrews News Release

October 31, 2007December 26, 2015 by Fraser Cain

Detailed Images of Comet Holmes

Late last week, the normally dim Comet 17P/Holmes suddenly blazed into view, increasing in brightness by a factor of a million. Before the eruption you needed a large telescope to see it, and now you can make it out with the unaided eye – even in the light-polluted city skies.

There are now many amateur and professional astronomers turning their gaze towards the newly brightened comet.

Eric Allen has been capturing images for several days, and stitched them together into an animation that shows the expanding coma. Even cooler, he compares it to Jupiter visually, so you can see just how big and bright it has gotten.

UK astronomers tuned in with the powerful Isaac Newton Telescope in La Palma, showing the fuzzy coma. They also tucked in an image of the Earth in the bottom corner, for scale.

Astronomers from the University of Montreal captured this image that seems to show that the comet has an actual tail.

Probably the best image I’ve seen was captured by Mario Motta from the Amateur Telescope Makers in Boston. His image shows what clearly looks like a jet, blasting off one side of the comet.

Still want more images? Space Weather has this enormous photo gallery of images of Comet 17P/Holmes.

Over the next few days/weeks, I’m sure some even bigger telescopes will be joining the fray, so stay tuned.

October 31, 2007December 26, 2015 by Fraser Cain

Better View of the Damaged Panel

With all that fancy camera equipment, the NASA astronauts took more detailed images of the damaged solar panels on the International Space Station. These are the images NASA engineers will use to figure out what kind of risk the panel faces if it’s fully deployed, and what kinds of repairs could be done to minimize the damage. Oh, and the next spacewalk has been delayed to Friday.

Because of the damaged panel, managers at NASA decided to change up their plans for the next few days. Instead of their originally scheduled spacewalk, to demonstrate tile repair techniques, the astronauts will now be focusing on damage assessment and repair.

They’ve got to have another look at the malfunctioning rotary joint on the right-hand side of the station. The joint is currently parked because the mechanism was vibrating too much, and consuming energy. When astronaut Daniel Tani looked inside, he found evidence that the mechanism was grinding together, shedding tiny metal shavings. During the latest spacewalk, the astronauts looked at the right-hand side and found that it was working fine.

The tear in the solar array happened during the latest spacewalk on Tuesday. The astronauts had just completed the redeployment of the solar array to its new home, and were extending the panels. A portion of the panels were invisible in the glare of the Sun, so the astronauts didn’t notice its damage until it was too late.

The 80 cm tear in the array was probably caused when a guide wire snagged one of the hinges that allow the panels to fold up tight. As the panel was extended, one flap hooked onto this guide wire and tore along the fold.

NASA is now in a bit of a bind. Although they’re generating power now, they’ll work best when fully extended. There are also structural problems with having the array not fully extended. For the time being, both rotary joints have been locked shut, protecting the panels, but reducing the station’s ability to generate power.

Original Source: NASA News Release

October 30, 2007December 26, 2015 by Fraser Cain

Hubble Sees Beautiful Carnage

Ahh, another beautiful photograph captured by the Hubble Space Telescope. This time we’re looking at two big, beautiful spiral galaxies… tearing each other apart. The large, face-on spiral is NGC 3808, while its dueling partner is the smaller, edge-on NGC 3808A. And between the two is a long today tail of stars, gas and dust, transferring from one to the other.

The two galaxies are collectively known as Arp 87; just one of the hundreds of interacting galaxies seen by astronomers. It was cataloged by the famous Halton Arp in the 1960’s, who maintained his Atlas of Peculiar Galaxies. And this collision is plenty peculiar, thanks to Hubble’s optics and resolution of fine details.

A stream of gas, stars and dust is flowing from NGC 3808 to its companion, enveloping it in a starry embrace. Because the NGC 3808A is seen nearly edge-on, you can make out the twisting trail of stars wrapping around it. Both galaxies have been distorted by their gravitational interaction.

When galaxies interact, stars are born. And this is the case for Arp 87. The colour of the stars and the intensity of heated interstellar dust show that both galaxies are undergoing furious rates of star formation.

Original Source: Hubble News Release

October 30, 2007December 26, 2015 by Fraser Cain

An Even More Massive Black Hole

Wait, stop the internet! Remember when I said the most massive black hole had been discovered? Sorry, that record has been broken by an even more “most massive black hole”. 16 times the mass of the Sun? Please. This new one raises the bar with a mass of 24 to 33 times the mass of our Sun.

As with the previous black hole, located in the nearby galaxy M33, this newly announced black hole is in a binary system. It’s located in the nearby dwarf galaxy IC 10, 1.8 million light-years from Earth in the constellation Cassiopeia. Since it’s orbiting another star, astronomers were able to calculate its mass – 24-33 solar masses.

The discovering team, led by Andrea Prestwich of the Harvard-Smithsonian Center for Astrophysics used NASA’s Chandra X-ray Observatory to study IC 10. They observed that the galaxy’s brightest X-ray source, IC 10 X-1, varied in brightness. This led them to believe that a star was periodically passing in front of a black hole, briefly obscuring it from view.

Follow up observations with NASA’s Swift satellite confirmed that the black hole was being eclipsed by the companion star, and gathered enough data that astronomers could work out the orbital period, and thus the masses of both objects.

A black hole this massive is surprising. Astronomers calculate that massive stars should throw off most of their gas before detonating as supernovae. No black hole should be able to exceed 15 times the mass of the Sun.

In the case of IC 10 X-1; however, it’s blown past that theoretical limit. Of course, it could have detonated as its largest size, and then consumed material from its companion article. But according to their calculations, it could only have gained 1 or 2 solar masses over the years.

So how did it get so large?

It probably started life with about 60 times the mass of the Sun. Since its host galaxy is deficient in any heavier elements, it was probably composed largely of hydrogen and helium. The heavier elements are actually easier to blow away from the star on the solar wind, so it maintained most of its mass right up until the end.

Original Source: CfA News Release

October 30, 2007December 26, 2015 by Fraser Cain

Station Solar Array Tears During Redeployment

The third spacewalk of STS-120 involved moving a large solar array panel to a new position on the International Space Station. Just as the supposedly successful spacewalk was coming to a close, the astronauts noticed that at least one panel on the array has torn. The astronauts halted extending the array, took a bunch of photographs, and now NASA engineers are working to figure out what to do next.

They were so close. Astronauts Scott Parazynski and Doug Wheelock had just finished installing the P6 truss with the help of the station and shuttle’s robotic arms. Completing this task had been done over the course of three different spacewalks – over 7 hours of work on today’s walk alone.

As the solar array was almost completely unfurled, the astronauts noticed that a section about 80 cm (2.5 feet) in length had torn. They didn’t notice the damage earlier, because sunlight was obscuring the view to the torn section.

Once they noticed the damage, the astronauts halted the operation, and reported the problem to NASA. Then they took a series of photographs so that engineers can study the damage and determine what will happen if they try to continue opening up the panels.

NASA has already decided to add an extra day to Discovery’s mission, giving the astronauts an extra spacewalk can be performed on Thursday. During this trip outside the station, the astronauts will study the troublesome joint that was found damaged during the second spacewalk of the mission.

Mike Suffredini, NASA’s International Space Station, isn’t worried about the power generating capacity of the panels, “if we get the array down and we cut the snag and we figure out how to reinforce it, we’ll redeploy the array. It’s giving all the power we need. It doesn’t have to look good; it’s not about style points.”

During today’s spacewalk, the astronauts also examined the port rotary joint, and didn’t find the same evidence of metal filings that were discovered in the starboard joint. Scott Parazynski described the joint’s race rings as “nice and clean.”

Discovery is now due to undock from the space station on Monday, and return to Earth on November 7th.

Original Source: NASA News Release