Author: Fraser Cain

Galaxies, like people, tend to stick together. These galaxies collect together into communities large and small, called clusters and even superclusters. According to new research gathered by NASA’s Spitzer Space Telescope, stars seem to form better in the cosmic suburbs of these clusters.

Galaxy clusters can be enormous, locking together thousands of galaxies into a mutual gravitational dance. Seen from afar, these groups of galaxies form large blobs (the clusters) linked together by spider web-like filaments that stretch for millions of light-years. The filaments contain the smaller collections of galaxies working their way towards the largest clusters.

Spitzer’s infrared view revealed two of these filaments in the galaxy cluster Abell 1763. Galaxies are traveling along these filaments, and will eventually collide with the larger cluster itself.

The researchers used Spitzer to measure the rates of star formation in both filaments and the larger galaxy cluster itself. They found that the filaments have much higher rates of star formation than the cluster.

“This is the first time we’ve ever seen a filament leading into a cluster with an infrared telescope,” says Dario Fadda, of the Herschel Science Center, which is located at the California Institute of Technology in Pasadena, California. “Our observations show that the fraction of starburst galaxies in the filaments is more than double the number of starburst galaxies inside the cluster region.”

Upcoming space missions, such as ESA’s Herschel Space Telescope, will take these infrared observations to the next level, watching how filaments and clusters affect the growth of galaxies in greater detail.

Original Source: NASA/Spitzer News Release

Years of work are about to pay off, as Europe’s Large Hadron Collider is almost ready to come online. Soon physicists will be awash in data from the highly energetic particle collisions generated in the facility. But Nature, as usual, already has the upper hand, with a natural particle accelerator capable of pushing particles with 20 times as much energy as the LHC.

ESA’s Integral gamma ray observatory has been watching one of the brightest X-ray regions in the sky, known as the Ophiuchus galaxy cluster. And it’s turned up evidence that the violent region is acting like a natural particle accelerator, pushing electrons to enormous energies.

What kind of environment could create this?

You think the Sun is hot, clocking at a few thousand degrees Kelvin. But the gas in Ophiuchus is more than 100 million degrees Kelvin. Ophiuchus actually contains two galaxies clusters in the process of merging. The violence of this merger sends intense shockwaves rippling through the superheated gas.

The researchers are considering two specific mechanisms for how these X-rays are produced, and are planning follow-up observations to understand it better. In one situation, electrons are caught in the magnetic field threading through the cluster. As they spiral around, they would release the X-ray radiation. In a second scenario, the electrons would actually carry 100,000 times as much energy, and might be colliding with the background microwave radiation in the Universe, left over from the Big Bang.

It’s this X-ray radiation that Integral spotted.

Ophiuchus is able to give particles 20 times as much energy as researcher are hoping to coax out of the Large Hadron Collider.

“Of course the Ophiuchus cluster is somewhat bigger,” says Stéphane Paltani, a member of the team. While LHC is 27 km across, the Ophiuchus galaxy cluster is over two million light-years in diameter.”

Original Source: ESA News Release

Astronomers used to think that brief stellar eruptions called novae generated massive amounts of dust. But new observations of a well known nova system called RS Ophiuchus shows that isn’t the case. The dust was there already, and a nova blast just clears it all away.

The discovery was made using the massive Keck Interferometer, where the two 10-metre (33 feet) Keck telescopes on Hawaii’s Mauna Kea are merged together into a single super-telescope. It’s not like some kind of Japanese anime robot linking together; the telescopes just sit there. All the merging is done behind the scenes, through optics, electronics, and computers.

The Keck Interferometer can null the light coming from a star, revealing its surroundings. This allows the combined instrument to see objects with 10 times more resolving power than a single telescope working alone.

This “nulling mode” is largely used to reveal planet-forming disks of gas and dust surrounding distant stars. With the nuller blocking the starlight, the dimmer disk can be revealed.

In this recent observation, the Keck Interferometer observed a nova in a star surrounded by a dusty disk. The system contains a white dwarf and a red giant. The red giant is shedding its outside layers, while the white dwarf is gobbling it up.

Once a certain amount of matter piles up on the surface of the white dwarf, it explodes in a bright nova. This star has had 5 outburst over the last 100 years, so astronomers knew it would be flaring up again shortly.

The astronomers didn’t see any dust in the inner regions near the star – it was probably vaporized in the explosion. But around 20 times the Earth-sun distance, the researchers did see the dust again.

This flies in the face of what we expected. Astronomers had previously thought that nova explosions actually create dust,” said Richard Barry of Goddard, lead author of the paper on the observations that will appear in the Astrophysical Journal. They were expecting the nova to generate the dust. But instead, the dust was already there, and the nova just illuminated it.

The researchers now think that the dust is created as the star passes through the red giant’s wind, creating a pinwheel pattern around it. The denser regions in this pinwheel are cool enough to stick together to form dust particles. The blast wave from the nova destroys the pinwheel of dust, but it’ll reform again in the next few years.

Ready for another nova blast to blow it all apart again.

Original Source: NASA/JPL News Release

You weren’t imagining things, 2007 really was an unseasonably hot year. In fact, it was tied with 1998 for the second hottest year on record. All in all, the 8 warmest years have all occurred since 1998, and the 14 warmest years since 1990. This mini-record was announced by NASA climatologists this week.

Researchers from NASA’s Goddard Institute for Space Studies used temperature data from weather stations on land, satellite measurements of sea ice temperatures since 1982 and data from ships for earlier years.

“As we predicted last year, 2007 was warmer than 2006, continuing the strong warming trend of the past 30 years that has been confidently attributed to the effect of increasing human-made greenhouse gases,” said James Hansen, director of NASA GISS.

Perhaps the most warming occurred up in the Arctic and high latitude regions of the planet, where vast regions of ice melted away. In fact, the Northwest Passage opened up for the first time, and scientists are predicting that the region could be ice free in the Summer in less than a decade.

The lower ice levels in the Arctic provides more open water and reduces the amount of sunlight reflected back into space. This is expected to increase the rate of warming.

Let’s hope 2008 isn’t so hot.

Original Source: NASA News Release