A Galaxy Cluster Gets Sloshed

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Like wine in a glass, vast clouds of hot gas are sloshing back and forth in Abell 2052, a galaxy cluster located about 480 million light years from Earth. By the way, for those who don't know what light year is, this is the distance covered by light after a year, as we know, light travels at an estimated speed of 186,000 miles/second. So when we say light year, that would be (186,000 miles x 60 sec. x 60 minutes x 24 hrs. x 365days). That's how far a single light year is.

Now, according to NASA, X-ray data (blue) from NASA's Chandra X-ray Observatory shows the hot gas in this dynamic system, and optical data (gold) from the Very Large Telescope shows the galaxies. The hot, X-ray bright gas has an average temperature of about 30 million degrees, and we know that's too hot.

A huge spiral structure in the hot gas - spanning almost a million light years - is seen around the outside of the image, surrounding a giant elliptical galaxy at the center. This spiral was created when a small cluster of galaxies smashed into a larger one that surrounds the central elliptical galaxy.

The smaller cluster passed the cluster core, the direction of motion of the cluster gas reversed and it traveled back towards the cluster center. The cluster gas moved through the center again and "sloshed" back and forth, similar to wine sloshing in a glass that was jerked sideways. The sloshing gas ended up in a spiral pattern because the collision between the two clusters was off-center.

The Chandra data show clear bubbles evacuated by material blasted away from the black hole, which are surrounded by dense, bright, cool rims. As with the sloshing, this activity helps prevent cooling of the gas in the cluster's core, setting limits on the growth of the giant elliptical galaxy and its supermassive black hole.

~Source: NASA.gov

Milky Way Radiation Reveals Itself to Distant NASA Probes

The Voyager 1 spacecraft

It has been decades since NASA's Voyager spacecraft began hurtling towards interstellar space, and the twin probes are still shedding light on the universe, now by offering an unprecedented view of our own galaxy.

As they roam ever outward to the edge of the solar system, the two Voyager spacecraft are providing the first glimpse of Milky Way radiation that scientists have already seen coming from other galaxies. The data could lead to a better understanding of star formation, including the mystery surrounding the earliest stars in the universe, researchers said.
NASA (National Aeronautics and Space Administration) launched the two Voyager spacecraft in 1977 to explore our solar system's giant planets and to study the electrical charged solar wind streaming from the sun. The probes far exceeded the expectations of mission planners, and to this day, they continue to beam back data.
The Voyagers are now providing us with the first glimpse of a critical type of ultraviolet (UV) radiation from our galaxy known as the Lyman-alpha line. This is the brightest band of light shed by hydrogen, the most abundant element in the universe.

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Studying the Lyman-alpha line can offer many insights into cosmic phenomena, such as star formation, the electrically charged environments in which the atmospheres of young planets evolve, and the shocked gas in interstellar space

Astronomers have seen Lyman-alpha rays from other galaxies, helping them peer into the universe's early history. However, we have never seen ones from our own galaxy, because our sun essentially blinds our view. Specifically, ultraviolet rays from our sun get scattered around by hydrogen entering our solar system from interstellar space. This leads to a haze that blinds us to Lyman-alpha rays from elsewhere in our galaxy. We can detect other galaxies' Lyman-alpha rays because they have shifted into longer optical and infrared wavelengths — which are no longer get scattered by this hydrogen — as their galaxies rush away from us. This is similar to how ambulance sirens grow lower in pitch as the vehicle drives farther away.

Now Voyager 1 and 2 are far enough away from this ultraviolet haze for them to get a clear view of the Milky Way's Lyman-alpha rays.

"It is like beginning to see small candles within a brightly lit room," study lead author Rosine Lallement, a space scientist and astronomer at the Paris Observatory in Meudon, France, told SPACE.com in an interview.

The spacecraft have confirmed that most of these newfound rays appear to come from star-forming regions, as astronomers expected. Future study of the Milky Way's Lyman-alpha rays could help us better understand those from other galaxies, researchers added.

"This radiation traces where young hot stars are being born — therefore, knowing the amount of emitted Lyman-alpha radiation from a galaxy corresponds to the rate at which stars are being born," Lallement said. "A major goal is to detect the first apparition of stars in the young universe, so detecting Lyman-alpha from the most-distant ones and correctly interpreting the signal is one of the major challenges."

Ironically, just as the Voyager probes are getting their best views of these Milky Way rays, their ability to see them is failing. Due to lack of power, the ultraviolet spectrometer on Voyager 2 has been switched off, and that same instrument on Voyager 1 could get turned off soon as well.

Still, NASA's New Horizons spacecraft, which is currently on its way to Pluto, might soon be able to monitor these rays as well.

Lallement and her colleagues detailed their findings online in the Dec. 1 issue of the journal Science.