Giant Gas Hook is Pulling Milky Way & Nearby Galaxies Together

A giant hook-like gas finger emanating from two neighboring galaxies has snagged the disk of the Milky Way and is pulling three galaxies closer. This extremity of hydrogen gas is actually the pointy end of the so-called Leading Arm of gas that streams ahead of two irregular galaxies called the Large and Small Magellanic Clouds.

The fate of these nearby galaxies, which are impacted by the Milky Way's gravity, has been somewhat of a mystery. The new finger findings suggest that the Magellanic Clouds will eventually merge with the Milky Way rather than zooming past.

Located about 160,000 light-years from Earth, the Large Magellanic Cloud (LMC) is only one-twentieth the diameter of our galaxy and contains one-tenth as many stars. The Small Magellanic Cloud resides 200,000 light-years from Earth and is about 100 times smaller than the Milky Way.

"We're thrilled, because we can determine exactly where this gas is ploughing into the Milky Way - it's usually extremely hard to get distances to such gas features," said the research team leader, Dr Naomi McClure-Griffiths of CSIRO's Australia Telescope National Facility.

Called HVC306-2+230, the gas finger is gouging into our galaxy's starry disk about 70,000 light-years away from Earth. In the night sky, the contact point would be nearest the Southern Cross.

Until last year, astronomers generally thought that the Magellanic Clouds had orbited our Galaxy many times, and were doomed to be ripped apart and swallowed by their gravitational overlord.

But then new Hubble Space Telescope measurements showed the Clouds were moving much faster than previously thought. In turn, this implied that the Clouds are paying our Galaxy a one-time visit rather than being its long-term companions.

Knowing where the Leading Arm is crossing the Galactic Disk may help astronomers to predict where the Clouds themselves will go in future.

"We think the Leading Arm is a tidal feature, gas pulled out of the Magellanic Clouds by the Milky Way's gravity," said Dr McClure-Griffiths.

"Where this gas goes, we'd expect the Clouds to follow, at least approximately."

The team's measurement of where the Leading Arm intrudes into the Milky Way is more in line with the models that assume the Magellanic Clouds have been orbiting our Galaxy than with the models that have the Clouds just passing by.

McClure-Griffiths cautions that this is not the final word on the subject, saying that the latter models were far from ruled out. But the new result suggests that the Magellanic Clouds will eventually merge with the Milky Way, rather than zooming past.

Posted by Casey Kazan.

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Source: N. M. McClure-Griffiths et al. "An Interaction of a Magellanic Leading Arm High Velocity Cloud with the Milky Way Disk." Astrophysical Journal Letters; Vol 673 No L143; 1 February 2008.

Comments

[Alkhemist]

It's interesting from a spiritual perspective -- the goal of the mystic is to eventually return to the Source. It seems that galaxies tend to do the same, eventually all joining into one mass. Who is it that said, "We are stardust"?