The star factory: observing Arp 220

February 18, 2012, Natural Sciences and Engineering Research Council

Using the Herschel Space Observatory, Wilson's group has found Arp 220 to have large amounts of very warm molecular hydrogen gas, a surprising find that implies molecular hydrogen is the dominant coolant in the high-temperature gas. Wilson's team has also observed a massive wind from the center of the galaxy, removing molecular gas from the central star forming core.

The galaxy Arp 220 is home to several giant —about 10 million solar masses—that are twice as massive as any comparable star cluster in the Milky Way Galaxy. McMaster University's Christine Wilson is captivated by this turbulent galaxy that provides such a target-rich environment for watching stars form.

The reason that star formation is going wild is that the galaxy is in the late stages of a merger between two larger galaxies. "This is a nearby look at a phenomenon that was common in the early universe, when many galaxies were merging," says Wilson.

At this week's meeting of the American Association for the Advancement of Science (AAAS) in Vancouver, Wilson will be presenting findings on Arp 220's dazzling rate of star formation—200 times faster than our own Milky Way. What's more, it's all happening in a much smaller space. The star forming core of Arp 220 is only about 3,000 light years across, compared to our own galaxy which measures about 60,000 light years.

Using the Herschel , an orbiting telescope, Wilson's group has found Arp 220 to have large amounts of very warm molecular , a surprising find that implies is the dominant coolant in the high-temperature gas. Wilson's team has also observed a massive wind from the centre of the galaxy, removing molecular gas from the central star forming core.

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1 / 5 (4) Feb 24, 2012
Some of Wilsons conclusions in this ultraluminous infrared galaxy:
1. Highly concentrated central star forming region only 3,000 light years across and obscured by dust and gas is 200 times more luminous than Milky Way, and likely powered by a hidden AGN, is populated with many young globular clusters located preferentially toward the center of the core region.

2. Massive outflows of warm hydrogen gas from the core have insufficient velocity to escape the central region. The gas is shown to be warmed mechanically rather than from an ionized source.

3. Two supermassive cores populate the core region and are located only 1000 light years apart.
1 / 5 (4) Feb 24, 2012
LaViolette's continuous creation cosmology model again fits these observations:

1. Dual mother stars in the nucleus greatly increase the mass concentration of this star-forming region, greatly accelerating the nucleation rate of new matter therein and internal instability of the mother core stars, which mechanically eject the gas observed in the massive wind.

2. The low velocity gas concentrating in this central region serves as a positive feedback mechanism to further enhance the mass density of the region and therefore augment the nucleation rate of new matter therein, and enhance the growth of nearby stars into clusters.
1 / 5 (4) Feb 24, 2012
Eventually the accelerated growth and volatility of the core may dissipate the surrounding gas and dust, leaving the core exposed, and forming the basis of a new galactic cluster, as in this example.

1 / 5 (3) Mar 01, 2012
LaViolette has now commented on this story, detailing his view that these are likely two mother core stars separating from each other, rather than the product of colliding galaxies. He details his model as to how the original core star likely explosively divided into two galactic core stars, located within the same disk of orbiting stars some 7,000 light-years in diameter.


He references the discovered superwind lobes emanating some 75,000 light years from this object.


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