Galaxy in its death throes may hold clues to birth of dwarf systems

Jun 04, 2013 by Eric Gershon
Galaxy in its death throes may hold clues to birth of dwarf systems
Astronomers believe a bright dwarf galaxy relatively close to Earth’s Milky Way and trailing fireballs is the first clear example of a galaxy in the act of dying. The galaxy, in the Virgo Cluster, is called IC3418. Here is a false-color ultraviolet image of the dwarf galaxy IC3418 with its ram-pressure-stripped tail of young stars (from the GALEX satellite), shown on a false-color X-Ray image of the Virgo cluster, showing hot gas in the cluster (from the ROSAT satellite). The size of IC3418 is magnified by a factor of 10 relative to the cluster, in order to make it easier to see.

(Phys.org) —A bright dwarf galaxy relatively close to Earth's Milky Way and trailing fireballs is the first clear example of a galaxy in the act of dying, scientists argue in new research.

The work gives a known galaxy new status and offers the potential for better understanding of the mysterious origin of dwarf , a of the universe's most common type of galaxy.

"We think we're witnessing a critical stage in the transformation of a gas-rich dwarf irregular galaxy into a gas-poor dwarf elliptical galaxy—the depletion of its lifeblood," said Jeffrey D.P. Kenney of Yale University, the principal investigator. "Until now, there has been no clear example of this transformation happening."

Kenney presented the research June 3 at the 222nd meeting in Indianapolis.

Star formation is the essence of galactic vitality, and many of the universe's known are active star factories. But due to gas depletion, many others have stopped making stars, rendering them in a sense lifeless. The subject galaxy—known as IC3418 and located deep inside the Virgo Cluster—is now all but totally out of gas, the researchers said.

When there's none left, the galaxy will no longer be fertile. "Stars, planets, and life can form only if a galaxy has gas to make them," Kenney said.

The Virgo Cluster is a mass of about 1,000 galaxies and the nearest large galaxy collection to the group that includes the .

The core of IC3418 stopped making stars between 200 and 300 million years ago, according to the researchers. But its distinctive fireball-dotted tail shows evidence of recent star formation—within the last few million years or less, they estimate. The depletion of the core and the generation of the fireballs are probably the result of the process that's killing the galaxy: "ram pressure stripping."

In this process, the interaction of gases in the space between galaxies generates an enormous pressure that can force out an individual galaxy's interior gas, while leaving existing stars untouched. Ram pressure pushes gas away from the galaxy, forming stars that don't feel the ram pressure and remain behind.

The tail's fireballs—bright blobs of gas lit up by newly formed stars—are clear signatures of active ram pressure, according to researchers. is occurring at the heads of the fireballs.

"If you hold popcorn and unpopped kernels of corn in your hand and stick it out the car window as you drive, the wind caused by the car's motion through the air will blow away the popcorn but leave the denser unpopped kernels in your hand," Kenney said. "This is like the gas clouds in galaxies being blown out of the galaxy by the wind of cluster gas, while the denser stars remain behind."

The researchers used the WIYN 3.5-meter telescope in Arizona and the twin Keck 10-meter telescopes in Hawaii and performed both optical imaging and spectroscopy techniques.

Previous studies by other astronomers have proposed that IC3418 is experiencing ram pressure stripping. The new paper provides additional evidence and new details, and explicitly makes the case that the galaxy is an example of a galaxy near death.

"It's gratifying to find a clear example of an important process in galaxy evolution," said Kenney. "I enjoy digging through evidence to assemble a story about what happens to galaxies. I've come to think of myself as an intergalactic forensic pathologist—someone who studies the bodies of galaxies seeking evidence of traumatic events responsible for the present state of the galaxy."

The paper is titled "Transformation of a Virgo Cluster Dwarf Irregular Galaxy by Ram Pressure Stripping: IC3418 and its Fireballs." It will be submitted to Astrophysical Journal.

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cantdrive85
1 / 5 (7) Jun 04, 2013
But its distinctive fireball-dotted tail shows evidence of recent star formation—within the last few million years or less, they estimate. The depletion of the core and the generation of the fireballs are probably the result of the process that's killing the galaxy: "ram pressure stripping."

Halton Arp has suggested through his research of quasars, that new galaxies are ejected or "birthed" from their "parent" galaxies. What we have here is more evidence that supports such notion. The above suggestion of "ram pressure stripping" is NOT viable, galaxies consist largely of plasma, which is NOT subject to the mentioned mechanism.

Tuxford
1 / 5 (5) Jun 04, 2013
It's just popcorn analysis. Movie time!
GSwift7
5 / 5 (2) Jun 05, 2013
Halton Arp has suggested through his research of quasars, that new galaxies are ejected or "birthed" from their "parent" galaxies. What we have here is more evidence that supports such notion. The above suggestion of "ram pressure stripping" is NOT viable, galaxies consist largely of plasma, which is NOT subject to the mentioned mechanism


B.S.
cantdrive85
1 / 5 (3) Jun 05, 2013
Just the concise refutation I'd expect from you. Absolutely nothing to address to points made other than the high minded approach to claim "BS". BRILLIANT!
Fleetfoot
5 / 5 (4) Jun 05, 2013
The above suggestion of "ram pressure stripping" is NOT viable, galaxies consist largely of plasma, which is NOT subject to the mentioned mechanism.


What makes you imagine plasma is immune? Protons collide just as easily hydrogen atoms so of course plasma is subject to the same effect. In fact, the effect of such collisions is to heat the plasma and cause it to emit x-rays allowing us to see where it is. It is the two pink regions in this famous image:

http://apod.nasa....824.html
Torbjorn_Larsson_OM
5 / 5 (3) Jun 09, 2013
@cantdrive: B.S. First, the result doesn't support Arp. Second, there is no Arp mechanism anymore, since it was found he was wrong on the positions of galaxies.

As everyone knows that, it is enough to make the point: B.S. But you just have to throw out more "high minded" B.S.

It is one thing to push fringe ideas, like Steinhardt's cyclic universe which could work. That is still science, just not very productive one. But it is important to criticize and/or show alternatives.

It is another to push crackpot ideas known not to work. That isn't science, and it matters to nobody but the bloody fools that do so, and perhaps the poor idiots that are fooled by them.

"The above suggestion of "ram pressure stripping" is NOT viable, galaxies consist largely of plasma, which is NOT subject to the mentioned mechanism."

Ram pressure is a collisional pressure, so affects ions as well as neutrals. This has been seen in images of ram pressure stars, which leaves a trail of gas behind.
ValeriaT
1 / 5 (2) Jun 09, 2013
bright dwarf galaxy relatively close to Earth's Milky Way and trailing fireballs is the first clear example of a galaxy in the act of dying
The general understanding is, that the dwarf galaxies are remnant of ancient galaxies (some of which could be older than the observable Universe in steady state Universe model of dense aether theory). In this sense the finding of dwarf galaxy in the act of dying is not so surprising (until you don't expect a colored trail behind such a galaxy).
ValeriaT
1 / 5 (2) Jun 09, 2013
Please note, that these galaxies don't contain any apparent black holes - i.e. everything is evaporated already - i.e. there must exist some mechanism for evaporation of these holes, independent of Hawking's evaporation theory, which is too slow (and actually reversed for quite large black holes).
Fleetfoot
5 / 5 (2) Jun 09, 2013
Please note, that these galaxies don't contain any apparent black holes - i.e. everything is evaporated already - i.e. there must exist some mechanism for evaporation of these holes, ..


They probably never did have significant black holes, these are dwarf galaxies, which are still being merged into larger ones.