Skip to comments.A Big Boom in a Quiet Galaxy
Posted on 05/16/2008 12:49:36 AM PDT by neverdem
Younger than it looks.
Astronomers compared radio (left, blue) and x-ray images (red) of this supernova remnant to determine that the explosion had occurred only 100 years before.
Credit: NRAO (radio)/Chandra (x-ray)
U.S. and British astronomers have located the youngest known remnant of an exploding star in the Milky Way. The discovery might help researchers understand why our galaxy seems to have so few supernovas and where the raw materials of planets and life came from.
The Milky Way is a perfectly ordinary spiral galaxy, except for a shortage of supernova activity. These titanic explosions, which mark the deaths of giant stars, produce the heavy elements--including oxygen and carbon--necessary to form planets, life, and people. With more than 300 billion stars in the Milky Way, astronomers expect to observe a supernova about three times every century. That should translate into about 60 supernova remnants in the galaxy that are under 2000 years old, after which they begin to fade away and become undetectable. But so far, astronomers have found fewer than 10.
The discrepancy is so large that theoretical physicists wonder if the Milky Way is unusual in some unknown respect. Another possibility is that somehow the missing supernova remnants occur at energies and wavelengths that make them difficult to detect.
The new object could help answer these questions. It's called G1.9+0.3 and is located about 26,000 light-years from Earth, near the center of the Milky Way. Astronomers first studied it in 1985, but they didn't recognize its age. Then last year, researchers using NASA's orbiting Chandra X-ray Observatory took another look at the object and realized that its boundaries had expanded by 16% in the intervening 22 years. A second viewing by an earthbound radio telescope array confirmed the size of the expansion, and team members calculated that the debris of G1.9+0.3 is moving faster than any supernova remnant ever seen before--some 15,000 kilometers per second. Based on that speed, the team is reporting jointly in upcoming editions of Astrophysical Journal Letters and the Monthly Notices of the Royal Astronomy Society that G1.9+0.3 expanded to its current size in only about 100 years.
Given its speed, G1.9+0.3 could be expelling energy at wavelengths that researchers don't usually check for, co-author David Green of Cambridge University in the U.K. said at a teleconference today. If other young supernovas do the same, he said, it might explain why they've been overlooked in previous searches. Still, the work "highlights the fact that the other [young] remnants are still missing," said lead author Stephen Reynolds of North Carolina State University in Raleigh. "It's a serious problem," he told reporters at the same teleconference. The discovery "is a step in the right direction," Reynolds added, "but there are a lot of steps."
The find is a "cause for celebration," says astronomer Shri Kulkarni of the California Institute of Technology in Pasadena. "We have what finally appears to be a genuine young supernova remnant." Researchers still don't understand where in the supernova and when the heavy elements form, so Kulkarni predicts there will be a "mad scramble" to detect them in G1.9+0.3. And astronomer James Lloyd of Cornell University says it's an "important discovery" with "profound implications" for our understanding formation of "the necessary ingredients for life throughout the universe."
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“produce the heavy elements—including oxygen and carbon”
Oxygen is a “heavy element”?
Compared to hydrogen and helium, I guess so. I didn't write it. The images are interesting.
Sorry. Try this one instead:
It should have been 'heavier' elements. Oxygen is only #8 in the periodic table. On the other hand, compared to hydrogen and helium it's pretty heavy.
With a 25,000 light year distance, that 'puppy' may have
already mailed its candygram 25 millenia ago (postage was reportedly much cheaper then).
The Milky Way is a perfectly ordinary spiral galaxy, except for a shortage of supernova activity.
I don’t think I ever heard this before. Worth mulling over in a philosophical and religious sense, as well as a scientific sense, if this is accurate.
In the science of star processes, at times even Helium is considered “heavy”, but more typically the “light” elements are Hydrogen, Helium, Lithium, and Beryllium. Everything else is typically considered “heavy”, but Oxygen is definitely, always, considered “heavy” in a star.
Simple star fusion processes will result in a release of energy up to the element Iron, but since there are so few atoms of anything other than Hydrogen or Helium, the chances of them coming into sufficient proximity is extremely small, so for most of the life of a star, very little heavy atom building occurs.
When elements heavier than Iron are built, it takes energy OUT of the system, instead of releasing it. That process almost never occurs in a normal star, but only in supernova events.
I probably should have added, that although Beryllium and Lithium are usually considered “light” in star processes, they are very rare in a star due to not being very stable, so they don’t last long enough to take part in any further reactions. Carbon is the smallest stable nucleus other than H or He for stellar processes. This renders the usage of the term “light” to effectively mean H or He.
The Cycle of Cosmic Catastrophes:
Flood, Fire, and Famine
in the History of Civilization
by Richard Firestone,
Allen West, and
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LOL good one. Yes it is like a “dawn explosion”.
The discovery helps fill in the deficit of supernovas for the Milky Way, where the rate of explosions appears much lower than in similar spiral galaxies.
"This lack is a significant puzzle," Reynolds said. Either astronomers have not been able to identify the remnants, or the Milky Way is somehow different.
Here's another reference to the Milky Way's relative dearth of supernovas, FWIW.
DB: you’re welcome.
neverdem: There’s something really screwy about this, though. If all of a sudden we are “seeing” more supernovas in the Milky Way, I suspect that those same techniques applied to other galaxies will see more there, too. If so, the Milky Way will still be a “significant puzzle” and remain “different”.
If this proves to be so, it will remain worth mulling over, as I said.