Wednesday, June 08, 2005

Quasar theory supported by dust finding

Quasar: An extremely distant, and thus old, celestial object whose power output is several thousand times that of our entire galaxy.

Stick with me, I am off track with an astronomy story.

Astronomer Lei Hao thinks about dust alot, and recently she found a bunch of dust other atronomers are excited to know about. Acutally, the dust is between 0.88 billion and 2.4 billion light years away from Hao's office, in galaxies scientists classify as active galactic nuclei (AGNs).

Okay, I could not resist....

According to a press release from Cornell University, by confirming that the dust exists, Hao and her team have given new weight to a popular, but not universally accepted, theory of AGNs. Since the early 1980s, the most widely accepted model of AGNs, called the unified theory, involves a basic structure: a black hole at the center, an accretion disc (a round, flat sheet of gas) around it, and a doughnut-shaped ring of dusty gas, called a torus, around the accretion disc. Jets of matter are propelled out from the center perpendicular to the plane of the accretion disc.

Are you still with me?

Hao says AGNs include quasars, which look like stars in optical telescopes but emit massive amounts of radiation; Seyfert galaxies, which are low-energy counterparts of quasars; and blazars, which are AGNs viewed pole-on and which show rapid variations in radiation output over short intervals.

However, Hao says, for years, a key piece of evidence has been missing.

According to her observations, Hao believes that she has an important discovery because she sees more dust than previously noted. Hao says her finding has just been recognized by other astronomers. "You can see," she says, "that we verified the unification model."

The new report can be found in the Astrophysical Journal - shouldn't you have this on your reading list?

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