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The Tadpoles of IC 410

Explanation: This telescopic close-up shows off the otherwise faint emission nebula IC 410 in striking false-colors. It also features two remarkable inhabitants of the cosmic pond of gas and dust above and left of center, the tadpoles of IC 410. The picture is a composite of images taken through both broad and narrow band filters. The narrow band data traces atoms in the nebula, with emission from sulfur atoms in red, hydrogen atoms in green, and oxygen in blue. Partly obscured by foreground dust, the nebula itself surrounds NGC 1893, a young galactic cluster of stars that energizes the glowing gas. Composed of denser cooler gas and dust the tadpoles are around 10 light-years long, potentially sites of ongoing star formation. Sculpted by wind and radiation from the cluster stars, their tails trail away from the cluster's central region. IC 410 lies some 12,000 light-years away, toward the constellation Auriga.

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Composed of denser cooler gas and dust the tadpoles are around 10 light-years long,

Hmm. A 10 light year long cloud that's "dense"? I'm figuring that means, like, one atom of gas or dust per every cubic million miles or something like that?

Jim Leff wrote:

Composed of denser cooler gas and dust the tadpoles are around 10 light-years long,

Hmm. A 10 light year long cloud that's "dense"? I'm figuring that means, like, one atom of gas or dust per every cubic million miles or something like that?

Probably more on the order of a few hundred particles per cubic centimeter. What you'd call a very hard vacuum in a lab, but still dense on the scale of interstellar dust and molecule clouds.

APOD Robot wrote: hydrogen atoms in green,

I was surprised that there wasn't more green in the picture.

Beautiful photo!! Enjoyed Mark Hanson's website.

Chris Peterson wrote:

Jim Leff wrote:A 10 light year long cloud that's "dense"? I'm figuring that means, like, one atom of gas or dust per every cubic million miles or something like that?

Probably more on the order of a few hundred particles per cubic centimeter. What you'd call a very hard vacuum in a lab, but still dense on the scale of interstellar dust and molecule clouds.

That sounds incredibly dense, actually. A few hundred particles (at 3 trillion atoms per dust speck) per cubic centimeter for a total volume that's ten light years long by, idunno, a light year wide? Wouldn't that add up to an unrealistically enormous amount of matter?

Fast calculations by a terrible mathematician: A dust speck contains around 3 trillion atoms. 300 particles/cubic inch means around a quadrillion atoms per cubic inch. 10 cubic light years = 5 x 10^53 cubic inches, so that means 5.0 × 10^68 atoms. Is that possible?

Jim Leff wrote:That sounds incredibly dense, actually. A few hundred particles (at 3 trillion atoms per dust speck) per cubic centimeter for a total volume that's ten light years long by, idunno, a light year wide? Wouldn't that add up to an unrealistically enormous amount of matter?

Fast calculations by a terrible mathematician: A dust speck contains around 3 trillion atoms. 300 particles/cubic inch means around a quadrillion atoms per cubic inch. 10 cubic light years = 5 x 10^53 cubic inches, so that means 5.0 × 10^68 atoms. Is that possible?

I think you're off a bit, but perhaps not by as much as you think. A typical star like the Sun contains around 10^57 atoms, so the number you came up with is around 100 billion suns, which is more like the mass of a galaxy than a molecular cloud. Here's where things went wrong: in the astronomical lingo of molecular clouds, "particle" doesn't just mean dust, it means any matter. And in one of these dust clouds, the majority of the mass is made up of hydrogen atoms. These are the dominant "particles", by many orders of magnitude. Clouds like this typically have a mass on the order of a few thousand to a few tens of thousands of suns (there is a wide range, and I don't know the specifics for this particular nebula).

Jim Leff wrote:Wouldn't that add up to an unrealistically enormous amount of matter?

Thanks for the conversation on this topic. On pondering those clouds I was wondering myself how many solar systems that dust/gas might be able to form into.

-Noel

In looking at the picture, I noticed that each of these elongated "tadpole" clouds seemed to have done a 90 degree shift upward (left-to-right, from the direction of the picture) at approximately the same time, almost as if a very strong wind had blown them off course. There also seems to have been a small (in astrological terms) explosion at the point where they both turned. So I am thinking there might be an interesting explanation for this kind of movement, and could it possibly have affected other things (like our Sun's movement around the Galaxy)?

Could it be that one of the energetic stars in the cluster burst into life and began emitting a stellar wind, which changed the direction the clouds were being pushed?

-Noel