Starship Asterisk*

I am intrigued by the statement in the Oct 25 APOD:

"The expanding shell from this explosion now spans 80 light-years and has swept up about 600 Suns worth of mass."

How is this "swept up mass" estimated? Is there perhaps a deceleration of the ejected matter that can be observed?

Is this "swept up mass" related to so-called dark matter? If so, does this provide a way to estimate the density of dark matter, at least in certain regions?

Just curious.

dlw wrote:I am intrigued by the statement in the Oct 25 APOD:

"The expanding shell from this explosion now spans 80 light-years and has swept up about 600 Suns worth of mass."

How is this "swept up mass" estimated? Is there perhaps a deceleration of the ejected matter that can be observed?

Is this "swept up mass" related to so-called dark matter? If so, does this provide a way to estimate the density of dark matter, at least in certain regions?

Just curious.

just at a glance, I would think it means that it picked up all that dust along the way, and that dust (visible or invisible) just adds up to all that mass. I think the question is: is that matter flowing along with the wave??? if so, how much matter can it pick up and move and for how long?

The 600 solar masses is the amount of mass contained in the expanding shell from both the material ejected from the nova and the other nebula gasses that were displaced from the shock wave. Dark matter isn't an issue here.

Very near the top right hand corner, almost on the diagonal, is a comet-like streak.

What could this be?

Is it the small hook above the 2 vertical yellow stars just to the left to the bright yellow star?

It seems in my memory that when I was a young woman in college, we learned that a star explosion was called a "Nova," and that a few really large ones were named "Supernovae." But now I seem never to hear of a simple Nova. Instead, everything seems to be a Supernova, and there is talk of even a Hypernova from time to time. Has the term "Nova" been relegated to history?
- Dianne

The terns are sometime misused, or the term nova is used as a general word for all nova types.

Nova: exploding star producing a dwarf of various types
Super Nova: creates a neutron star
Hyper nova: creates a black hole

sylvester wrote:Very near the top right hand corner, almost on the diagonal, is a comet-like streak.

What could this be?

http://www1.nasa.gov/images/content/137 ... s_full.jpg

This might explain what it is.

80 light years would most likely reach other star systems. Would these remnant gasses affect other worlds; or would they be too rarefied to be an effect???
Orin

S. Bilderback wrote:

sylvester wrote:Very near the top right hand corner, almost on the diagonal, is a comet-like streak.

What could this be?

http://www1.nasa.gov/images/content/137 ... s_full.jpg

This might explain what it is.

there is too much blue in that picture.

It would be no different than our solar system; the Suns heliosphere protects us via the solar winds.