Starship Asterisk*

will hunt wrote:One of the most interesting assertions I have ever seen, vis-a-vis humanity's interaction with the cosmos, was today's "... the expanding debris cloud of a star that was seen to explode about 11,000 years ago." (emphasis added)

I don't doubt it could have and may have been seen, but what historical evidence do we have that the explosion was observed by human beings? Surely that proof is one of archeology's triumphant moments.

I want to believe it. Help, please.

samueltownsend wrote:Yesterday I posed the question "what forces cause this reported shock wave in interstellar space to slow down from millions of kph to .5million kph?"
OK, let's say an explosion of particles occurs, and the density of all those particles decreases as a function of the radial distance traveled. In a relatively short time the ratio between the particle diameter and the distance between particles becomes "astronomical", which is also the case with interstellar space. The odds of collision of particles becomes so low that the great majority of particles travel without encounter, therefore no loss of momentum. So what am I missing here?

DavidLeodis wrote:
I assume that the short bright red filaments are ionized Hydrogen and the longer more numerous blue filaments are ionized Oxygen, but I wonder if the pale diffuse red all over the image is also due to ionized Hydrogen . I would appreciate any help on this query.

Chris Peterson wrote:

neufer wrote:
Friction implies a loss of momentum.
However, momentum could be conserved if the nebula mass grows inversely with the velocity.

No, friction implies a transfer of momentum. Momentum is always conserved (unless you choose to limit the system to just the particles originally ejected, which would make no sense at all).

neufer wrote:Friction implies a loss of momentum.
However, momentum could be conserved if the nebula mass grows inversely with the velocity.

samueltownsend wrote:Just a question: what forces cause this reported shock wave in interstellar space to slow down from millions of kph to .5million kph?

ajg_oz wrote:By my rough calculations the Vela remnant will sweep past the solar system in 25-30 thousand years (very rough cals).

What will happen to the sun during this event?

ajg_oz wrote:
By my rough calculations the Vela remnant will sweep past the solar system in 25-30 thousand years (very rough cals).

ajg_oz wrote:
What will happen to the sun during this event?
Perhaps nothing - the gases will be too thin by then.
Small change in it's output - only measurable by its spectral change.
Something much larger??

• It will just be more Local Fluff to contend with (PILLOW FIGHT ) :

http://en.wikipedia.org/wiki/Local_Fluff wrote:

[b][color=#0000FF]Diagram of the local clouds of matter that Earth's solar system is moving through, with arrows indicating cloud motion.[/color][/b]

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<<The Local Interstellar Cloud (or Local Fluff or LIC) is the interstellar cloud roughly 30 light years or 9.2 parsecs across through which the Earth's Solar System is currently moving. The Solar System is thought to have entered the Local Interstellar Cloud at some time between 44,000 and 150,000 years ago and is expected to remain within it for another 10,000 to 20,000 years. The cloud has a temperature of about 6,000 K, about the same temperature as the surface of the Sun. However, its specific heat capacity is very low as it is not very dense, with 0.3 atoms per cubic centimeter; less dense than the average for the interstellar medium in the Milky Way (0.5 atoms/cm³), though six times denser than the gas in the Local Bubble (0.05 atoms/cm³) which surrounds the local cloud. In comparison, Earth's atmosphere at the edge of space has 12 billion atoms per cubic centimeter, dropping to 52 million at 150 km.

The cloud is flowing outwards from the Scorpius-Centaurus Association, a stellar association that is a star-forming region.

The Local Interstellar Cloud's potential effects on Earth are prevented by the solar wind and the Sun's magnetic field. This interaction with the heliosphere is under study by the Interstellar Boundary Explorer (IBEX), a NASA satellite mapping the boundary between the Solar System and interstellar space.>>

Boomer12k wrote:

samueltownsend wrote:Just a question: what forces cause this reported shock wave in interstellar space to slow down from millions of kph to .5million kph?

It is explained in the caption...."sweeping up surrounding interstellar material."

It is running into the fine interstellar medium and the collision evidently slows it down. It is thus accruing more MASS, or running into slight masses as it moves...which dissipates the energy. I assume. Think of it like an airplane crashing on a runway, and running into the soft, breakable concrete to slow down. As the plane's wheels crunch more breakable concrete, the energy is dissipated. Transferred to the concrete and the ground. Thus slowing the plane with friction.

I hope that is essentially correct.

samueltownsend wrote:Just a question: what forces cause this reported shock wave in interstellar space to slow down from millions of kph to .5million kph?

Ann wrote:It's a beautiful picture, and I'm impressed that narrowband photography can produce such delicate color images.

GTChappy wrote:The Pencil Nebula...What would happen if our solar system just happened to be in the way of this thing? Shock wave? Instantaneous vaporization of the entire planet? Perhaps it would bring a solution to global warming?