Reflecting Merope (APOD 15 Jul 2006)

orin stepanek · Post by **orin stepanek** » Wed Jul 19, 2006 1:37 pm

http://apod.nasa.gov/apod/ap060715.html

Pressure of the star's light significantly repels the dust in the reflection nebula, and smaller dust particles are repelled more strongly. As a result, parts of the dust cloud have become stratified, pointing toward Merope. The closest particles are the most massive and the least affected by the radiation pressure. A longer-term result will be the general destruction of the dust by the energetic starlight.

The particles seem to be toward the star. If the star were repelling the dust wouldn't they be on the other side of the dust cloud? Maybe the star is actually absorbing the dust cloud.

Orin

Qev · Post by **Qev** » Wed Jul 19, 2006 5:42 pm

What's happening there is that the 'points' that seem drawn towards the star are actually the heavier particles. They used to be inside the cloud itself, but the light-pressure from Merope has blown the lighter dust particles back, leaving behind the long streamers of heavier particles pointing towards the star.

You can see a similar effect if you have a flat surface covered in a thin layer of sand (light dust particles). Scatter some large pebbles (heavy dust particles) over it, then let water wash across the surface from one direction. You'll end up with long 'streamers' tipped with the heavy pebbles pointing into the flow of water, while all the sand gets pushed away.

orin stepanek · Post by **orin stepanek** » Wed Jul 19, 2006 5:49 pm

Hello Qev! So your saying that the cloud itself is made up of the lighter particles.
Orin

BMAONE23 · Post by **BMAONE23** » Wed Jul 19, 2006 7:36 pm

Qev
You can get the same effect by using a leaf blower on it too. The lighter weight (Smaller?) particles scatter farther faster than the heavier (Larger) particles do. I am curious though, how much heavier material is made up from heavier elements vs gravitationally clinging elements.

But the same thing happens with a blow drier and flower on a surface. More densly packed portions withstand more pressure than less densly packed particles do. So it could be dense areas of matter that are more restant to the Light Pressure.

orin stepanek · Post by **orin stepanek** » Sat Jul 22, 2006 3:44 pm

Aren't stars created from condensation so to speak? Wouldn't the reverse effect on dust apply if you used a vacuum as opposed to a blower? Wouldn't it look about the same? Isn't the little cloud maybe a little leftover from the formation of the star? I'm not doubting Qev's answer as I'm sure it is probably correct , but I'm sure sure other forces could apply. Suppose the particles are heaver than what stellar wind could blow apart. What than? Doesn't the star have a little gravitational pull? The more we learn the more ?'s there are

Orin

Qev · Post by **Qev** » Sat Jul 22, 2006 6:53 pm

Well, remember, objects in a gravitational field all accelerate at the same rate, regardless of their mass or density (in a vacuum), so you wouldn't see stratification of gas clouds like this caused solely by a gravitational field: the whole cloud would stay together and move towards the star (well, actually, the parts nearer the star would accelerate slightly faster than those further away, so the cloud would 'stretch', but not in this fashion).

The cloud likely is a remnant of the stellar nursery where the star formed, and is definitely feeling the influence of the star's gravity, but the cloud is most likely being shaped by light-pressure (and perhaps stellar wind).

orin stepanek · Post by **orin stepanek** » Sun Jul 23, 2006 4:37 am

Makes sense Qev; I wonder what becomes of that material after the cloud is dissolved??

Orin

Qev · Post by **Qev** » Sun Jul 23, 2006 8:00 am

I imagine it hangs around, just more diffuse than it was before, like smoke scattering in the wind. The denser parts will hold out longer, but eventually they'll be dispersed as well.

harry · Post by **harry** » Sun Jul 23, 2006 11:34 am

Hello All

In time dust and atoms will form part of the star or future solar systems.

It will be in chaos for billions of years.

Similar to the origin of our solar system.

-------------------------------------------------------------------

The seed of most stars forms at the same time the supernova occurs.

Starformation evolution,,,,,,,,search google
and supernova.

orin stepanek · Post by **orin stepanek** » Fri Jul 28, 2006 3:53 pm

Other than gas; what are these dust particles made of? The gas and dust condense into stars and the leftovers just blow away? Do they maybe become the planets and comets?

Might be nice to be able to get a sample of these building blocks.

How long before we have faster than light travel?

Orin

harry · Post by **harry** » Sun Jul 30, 2006 1:11 pm

Hello Orin

The dust and all matter that is out there is made from

Star formation,,,,,,,,,during nova,,,,,,,different types and supernova diffrent types giving us the range of elements that we know.

also from Black hole jets,,,,,,,,,subatomic particals that are ejected re contruct themselves into the varies elements that feed the future stars of the surrounding.

Interesting complex carbon compounds are also formed.

-----------------------------------------------------------------
There's varies theories how our solar system evolved. From reading many of the different theories the main one is from a supernova that left a compact core that seeded our sun and the remaining nebula formed our planets.

Qev · Post by **Qev** » Sun Jul 30, 2006 5:11 pm

orin stepanek wrote:Other than gas; what are these dust particles made of? The gas and dust condense into stars and the leftovers just blow away? Do they maybe become the planets and comets? Might be nice to be able to get a sample of these building blocks. How long before we have faster than light travel?
Orin

A lot of interstellar dust is generated in the atmospheres of red giant stars, and ejected by their stellar winds. A large part of it is carbon.

We'll probably have FTL when we have reliable fusion power, so always about 50 years in the future.