Celestia Forums

I used to think that space far away from sun is always cold. However I come across this article on American Scientist saying that it can actually get very hot:
http://www.americanscientist.org/templa ... 173/page/2

The sun is on the edge of what is sometimes called the Local Bubble, a great void in the distribution of interstellar gas in the nearby galactic neighborhood. As voids go, the Local Bubble interior is one of the most extreme vacuums yet discovered. The very best laboratory vacuum is about 10,000 times denser than a typical interstellar cloud, which in turn is thousands of times less dense than the Local Bubble. The Local Bubble is not only relatively empty (with a density of less than 0.001 atoms per cubic centimeter); it is also quite hot, about one million degrees kelvin. By comparison, the interstellar cloud around the solar system is merely warm, about 7,000 degrees, with a density of about 0.3 atoms per cubic centimeter.

Does that mean if today I put a space shuttle in there, it will be instantly destroyed by the heat?? And those spacecraft NASA sent so many years ago that left the solar system heliosphere are actually turned into metal gas?

Additional question:

Will this hot local bubble distort the view of the distant space and make star distant measurment inaccurate?

The interstellar molecules within the bubble are so few and far apart that the total heat transferred by them to a body in the bubble would be negligible. Even dense interstellar clouds are emptier than the the vacuum in a "vacuum bottle" that people use to keep coffee hot or iced tea cold.

Similarly, the low density in the bubble minimizes any distortions. More problems are seen when trying to look through colder, denser dust and gas clouds. Those clouds attenuate visible light and make the stars behind them dimmer than the same stars would be if the clouds weren't there. Compensating for that attenuation can get to be quite complex.

I must say, I was not excited about the style and content of this article. But perhaps that's the desired style of science magazins for the public. I rarely read such articles.

I would have appreciated for example a concise summary about the measuring techniques (and their limitations) that are required to extract all the mentioned subtle properties (beyond doubt) from regions of space where noone has ever been... So how does one achieve this supposedly detailed knowledge with the standard "remote" tools like IR and X-ray astronomy and spectral analysis? Could have been interesting to read about.

Otherwise such articles sound like "ferry tales" without clear distinction what are the facts and where speculation starts...

Bye Fridger

"The interstellar molecules within the bubble are so few and far apart that the total heat transferred by them to a body in the bubble would be negligible." - Selden
This is what I would believe also.

So, of the claim in the article about the region being very hot -
What type of energy (or manner of forces present) would create this heat?
And more-so, in such a void, what would retain this heat to make this hot region?
I don't see anything in the article which explains this.



"More problems are seen when trying to look through colder, denser dust and gas clouds." - Selden

"LIGHT HAS BEEN SLOWED TO A SPEED OF 17 METERS/SECOND by passing it through a Bose- Einstein condensate (BEC) of sodium atoms at nK temperatures."
[url=http://www.aip.org/pnu/1999/split/pnu415-1.htm]AIP Physics News Update
February 18, 1999 by Phillip F. Schewe and Ben Stein[/url]

Old news, proved possible in the lab. So aside from having to worry about compensation for dust cloud density, one would also need to have an idea of the cloud temperature as well?

Interesting stuff.

You might want to consider reading some of the papers by Priscilla C. Frisch.
http://astro.uchicago.edu/home/web/frisch/
They'll answer your questions about the ISM much better than I can.

Thank you for everyone above took the time to reply my question. Especially selden for the link, I didn't come across that link before. I will try to go through those paper, though I am not sure if I can understand 5% of them

I did try to get more info from the web before I post my initial question. And seems this hot local bubble and hot local wind theory thing surface as early as the 50's, and observation and measurment were made contiously, even today. They mention something about near infra-red and x-ray measurment (I have totally no idea what are they talking about, never mind those formula ...)

Just wondering one more thing, isn't that heat can transfer in open space via radiation, just like light and heat from the sun?

Often you can learn interesting things even when skipping over all the equations.

Yes, radiative transfer works in deep space just as it does in the solar system. Photon density is a lot lower when you're so far from a star, though.

Also, radiative transfer is much less effective than convection in the Earth's atmosphere or conduction between two objects that are in physical contact with one another -- which is why a thermos bottle works so well.

Thanks for the link!

OK, its turn out that selden is right

I found the following paragraph, http://science.nasa.gov/headlines/y2004 ... eldsup.htm

Its temperature, 6000 C, is about the same as the surface temperature of the sun. A spacecraft flying through the stream won't melt, though, or even notice the heat. The gas in the stream is too wispy-thin, explains Moebius. "There are only 0.015 helium atoms per cubic centimeter." Earth's atmosphere at sea level, for comparison, is a thousand billion billion (1021) times denser. And, finally, the velocity of the stream is 26 km/s or 58,000 mph.