星際氣體有機化合物探索

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Wah!!
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文章 Wah!! » 週四 15 5月, 2014 14:41

WFPC2 寫:
Wah!! 寫:Wait a minute, is Blackbody Radiation theory only for solid and liquid, but not for gas?

Then what will low temperature gas emit?
The current absolute temperature of our universe has been
measured as 2.7 Kelvin which the microwave emitted are
regarded as Blackbody Radiation,where the most part of
normal matter in our universe are gaseous in phase like
hydrogen and helium gases. So by logical thinking I conclude
that Black Body Radiation is also emitted by cold gases.
That's not the same thing. The microwave background was emitted by extremely hot gas long time ago, and the intensity should be much higher than cold gas.

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文章 WFPC2 » 週四 15 5月, 2014 15:21

Wah!! 寫:
WFPC2 寫:
Wah!! 寫:Wait a minute, is Blackbody Radiation theory only for solid and liquid, but not for gas?

Then what will low temperature gas emit?
The current absolute temperature of our universe has been
measured as 2.7 Kelvin which the microwave emitted are
regarded as Blackbody Radiation,where the most part of
normal matter in our universe are gaseous in phase like
hydrogen and helium gases. So by logical thinking I conclude
that Black Body Radiation is also emitted by cold gases.
That's not the same thing. The microwave background was emitted by extremely hot gas long time ago, and the intensity should be much higher than cold gas.
The current temperature of our universe is 2.7 Kelvin. It is exactly
the same as the microwave background radiation has been measured.It is because CMB wave are evenly distribute across the whole universe which left some small amount heat within it. So I think cold gas within the universe is also emitted blackbody radiation.
http://www.experimentation-online.co.uk ... hp?id=1325

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Wah!!
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文章 Wah!! » 週四 15 5月, 2014 15:38

The "temperature" of universe was measured by the CMB, but the source of the microwave was not from cold gas, but extremely hot gas 13.7 billion years ago. The CME microwaves were once very very short wavelength gamma rays.
So we cannot use CMB to say cold gas can be easily detected by equipment, because the intensity of microwave from cold gas should be much much lower than those from CMB.

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文章 鄧登凳 » 週四 15 5月, 2014 16:17

Wah!! 寫:The "temperature" of universe was measured by the CMB, but the source of the microwave was not from cold gas, but extremely hot gas 13.7 billion years ago. The CME microwaves were once very very short wavelength gamma rays.
So we cannot use CMB to say cold gas can be easily detected by equipment, because the intensity of microwave from cold gas should be much much lower than those from CMB.
[Good Job]

On the other hand, if the Universe (a close system definitely) at an earlier time was a huge lump of relatively uniform cold gas at 2.7k, now becomes a place with the sun and stars at temperature >3000k and galaxies with such orderly complexity, then all the Laws of Thermodynamics can be throw into the dustbin.

Unfortunately, this is not the case. If the Laws of Thermodynamics were really wrong, I should join you in designing a perpetual machine and probably get very rich.

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文章 WFPC2 » 週四 15 5月, 2014 17:48

Wah!! 寫:The "temperature" of universe was measured by the CMB, but the source of the microwave was not from cold gas, but extremely hot gas 13.7 billion years ago. The CME microwaves were once very very short wavelength gamma rays.
So we cannot use CMB to say cold gas can be easily detected by equipment, because the intensity of microwave from cold gas should be much much lower than those from CMB.
I was not mean that we can use CMB to say cold gas can easily
detected by equipment. It is not match to what I think.However
gas across the universe today are not generally colder than 2.7 Kelvin since gravitational contraction and radiation from stars
are heating them up to higher temperature which can be easily
detectable by equipment.



No matter gas temperature lower than 2.7 Kelvin.Astronomer
have successfully measured the rare extremely cold gas surrounded the pre-planetary nebula named Bloomerang Nebula which temperature is closed to 1 Kelvin.

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Wah!!
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文章 Wah!! » 週四 15 5月, 2014 18:08

What's the wavelength of EM wave radiated from 1K cold gas?

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文章 鄧登凳 » 週四 15 5月, 2014 18:32

Wah!! 寫:What's the wavelength of EM wave radiated from 1K cold gas?
Readily available is the spectrum of 2.7K (in discussion that the CBM fits a model of blackbody radiation)

圖檔
from Cambridge University (http://www.damtp.cam.ac.uk/)

The peak is at 5.3 cm^-1. The graph drops to close to zero at around 22 cm^-1. At 1k, the peak moves to the left

Where is the typical organic compound absorption spectrum? It is 300 cm^-1 to 4000cm^-1. The blackbody radiation is never absolutely zero, but as far as measurement/detection is concerned, it is practically zero for a gas at 1K to a few K in temperature for that regoin.

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文章 Wah!! » 週四 15 5月, 2014 19:15

For 1K, the peak should move to the right.

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文章 WFPC2 » 週四 15 5月, 2014 19:18

鄧登凳 寫:
Wah!! 寫:>"Organic molecules in general do not radiate any EM waves."
I think it is not absolutely ZERO.
But the low intensity & long wavelength may not be detectable by professional equipment.
Correct, you have to read my respond in the context of what is said in #2. The words "in general" quantified the statement not to mean any thing absolute.

You as a black body radiator will radiate X-ray and Gamma ray according to the prediction of Planck's Law. However, rest assured the your son and daughter are perfectly safe to give you a hug. The levels are way below detectable limits.

I am still waiting that someone can locate the data that show Large Aperture Infrared Space Telescope like Herschel Telescope with very big infrared light gathering power has registered any black body radiation from low temperature molecular clouds (not being excited by other energy sources) :D

PS: Planck's Law and the general concept of black body radiator can be applied to a single particle. So gases, which are made by particles, give black body radiation. That said, the particle density of gases are much lower than solid and liquid. The black body radiation given by a gas per unit volumn is therefore much lower than that of solids and liquids.


yes,if what he said is right,then what you said at first is definitely wrong,please well organize your points logically without any
contridictions e.g molecular cloud does not emit any EM wave.

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文章 鄧登凳 » 週四 15 5月, 2014 19:26

Wah!! 寫:For 1K, the peak should move to the right.
The unit of the X axis is number of waves per centimeter, a unit we call wave number. To the right means more waves per centimeter, i.e. shorter wavelength and higher frequency. By E = hc/λ, shorter wavelength means photon with higher energy.

Lower the temperature, the portorn of photons with higher enery decreases and that of lower energy increases. The peak shift to the right.

This plot by Cambridge university does not follow the usual spectrum convention.

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文章 鄧登凳 » 週四 15 5月, 2014 19:44

The ALMA in photo:

圖檔
from http://www.eso.org/

Someone who just throws in information without any understanding is implying that we can detect organic compounds using this.

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文章 WFPC2 » 週四 15 5月, 2014 20:35

The infrared spectrum is mostly dependent on the molecular vibration and molecular structures.

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文章 WFPC2 » 週四 15 5月, 2014 20:39


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文章 WFPC2 » 週四 15 5月, 2014 22:18

鄧登凳 寫:
Wah!! 寫:What's the wavelength of EM wave radiated from 1K cold gas?
Readily available is the spectrum of 2.7K (in discussion that the CBM fits a model of blackbody radiation)

圖檔9
from Cambridge University (http://www.damtp.cam.ac.uk/)

The peak is at 5.3 cm^-1. The graph drops to close to zero at around 22 cm^-1. At 1k, the peak moves to the left

Where is the typical organic compound absorption spectrum? It is 300 cm^-1 to 4000cm^-1. The blackbody radiation is never absolutely zero, but as far as
measurement/detection is concerned, it is practically zero for a gas at 1K to
a few K in temperature for that regoin.
The graph you posted is not match to the question required.
The graph is just for the 2.7K microwave blackbody radiation
but not for cold gas 1K warmer than absolute zero .

You are just roughly guessing the answer but not finding out
the accurate value.So what you have done is nothing to do with the true
mathesmatical method.Your work do not involved in any calculations
at all.
at all.

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文章 鄧登凳 » 週四 15 5月, 2014 22:57

Good. Please keep it up to show us more about your ignorance in IR spectroscopy of organic molecules and microwave astronomy.

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