How to interpret this new Keck spectrum picture of Jupiter?

  • #1
Dave Gungan
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Last night, on Wednesday, November 9, the KPF team successfully captured a first light spectrum of Jupiter with the next-generation instrument

This spectrometer picture of Jupiter has just been taken by the Keck, but I don't understand it. Wiki says Jupter is "89%±2.0% hydrogen" and
"10%±2.0% helium", but that spectrometer picture looks like Jupiter has 100s of element in it, if each of those blank bits are seperate elements? Could someone please clarify my confusion.

The origional atricle I found the picture from this at phys.org
 

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  • #2
Andy Resnick
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Last night, on Wednesday, November 9, the KPF team successfully captured a first light spectrum of Jupiter with the next-generation instrument

This spectrometer picture of Jupiter has just been taken by the Keck, but I don't understand it. Wiki says Jupter is "89%±2.0% hydrogen" and
"10%±2.0% helium", but that spectrometer picture looks like Jupiter has 100s of element in it, if each of those blank bits are seperate elements? Could someone please clarify my confusion.

The origional atricle I found the picture from this at phys.org
If I had to guess, I would say that the spectrometer design is good enough to measure atmospheric components in the part-per-million (ppm) range.
 
  • #3
Vanadium 50
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looks like Jupiter has 100s of element in it
There aren't 100's of elements. Just under 100 in nature.

There can, however, be hundreds of spectral lines.
 
  • #4
DaveE
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OK, IDK, this is way above my pay grade. However, it seems like you are mixing qualitative analysis with quantitative analysis. Sure, there's 100's of things, but most of them may be just a few types.
 
  • #5
Drakkith
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This spectrometer picture of Jupiter has just been taken by the Keck, but I don't understand it. Wiki says Jupter is "89%±2.0% hydrogen" and
"10%±2.0% helium", but that spectrometer picture looks like Jupiter has 100s of element in it, if each of those blank bits are seperate elements? Could someone please clarify my confusion.
Jupiter is composed of a great many things. It is mostly hydrogen and helium, but it also has other stuff. Per wiki:
Jupiter's upper atmosphere is about 90% hydrogen and 10% helium by volume. Since helium atoms are more massive than hydrogen molecules, Jupiter's atmosphere is approximately 24% helium by mass. The atmosphere contains trace amounts of methane, water vapour, ammonia, and silicon-based compounds. There are also fractional amounts of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, and sulfur. The outermost layer of the atmosphere contains crystals of frozen ammonia. Through infrared and ultraviolet measurements, trace amounts of benzene and other hydrocarbons have also been found. The interior of Jupiter contains denser materials—by mass it is roughly 71% hydrogen, 24% helium, and 5% other elements.
All of these will show up in a spectrograph to some extent.

Also, note that each absorption line in a spectrum doesn't represent a single element or chemical compound. Each element or compound generates multiple lines, though not all of them always show up in the visible range.
 
  • #6
Dave Gungan
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So that's a perfectly normal spectrum for a body made of "mostly 1 or 2 elements"?

Edit: I realise they will be other elements in the planet of course, but do they really manifest as that many absorption lines?
 
  • #7
Drakkith
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So that's a perfectly normal spectrum for a body made of "mostly 1 or 2 elements"?

Edit: I realise they will be other elements in the planet of course, but do they really manifest as that many absorption lines?
Yep. Even the Sun's spectrum is complicated, despite also being composed of mostly hydrogen and helium and being too hot for most compounds to form:
sun_spectrum_lines_noao_900x600.jpg
 
  • #8
Dave Gungan
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Wow thanks, thats changed my misconception of each atom only having 1 line as seen on tv shows, which i should have known better from warnings about sources I read here.

Can scientists actually pull out the types and concentrations of each atom from such a complicated picture? with AI learning perhaps?
 
  • #10
Dave Gungan
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Thanks I didnt realise it was so old.

Could anyone make a guess how many elements in the OP please? I'm curious just how good this new spectrometer is.
 
  • #12
Drakkith
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Can scientists actually pull out the types and concentrations of each atom from such a complicated picture? with AI learning perhaps?

Nope. This predates AI. This predates computers.
Indeed. Joseph von Fraunhofer first observed dark lines in the Sun's spectrum around 1814, which was about a decade before photography was invented. 'Proper' spectroscopy began in 1859, when Gustav Kirchhoff and Robert Bunsen (the inventor of the lab device now called a 'Bunsen Burner') discovered the cause of the dark lines in stellar spectra and then identified 16 elements in the Sun's spectrum over the next few years.

Wow thanks, thats changed my misconception of each atom only having 1 line as seen on tv shows, which i should have known better from warnings about sources I read here.
Each atom can have potentially a great many spectra lines, as each line corresponds to a transition between two particular electronic states, commonly described as electrons moving between energy levels. Hydrogen has 4 lines in the visible spectrum, but many more outside of that. Here's an image with many of them:
500px-Hydrogen_spectrum.svg.png

Note that this is only for a single atom with only a single electron. Atoms with multiple electrons have far more complicated spectra. Iron itself is known to have around 37,000 spectral lines (Part 7 in this paper), of which about 25,000 have been identified and categorized.

Edit: Just a piece of trivia, but did you know that the spectral lines of helium were observed in the Sun's spectrum before helium was ever discovered? The discovery of these lines spurred an investigation from the 1860's to the 1890's when helium was finally isolated in 1895. So, in effect, helium was discovered in the Sun before it was discovered on Earth. Hence its name, helium, after helios, which is the Greek word for Sun.
 
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  • #13
andrew s 1905
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I maybe missing something but won't the spectrum be of reflected sun light? So it will show the solar spectrum with some modifications due to the refective properties of Jupiter's atmosphere.
Regards Andrew
 
  • #14
Drakkith
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I maybe missing something but won't the spectrum be of reflected sun light? So it will show the solar spectrum with some modifications due to the refective properties of Jupiter's atmosphere.
Regards Andrew
Yes, that makes sense to me. I'm guessing that the Sun's spectrum can be 'subtracted' from Jupiter's or something in order to get the actual spectrum of Jupiter though.
 
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