How scientists are able to identify the elements in a star

In summary, scientists are able to identify the elements in a star without sending a space probe by using the concept of electronic transitions. When electrons in an atom move from lower energy levels to higher energy levels, they consume energy in the form of light. Conversely, when they move from higher energy levels to lower ones, they give off energy in the form of light with frequencies characteristic to that particular element and transition. By studying the spectrum of a star's light, scientists can determine the elements present in the star's composition. Although the composition of some stars may change over time, the changes are minimal and difficult to observe. Temperature also plays a role in the frequency distribution of radiation from a star's surface, but the important factor is the spectral lines
  • #1
dynamic998
Explain how scientists are able to identify the elements in a star without sending a space probe question.

I remember my teacher telling me that the answer was something about the spectrum, don't know what my teacher meant about it or what it means. Anyone can explain to me?
 
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  • #2
Atoms undergo what are known as electronic transitions.
this involves electrons moving from lower energy levels (sub-shells)
to higher energy levels..u may have studied this.
in order that an atom move from a lower energy level to a higher energy level some work (so to speak ) needs to be done and the atom needs to consume energy to make this transition..(in the form of light of specific wavelengths depending on the kind of transition etc.)
now , to answer your question , the reverse also occurs.
ie. when electrons in an atom move from higher energy levels to lower
energy levels they give out energy in the form of light .

The light emitted will have frequency or wavelength characteristic to that particular element and that particular transition .of course each atom can emit a range of frequencies (spectrum) because there are several energy levels .

therefore, suppose we were to compare to frequency of sun light , we would find principally that it correlated with the frequency (ie. the range of frequencies -spectrum )emitted by hydrogen . so we can say that sun contains hydrogen , or helium for that matter.
well it is'nt this simple...but it's the basic idea

hope the above helps!
 
  • #3
thx

Thx alot. I now get what my teacher means with the spectrum.
 
  • #4
quick question

Since the composition of some stars changes with its life (hydrogen fusing into helium, helium into carbon) does the frequency of light emmited change with the core of the star? it would seem logical to me that it does but I am not sure.

thanks
 
  • #5
logically , the frequency should change over time as the life cycle of the star progresses but my guess is that the changes involved are way too minimal to observe over even a thousand years ...that is why with respect to the sun the frequencies emitted seem more or less constant.
so how do we know that stars go through the carbon phase..well , we know from stars that are very far away and have already come to their white giant stage,by studying their spectrum..and their spectra has shown evidence of carbon.
 
  • #6
Helium was discovered by observing the spectral lines of the sun. The name Helium is derived from the word Helios which was what the ancient Greeks (I think) called the sun.
 
  • #7
Since the composition of some stars changes with its life (hydrogen fusing into helium, helium into carbon) does the frequency of light emmited change with the core of the star? it would seem logical to me that it does but I am not sure.
That is correct. But this is usually swamped by the effect of changes in temperature in the star. Eg. as star fuses helium, it cools greatly and glows red instead of orange/blue.

What is important is generally not the spectrum in it's entirity, but the spectral lines(visible as black lines) on them. These correspond to the emmission/absorption spectra of various elements, and so allow our match.
 
  • #8
Well Ill be. I knew that temp changed its color but for whatever reason -probably because I am slow sometimes - but I never put 2 and 2 together. Thanks for the info it is greatly appreciated :)

and by the way...excellent board you guys have here!

peace
hybrid
 
  • #9
Well, the exact relation between temperature and frequency of radiation is very complex. A high temperature increases the rate of radiation of energy from the surface of the object, and this affects it's frequency distribution of radiation by Planck's equations.
http://zebu.uoregon.edu/~js/glossary/planck_curve.html [Broken]
 
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What is spectroscopy and how does it help identify elements in a star?

Spectroscopy is a scientific technique used to study the interaction between matter and electromagnetic radiation. In the case of identifying elements in a star, spectroscopy measures the light emitted or absorbed by the star, which can reveal the specific elements present in the star's atmosphere.

What type of light is used in spectroscopy to identify elements in a star?

The light used in spectroscopy is called electromagnetic radiation, which includes all forms of light, such as radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Each of these forms of light corresponds to a specific range of wavelengths, and by analyzing the wavelengths of light emitted or absorbed by a star, scientists can identify the elements present.

How do scientists determine the composition of a star's atmosphere?

By using spectroscopy, scientists can analyze the light emitted or absorbed by a star and determine the wavelengths of the light. These wavelengths correspond to the specific elements present in the star's atmosphere, allowing scientists to determine the composition of the atmosphere.

What is the process of matching spectral lines to specific elements?

Spectral lines are the dark or bright lines observed in a spectrum, which correspond to specific wavelengths of light. These lines are unique to each element, and scientists use reference spectra to match the observed spectral lines to specific elements, allowing them to identify the elements present in a star's atmosphere.

How do scientists use the information about elements in a star to learn about its age and evolutionary stage?

The elements present in a star's atmosphere can reveal information about its age, evolutionary stage, and other properties. For example, the abundance of heavier elements can indicate the age of the star, while the presence of certain elements, such as hydrogen and helium, can indicate its stage in the formation process. By analyzing the composition of a star's atmosphere, scientists can gain insights into its properties and evolutionary history.

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