What is the similarity between the spectra of white dwarfs and the sun?

In summary, a white dwarf has a spectrum similar to that of the sun because they have a similar temperature, which is around 10,000 degrees. However, the spectrum is only from the shell of gas on the surface of the star and the interior is completely different. While most white dwarfs are hotter than the sun, they both show broad hydrogen lines. Other elements, such as sodium, calcium, and iron, are more prominent in the sun's spectrum. This can be seen in a comparison of the spectra of the sun, a white dwarf, and a blue giant.
  • #1
MMS
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Hello,

I read at a couple of places about white dwarfs having a spectrum similar to that of the sun.
What does that mean or associate to?

Thanks in advance.
 
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  • #2
MMS said:
read at a couple of places about white dwarfs having a spectrum similar to that of the sun.
What does that mean or associate to?

Sun is called yellow dwarf star and its on the way to become a white dwarf- perhaps have journey time left of the order of few billion years.
the spectrum of white dwarf has similarities because of temperature of the star.

it is burning about 600 million tonnes of hydrogen per second in its core -if they burn up then it turns into a red giant star a small sparkling jewel of a white dwarf star will remain. This tiny remnant will have a mass of around half that of our present Sun,
 
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  • #3
drvrm said:
Sun is called yellow dwarf star and its on the way to become a white dwarf- perhaps have journey time left of the order of few billion years.
the spectrum of white dwarf has similarities because of temperature of the star.

it is burning about 600 million tonnes of hydrogen per second in its core -if they burn up then it turns into a red giant star a small sparkling jewel of a white dwarf star will remain. This tiny remnant will have a mass of around half that of our present Sun,
Thanks for the reply.

So when it is said that a white dwarf has a similar spectrum as the sun, what is meant by that is that they have the same temperature?
 
  • #4
MMS said:
white dwarf has a similar spectrum as the sun, what is meant by that is that they have the same temperature?

It should be of the same order of magnitude...nearly 10,000 degree
 
  • #5
And bear in mind that the spectrum is light that comes from the shell of gas that clings to the surface of the star. That's what is similar in the two cases. You cannot see the interior of the star, and it is completely different in those two cases.
 
  • #6
MMS said:
I read at a couple of places about white dwarfs having a spectrum similar to that of the sun

Where?

I find this surprising. Most, but not all, white dwarfs are significantly hotter than the sun. A white dwarf shows broad hydrogen lines and little else. The sun shows only weak and narrow hydrogen lines, but prominent sodium, calcium and iron lines.
 
  • #7
For example, this site compares the spectra of the Sun, a white dwarf and a blue giant. The White dwarf's is closer to that of the blue giant's but with broader lines.
http://hubblesite.org/newscenter/archive/releases/2012/25/image/b/
 

Related to What is the similarity between the spectra of white dwarfs and the sun?

1. What is a white dwarf?

A white dwarf is a small, dense star that is formed when a medium-sized star runs out of fuel and collapses in on itself. It is composed of degenerate matter, which is extremely dense and does not follow the standard gas laws.

2. How does a white dwarf produce its spectrum?

A white dwarf produces its spectrum through the process of nuclear fusion. The intense pressure and heat within the star's core causes atoms to fuse together, releasing energy in the form of light. The specific elements present in the white dwarf will determine the colors and patterns seen in its spectrum.

3. What is the significance of the spectrum of a white dwarf?

The spectrum of a white dwarf provides valuable information about the star's composition, temperature, and age. By analyzing the spectrum, scientists can determine the elements present in the star and make predictions about its evolution and eventual fate.

4. How is the spectrum of a white dwarf different from that of a main sequence star?

The main difference between the spectra of white dwarfs and main sequence stars is the presence of absorption lines. White dwarfs have much stronger absorption lines due to their higher density and lower surface temperature. Main sequence stars, on the other hand, have more prominent emission lines due to the fusion processes happening within their cores.

5. Can the spectrum of a white dwarf change over time?

Yes, the spectrum of a white dwarf can change over time as the star cools and its composition changes. As the star ages, it will no longer be able to sustain nuclear fusion and will gradually become cooler and dimmer. This will cause changes in the elements present in the star and therefore its spectrum.

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