How do astronomers usage light to study stars and plalifwynnfoundation.orgs?

I often hear researchers talking around using "spectroscopy" to study remote stars. Exactly how does the work and what can you really tell around an thing by the irradiate it provides off?

By Stuart Gary


Spectroscopy lets scientists determine silicon dust in the clouds of gas large plalifwynnfoundation.orgs like HD 209458b located 150 light-years away. (Source: NASA/JPL-Caltech )

As a fan of StarStuff, I often hear scientists talking about using "spectroscopy" come study distant stars. Exactly how does that work and what have the right to you yes, really tell about an object by the irradiate it provides off?— Anthony

Just recently, astronomers uncovered a distant solar system, 127 light years away v up to 7 plalifwynnfoundation.orgs orbiting a Sun-like star referred to as HD 10180.

You are watching: What information does a star’s spectrum offer about the star?

Like the very very first 51-Pegusus uncovered in 1995, this new system was uncovered using the scientific research of spectroscopy.

In fact, most of the roughly 500 plalifwynnfoundation.orgs so far found orbiting various other stars, to be detected through the exact same method.

Spectroscopy — the use of light from a far-off object to work out the object is made of — can be the single-most powerful tool astronomers use, claims Professor Fred Watson native the Australian expensive Observatory.

"You take the irradiate from a star, or galaxy and also pass it through a spectroscope, i beg your pardon is a little bit like a prism letting you split the light right into its component colours.

"It allows you watch the chemistry being took in or emitted through the light source. Indigenous this you deserve to work the end all species of things," says Watson.

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The chemical fingerprint

When cook or once electrically charged, details chemicals emit radiation at very specific colours or wavelengths referred to as emission lines.

There are additionally absorption present that show up as dark marks dividing the spectrum at details wavelengths.

Absorption present are developed when light from something warm like a star passes through a cooler gas, cancelling out the emission lines the chemicals in the gas would typically create.

When you look at the spectrum the a star, for example, you can see absorb lines due to the fact that the star"s outer atmosphere is cooler than the main part, explains Watson.

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Doppler effect


Astronomers division stars right into seven key spectral species OBAFGKM. O is the peak line, adhered to by two lines because that each of the remaining six spectra. Our sunlight is "G" spectra.(Source: KPNO 0.9-m Telescope, AURA, NOAO, NSF)

Spectroscopy additionally lets you recognize if things is relocating towards or far from friend by the readjust in frequency of the wavelength — or the Doppler effect.

When miscellaneous moves in the direction of you it compresses the signal wavelength it emits, when if it"s moving away indigenous you, that stretches that waveform.

"We hear it as the adjust in key of a train"s horn together it overcome us," claims Watson.

"In light waves, it causes things relocating towards girlfriend to change to much shorter wavelengths at the blue end of the spectrum. And also objects moving away indigenous you shift to longer frequencies, in ~ the red finish of the spectrum."

Astronomers offered the Doppler effect to discover the new solar system, states Watson.

As plalifwynnfoundation.orgs orbit a star, they cause it come wobble ever before so slightly. By watching the stars" spectrum, scientists can see a slight change in wherein the element absorption currently are contrasted to wherein they must be, i beg your pardon told lock a to be making the star wobble.

"The level of the wobble told them how huge the resulting in it was, the price of wobble told castle how far out the to be orbiting, and the reality that there were multiple wobbles, every slightly different, told researchers how many plalifwynnfoundation.orgs over there were," claims Watson.

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Working the end a star"s age


Spectroscopy likewise tells us the age of a star by looking at the lot of its matter consisted of of chemical elements other than hydrogen and also helium.

"The faster stars were written of simply hydrogen and helium due to the fact that they to be the first elements to kind after the huge Bang".

As these very first stars reached the end of your lives and also ran the end of hydrogen fuel come fuse right into helium, they started fusing helium right into heavier and also heavier elements, eventually creating iron.

Because stars can"t fuse iron into anything heavier, heaviness takes over, collapsing the star and also causing a supernova explosion, seeding the world in heavier elements from which the next generation of stars space born.

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Other signs

Spectroscopy likewise tells you a star"s temperature, mass and surface gravity.

A star"s mass effects the way atoms in its setting act, giving really narrow spectrum lines. And also the very same is true v temperature.

"By looking at the thickness and fuzziness the the lines, you have the right to work the end the temperature, mass and also pressure and also hence, surface ar gravity.

"The speed at i beg your pardon a star rotates will likewise show increase in the spectrum through smearing the the lines," defines Watson.

Perhaps the divine grail of all this, according to Watson, is the opportunity that at some point spectroscopy might be offered to find life in other places in the universe.

"The next generation that really huge telescopes will be powerful enough come see distant plalifwynnfoundation.orgs and study their atmospheric spectrum.

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"You can then look because that bio-markers, chemistry signatures which deserve to only be produced by living processes.

"Perhaps also look for traces that gases that only come from industrial activity. Chemicals that have the right to only be produced by intelligent life."

Professor Fred Watson was interviewed by Stuart Gary