How is spectroscopy used to study the universe and its composition?
Spectroscopy is a powerful tool in which astronomers can use to work out a celestial body’s chemical composition. Using optical, radio and x-ray spectroscopy; the parts of far-away stars, intergalactic molecules, and even the abundance of elements before the first stars were formed can be determined.
Using the science of spectroscopy, the wondrous first discovery of a distant solar system 127 light years away was found – with up to 7 planets orbiting a Sun-like star named HD 10180. In fact, most of the 500 planets that have been found so far was detected using the method of spectroscopy. Since spectroscopy analyses light, astronomers can then study a star’s spectrum. For example, scientists can work out a star’s chemical make-up and temperature and the velocities of galaxies and supernovae by measuring its red shift (called the ‘Doppler effect’; if the star is further away from the earth, meaning the frequencies are longer, it is red; if the opposite happens, meaning the wavelength is shorter; the star turns blue). |
Professor Fred Watson from the Australian Astronomical Observatory says, "You take the light from a star, planet or galaxy and pass it through a spectroscope, which is a bit like a prism letting you split the light into its component colours. It lets you see the chemicals being absorbed or emitted by the light source. From this you can work out all sorts of things.”
Working out a star's age
Spectroscopy can tell scientists the age of a star by looking at the amount of chemical elements in its matter other than hydrogen and helium. The earliest stars were composed of just hydrogen and helium because they were the first elements to form after the Big Bang.
Eventually as these first stars ran out of hydrogen to fuse into helium, soon the latter fused into heavier elements which became iron. Since stars cannot fuse iron into anything heavier, the star causes a supernova explosion and new stars are born.
Eventually as these first stars ran out of hydrogen to fuse into helium, soon the latter fused into heavier elements which became iron. Since stars cannot fuse iron into anything heavier, the star causes a supernova explosion and new stars are born.
Other signs
Spectroscopy can also tell the temperature, mass and surface gravity of a star.
Since a star's mass affects the way atoms in its atmosphere act, you can look at the thickness and fuzziness of the lines in the spectrum and work out the temperature, mass, pressure and surface gravity.
To work out the speed, the spectrum will simply smear the lines at the speed at which a star rotates.
The holy grail of all of this is that there is a possibility that one day spectroscopy may be used to find life at some place in our vast universe. Eventually in a few years’ time, the advancement of telescopes will be powerful enough to see distant planets and study their spectrum.
Since a star's mass affects the way atoms in its atmosphere act, you can look at the thickness and fuzziness of the lines in the spectrum and work out the temperature, mass, pressure and surface gravity.
To work out the speed, the spectrum will simply smear the lines at the speed at which a star rotates.
The holy grail of all of this is that there is a possibility that one day spectroscopy may be used to find life at some place in our vast universe. Eventually in a few years’ time, the advancement of telescopes will be powerful enough to see distant planets and study their spectrum.