Why do stars have emission lines?

As the light passes through a hydrogen cloud in the outer layers of the star, some red light is absorbed by the hydrogen. These peaks are called “emission lines,” because the cloud emits light. Emission lines also depend on the temperature of a star; they only appear if a star is at the right temperature.

WHY IS A stars spectral lines important?

From spectral lines astronomers can determine not only the element, but the temperature and density of that element in the star. The spectral line also can tell us about any magnetic field of the star. The width of the line can tell us how fast the material is moving. We can learn about winds in stars from this.

Why is the star important to astronomers?

Stars are the most widely recognized astronomical objects, and represent the most fundamental building blocks of galaxies. The age, distribution, and composition of the stars in a galaxy trace the history, dynamics, and evolution of that galaxy.

What is redshift and what does it tell us about the universe?

Bottom line: A redshift reveals how an object in space (star/planet/galaxy) is moving compared to us. It lets astronomers measure a distance for the most distant (and therefore oldest) objects in our universe.

What is an emission line star?

An emission-line star is a star whose spectrum exhibits emission lines in the optical spectra. Common types include: Shell star. Wolf–Rayet star.

Why the study of emission spectrum is important?

The different colors of light produced by emission spectra of different elements allows them to be identified. So elements can be identified by the colors their atoms produce when energy (by heating or electric current) is used to reveal their emission fingerprints.

How do scientists apply emission spectra to stars?

The most common method astronomers use to determine the composition of stars, planets, and other objects is spectroscopy. Today, this process uses instruments with a grating that spreads out the light from an object by wavelength. This spread-out light is called a spectrum.

How do astronomers use constellations?

constellation, in astronomy, any of certain groupings of stars that were imagined—at least by those who named them—to form conspicuous configurations of objects or creatures in the sky. Constellations are useful in assisting astronomers and navigators to locate certain stars.

Why study stars what benefits do we get from studying them?

Once we look beyond the solar system, most of what we can learn about the Universe is based on observing stars. Not only do they light up the sky, they produce the raw materials that make life possible, and if there is life out there, it is most likely orbiting a star on its planet.

How does light from stars indicate the universe is expanding?

When looking at the radiation emitted by distant stars or galaxies, scientists see emission spectra ‘shifted’ towards the red end of the electromagnetic spectrum—the observed wavelengths are longer than expected. Something causes the wavelength of the radiation (emitted by faraway stars and galaxies) to ‘stretch’.

How do astronomers use redshift to determine distances?

Astronomers also use redshift to measure approximate distances to very distant galaxies. The more distant an object, the more it will be redshifted. Some very distant objects may emit energy in the ultraviolet or even higher energy wavelengths.

What causes a star to emit emission lines in space?

Low-density clouds of gas floating in space will emit emission lines if they are excited by energy from nearby stars. Planetary nebulae, for example, are the remnants of stars which have gently pushed their outer envelopes outwards into space. Some of them are very pretty:

Why do we see absorption lines in the spectrum of stars?

through a cloud of hydrogen gas, we will see a dark absorption line at 121 nm. We see absorption lines in the spectra of ordinary stars like the Sun because the tenuous outer layers of the stellar atmosphere — called the photosphere — absorb some of the continuous light coming from the hot, dense interior.

Why do different elements have different emission and absorption lines?

For most elements, there is a certain temperature at which their emission and absorption lines are strongest. The lines you see in a star’s spectrum act like thermometers. Some compounds, like titanium oxide, only appear in the spectra of very cool stars. Others, like helium, appear only in the spectra of very hot stars.

What can we learn about a star from its spectra?

If the lines shift back and forth we can learn that the star may be orbiting another star. We can estimate the mass and size of the star from this. If the lines grow and fade in strength we can learn about the physical changes in the star. Spectral information can also tell us about material around stars.