Star Spectra Check In

Which of the following elements is/are represented in the star spectrum from the image?

• Hydrogen only

• Helium only

• Hydrogen & Helium

• Calcium only

• Calcium & Hydrogen

Answer explanation

Comparison shows that the star spectrum is identical to the spectrum of calcium. Although the spectrum of calcium is similar to the combination of hydrogen and helium, there are several differences. For example, calcium has strong spectral lines in the green and orange parts of the spectrum, while helium and hydrogen are represented in the yellow and red regions. A star spectrum showing only calcium does not mean that the star only contains calcium, or even that the star contains more calcium than any other star. Instead, it is indicative of a star with a moderate surface temperature, probably a class G or K star.

Tags

NGSS.HS-ESS1-2

1. The Sun's spectrum contains spectral lines from neutral sodium and calcium as well as ionized magnesium and iron. Of the choices below, which could be the surface temperature of the Sun? (HINT: Use the Star Classification Table from your Star Spectra Lab Gizmo)

• 4,200 K

• 5,800 K

• 8,900 K

• 14,300 K

Answer explanation

According to the classification system shown in the Exploration Guide, a star with neutral sodium and calcium and ionized heavy metals is a class G star, with surface temperatures ranging from 5,000 to 6,000 K. Most estimates place the Sun's surface temperature at around 5,800 K.

Tags

NGSS.HS-PS4-1

The spectrum of a distant star contains sodium lines that are offset from their normal position, as shown. What is the most likely explanation?

• The star is relatively hot.

• The star is relatively cool.

• The star is moving rapidly toward us.

• The star is moving rapidly away from us.

Answer explanation

When a star moves away from us, the light waves get stretched out, which causes the spectral lines to shift towards the red end of the spectrum. When a star moves towards us, the light waves are compressed, causing a blue shift. The spectrum shown is substantially blue-shifted, so the star is moving towards us very quickly.

Tags

NGSS.HS-ESS1-2

NGSS.HS-PS4-3

1. In the 1920s, Edwin Hubble looked at the spectra of stars from distant galaxies. To his surprise, he found that all of these spectra were red-shifted, and that the more distant the galaxy, the greater the red-shift. What is a reasonable conclusion from this evidence?

• The universe is expanding.

• The universe is contracting.

• The universe is unchanging.

• The universe is curved.

Answer explanation

If every galaxy is moving away from our own galaxy, it indicates that the universe is expanding. You can model this by placing small stickers (representing galaxies) on a balloon. When the balloon is blown up, each sticker will get farther away from all of its neighboring stickers, as shown below.

Based on this fact, astronomers concluded that the entire universe must have begun at a single point. The tremendous explosion that formed our expanding universe was dubbed "The Big Bang."

Tags

NGSS.HS-ESS1-2

Which element is not represented in the star spectrum below?

• Hydrogen

• Helium

• Calcium

• Magnesium

Answer explanation

Close analysis shows that the spectrum contains spectral lines from hydrogen, calcium, and magnesium, but not from helium. The easiest way to see this is that helium has a strong line in the middle of the yellow part of the spectrum. This line is not found in the star spectrum. Helium is characteristic of spectra from high-temperature stars, while neutral metals are characteristic of spectra from medium and low-temperature stars. Hydrogen lines can be found in almost any star spectrum, with varying degrees of intensity.

Tags

NGSS.HS-ESS1-3

A​(n) ​ ​ (a)   contains dark lines superimposed on a bright continuous spectrum. ​

• Absorption spectrum
• emission spectrum
• spectrum

Tags

NGSS.HS-PS4-3

NGSS.HS-PS4-4

A pair of stars that orbit one another are called​ (a)  

• Binary stars
• cephelid variable
• Giant Star
• nebula

Match the following terms to its correct description.

• spectrum

• the phenomenon in which light moving rapidly away from an observer appears shifted toward the red end of the spectrum

• Redshift

• a spectrum of colored lines on a dark background. Also called a bright line spectrum.

• Blueshift

• the phenomenon in which light from a source that is moving toward an observer is shifted toward the blue end of the spectrum.

• emission spectrum

• the band of colors produced when light is passed through a prism or similar device.

• nebula

• a cloud of gas and dust in interstellar space.

Tags

NGSS.HS-ESS1-2

NGSS.HS-PS4-1

NGSS.HS-PS4-3

NGSS.HS-PS4-4

Match the following

• Cepheid variable

• A bright, very large star with a low density and a relatively low surface temperature.

• Giant Star

• A star that expands and contracts in a regularly repeating cycle

• Star

• a massive ball of plasma that radiates light.

The high temperatures inside stars are produced by ​ (a)   reactions inside the core of the star. These reactions convert hydrogen to ​ (b)   .

• nuclear fusion
• helium
• nuclear fission
• iron
• carbon

Tags

NGSS.HS-ESS1-1

NGSS.HS-PS1-8