Astro 1500 Trivia October 3 (Lecture 11)

The spectral classes, O B A F G K M, are an analogue for...

• Temperature

• Mass

• Radius

• Distance

Answer explanation

The spectral lines exhibited by a star depend on the star's exterior temperature because that heat is what can excite or ionize the star's atmospheric atoms. How much heat the star puts out affects what atoms can be excited or ionized.

Tags

NGSS.HS-ESS1-1

Why don't O-type stars have hydrogen lines in their spectra?

• They aren't made of hydrogen

• They're too cold to excite hydrogen atoms

• They're so hot they ionize the hydrogen

• They're blocked out by other atoms' lines

Tags

NGSS.HS-PS4-3

Which of the following is FALSE about brown dwarfs?

• They're all nearly the same size

• They slowly cool off and move through the L, T, and Y spectral types

• They fuse regular hydrogen

• The have masses between 13 and 80 times that of Jupiter

Answer explanation

Brown dwarfs lack the mass to fuse hydrogen in their cores. They are massive enough to fuse deuterium, though. Deuterium are hydrogen atoms with a proton and a neutron in their nuclei. Regular hydrogen has a nucleus that's just a proton.

Which kind of binary does not actually have the stars orbiting each other?

• Spectroscopic binary

• Visual binary

• Optical double

Why are binary stars important in astronomy?

• They are rare and interesting

• They help us learn stellar spectral types

• They help us learn stellar masses

• They're not important unless you study binary stars

Answer explanation

By using Newton's formulation of Kepler's third law, we can take an important step in determining the masses of the component stars in a binary system. If we can find the masses and spectral types of those component stars, we can thereby find the masses of all stars of the same spectral type.

Most stars masses are...

• Less than the Sun's mass

• Similar to the Sun's mass

• Greater than the Sun's mass

• There are about as many stars with masses less than and greater than the Sun's

• 2x greater

• 4x greater

• 8x greater

• 16x greater

Tags

NGSS.HS-ESS1-3

The top right of the HR diagram has _______ stars, the long middle band has _______ stars, and the bottom left has ________ stars.

• White dwarf, giant, main sequence

• White dwarf, main sequence, giant

• Giant, white dwarf, main sequence

• Giant, main sequence, white dwarf

If an ambitious astronomer is making an HR diagram of all stars that they can see with the unaided eye, which stars will be underrepresented?

• Red dwarfs

• Sun-like stars

• Red giants

• Blue giants

Answer explanation

Red giants will be underrepresented on the diagram because while these stars are the most plentiful in the Universe, they are also very faint and hard to see.