Dr. K Astronomy

Suppose a source at rest emits a spectrum that looks like the following: Which of the following indicates the source moving away from you the fastest?

*The greater the redshift, the faster the speed away from you.

Sun will be M-S star for _________

10 billion years

what is the correct composition of a neutral atom of helium -4?

2 protons, 2 neutrons , 2 electrons *Helium has atomic number 2, meaning 2 protons, so helium-4 must also have 2 neutrons. A neutral atom always has the same number of protons and electrons.

Sun's age is ______

4.6 billion years

Sun has _____ of original hydrogen

54%

Sun's original Hydrogen content was___

75%

Which of the following type of spectrum would you expect if you view star light that has passed through a cool cloud of interstellar gas on its way to Earth?

an absorption line spectrum *The starlight will contain light of nearly all wavelengths, so atoms in the cloud will absorb light with the wavelengths corresponding to energy level transitions in those atoms. Therefore you will see an absorption line spectrum.

the sum of the number of protons and neutrons in an atom is called the

atomic mass number

each chemical element has a unique

atomic number

the number of protons in an atom is called the atom's

atomic number

an atom with more electrons than protons has a negative

electric charge

Most hydrogen atoms have only a single proton in their nucleus, so a hydrogen atom that also has one neutron is an ___________ of hydrogen

isotope