Test #2 Astronomy

A star with a proper name (like sirius) is most likely a ____ star

Bright

Compared to the Earth-Sun distance (=1 astronomical unit), stars are ____ from Earth.

Much more distant

A star whose measured parallax is 0.1 seconds of arc is located at a distance of ____ parsecs

10

The apparent brightness (apparent magnitude m) of a star just barely visible to the naked eye is _____

6

The greater the distance Modulus (m - M) of a star, the ____ distant it is from Earth

More

All other things being equal for these two stars, the blue star is _____ the red star

Hotter than

All other things being equal for these two stars, the blue star is ____ the red star

More luminous than

A star like the Sun has a spectral class ____

G

The hottest stars have spectral class

O

Stars are composed mainly of

hydrogen

The wavelength range for visible light is 400 to 700 nanometers. For diffraction to happen for visible light the obstacle

Must be in this range of sizes

The most energetic light is

Blue

The energy of the first level of hydrogen is

-13.6

The energy of the second level of hydrogen is

-3.4