Binary Stars Trivia Quiz

Answer: Both stars orbit around a common center of mass.

For simplicity's sake, though, orbits are often plotted as the path of the secondary star with respect to the primary.

Answer: the brighter

Brightness is about the only one of those qualities that can be determined in one observation through a telescope. Mass can't be determined until an accurate orbit is calculated and Kepler's laws can be used.

Answer: astrometric

A star's apparent motion across the sky is called its 'proper motion,' and is determined by its distance from Earth, among other things. Single stars seem to travel in a straight line, but the orbital motion of binary stars causes them to 'wobble' in their motion.

Answer: visual

Through a telescope of sufficient magnification, visual binaries appear as multiple points of light - they are 'resolved' into the correct image. Eclipsing binaries are oriented such that, from our perspective, one star passes in front of the other during the course of its orbit.

These are detected by changes in brightness. Spectroscopic binaries are too close to be resolved by a telescope, and are detected by changes in their spectra - analyses of their light output.

Answer: Alcor and Mizar

Although Alcor and Mizar are not a binary pair, each of those 'stars' is actually a binary star system in itself.

Answer: False

The International Astronomical Union's current estimates are that roughly sixty percent of all known stars are components of binary or multiple star systems. It was once thought that binary stars were the exception to the general rule - now, they ARE the rule.

Answer: speckle interferometry

Speckle interferometry is so named because the stars appear as thousands of little 'speckles' in the image. Filar micrometry is a tool to aid visual observation through the eyepiece. Hipparcos was a cataloguing satellite launched by the European Space Agency (ESA) in 1991, and CCD cameras are standard astronomical recording equipment.

Answer: True

Although the gravitational dynamics are complex, planets can and do exist in stable orbits in a binary star system. The planet can either make a wide orbit around a close binary (in which case it's so far away that the stars are in effect one center of mass), or in a close orbit around one component of a wide binary (in which case the stellar companion has negligible gravitational effect on the planet).

Answer: angular separation between the two stars

We observe stars from one point in the galaxy - Earth. (Interstellar distances are so vast that our planet can be treated as a single point.) Thus, we aren't in a position to measure linear distances - but we CAN measure the apparent separation in the arc of the sky.

This is called angular measure and the basic unit is the degree, although the separations are so small that we mostly use arcminutes (a sixtieth of a degree) and arcseconds (a sixtieth of an arcminute).

Answer: Sir William Herschel

Herschel, discoverer of the planet Uranus and first to posit our galaxy's spiral shape, used the term in an 1802 paper, 'On the Construction of the Universe.' Here's hoping this quiz has helped you construct YOUR vision of the universe.