Binary Star Systems Quiz-1

What is a binary star system?

• A single star with a large planetary system.

• Two or more stars orbiting a common center of mass.

• A star and a nebula.

• A star that appears to be two due to an optical illusion.

Answer explanation

A binary star system consists of two or more stars that orbit around a common center of mass, distinguishing it from single stars or other celestial objects.

What is an optical binary system?

• A system where two stars are very close and touching.

• A system where two stars appear close together from our viewpoint but are actually far apart.

• A system with one star eclipsing the other.

• A system with stars that have very similar spectra.

Answer explanation

An optical binary system consists of two stars that appear close together in the sky from our perspective, but they are actually at different distances from us, making them not physically close.

In a visual binary system, what can be directly observed over time?

• The light shift between the stars.

• The change in the spectrum of the stars.

• The movement of one star around the other.

• The dimming and brightening of the system's light.

Answer explanation

In a visual binary system, the movement of one star around the other can be directly observed over time, allowing us to track their orbital dynamics. This is a key characteristic of such systems.

What characterizes an eclipsing binary system?

• Stars that appear close together from Earth but are far apart.

• Stars that are very close and have overlapping atmospheres.

• A system where one star passes in front of the other, causing dips in brightness.

• A system where the stars show a shift in spectral lines.

Answer explanation

An eclipsing binary system is characterized by one star passing in front of another, leading to observable dips in brightness. This phenomenon allows astronomers to study the properties of the stars involved.

What is an astrometric binary?

• A binary system where the stars have different spectral types.

• A system where the wobble of one star indicates the presence of another, unseen star.

• A system where the stars are in physical contact with each other.

• A system where one star is completely blocked by the other.

Answer explanation

An astrometric binary is identified by the gravitational influence of an unseen star, causing the visible star to wobble. This wobble indicates the presence of the companion star, making the second choice the correct answer.

How is a spectroscopic binary identified?

• By direct observation of the stars.

• By changes in the total brightness of the system.

• By the Doppler shifts in the spectral lines.

• By the physical contact of two stars.

Answer explanation

A spectroscopic binary is identified by observing the Doppler shifts in the spectral lines of the stars. This shift indicates the motion of the stars towards or away from us, revealing their orbital dynamics.

What defines a spectrum binary?

• A binary that has a shifting of its spectral lines.

• A binary system where the spectrum shows indicators of two different stars.

• A system where one star is blocking the other star.

• A system with one star moving around the other.

Answer explanation

A spectrum binary is characterized by the presence of spectral lines from two different stars, indicating that the system consists of two distinct stellar components, making the second answer choice correct.

What are contact binaries?

• Binary stars that are far apart, but appear close together from Earth.

• Binary stars where the two stars are so close that they share a common outer atmosphere or material.

• Binary stars that periodically eclipse each other.

• Binary stars where only one star is visible.

Answer explanation

Contact binaries are binary stars that are so close together that they share a common outer atmosphere or material, distinguishing them from other types of binary stars that are either far apart or do not interact.

What is the angle of inclination in the context of eclipsing binaries?

• The angle between the two stars in the system.

• The angle between the observer and the orbital plane.

• The angle between the line of sight from Earth and the normal to the orbital plane.

• The angle between the major and minor axes of the orbit.

Answer explanation

The angle of inclination refers to the angle between the line of sight from Earth and the normal to the orbital plane. This angle is crucial for understanding the dynamics of eclipsing binaries.

What is the significance of the Roche lobe?

• It is the region where the stars are most luminous.

• It is the region around a star where its gravity dominates.

• It is the area between the orbits of stars.

• It is the region where stars are physically in contact.

Answer explanation

The Roche lobe is the region around a star where its gravity dominates, defining the area within which it can retain orbiting material. This concept is crucial in understanding binary star systems and mass transfer.