Rapid Rotators

Stellar rotation causes a star's shape to be flattened at the poles and bulged at the equator. The CHARA Array can measure the size and shape of rapidly rotating stars. Because the equator is further from the center of the star, it will appear cooler than the poles, an effect called "gravity darkening".

Stellar Diameters

The CHARA Array measures the sizes of stars across a large range of masses and evolutionary stages.

Nova Explosions

A nova occurs following the build-up of a thin layer of hydrogen on the surface of a white dwarf -  a highly evolved star with the diameter of the Earth and the mass of the sun.  The hydrogen is provided by a close binary companion.  As the pressure in the layer of accreted hydrogen builds and the temperature reaches a critical level, it triggers a thermonuclear runaway.  The light from the explosion significantly exceeds the star's normal brightness and the outer layers are ejected away at high velocities. Over time, the star slowly fades as the fireball expands and cools.  The CHARA Array can image the expanding fireball at the earliest stages after a nova explosion.

Spotted Magnetic Stars

Sunspots and starspots are cooler, darker areas on the surface of a star that form when stronger regions of the magnetic field block the flow of heat and energy in patches.  The high angular resolution of the CHARA Array can be used to image the surfaces of stars and study starspots on magnetically active stars.

Eclipsing Binaries

A binary star is a system of two stars that orbit around their center of mass.  In an eclipsing binary, the orbit is aligned so that one star passes in front of the other along our line of sight.  This causes a periodic dimming in light as the stars pass in front of each other.  The CHARA Array can study eclipsing binaries by spatially resolving the component stars.

Be Stars

Be Stars are rapidly rotating massive stars that eject gas into a circumstellar disk.  Long baseline optical/infrared interferometry can spatially resolve the disks around Be stars.