Delta Ceti

A hot blue subgiant star an estimated 650 light years from the Solar System, Delta Ceti lies in the northeastern parts of the constellation Cetus, close to the line of the celestial equator. This is a massive star, with some eight times the mass and four times the diameter of the Sun. It shows an unsually slow rate of rotation, which likely implies that the star is oriented so that it is viewed from a nearly polar perspective as seen from Earth.

As its blue colouration indicates, Delta Ceti is a great deal hotter and more luminous than the Sun, with a surface temperature of over 20,000 K. The high temperature in its core, and specifically its effect on the iron in that core, causes a periodic build-up and release of energy within the star, which in turn causes the star to swell and contract. As a result, Delta Ceti is a pulsating variable of the Beta Cephei type, and its brightness increases and decreases over a regular period of some 3.8 hours.