HD 12039, also known as DK Ceti, is a variable star in the constellation of Cetus at a distance of 135 ly (41 pc).

It is categorized as a BY Draconis variable because of luminosity changes caused by surface magnetic activity coupled with rotation of the star.

[10] The stellar classification G4V is similar to the Sun, indicating this is a main sequence star that is generating energy at its core through the thermonuclear fusion of hydrogen.

[10] In 2006, a debris field was discovered in orbit around this star using infrared observations by the Spitzer Space Telescope.

[13] The star system does not show any excess emission at 70 μm, indicating it does not have a cold outer dust disk.