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Astronomers have discovered a new kind of supernova called Type Iax which is a star explosion so weak that scientists have coined it a miniature stellar blast.

Astronomers had previously divided supernovae into two types, known as core-collapse and Type Ia. Core-collapse supernovae are the explosion of a star about 10 to 100 times the size of the sun, while Type Ia supernovae are the complete explosion of a tiny white dwarf.

But a team of astronomers including Carnegie's Wendy Freedman, Mark Phillips and Eric Persson is reporting the discovery of a new type of supernova called Type Iax.

"A Type Iax supernova is essentially a mini supernova," lead study author Ryan Foley of the Harvard-Smithsonian Center for Astrophysics said. "It's the runt of the supernova litter." The new supernova is fainter and less energetic than Type Ia.  

Foley and his colleagues identified 25 examples of the new type of supernova. The research has been accepted for publication in the Astrophysical Journal.

According to the study, the researchers concluded that based on a variety of observational data, a Type Iax supernova comes from a binary star system containing a white dwarf and a companion star that's lost its outer hydrogen, which leaves it helium dominated. The white dwarf collections helium from the normal star.

Researchers aren't sure what triggers a Type Iax. It's possible that the outer helium layer ignites first, sending a shock wave into the white dwarf. Alternatively, the white dwarf might ignite first due to the influence of the overlying helium shell.