PASADENA - Caltech and UC Berkeley astronomers reported a new kind of cosmic explosion Wednesday - even though it occurred 49 million years ago.

A flash seen in the Virgo cluster in a galaxy known as Messier 85 is believed to have occurred from the merger of two ordinary stars.

"The discovery of this enigmatic event is merely the tip of the proverbial iceberg for an emerging class of cosmic transients," said Shrinivas Kulkarni, the Caltech professor who led the team that discovered the explosion.

The flash was observed while astronomers were mapping supernova, but the emission was too faint to be an exploding star and too bright to be a nova, or a thermonuclear explosion on the surface of a white dwarf star, according to Caltech.

"I was simply floored," said Arne Rau, a post-doctoral fellow working with Kulkarni. "In a short time, we went from speculation to real discovery."

The new class of object has been dubbed luminous red novae, because they have a distinct red color and expand slowly compared to other kinds of cosmic explosions.

The galaxy in which the event occurred is made up of mostly old stars, and astronomers believe the two stars that exploded were similar in mass to that of our sun.