CK Vulpeculae (also Nova Vulpeculae 1670) is considered to be the oldest reliably-documented nova. It consists of a compact central object surrounded by a bipolar nebula. Models suggest CK Vulpeculae may not be a classic nova; rather it may be classified as a luminous red nova which is the result of two main sequence stars colliding and merging. A 2018 study found it was most likely the result of an unusual collision of a white dwarf and a brown dwarf. A 2020 article ruled out this proposed mechanism and proposes that CK Vulpeculae is an intermediate luminosity optical transient, i.e. an object in the luminosity gap between supernovae and novae.