ZTF J1901+1458

ZTF J1901+1458 is a white dwarf, about 135 light years away roughly in the direction of Epsilon Aquilae, discovered by the Zwicky Transient Facility circa 2021. It is the most massive white dwarf yet found, having 1.35 times the mass of the Sun, nearly the largest expected mass for this type of object, which is defined by the Chandrasekhar limit. Its radius is about, between the sizes of Moon and Mercury, and it rotates once every 7 minutes. Its effective temperature is about.
The object's extreme rate of spin is hard to explain without supposing ZTF J1901+1458 to be the result of a white dwarf merger, near the upper mass limit of a stable end product. Larger white dwarf mergers could be another mechanism of supernova production, which is not necessarily taken into account in how we have traditionally inferred dark energy from supernova observations.