WD 1337+705

Shining with an apparent magnitude of 12.8, it is white dwarf 0.59 times as massive as the Sun.

[3] In 1997, Jay Holberg and colleagues discovered magnesium in its spectrum, which suggests that it has some low mass companion or accretion of material happening as the star's temperature is not hot enough for its intrinsic emission.

The presence of nitrogen on the other hand shows that an icy Kuiper Belt Object was accreted as well.

KBOs are also rich in other ices (H2O, CO, CO2) containing carbon and oxygen, which are also present in this white dwarf.

Other detected elements are Magnesium, Aluminium, Silicon, Phosphorus, Sulfur and Calcium.