We present the discovery of an unusual , tidally-distorted extremely low mass white dwarf ( WD ) with nearly solar metallicity .
Radial velocity measurements confirm that this is a compact binary with an orbital period of 2.6975 hrs and a velocity semi-amplitude of K = 108.7 km s ^ { -1 } .
Analysis of the hydrogen Balmer lines yields an effective temperature of T _ { eff } = 8380 K and a surface gravity of \log g = 6.21 that in turn indicate a mass of M = 0.16 M _ { \odot } and a cooling age of 4.2 Gyr .
In addition , a detailed analysis of the observed metal lines yields abundances of \log ( Mg/H ) = - 3.90 , \log ( Ca/H ) = - 5.80 , \log ( Ti/H ) = - 6.10 , \log ( Cr/H ) = - 5.60 , and \log ( Fe/H ) = - 4.50 , similar to the sun .
We see no evidence of a debris disk from which these metals would be accreted though the possibility can not entirely be ruled out .
Other potential mechanisms to explain the presence of heavy elements are discussed .
Finally , we expect this system to ultimately undergo unstable mass transfer and merge to form a \sim 0.3–0.6 M _ { \odot } WD in a few Gyr .