Entitled 'WISE J0304-2705', the object was a member of the recently established 'Y dwarf' class, the coolest stellar temperature class yet defined, added to the end of the sequence
OBAFGKMLT. Although its temperature was not far off that of our own world, the object was not like the rocky Earth-like planets and instead was a giant ball of gas like Jupiter.
Recent surprises: (a) L-type spectra (with strong features due to the alkali metals lithium, sodium, and so forth) switch over to T-type spectra (with features due mostly to methane) over a very narrow range of temperatures near 1,300 Kelvin, accounting for the absence of transitional types and representing the sharpest change between adjacent spectral types anywhere along the sequence
OBAFGKMLT. And (b), among the cooler Ls, a sodium feature removes so much yellow light that a suitably tuned detector might record the complementary color--you may never see a purple cow, but purple stars are possible.