Elias 2-27 (2MASS J16264502-2423077)[3] is a YSO star[3] with a protoplanetary disk around it, located in the Ophiuchus Molecular Cloud (ρ Oph Cld, 5 Oph Cld, Ophiuchus Dark Cloud), a star-forming region in the Ophiuchus constellation, some 360 light-years (110 parsecs) away.

This star system became the first ever observed with density waves in the disk, giving it a spiral structure.

[5][6] In 2016, it was discovered that disk perturbations from density waves organized the disk debris into a pinwheel structure, with sweeping spiral arms; using observations from the Atacama Large Millimeter Array (ALMA) radio telescope.

This marks the first instance of such an observation in a protoplanetary disk, though they have been previously predicted.

The spiral arms start at 100 AU (9.3×109 mi; 1.5×1010 km) and extend out to 300 AU (2.8×1010 mi; 4.5×1010 km).