Its location and kinematics suggest it belongs to a stream of tidal-tail gas falling back into the remnant." It continues: "This large discrepancy suggests that the nebula is a faint ionization echo excited by a mildly active nucleus that has declined by ~3 orders of magnitude over the past 20,000–200,000 years. In many ways this nebula resembles the prototypical `Hanny's Voorwerp' near IC 2497, but its size is 3x smaller."
Its position and dynamics indicate it is part of a stream of tidal-tail gas returning to the remnant. It continues: "This significant difference implies that the nebula is a faint ionization echo excited by a moderately active nucleus that has decreased in intensity by ~3 orders of magnitude over the past 20,000–200,000 years. In many ways this nebula resembles the prototypical `Hanny's Voorwerp' near IC 2497, but its size is 3x smaller."