IC 2497

IC 2497 is a spiral galaxy close to the intergalactic cloud Hanny's Voorwerp.

IC 2497 is a former quasar, whose light lit up Hanny's Voorwerp, which is now a light echo of that extinct quasar. It is about 45,000–70,000 light-years (14,000–21,000 pc) away from Hanny's Voorwerp. The quasar shut down sometime in the last 70,000 years. This revises current theories of quasar operation, as the quasar is quiescient, shutting down much faster than was thought possible, and is much cooler than predicted. The galaxy is currently 100 to 10,000 times dimmer than it was when its quasar burned into Hanny's Voorwerp. It is currently the nearest known quasar, being 730 million light years away, and the one with the best view of its host galaxy. The nearest active quasar is 3C 273, 1.7 billion light years further away.