Hoag's Object (May 19, 2020)

Can you see it?  Hoag's Object looks like a yellow star with a ring around it.

Hoag's Object is also called PGC 54559.  It lies in the constellation Serpens.

It is a galaxy, but astronomers were initially unsure how to characterize it.  Its discoverer in 1950, Arthur Hoag, thought it might be a galaxy or a planetary nebula.  Hoag also proposed that it was a galaxy gravitationally lensing another galaxy far behind it, bending the farther galaxy's light into a ring.

But the yellow-red center of Hoag's Object and the ring surrounding it sit at the same distance from us, so the system could not be a gravitational lens.  Also, the center is not bright enough to be that massive. Hubble images clearly show the yellowed, older center to be ringed by a blue crop of newer stars. Relatively recent studies have shown that the blue ring lights up the inner edge of a larger ring of hydrogen surrounding the galaxy. https://arxiv.org/pdf/1307.6368.pdf

Unlike some ring galaxies that seem to have formed from a collision, Hoag's Object seems peaceful, copacetic.  It is about 600 million light years away.

PGC 1659902 is on the far right, mag 16.68, 1.2 billion light years away.

PGC 1658877 is just above it and a little left, mag 18.11, 1.3 billion light years away.

PGC 1652138, almost directly below Hoag's Object in roughly the middle of the frame, is mag 17.14, 620 million light years.

Lower far left, PGC 1647373, mag 17.42, 1.3 billion light years.

I did not find labels for the other galaxies in the image.

The faintest stars in the image are < mag 19.

This is 11x900" with the 203mm Synta-ONTC Newtonian, taken with the Atik 460EXC.

Or try the inverted monochrome version: