M53, NGC 5053, and NGC 5466 are an odd ménage in Coma-Böotes. At 45x M53 is an easy find at mag 7.6. At 163x, M53’s halo red giants are a dozen to fifteen mag 13.8 to ~14 specks circling a shimmery opal. It’s amazing we can see them at all, since M53 is 58,000 light years away. But since it is almost directly above the Milky Way plane, dust between us and it only robs 1/20th of its light. WYS95%WYG. At birth 12.7 Gyr ago M53 weighed about a million solar masses. Now it is 826,000 msols. Its early halo striplings now populate the Milky Way’s outer halo, where astronomers have found a few of what might be M53’s long-lost cousins. They are revealed by their spectral similarity, and by their orbits at the same distance, ellipticity, and direction. The child may leave the home, but the home will never leave the child. However, M53 developed a tough hide out there. Its estimated lifespan is
30 times the present age of the Universe.
Nearby NGC 5053, as many a rueful CN post attests, would be easy if it was the mag 9.96 that Simbad says it is. But at the eyepiece it is a lusterless pearl on a black button in the moonlight—and all too often a pain in certain portions of the anatomy that don‘t happen to be the eyes. N5053’s already modest film of luminosity is spread over 64 sq arcmins of sky, for a surface brightness of 22.4 mag sq arcsec. N5053 is actually 4500 light years closer to us than M53—53,500 -vs- 58,000. It’s so tough because it is so spread out: its 27,700 solar luminosities dribble amid 163 light years of not very much. M53 radiates 227,000 times the Sun’s light across 219 light years of diameter. N5053 is so dispersed that astronomers still can’t say exactly where its centre lies—and indeed, its centre never resides twice in one place. N5053 looks more like an ancient open cluster such as NGC 188 in Ursa Minor or Collinder 261 above me in Musca.
When we do finally glimpse N5053 we are looking at one of the oldest and least populous of the Galaxy’s globulars, only ~16,000 solar masses. As a Class XI globular, there is a lot of darkness between its mag 13.6 red giants. It is one of my favourites because at 163x it trembles a feeble underlay of tiny speckles so hesitant they are more often maybe-not than maybe. Most of those are actually nearby field stars. Of the dozen I see, perhaps two or three belong to N5053. Like its coeval colleague M92, N5053 began life much more populous and centrally concentrated. But unlike M92, about 60% of N5053’s original stars have gone astray. It lives 53,500 light years out and these days almost directly above the Galactic plane, just a few thousand light years away from M53. But the thrall of astronomy is that we can we visualise what we cannot see—
in the 10 arcmin circle of that elusive patch there are two quasars, fifteen galaxies in two groups, a solo elliptical galaxy near N5053’s centre, and the nine mag 16.5 to 18.0 RR Lyrae stars by which we come to know its distance, its great antiquity, and thus its wonders. The Universe itself is only 4% older than N5053.
