NGC 2573

Lore & Background

NGC 2573 was discovered on March 29th, 1837 by English astronomer John Herschel. Its nickname, Polarissima Australis, reflects its position as the nearest NGC object to the south celestial pole. The galaxy has an apparent magnitude of 13.25, making it readily visible in medium-sized telescopes but not to the naked eye. It is located at a distance of 84 million light years, though a redshift of z = 0.08102 suggests a greater distance of 109 million light years. The galaxy is currently receding with a heliocentric radial velocity. In the De Vaucouleurs system, NGC 2573 has a morphological classification of SAB(s)cd:, indicating it is a weakly-barred spiral galaxy with loosely bound spiral arms and a small, faint bulge. The (s) notation denotes a purely spiral structure, though there is uncertainty about the classification, possibly due to the galaxy's faintness. NGC 2573 is estimated to be 77,800 light years across, similar in size to the Milky Way, and has a central mass that is 28% of the latter's mass.

Reader's Guide

NGC 2573 holds significance as the southern counterpart to NGC 3172, the closest NGC object to the north celestial pole. Its nickname Polarissima Australis underscores its unique positional distinction. The galaxy's classification as SAB(s)cd: reflects a weakly-barred spiral structure with loosely bound arms, though the uncertainty in its morphology highlights the challenges of observing faint objects. Its size, comparable to the Milky Way, and its central mass—28% of the Milky Way's—provide context for its physical scale. The discrepancy in distance measurements (84 million light years versus 109 million light years from redshift) illustrates the complexities in determining extragalactic distances. Discovered by John Herschel in 1837, the galaxy remains a subject of interest for its polar proximity and structural characteristics, contributing to the study of spiral galaxies in the southern sky.

Did You Know?

• NGC 2573 is also known as Polarissima Australis because it is the closest NGC object to the south celestial pole.
• It was discovered by English astronomer John Herschel on March 29th, 1837.
• The galaxy has an apparent magnitude of 13.25, visible in medium-sized telescopes.
• Its morphological classification is SAB(s)cd:, indicating a weakly-barred spiral with loosely bound arms.