The 2188

Lore & Background

NGC 2188 was discovered by British Astronomer John Herschel on January 9, 1836. It is a barred spiral galaxy in the constellation Columba, approximately 25 million light years from Earth. The galaxy is estimated to span about 50,000 light-years in length. Because it is observed nearly edge-on, only the thin outer edge of its galactic disc is visible; its central bulge and spiral arms are tilted away from the line of sight. The true morphology has been determined through analyses of stellar distribution in the bulge and disc, as well as studies of stellar colors. The galaxy is close enough that its stars can be resolved, with the brightest having an apparent magnitude of about 21. Observations in neutral hydrogen HI show an asymmetrical structure, which may suggest a recent galactic interaction. The hydrogen gas is more abundant in one end of the galaxy and extends over 4 kpc away from the galactic plane. Other features visible are some filaments and a superbubble with a diameter of 15 arcseconds. These filaments have been associated with a HII region located in the galactic halo. The total hydrogen mass of the galaxy is estimated to be 3×10^8 M☉, while it is of low metallicity. NGC 2188 has been found to have three smaller companions: HIPASS J0607-34, ESO364-029, and KK 55.

In Their Own Story

On January 9, 1836, British Astronomer John Herschel first recorded NGC 2188 in the constellation Columba. Over a century later, astronomers determined it is a barred spiral galaxy about 25 million light years from Earth, spanning roughly 50,000 light-years. Because it is seen nearly edge-on, only the thin outer edge of its disc is visible from our vantage point. By analyzing stellar distribution and colors, researchers mapped its true morphology. The galaxy is close enough that individual stars can be resolved, with the brightest shining at apparent magnitude 21. Radio observations in neutral hydrogen HI revealed an asymmetrical structure—hydrogen gas is more abundant at one end and extends over 4 kpc from the galactic plane. This asymmetry may indicate a recent galactic interaction. Within the galaxy, filaments associated with an HII region in the halo and a superbubble 15 arcseconds across have been spotted. The total hydrogen mass is estimated at 3×10^8 solar masses, and the galaxy has low metallicity. Three smaller companions—HIPASS J0607-34, ESO364-029, and KK 55—orbit NGC 2188.

Reader's Guide

NGC 2188 is a barred spiral galaxy in the constellation Columba, about 25 million light years away. It spans an estimated 50,000 light-years in length. The galaxy is observed nearly edge-on, so only the thin outer edge of its disc is visible; its central bulge and spiral arms are tilted away. To study its true morphology, astronomers analyze stellar distribution in the bulge and disc, as well as stellar colors. The galaxy is close enough that its stars can be resolved, with the brightest at apparent magnitude 21. Observations in neutral hydrogen HI show an asymmetrical structure—hydrogen gas is more abundant at one end and extends over 4 kpc from the galactic plane. This may suggest a recent galactic interaction. Other features include filaments associated with an HII region in the galactic halo and a superbubble with a diameter of 15 arcseconds. The total hydrogen mass is estimated at 3×10^8 M☉, and the galaxy has low metallicity. NGC 2188 has three smaller companions: HIPASS J0607-34, ESO364-029, and KK 55. To locate it, look toward the constellation Columba; detailed images are available via DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, and other surveys.

Did You Know?

• NGC 2188 was discovered by British Astronomer John Herschel on January 9, 1836.
• The galaxy is estimated to span about 50,000 light-years in length.
• The brightest stars in NGC 2188 have an apparent magnitude of about 21.
• Hydrogen gas extends over 4 kpc away from the galactic plane.
• NGC 2188 has three smaller companions: HIPASS J0607-34, ESO364-029, and KK 55.