NGC 2681

Lore & Background

NGC 2681 is a lenticular galaxy in Ursa Major, lying 50 million light years away and spanning about 55,000 light years. Its active galactic nucleus is a type 3 Seyfert, and the nucleus is also a low-ionization nuclear emission-line region. The galaxy is seen nearly face-on, and Earth-based observations in B-I images show neither grand design spirals nor a ring, but two symmetrical spiral arms starting from the end of the primary bar. In Hα images, HII regions are observed in these spiral arms. Hubble Space Telescope images reveal a dust spiral extending to the center. The galaxy possibly has three bars, with a relatively large bar on the outer side; because the galaxy is face-on, these bar-like structures cannot be projection effects.

Dynamical modeling of velocity dispersions suggests the presence of a supermassive black hole with an upper mass limit of 6×10^7 M⊙. Observations from the Chandra X-ray Observatory show three stellar sources within the central kiloparsec. The active galactic nucleus has a luminosity of 1.8×10^38 erg/s, accounting for about 20% of the total luminosity of the central kiloparsec. The lack of stellar gradient in the central regions, along with data from the Faint Object Camera, Faint Object Spectrograph, and International Ultraviolet Explorer, indicates that the galaxy experienced a starburst event approximately one billion years ago, possibly after a tidal interaction with another galaxy, which involved the entire galaxy.

Reader's Guide

NGC 2681 holds significance as a nearby example of a lenticular galaxy with an active nucleus and complex barred morphology. Its triple-barred structure, confirmed by face-on orientation, provides a rare case for studying bar formation and evolution. The galaxy's active galactic nucleus, a type 3 Seyfert with a low-ionization nuclear emission-line region, contributes to understanding the diversity of AGN activity. The presence of a supermassive black hole with an upper mass limit of 6×10^7 M⊙, derived from dynamical modeling, adds to the census of black hole masses in nearby galaxies. The starburst event about one billion years ago, likely triggered by a tidal interaction, offers insight into how galaxy interactions can drive star formation across an entire galaxy. The Chandra detection of three stellar sources within the central kiloparsec and the AGN's luminosity accounting for 20% of the central region's total luminosity highlight the interplay between nuclear activity and stellar populations. The dust spiral seen by Hubble further illustrates the fine-scale structure in the galaxy's inner regions.

Did You Know?

• NGC 2681 is a type 3 Seyfert galaxy with a low-ionization nuclear emission-line region.
• The supermassive black hole in NGC 2681 has an upper mass limit of 6×10^7 M⊙.