NGC 2787
A small, isolated barred lenticular galaxy with a LINER core.
NGC 2787 is a barred lenticular galaxy in the northern constellation Ursa Major, about 24 million light-years from Earth. German-born astronomer William Herschel first spotted it on December 3, 1788. J. L. E. Dreyer later described it as bright, fairly large, slightly elongated at a 90° angle, with a much brighter central region, mottled but unresolved, and a very small, faint star involved to the southeast. Its visible portion spans an angular size of a few arcminutes, and its apparent visual magnitude is 11.8.
This galaxy is small and isolated, classified as SB(r)0+, meaning it is a barred spiral with a ring encircling the bar. As a lenticular galaxy, it possesses the large halo typical of an elliptical. Its disk is tilted relative to Earth’s line of sight, with its major axis aligned at a specific position angle. NGC 2787 has an unusually high mass-to-light ratio—much higher than that of a typical spiral. Its neutral hydrogen forms a clumpy ring with a radius twice that of the visible galaxy, containing a certain mass, and this ring is misaligned with the central disk.
At its core lies a low-ionization nuclear emission-line region (LINER), characterized by spectral emission from weakly ionized atoms. Such regions are common in lenticular galaxies, appearing in about one-fifth of nearby examples. The central supermassive black hole has a known mass. Dust rings in the galaxy’s center are tilted relative to the disk, possibly due to a past encounter with another galaxy.
NGC 2787 belongs to the Ursa Major Cloud, which is part of the Virgo Supercluster.
Quick Facts
- Epoch
- J2000
- Constellation Name
- Ursa Major
- Ra
- 09 · 19 · 18.60430
- Dec
- +69 · 12 · 11.6429
- Dist Ly
- 7.41 ±
- Appmag V
- 11.79
- Appmag B
- 12.92
- Absmag B
- −18.84
- Mass Light Ratio
- 50
- Notes
- Barred lenticular; LINER
- Names
- PGC 26341, UGC 4914
Facts from the source article.
Lore & Background
NGC 2787 was discovered on December 3, 1788 by German-born astronomer William Herschel. J. L. E. Dreyer described it as 'bright, pretty large, a little extended 90°, much brighter middle, mottled but not resolved, very small (faint) star involved to the southeast'. The galaxy has a morphological classification of SB(r)0+, indicating a barred spiral with a ring around the bar. As a lenticular galaxy, it possesses the large halo of an elliptical galaxy. The distribution of neutral hydrogen forms a clumpy ring with a radius double that of the visible galaxy, and this ring appears misaligned with the central disk. The central region contains dust rings tilted with respect to the disk, possibly resulting from an encounter with another galaxy.
Reader's Guide
NGC 2787 is significant for its unusually high mass-to-light ratio, much greater than that of a typical spiral galaxy, suggesting a substantial dark matter component. Its LINER core is characteristic of many lenticular galaxies, with about one-fifth of nearby lenticulars containing such regions. The supermassive black hole at its center, along with the misaligned hydrogen ring and tilted dust rings, indicates a complex dynamical history, possibly involving a past galactic interaction. The galaxy is part of the Ursa Major Cloud, which itself belongs to the Virgo Supercluster, placing it within the larger structure of the local universe. Its small, isolated nature makes it a valuable object for studying the evolution of lenticular galaxies and the processes that shape their morphology and nuclear activity.
Did You Know?
- The galaxy contains a low-ionization nuclear emission-line region (LINER) at its core.
- The central dust rings are tilted with respect to the disk, possibly from an encounter with another galaxy.
More in NGC Objects, Part 4 1-24
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