NGC 3109

RA:

10 : 03.1

Dec:

-26 : 09

Type:

Ir+ IV-V

RV:

+131 km/s

Distance:

4500 kly

Apparent Dimension:

16.0 x 2.9 arc min

Diameter:

Brightness:

10. m_p

Abs. Mag:

Mass:

NGC 3109 was discovered by John Herschel from South Africa in 1835, and cataloged as h 3221 and later GC 2003.

NGC 3109 is a considerably small irregular galaxy at a distance of probably about 4.5 million light-years. Nevertheless, it is the dominating member of a small group of dwarf galaxies, all of them Local Group member candidates, which also contains Sextans A, Sextans B, the Antlia Dwarf and perhaps Leo A.

It is still not finally clear if these galaxies are gravitationally bound to the Local Group of Galaxies, thus forming a subgroup of the Local Group, or if this is the nearest independent small group of galaxies. Yahil et.al. (1977) rated NGC 3109, together with all other members of its group, with the exception of Leo A, as a possible, but unlikely member of the Local Group; for Leo A they thought membership is likely. Mateo (1999) takes NGC 3109 and all the members in its group as Local Group members, forming a subgroup. Van den Bergh (1999) assumes they for an independent small group (and also counts Leo A to the Local Group).

Mike Irwin and Mateo (1999) give the distance of NGC 3109 at values which, adjusted for our scale, are at about 4.5 million light-years, while Van den Bergh (1999)'s value corresponds to almost 4.9 million ly.

The image in this page was obtained by Michael Purcell on April 17, 1996 with an ST-7 CCD camera on a Meade 10" LX200 telescope from New Mexico (see Michael's NGC 3109 page for more details on this image).