Leo A

Irregular Galaxy Leo A (Leo III, UGC 5364, DDO 69, A0956), type IBm V, in Leo

[Leo A image, D.A. Hunter]

RA:
09 : 59.4
Dec:
+30 : 45
Type:
IBm V
RV:
- 26 km/s
Distance:
2500 kly
Apparent Dimension:
5.1 x 3.1 arc min
Diameter:
Brightness:
12.9 mag vis
Abs. Mag:
Mass:
This galaxy was first cataloged in the DDO survey (van den Bergh 1966). Leo A was listed by Yahil et.al. (1977) as one of six "New Probably Members of the Local Group," together with IC 10, IC 5152, the Aquarius Dwarf, the Pegasus Dwarf and WLM.

Because of its large estimated distance, the dwarf irregular galaxy Leo A was longly thought to lie at the very edge of the Local Group. Its distance estimated at about 7 million light-years, it was uncertain if it was actually a member of the group, although this was indicated by its negative radial velocity: This small galaxy is approachig us at 26 km/s. Thus, Kraan-Korteweg and Tammann (1979) lists at as a probably member galaxy, van den Bergh (1994) has it as possible member. However, a new determination yielded a distance of only 2.5 million light-years (adjusted to the scale we use here), and thus certainly within the volume occupied by the Local Group. Therefore, the new lists of Mike Irwin, Mateo (1998) and van den Bergh (2000) have it as a certain member. It is slightly more than half-way between the satellite system of the Milky Way (Milky Way subgroup) and the outlying NGC 3109 subgroup.

Our photograph of Leo A was obtained by Deidre A. Hunter of Lowell Observatory. It is an UBV image, i.e. a combination of images obtained in the U-band (UV) and assigned blue, B-band (blue) assigned green, and V-band (visible light) represented red. It was taken from D.A. Hunter's UBV collection.

References:


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Hartmut Frommert
Christine Kronberg
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Last Modification: June 22, 2003