Aquarius Dwarf

Irregular Galaxy Aquarius Dwarf (DDO 210, AqrDIG, PGC 65367), type Im V, in Aquarius

[Aqr Dwarf, M. Germano]

RA:
20 : 46.8
Dec:
-12 : 51
Type:
Im V
RV:
Distance:
3400 kly
Apparent Dimension:
2.3 x 1.2 arc min
Diameter:
Brightness:
13.9 m_v
Abs. Mag:
Mass:
The Aquarius Dwarf was apparently first cataloged in the DDO survey (van den Bergh 1966). It was found to be a nearby galaxy because of negative radial velocity (blueshift); it is approaching us at 137 km/s. Yahil, Tammann and Sandage (1977) identify it as one of six "New Probably Members of the Local Group," together with IC 10, Leo A, IC 5152, the Pegasus Dwarf and WLM.

According to Mike Irwin's group, the membership of this galaxy in the Local Group is still doubtful. However, Sidney van den Bergh (2000) regards this question as positively solved and Aquarius Dwarf a confirmed Local Group member because of a distance derivation by Lee et.al. (1999) who derive a distance of 950 kpc (3.1 million light-years) both from our Milky Way galaxy and from the presumable barycenter of the Local Group, from the apparent magnitudes of giant stars at the tip of the red giant branch. Adjusted for our Hipparcos corrected distance for the Large Magellanic Cloud this value becomes 3.4 million light-years.

The image in this page was obtained by Martin Germano.

  • Nordic Optical Telescope (NOT) image of the Aquarius Dwarf, taken by A. Oksanen. This image was featured as Astronomy Picture of the Day (APOD) February 4, 1996 (but erroneously assigned to SagDEG), and (correctly assigned) as APOD for July 27, 2003.

    References


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    Last Modification: March 14, 1998