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Astron. Astrophys. 342, L9-L12 (1999)

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4. Conclusions

We resolved a red population of stars in the newly found And VI dwarf galaxy, also designated Pegasus dwarf. This `red tangle' is most probably composed of red giant stars, plus some stars from an old asymptotic giant branch. The population seems to be old and metal-poor. Applying the TRGB method, we derived a true distance modulus which places And VI at the distance of M31. Thus, the total magnitude turns into a rather low absolute one, [FORMULA] only! This is one of the faintest galaxies found so far. The metric value of the scale length of the surface brightness distribution is [FORMULA] pc. The structural parameters and the resolved population indicate that And VI is a dSph galaxy.

The newly derived distance modulus suggests that And VI is a companion of M31. The projected distance between M31 and the And VI dwarf galaxy is about 271 kpc, as large as that of the most distant dSph companion of the MWG (Leo I, Mateo, 1998). And VI is situated in a region which so far was free of known M31 satellites (see Fig. 2 of Armandroff et al, 1998). The question has arisen whether or not the M31 dSph system is different from the MWG, which is populated by at least 9 dSphs. The detection of two new dSph galaxies associated with M31, namely And V (Armandroff et al., 1998) and And VI (Karachentsev & Karachentseva, 1998, Armandroff et al. 1999, this work) now brings the census of M31 dSph companions up to 5 (or 8 icluding the dE's NGC 147, 185, and 205), close to what has been observed in the vicinity of the MWG. We derive a very faint absolute V magnitude for And VI, confirming that dSphs as faint as Draco and Ursa Minor exist around M31, as previously suspected (Armandroff et al. 1998).

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© European Southern Observatory (ESO) 1999

Online publication: December 22, 1998
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