Astrophys. J., 798, 77 (2015/January-2)
Metallicity evolution of the six most luminous M31 dwarf satellites.
HO N., GEHA M., TOLLERUD E.J., ZINN R., GUHATHAKURTA P. and VARGAS L.C.
Abstract (from CDS):
We present global metallicity properties, metallicity distribution functions (MDFs), and radial metallicity profiles for the six most luminous M31 dwarf galaxy satellites: M32, NGC 205, NGC 185, NGC 147, Andromeda VII, and Andromeda II. The results presented are the first spectroscopic MDFs for dwarf systems surrounding a host galaxy other than the Milky Way (MW). Our sample consists of individual metallicity measurements for 1243 red giant branch member stars spread across these six systems. We determine metallicities based on the strength of the Ca II triplet lines using the empirical calibration of Carrera et al., which is calibrated over the metallicity range -4 < [Fe/H] <+0.5. We find that these M31 satellites lie on the same luminosity-metallicity relationship as the MW dwarf satellites. We do not find a trend between the internal metallicity spread and galaxy luminosity, contrary to previous studies. The MDF widths of And II and And VII are similar to the MW dwarf spheroidal (dSph) satellites of comparable luminosity; however, our four brightest M31 dwarf satellites are more luminous than any of the MW dSphs and have broader MDFs. The MDFs of our six M31 dwarf satellites are consistent with the leaky box model of chemical evolution, although our metallicity errors allow a wide range of evolution models. We find a significant radial gradient in metallicity in only two of our six systems, NGC 185 and Andromeda II, and flat radial metallicity gradients in the rest of our sample with no observed correlation between rotational support and radial metallicity gradients. Although the average properties and radial trends of the M31 dwarf galaxies agree with their MW counterparts at similar luminosity, the detailed MDFs are different, particularly at the metal-rich end.
galaxies: abundances - galaxies: dwarf - galaxies: individual: (M32, NGC 205, NGC 185, NGC 147, And VII, And II) - Local Group
VizieR on-line data:
<Available at CDS (J/ApJ/798/77): table1.dat table2.dat>
Table 2: [HGT2015] M32 NN (Nos 1-64), [HGT2015] NGC205 NNN (Nos 1-224), [HGT2015] NGC185 NNN (Nos 1-321), [HGT2015] NGC147 NNN (Nos 1-230), [HGT2015] AndVII NNN (Nos 1-104), [HGT2015] AndII NNN (Nos 1-300).
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