SIMBAD references

We present results from spectroscopic observations with the Michigan/Magellan Fiber System (M2FS) of 147 stellar targets along the line of sight to the newly discovered "ultrafaint" stellar systems Tucana 2 (Tuc 2) and Grus 1 (Gru 1). Based on simultaneous estimates of line of sight velocity and stellar-atmospheric parameters, we identify 8 and 7 stars as probable members of Tuc 2 and and Gru 1, respectively. Our sample for Tuc 2 is sufficient to resolve an internal velocity dispersion of 8.6_–2.7^+4.4 km s^–1 about a mean of -129.1_–3.5^+3.5 km s^–1 (solar rest frame), and to estimate a mean metallicity of [Fe/H] = -2.23_–0.12^+0.18. These results place Tuc 2 on chemodynamical scaling relations followed by dwarf galaxies, suggesting a dominant dark matter component with dynamical mass 2.7_–1.3^+3.1×10⁶M_☉ enclosed within the central ∼160 pc, and dynamical mass-to-light ratio 1913_–950⁺²²³⁴M_☉/L_V,☉. For Gru 1 we estimate a mean velocity of -140.5_–1.6^+2.4 km s^–1 and a mean metallicity of [Fe/H] = -1.42_–0.42^+0.55 but our sample does not resolve Gru 1's velocity dispersion. The radial coordinates of Tuc 2 and Gru 1 in Galactic phase space suggest that their orbits are among the most energetic within a distance of ≲300 kpc. Moreover, their proximity to each other in this space arises naturally if both objects are trailing the Large Magellanic Cloud.