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Alexandra Gregory


Postgraduate Research Student
MSci Physics

Academic and research departments

Astrophysics Research Group.

My research project

My publications

Publications

Gregory Alexandra L, Collins Michelle L M, Read Justin, Irwin Michael J, Ibata Rodrigo A, Martin Nicolas F, McConnachie Alan W, Weisz Daniel R (2019) Kinematics of the Tucana Dwarf Galaxy: an unusually dense dwarf in the Local Group, Monthly Notices of the Royal Astronomical Society 485 (2) pp. 2010-2025 Oxford University Press (OUP)
We present new FLAMES+GIRAFFE spectroscopy of 36 member stars in the isolated Local Group dwarf spheroidal galaxy Tucana. We measure a systemic velocity for the system of vTuc=216.7+2.9?2.8vTuc=216.7?2.8+2.9 km s?1, and a velocity dispersion of Ãv,Tuc=14.4+2.8?2.3Ãv,Tuc=14.4?2.3+2.8 km s?1. We also detect a rotation gradient of dvrdÇ=7.6+4.2?4.3dvrdÇ=7.6?4.3+4.2 km s?1 kpc?1, which reduces the systemic velocity to vTuc=215.2+2.8?2.7vTuc=215.2?2.7+2.8 km s?1 and the velocity dispersion to Ãv,Tuc=13.3+2.7?2.3Ãv,Tuc=13.3?2.3+2.7 km s?1. We perform Jeans modelling of the density profile of Tucana, using the line-of-sight velocities of the member stars. We find that it favours a high central density consistent with ?pristine? subhaloes in › cold dark matter, and a massive dark matter halo (