Mapping the Stellar Dynamics of M31 Helen R. Merrett M.R.Merrifield, K.Kuijken, N.G.Douglas, A.J.Romanowsky, N.R.Napolitano, M.Arnaboldi, M.Capaccioli, K.C.Freeman, O.Gerhard, D.Carter, N.W.Evans, M.I.Wilkinson, C.Halliday, T.J.Bridges.

Mapping the Stellar Dynamics of M31 Overview Messier’s drawing of the Andromeda galaxy, 1773 Andromeda The PN.S Survey Preliminary results Rotation curve comparable to HI Velocity sub-structures possibly linked to halo structures ESO 2004 Mapping the Stellar Dynamics of M31

Mapping the Stellar Dynamics of M31 Andromeda Nearest large spiral galaxy D~770kpc Optical extent ~2° (27kpc) REU program/NOAO/AURA/NSF ESO 2004 Mapping the Stellar Dynamics of M31

Mapping the Stellar Dynamics of M31 Dynamical Studies Gas – Major axis rotation curves HI - Newton & Emerson 1977; Braun 1991 HII regions - Rubin & Ford 1970 Stars – Outer halo and regions of interest PNe - 37, Nolthenius and Ford 1977 Red giants - 99, Reitzel & Guhathakurta 2002; (184, Ibata et al 2004) Other – Outer halo Globular clusters - Huchra, Brodie & Kent 1991; ~300, Perrett et al 2002 Satellite galaxies - 15, Evans et al 2000 ESO 2004 Mapping the Stellar Dynamics of M31

Fibre Spectroscopy Study Collaborators Halliday, Carter, Bridges, Evans, Wilkinson Optical survey ~1300 objects Follow up spectroscopy ~750 velocities ESO 2004 Mapping the Stellar Dynamics of M31

Mapping the Stellar Dynamics of M31 Fibres v. PN.S Fibre Spectroscopy Imaging survey – detection Follow-up spectroscopy: 4 nights, ~300 velocities PN.S Detection and velocities at once: 6 nights, 2611 PNe + velocities ESO 2004 Mapping the Stellar Dynamics of M31

Mapping the Stellar Dynamics of M31 The PN.S Survey 2002 – PN.S 6 nights, 2°x2° over disk 2003 – INT-WFC narrow band survey 6 nights (5 clear), halo 2003 – PN.S 7 nights (3 clear); halo, northern spur, southern stream, major axis 225 fields – 2766 PNe Ferguson et al 2002 REU program/ NOAO/AURA/NSF ESO 2004 Mapping the Stellar Dynamics of M31

Mapping the Stellar Dynamics of M31 Rotation Curve ESO 2004 Mapping the Stellar Dynamics of M31

Mapping the Stellar Dynamics of M31 Rotation Curve ESO 2004 Mapping the Stellar Dynamics of M31

Velocity Sub-Structures Over 4σ from mean velocity of 30 nearest neighbours ESO 2004 Mapping the Stellar Dynamics of M31

Velocity Sub-Structures Orbit model - 1st attempt: Merrett et al 2003 ESO 2004 Mapping the Stellar Dynamics of M31

Mapping the Stellar Dynamics of M31 Interesting Regions Stellar Stream Moving inwards Northern Spur disk-like velocities ESO 2004 Mapping the Stellar Dynamics of M31

Dynamically distinct PNe Working towards 2nd round of orbit models ESO 2004 Mapping the Stellar Dynamics of M31

Mapping the Stellar Dynamics of M31 Summary Largest comprehensive survey of stellar dynamics in M31 Stellar velocities mapped out to extent of HI Velocity sub-structures found – possibly a continuation of the stellar stream ESO 2004 Mapping the Stellar Dynamics of M31