1. 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.

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

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

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

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

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

12. 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

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

14. 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