Sofia Feltzing: Talk given at Stars for all, Lund 2012 Stars as tools to unravel the history of the Milky Way Sofia Feltzing Department of Astronomy and Theoretical Physics tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Galaxy formation • Galaxy formation is believed to be initiated by cold dark matter (CDM) • Simulations suggest that galaxies grow through a sequence of infall events • Most accreted objects are so small nothing happens • Others create mild perturbations • A handful of events involve an object that causes a major convulsion tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Resulting in a merger tree Time Final galaxy/halo Credit: Marta Volonteri, Milky Way sized galaxy tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Stars tell us about the past In two ways • in their ages and elemental abundances • in their orbits (we hope) • Provide observational constraints that any model of galaxy formation must fulfill • We work with the Milky Way as this is the galaxy that can be studied in most detail tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Dark matter halo How stars move in the Milky Way Halo stars move on eccentric orbits – fluffy spheroid Galactic centre NGP Stellar disk(s) – circular motion mainly in a plane W GC Galactic bulge – U compact spheroid V The sun tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Dark matter halo How stars move in the Milky Way Halo stars move on eccentric orbits – fluffy spheroid Galactic centre NGP Stellar disk(s) – circular motion mainly in a plane W GC Galactic bulge – U compact spheroid V The sun tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Dark matter halo How stars move in the Milky Way Halo stars move on eccentric orbits – fluffy spheroid Galactic centre NGP Stellar disk(s) – circular motion mainly in a plane W GC Galactic bulge – U compact spheroid V The sun tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Dark matter halo How stars move in the Milky Way Halo stars move on eccentric orbits – fluffy spheroid Galactic centre NGP Stellar disk(s) – circular motion mainly in a plane W GC Galactic bulge – U compact spheroid V The sun tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Dark matter halo How stars move in the Milky Way Halo stars move on eccentric orbits – fluffy spheroid Galactic centre NGP Stellar disk(s) – circular motion mainly in a plane W GC Galactic bulge – U compact spheroid V The sun We can measure the thick disk and halo locally as the stars move past the sun tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Solar neighbourhood Sirius/UMa LSR–disk Hyades [Fe/H] decrease Age increases V km s -1 Hercules Pleiades Arcturus Halo U km s -1 tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Disk dynamics V km s -1 Bar and spiral arms in the model ➙ makes for more complex U km s -1 velocity-plane Antoja thesis tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Key result: abundance trends are tight (<0.05 dex) R mean is proportional to V Edvardsson et al. (1993) was one of the first papers to combine abundances and kinematics in a systematic way. The paper has been and is hugely influential. tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 SNII core collapse “No” selection τ lifetime < 10 6 -10 7 years SNIa d<25 pc degenerate system δ Teff δ >–15° τ lifetime could be up to a � Hubble time Fe – SNII+SNIa Mg – SNII Size=Age The elemental abundance trends divide in the solar neighbourhood. Volume complete sample. Fuhrmann 2004 AN 325 3 tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Bulge abundance trends Bulge dwarfs - observed when μ -lensed [Ti/Fe] Thick disk in SN Thin disk in SN All old Range of ages [Cr/Fe] [Ni/Fe] E93 Bensby et al. (in prep., 2011, 2010) tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Short “thick” disk Inner disk: 4<R sun <7 kpc Solar neighbourhood: R sun =8 kpc Outer disk: 9<R sun <13 kpc [Mg/Fe] [Si/Fe] [Ti/Fe] δ Teff ~ K giants Bensby, Alves-Brito, Oey, Yong, Meléndez (2011) ApJ 735 L46 tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Short “thick” disk Inner disk: 4<R sun <7 kpc Solar neighbourhood: R sun =8 kpc Outer disk: 9<R sun <13 kpc [Mg/Fe] [Si/Fe] [Ti/Fe] – 0.5 dex low α δ Teff ~ K giants Bensby, Alves-Brito, Oey, Yong, Meléndez (2011) ApJ 735 L46 tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 SEGUE probes the MW further away 0.6 lo g 10 N 0.5 1.0 1.5 2.0 2.5 1 1.80 . 2 0 0.4 2.00 0.3 [ α /Fe] 1.20 0.2 2.10 1 . 0.1 2 0 2.00 . 8 0 1 0.0 • SDSS stellar spectroscopy part – low -1.0 -0.5 0.0 [Fe/H] resolution spectra • Started to divide disk by abundance Lee et al. (2011) AJ 738187 tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Starting to test model predictions 0.4 Thin disk 0.1 ≤ |Z| < 0.8 kpc Thick disk 0.1 ≤ |Z| < 0.8 kpc 0.8 ≤ |Z| < 2.4 kpc 0.8 ≤ |Z| < 2.4 kpc Thin Thin Thick Thick 0.3 N/N total 0.2 0.1 0.0 0.4 0.1 ≤ |Z| < 0.8 kpc 0.8 ≤ |Z| < 2.4 kpc F u ll F u ll 0.3 N/N total 0.2 0.1 0.0 0.0 0.2 0.4 0.6 0.8 0.0 0.2 0.4 0.6 0.8 Eccentricity (e) Eccentricity (e) • Gas rich merger “favoured” Lee et al. (2011) AJ 738187 tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 No thick disk? Bovy et al. (2011) • Internal processes “favoured” arXiv:1111.1724 arXiv:1111.6585 tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 ??? All blue and red stars δ Teff 5200 - 6300 K have halo kinematics d<335 pc + have thick disk kinematics V tot >180km s -1 [Fe/H]> –1.6 Nissen & Schuster (2010) A&A 511 L10 tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 ??? Halo Disk δ Teff 5200 - 6300 K d<335 pc V tot >180km s -1 [Fe/H]> –1.6 Nissen & Schuster (2010) A&A 511 L10 tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 ??? Halo Disk δ Teff 5200 - 6300 K d<335 pc V tot >180km s -1 So far no good interpretation [Fe/H]> –1.6 for what this is – dual inner halo? Thick disk meets halo? Nissen & Schuster (2010) A&A 511 L10 tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 20% Parallax horizon for K5III stars 10 A V = 0 A V = 5 mag 10 kpc Bulge Sun 1 2 5 10 20% 1 2 Illustration by Lennart Lindegren ������������������������������������ ���������������������������� �� 5 tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 20% Parallax horizon for K5III stars Gaia 10 A V = 0 A V = 5 mag 10 kpc Bulge Sun But velocities missing below 1 2 5 10 20% G=17 and detailed elemental 1 abundances are also missing 2 Illustration by Lennart Lindegren ������������������������������������ ���������������������������� �� 5 tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Multiplex spectroscopy • Gaia follow-up is being pursued by the European community in two ways – using existing facilities and setting up a new infrastructure of spectrographs tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 Gaia-ESO Survey • One of two ESO public spectroscopic surveys, PIs: Gerry Gilmore and Sofia Randich • 300 nights over 5 years on VLT with FLAMES • High-resolution spectroscopy of all major stellar components(10 5 stars) and open clusters • Swedish members: Thomas Bensby leads the observers, Andreas Korn is leading the high- resolution abundance analysis, >10 people in Lund and Uppsala are members, SF member of Steering Committee tisdag den 7 februari 2012
� � Sofia Feltzing: Talk given at Stars for all, Lund 2012 Gaia-ESO Survey Observations have started tisdag den 7 februari 2012
Sofia Feltzing: Talk given at Stars for all, Lund 2012 … future spectrographs • 4MOST – massive multiplex for NTT or VISTA • MOONS – NIR “upgrade” of FLAMES on VLT • WEAVE – massive multiplex for William Herschel Telescope ➡ All are about 50-50 Gaia follow-up and extra-galactic science tisdag den 7 februari 2012
Recommend
More recommend
