WEAVE OC Survey
A. Vallenari INAF, Padova Contributors
A. Bragaglia-INAF L.Magrini-INAF E. Alfaro-IAA R. Sordo-INAF A. Frasca-INAF A. Spagna-INAF C. Jordi-UB A. Aparicio-IAC R. Carrera-IAC L. Casamiquela-UB L. Balaguer-UB C. Gallart-IAC A. Lanzafame-INAF M. Monelli-IAC C. Allende-Prieto-IAC S. Randich-INAF C Soubiran- Bordeaux S. Lucatello A new view of the Galaxy
How did the Galaxy come to be like that? Unveiling the complex history of the MW assembly and internal evolution is still one of the main interest of astrophysics However the specific questions we ask have evolved substantially The presence of radial migration in the disks has lead to a different way of describing stellar populations Much we have learned from RAVE, SDSS, APOGEE… much still to learn Diagnostics: Kinematics + chemistry of stars+ distance+ ages Bovy et al 2016 The importance of being an OCs
Their birth, internal kinematics/ dynamical evolution, evaporation, disruption, self-pollution (if any) trace the Galactic environment Tidal field (Berentzen & Athanassoula 2011, Kupper et al 2010) interaction with giant molecular clouds & spiral arms (Gieles et al 2006, Kujissen+2011) + stellar evolution effects (infant mortality)
Clusters age , metallicity, position trace the disk chemical gradient disk disk formation process Andriewski+ 2004, Magrini+2009, Chiappini+2001; Minchev+2015
Tracing radial migration ? (Wu+2007, vandePutte+ 2011, DeBattista+2015) Open questions
How do stars and clusters form and dynamically evolve to populate the MW field? Can we put further constraints on stellar physics to safely use stars as fossils for the Galactic formation and evolution? What is the shape of abundance gradients and their time evolution in the MW and Local group galaxies? What are clusters telling us about the assembly history and evolution of the main Galactic components? Present: GES@VLT
Cantat, Vallenari+2016 in prep
Jeffries+2014, Mapelli+2015
Targets: 60-70 Ocs New insight on cluster formation from dynamical analysis of star clusters by GES high precision radial velocities: Gamma2Vel Present: GES MW radial metallicity distribution
Jacobson+2016
Old Ocs have higher [Fe/H] Cantat+2016 than the younger ones Difficult to reconcile with simple chemical models.. Radial gas flows? Migrations? Gaia new view of OCs
Gaia: Derive distances + pm of individual stars in Ocs - at 1% for Mv=5 d < 1.2kpc - at 1% for M=0 d < 4kpc -at 10% for almost all known cluster accurate membership-- orbits
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Small velocity dispersion in OCs (1 - 2 km/sec) studies of the internal kinematics require ~ 0.2 km/sec – Gaia: accuracy better than 1% for transverse velocity G0 stars brighter than V~13 (d<500pc), K1 III (red clump in old OCs) V<14 :d < 5 kpc. • TGAS quality
NGC 2527, d=600 pc log(age)=8.6 Gaia view of OCs
Accretion (Cooper 2010) In situ (gas rich mergers) (Zolotov 2009, Font 2011)
B- V-I B- V V NGC 6705 Be 17 Be 29 (Tosi, (Vallenari+2013) (Vallenari+1999, Bragaglia 2006) D=1800 pc, Bragaglia+ 2006) D=13.05 Kpc, Age=250 Myr D=2600 pc, Age=3.7 Gyr Age=10 Gyr WEAVE OC science
Core Science: HR Survey : chemical abundances+ Vrad Goal 1. Formation of open clusters and associationsFGK stars in Cygnus: 19 objects Goal 2. Disruption of open clusters chemical tagging of young clusters in the field Goal 3. OCs as tracers of the Galactic disc and of its chemical evolution old Ocs (age >500 Myr): 25 Ocs +16 (anticenter) Goal 4 Early stellar evolution nearby Ocs: 25 objects lithium (nuclear ages, mixing, etc) accretion, activity: evolution and effect of environment Goal 5 Stellar evolution at later stages Goal 1: Cluster formation
Target stars : FGK green-red HR 14 < V < 17 for Cygnus and Perseus 19 young OCs/associations in synergy with Survey of OB stars with blue-green HR
Association lº bº dist. (pc) Clusters Angular Surface Cyg OB1 73 - 77 -0.50 -2.84 1400 IC 4996 10 SD NGC 6913 Ber 86 Ber 87 Per OB1 132 - 136 -2.5 - 5 2200 NGC 869 NGC 884 10 SD NGC 957 Ocs as disk tracers OC older than 500 Myrs Large age range and different Galactocentric distances Red clump stars as tracers: age > 0.5 Gyr– MS at age <1 Gyr Mv(RC)=0.5 V=12 at dist=2 Kpc V=13.5 at dist=4Kpc V=15.0 at dist=8 Kpc cluster at Rg=10-12 Kpc V=16.0 at dist=12 Kpc--- Rg=20 Kpc Initial list of 200 Ocs Two groups: large loose objects:25 Ocs >700 fibers in the center Small objects : 16 OCs in synergie with anticenter HR survey
Stello et al 2011 Global Target Distribution
Galactic structure
Cluster formation
Cluster structure Stellar evolution Complementary Surveys South: North GES – Flames VLT APOGEE But MS with Giraffe with IR limited lambda coverage Targetting a few stars per Ocs: Galah Large scatter in abundances 4MOST Difficulties to derive Na, Li MOONS
GES Calibrators Metallicity inter-survey calibration About 18 Ocs spanning a large range in [Fe/H]=-0.38(NGC 2420) ; +0.32 (NGC 6791) Different spectral types (giants + MS)
Kepler & Kepler 2 : 4 OCs NGC 6791 Platais et al 2011 Globulars Gaia-ESO: 8 OCs
APOGEE: 6 Ocs Conclusions
Gaia and complementing surveys will bring us in the 6D domain for 1 billion stars + chemistry and fundamental parameters for millions of stars –a revolution in MW science WEAVE will add new dimensions: its contribution is fundamental to go from the local to the Galactic scale