WEAVE OC Survey

A. VallenariINAF, Padova

A. Bragaglia-INAF

E. Alfaro-IAA

A. Frasca-INAF

C. Jordi-UB

R. Carrera-IAC

L. Balaguer-UB

A. Lanzafame-INAF

C. Allende-Prieto-IAC

C Soubiran- Bordeaux

Contributors

L.Magrini-INAF

R. Sordo-INAF

A. Spagna-INAF

A. Aparicio-IAC

L. Casamiquela-UB

C. Gallart-IAC

M. Monelli-IAC

S. Randich-INAF

S. Lucatello

Bovy et al 2016

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

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 thedisk chemical gradient disk disk formation process

Andriewski+ 2004, Magrini+2009,

Chiappini+2001; Minchev+2015

Tracing radial migration ? (Wu+2007, vandePutte+ 2011, DeBattista+2015)

The importance of being an OCs

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?

Open questions

Present: GES@VLT

Jeffries+2014, Mapelli+2015

Targets: 60-70 OcsNew insight on cluster formation from dynamical analysis of star clusters by GES high precision radial velocities: Gamma2Vel

Cantat, Vallenari+2016 in prep

Present: GES MW radial metallicity

distribution

Jacobson+2016

Cantat+2016Old Ocs have higher [Fe/H] than the younger onesDifficult to reconcile withsimple 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

-

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)

NGC 6705 (Vallenari+2013)

D=1800 pc,

Age=250 Myr

Be 17 (Vallenari+1999,

Bragaglia+ 2006) D=2600 pc,

Age=10 Gyr

Be 29 (Tosi,

Bragaglia 2006)

D=13.05 Kpc,

Age=3.7 Gyr

B-

VV-IB-

V

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

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

NGC 6913 Ber 86

Ber 87

10 SD

Per OB1 132 - 136 -2.5 - 5 2200 NGC 869 NGC 884

NGC 957

10 SD

Goal 1: Cluster formation

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

Ocs as disk tracers

Global Target Distribution

Galactic

structure

Cluster structure

Stellar evolution

Cluster

formation

Complementary SurveysSouth:

GES – Flames VLT

But MS with Giraffe with

limited lambda coverage

Galah

4MOST

MOONS

GES

North

APOGEE

IR

Targetting a few stars per Ocs:

Large scatter in abundances

Difficulties to derive Na, Li

CalibratorsMetallicity 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

Gaia-ESO: 8 OCs

APOGEE: 6 Ocs

NGC 6791 Platais et al 2011

Globulars

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