MOSAIC spectroscopy of cluster stars - astro.iag.usp.br

MOSAIC spectroscopy of cluster stars

Jorge Meléndez Departamento de Astronomia, IAG, Universidade do São Paulo

How chemically homogeneous are globular clusters?

Important consequences for: - testing model predictions (stellar evolution, stellar nucleosynthesis and globular cluster chemical evolution)

- setting constraints on the polluters (CNONaMgAl)

- understanding the origin & evolution of globular clusters

The globular cluster M80. HST

Many papers with important contributions from VLT+FLAMES Carretta et al.; Gratton et al.; Marino et al.; Yong et al.; etc

Globular cluster science Abundance variations in globular cluster stars

R = 20000 ok

NGC 6752

Globular cluster science Isotopic variations in globular cluster stars

R = 110 000

UVES+VLT

(single object)

Globular cluster science Isotopic variations in globular cluster stars

R ≥ 60 000 for dwarfs, R ≥ 80 000 for giants

-2.5 -2.0 -1.5 -1.0 -0.5

[Fe/H]

26M

g/2

4M

g

0.0

0

.05

0

.10

0

.15

0

.20

24Mg

25Mg

26Mg

M71 giants

R = 100 000

HIRES+Keck

(single object)

Globular cluster science Multiple branches in globular clusters

Globular cluster science Multiple branches in globular clusters

M 22

Globular cluster science Multiple branches in globular clusters and

variations in the heavy elements

7 arcmin

Almost 0.3 dex

variations in Fe

M 22

Globular cluster science Multiple branches in globular clusters

NGC 1851

Globular cluster science Multiple branches in globular clusters

NGC 6397

Globular cluster science Multiple branches in globular clusters

NGC 6752

NGC 6752

R = 20 000 ok

Cosmological lithium problem

Li-6

Li-7

BBN+WMAP

Primordial lithium

BBN

prediction is

about a factor

of 4-5 higher

than Li in field

halo stars

Evidences of Li depletion using

globular cluster stars Korn et al. 2006, Nature

442, 657 Lind et al. 2009

Difussion in

NGC 6397

NGC 6397

Evidences of atomic difussion in globular cluster stars Korn et al. 2006, Nature 442, 657

Difussion in

NGC 6397

VLT+FLAMES

would need 85h

230 h

NGC 6752

7 arcmin

http://www.spiegelteam.de/NGC6752.htm

NGC 6397

7 arcmin

http://imagensdouniverso.blogspot.com.br/2010/04/aglomerado-globular-ngc-6397.html

M 22

7 arcmin

http://apod.nasa.gov/apod/image/0506/m22_cfht_big.jpg

Studying open clusters with MOSAIC

There is not much information on main sequence stars in

OLD open clusters

- What is the evolution of Li ? - Transport mechanisms in stellar interiors

- Chemical signatures of planets?

M 67

Open cluster

Age = 4 Gyr

[Fe/H] = 0

7 arcmin

http://bf-astro.com/images/m67big.jpg

FLAMES/UVES

~ 20 hours needed for

solar twins (V = 14.6) in

M67 Coverage: 480 - 680 nm

R = 47 000, S/N=175

(S/N = 250 rebinned pixel) Precision 0.025 dex

Collinder 261

Age = 6 Gyr

[Fe/H] ~ 0

7 arcmin

http://aladin.u-strasbg.fr

Open cluster

About 180

hours would be

needed with

FLAMES+UVES

Solar twins in Collinder 261 are much fainter

About 150-180 hours would be

needed with FLAMES+UVES

We need the ELT+MOSAIC+HIRES !

VLT+FLAMES

R = 24 000

S/N = 150

230 hours!

VLT+FLAMES/UVES

R = 47 000

S/N = 100

330 hours!

ELT MOSAIC+HIRES

R = 47 000

S/N = 100

Only 10-14 hours!

ELT MOSAIC+HIRES

R = 100 000

S/N = 100

Only 2 nights!

Extremely high precision abundances (0.01 dex) in globular cluster stars: NGC 6752

R = 110 000, S/N > 200

Precision 0.01 dex

Extremely high precision abundances (0.01 dex) in globular cluster stars: NGC 6752

NGC 6752 is chemically

inhomogeneous in all elements!

We can reveal the hidden secrets of globular cluster stars, all we need is

very high resolution (R = 80 000 – 100 000) and high S/N (> 150-200) spectra.

A few (about 10) fibers from ELT/MOSAIC to ELT/HIRES would

open new windows on cluster studies