mosaic spectroscopy of cluster stars - astro.iag.usp.br
TRANSCRIPT
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MOSAIC spectroscopy of cluster stars
Jorge Meléndez Departamento de Astronomia, IAG, Universidade do São Paulo
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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
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Globular cluster science Abundance variations in globular cluster stars
R = 20000 ok
NGC 6752
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Globular cluster science Isotopic variations in globular cluster stars
R = 110 000
UVES+VLT
(single object)
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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)
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Globular cluster science Multiple branches in globular clusters
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Globular cluster science Multiple branches in globular clusters
M 22
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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
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Globular cluster science Multiple branches in globular clusters
NGC 1851
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Globular cluster science Multiple branches in globular clusters
NGC 6397
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Globular cluster science Multiple branches in globular clusters
NGC 6752
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NGC 6752
R = 20 000 ok
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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
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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
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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
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NGC 6752
7 arcmin
http://www.spiegelteam.de/NGC6752.htm
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NGC 6397
7 arcmin
http://imagensdouniverso.blogspot.com.br/2010/04/aglomerado-globular-ngc-6397.html
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M 22
7 arcmin
http://apod.nasa.gov/apod/image/0506/m22_cfht_big.jpg
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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?
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M 67
Open cluster
Age = 4 Gyr
[Fe/H] = 0
7 arcmin
http://bf-astro.com/images/m67big.jpg
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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
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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
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Solar twins in Collinder 261 are much fainter
About 150-180 hours would be
needed with FLAMES+UVES
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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!
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Extremely high precision abundances (0.01 dex) in globular cluster stars: NGC 6752
R = 110 000, S/N > 200
Precision 0.01 dex
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Extremely high precision abundances (0.01 dex) in globular cluster stars: NGC 6752
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NGC 6752 is chemically
inhomogeneous in all elements!
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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