Stellar population Studies with LAMOST Chen Bing

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Stellar population Studies with LAMOST- Chen
Bing -

• Contents
• Galactic structure Evolution
• Related Projects
• (SDSS/SUGUE, RAVE, AAOmage, GAIA)
• Collaboration Proposal

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Galactic structure

• Thin Disk
• color-magnitude diagram Hipparcos
  Density law Double exponential
• Scale length/Scale height 2250/350
  pc
• Age(0,10 Gyr), Fe/H (0.01, -0.37
  dex), dFe/H/dR-0.07
• (SigmaU, sigmaV, sigmaW) up to (43,
  27, 17) km/s, Vad up to 15 km/s
• Thick Disk
• color-magnitude diagram 47 Tuc
  Density law Double exponential
• Scale length/scale height 3500/750 pc
• Age11 Gyr, Fe/H -0.78, dFe/H/dR0
• (SigmaU, SigmaV, sigmaW) (67, 51, 42)
  km/s, Vad 53 km/s
• Halo
• color-magnitude diagram M13, density law
  Power law, Axial ratio0.55
• Age 14 Gry, Fe/H-1.78, dFe/H/dR0
• (SigmaU, SigmaV, sigmaW) (131, 106, 85)
  km/s, Vad 226 km/s
• Bulge
• Stellar streams, Dark matter

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Stellar populations in the Galaxy
A SDSS sample (run 752, 756), including
375693 objects

Simulated CMD with thick disk scale height of
1300 and 580 pc, respectively
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Ages of Galactic disk and halo
CMD for the Hipparcos data, Overlaid by isochrone
fits Jimenez et al. 1998
Isochrones are plotted for the Ages, 8, 11,
13, 15 Gyr, and Matallicities Fe/H -0.5,
0.0, 0.3
Globular cluster M4
Hansen et al., 2002
Age 12.7 Gyr for M4
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Stars at the solar neighbourhood
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2df kinematic survey-The Anglo Australian Old
stellar population Survey-
Using 2df multi-object spectrograph Spectral
resolution 2.5 A Velocity accuracy is 15
km/s 2000 stars B-V lt 0.7
V 17.0 19.5
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2df kinematic survey stars from a disrupted
satellite galaxy ?
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Halo stream around the Milky way
The peculiar main-sequence at a a distance of 11
kpc from the Sun in the direction of
(l,b)200,20)
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Halo stream around the Milky way
500 SDSS spectroscopic radial velocities Have
been taken
The tidal disruption of a galaxy By the Milky
Way ?
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Age-Metallicity-Kinematics at the solar
neighborhood
Edvardsson et al. 1993 189 F/G main sequence
stars -1.0 lt Me/H lt 0.3 Stromgren
photometry high resolution spectra from
ESO 1.4 m Mcdonald 2.7 m
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Local dark matter
Creze et al. 1998
The local dynamical density comes out as 0.076
Msun/pc3 The total mass density of stars and
interstellar metter 0.08 Msun/Pc3
Conclusion no room for disk shaped component
of dark matter
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The Thick disk Halo Interface
2df metallicities vs radial velocity
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Performance of survey telescope

• Telescope Aperture Field of View A F
• Gemini 8.1 0.17
  1.8
• WHT 4.2 0.5
  4.4
• VLT 8.1 0.4
  10
• SDSS/SEGUE 2.4 2.5
  36
• 2df/AAOmega 3.9 2.0
  61
• 6df/RAVE 1.2 6.6
  65
• LAMOST 4.0 5.0
  400

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SDSS Multi-object Spectrographs

End-to-end system throughput, including the
telescope
The two SDSS spectrographs. The square Black
openings accept the fiber optics Slitheads, 320
fibers each.
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SDSS Multi-object Spectrographs

• Number of spectrographs
  2
• Spectral resolution
  1800
• Blue Channel range
  3900-6000 A
• Red Channel range
  6000-9100 A
• Fiber inputs per spectrograph
  320
• Telescope aperture
  2.5 m
• Fiber diameter
  180 microns ( 3 )
• SDSS science plate targets
• 500 galaxies, 100 QSO, and 30
  stars
• SDSS key project
• redshifts for 106 galaxies and 105
  quasars

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SEGUE(Sloan Extension for Galactic underpinnings
and Evolution)

• The proposed Observing Strategy
• imaging 3500 square degrees mostly at b lt 30
• The spectroscopic targets from SDSS SEGUE
• 170 well-selected sky directions
• Two plates in each field, one normal
  exposure plate, and one double-length plate to a
  limit of g20.3

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SEGUE imaging and spectroscopic observing plan
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Allocation of fibers per plate pair

• 25 White dwarfs
• 175 Blue Horizontal Branch, F-turnoff
  stars
• 375 G dwarfs
• 200 K giant
• 200 Low-metallicity candidates
• 175 M and K dwarfs
• 130 sky fibers and calibration standards
• To an accuracy
• RVs Teff log g
  Fe/H
• 7 km/s 100-150 K
  0.3-0.5 dex 0.25-0.3 dex

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RAVE(Radial Velocity Experiment)

• Using the 1.2-m UK Schmidt telescope of the
  AAO,
• Observing strategy (use of the Ca-triplet at
  8400-8750, RVs better than 2 km/s)
• Pilot survey (2003-2005) bright-time at the 6df
• using the existing 150-fibre 6df system, 7
  diameter
• Main Survey (2006-2010)
• will use the proposed 2250 fibre system
• 50 million stars, magnitude limited (V16),
  all sky survey
• looking for a northern counterpart

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AAOmega

• A 3.9 m telescope providing a general purpose
  spectroscopic facility
• AAOmega multiple-object mode
• Field of view
  2 degrees
• Number of fibres
  350-392
• Angular size of fibre
  2
• Wavelength range 3700
  9500 A
• Peak system throughput (Blue/Red) 0.17/0.20
• Spectrl resolution
  1300 8000
• Spectral resolution
  3.5 A
• Limiting mag
  B22.0

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AAOmega Galaxy Science

• Still under investigation, proposal including
• Large AAOmega RAVE stellar population survey
• Halo structures, Thick disk metallicity
  kinematics
• DM distribution
• Input Catalogues exist (2MASS, )
• Complement SEGUE, LAMOST in the north ..

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GAIA ESA only mission
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GAIA

• Astrometry (V lt 20)
• Radial velocity ( V lt 16-17)
• Third component of space motion
• Photometry ( V lt 20)
• A Complete survey, launch date 2010-2012,
• 5 year observations, final catalog 2018

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DIVA German national Space science mission

• Magnitude limited all-sky surveys (V 15-16),
  a mission between Hipparcos GAIA
• DIVA and RAVE complement each other.
• permit to determine the full 6-D
  distribution
• CANCELLED !!
• unable to close the funding gap of 15
  million EURO
• A big loss for RAVE, and its science

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Collaboration Proposal
Spectroscopic surveys for stars are important
(RAVE, AAOmega, SEGUE) RAVE 1) Have
a clear Science goal, magnitude limited survey
(V16) 2) looking for a collaboration
in north (LAMOST is an option) 3)
Science quality is reduced after DIVA was
cancelled 4) GAIA final catalog
2018 AAOmega 1) A telescope
comparable with LAMOST 2) Science
goals not yet decided 3) A
general facility for all sciences ,
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One Proposal

• Observing all SDSS/SEGUE stellar objects
  between V1720 mag
• 4000 Fibres/field 7
  fields/night 200 nights/year
• 5.6 million
  stars/ year
• It can be finished before the launch of GAIA
  (probably 2012)
• Successful 2df kinematic survey
• Data can serve the whole community in our
  lifetime
• Stars observed include thin disk, thick disk,
  halo, stellar streams,
• many sciences can be done
• possible collaboration with GAIA mission

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Comments from Brian Yanny (SEGUE leader)
I think this is an excellent project for
LAMOST I understand that the resolution
might be a bit worse, but even if your resolution
is R 1000, you should be able to do radial
velocities to 30 km/s, if one is careful about
calibration I would push them to think
about their resolution and calibration schemes on
their LAMOST spectrograph so that they may be
able to get good radial velocities for many
stars I agree that LAMOST will be
especially unique in getting velocities of faint
stars, down to 20th magnitude or so, and in that
way be complementary to a project such as GAIA
which will get spectra for only brighter
objects ,
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My traces abroad

• 1989-1993, Ph.D, SIMBAD/CDS, France
• multi-color star count survey
• 1994-1999, Postdoc, Barcelona Spain
• Hipparcos GAIA
• 1999-2001, SDSS, Johns Hopkins USA
• SDSS
• 2001-now, XMM Madrid/ESA Spain
• XMM