Gbor Fursz, predoc fellow

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Application of Hectochelle
Dynamical Studies of Open Clusters
Gábor Furész, predoc fellow Harvard-Smithsonian
Center for Astrophysics
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Talk outline
Talk overview Brief description of the
Hectochelle Some scientific programs underway
with Hectochelle NGC 2264 signs of cluster
formation Orion Nebula Cluster birth of a
cluster NGC 1907 1912 interacting open
clusters Plans for the future

• Gábor Furész - Application of Hectochelle
  06/14/2006, Tucson

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The Hectochelle Team
PI A.Szentgyorgyi Detectors J.Geary,
B.McLeod, S.Amato Optical Design D.Fabricant,
H.Epps Operational Support N.Caldwell,
G.Williams Software M.Conroy, J.Roll Mech
Eng R.Eng, J.Barberis, M.Honsa,
P.Cheimets Struct Eng H.Bergner, R.Fata,
M.Pieri Elec Eng T.Gauron, D.Weaver
Fibers/Calibration J.Zajac Tech Support
F.Collette, W.Brymer, F.Rivera,
R.Goddard, S.Nichols Management L.Feldman,
C.Osterer, T.Norton, P.Sozanski Science Team
L.Hartmann, D.Latham, A. Dupree, S.Korzennik
, P.Nisenson, R.Noyes, S.Baliunis MMT
Staff Deputy.PI G.Furész
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Hectochelle Performance Parameters
A multiobject high resolution (echelle)
spectrograph for the post-conversion MMT,
operating at f/5

• Resolution 34,000
• Single order
• Order separation by filter
• Number of fibers 240
• Shares HectoRobot as Hectospec
• Number of available passbands, typically 150Å
  wide
• Typical efficiency 8
• Precision radial velocity (PRV) in development

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Fiber positioner
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Fiber positioner

• Fred and Ginger
• Twin gantry geometry
• Each robot ?
• 5 axes
• (x,y,z,?,?)

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Fiber positioner

• Positions 300 optical
• fibers on curved 1º
• focal plane in 5
• minutes with lt 25µ
• accuracy.
• Fibers magnetically
• attached to focal
• surface.
• Positioner consists of
• two robots operating
• simultaneously.
• Plate scale is
• 174µ/arcsec
• Fibers are 250µ dia.
• (1.4 arcsec)

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Bench spectrographs Hectospec and Hectochelle
Hectospec (left) and Hectochelle (right) in early
phase of integration at the MMT. The Hectochelle
is instrumented with a test fiber slit.
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Sample data

• 20 Minute exposure of Kepler field
• Color and pincushion present
• Slit tilt present

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Performance
RMS 225 m/s
RMS 56 m/s
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Examples of Science Programs In Progress

• Surveys of Young Clusters - Hartmann, Calvet et
  al.
• Kepler Ground Segment Latham, et.al.
• Internal Dynamics of Local Group dSphe
  Olszewski, Mateo et al.
• Majewski et al.
• PRV Extrasolar Planet Searches Korzennik,
  Noyes, Latham, c.
• Wisconsin Open Cluster Survey (WOCS) Mathieu,
  Latham, et al.
• Studies of Globular Cluster Spitzer Sources
  Dupree, et al.
• Absorption line distance to the Cygnus Loop
  Eriksen
• Chromospheric Activity of Solar-Type Stars -
  Baliunis et al.
• Open Cluster Dynamics Furész Hartmann, et al.

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Open cluster kinematics NGC 2264
targets based on a list of X-ray sources (Ramírez
et al. 2004) and later 2MASS sources added
(selected in color-color diagram)
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Open cluster kinematics NGC 2264
Radial velocity distribution
- distribution is not gaussian - s 3.5 km s-1
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Open cluster kinematics NGC 2264
Radial velocity vs. spatial distribution -
matching molecular gas
key Hectochelle targets in a given RV bin Ha
emission stars form Reipurth et al. 2004 13CO
channel maps from Ridge et al. 2003
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Open cluster kinematics NGC 2264
Radial velocity vs. spatial distribution
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Finite sheet evolution with gravity
Model simulation Finite sheet evolution with
gravity, initially elliptical, uniform ?

• pileup of material at edge, PLUS focal points at
  ends!

• then forms filament with higher concentrations
  of mass at ends!

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Finite sheet evolution with gravity rotating
ellipse

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Finite sheet evolution with gravity NGC 2264
faster infall at ends - focal point behavior
(GM/R (r/R))1/2 (G 4000 M?/3.5 pc
(0.55))1/2 1.6 km/s
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Open cluster kinematics ONC
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Finite sheet evolution with gravity ONC
Orion B
Orion A
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Finite sheet evolution with gravity ONC
Orion A has a similar structure (clumps along a
filament) as the Burkert-Hartmann theory predicts
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Open cluster kinematics ONC
Hectochelle field of view is shown in
cyan. Likely cluster members based on RV Green
errors less than 1 km/s Red- errors greater
than 1 km/s Blue- Observed on both nights Size of
dots is proportional to quality of radial
velocity larger dot-better velocity fit
IRAC image of the ONC with cluster members
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Open cluster kinematics ONC
Histogram of cluster members Average radial
velocity is 26.6 km/s Velocity dispersion 4
km/s
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Open cluster kinematics ONC
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Open cluster kinematics ONC
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ONC triggered star formation?
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Open cluster kinematics M 38
NGC 1907 1912age 250 Myr distance 1300
pc separation 18 pc supposed pair (Subramaniam
Sagar, 1999) photometryFLWO 48 and
MiniCam target selection for Hectochelle
spectroscopy, based on CMD
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Open cluster kinematics M 38
Photometric result average color inbetween the
clusters is closer to the value of clusters,
rather than field stars
hint for a tidal bridge?
also, signs for tidal tails
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Open cluster kinematics M 38
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Open cluster kinematics M 38
Region C (NGC 1912) total/member 106/45 mean RV
-0.9 ( 0.7) km/s dispersion 3.8 km/s Region B
(bridge) total/member 57/28 mean RV -0.7 (
1.1) km/s dispersion 3.6 km/s Region A (NGC
1907) total/member 35/10 mean RV -3.3 ( 1.1)
km/s dispersion 4.5 km/s
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Open cluster kinematics M 38
N body simulation using STARLAB fly-by of two
clusters, DV3 km/s
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Open cluster kinematics M 38
s1 3 km/s s2 3 km/s
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Future Plans
Histogram of stars from our sample which have
ages from Hillenbrand (1997). Ages were
determined by evolutionary track fitting. What
is the dispersion of so-called old and young
stars from our sample?
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Future Plans age determination
Empty Regions Why are these here? If all
off-cloud stars are ONC members, there should be
a continuous flow of stars, as in Trapezium
region (yellow rectangle).
Possible explanation is the off-cloud stars are
part of another, older association Orion OB1c To
answer this, age determination is necessary for
more stars.
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hectochelle_at_cfa.harvard.edu