application of hectochelle - mmt science symposium, 06/14/2006 gábor f ű rész, predoc fellow...

Application of Hectochelle - MMT Science Symposium, 06/14/2006

Gábor Fűrész, predoc fellow

Harvard-Smithsonian Center for Astrophysics

Application of Hectochelle:

Dynamical Studies of Open Clusters

Application of Hectochelle - MMT Science Symposium, 06/14/2006Gábor Fűrész - Application of Hectochelle; 06/14/2006, Tucson

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


The Hectochelle Team

PI: A.SzentgyorgyiDetectors: J.Geary, B.McLeod, S.Amato Optical Design: D.Fabricant, H.EppsOperational Support: N.Caldwell, G.WilliamsSoftware: M.Conroy, J.RollMech Eng: R.Eng, J.Barberis, M.Honsa, P.CheimetsStruct Eng: H.Bergner, R.Fata, M.PieriElec Eng: T.Gauron, D.Weaver Fibers/Calibration: J.ZajacTech Support: F.Collette, W.Brymer, F.Rivera, R.Goddard,

S.NicholsManagement: L.Feldman, C.Osterer, T.Norton, P.SozanskiScience Team: L.Hartmann, D.Latham, A. Dupree,

S.Korzennik, P.Nisenson, R.Noyes, S.BaliunisMMT Staff

“Deputy.PI”: G.Fűrész


Hectochelle Performance Parameters

A multiobject high resolution (echelle) spectrograph for thepost-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


Fiber positioner


Fiber positioner

• Fred and Ginger

• Twin gantry geometry

• Each robot 5 axes (x,y,z,,)


• Positions 300 optical fibers on curved 1º focal plane in 5 minutes with < 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)

Fiber positioner


Hectospec (left) and Hectochelle (right) in early phase of integration at the MMT. The Hectochelle is instrumented

with a test fiber slit.

Bench spectrographs: Hectospec and Hectochelle


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

Sample data


Performance

RMS:

56 m/s

RMS:

225 m/s


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 – Fűrész & Hartmann, et al.


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)



Radial velocity distribution

- distribution is not gaussian- ~ 3.5 km s-1



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



Radial velocity vs. spatial distribution


Model simulation: Finite sheet evolution with gravity,

initially elliptical, uniform :

then forms filament with higher concentrations of mass at ends!

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

Finite sheet evolution with gravity


velocity dispersion

Finite sheet evolution with gravity: rotating ellipse


Finite sheet evolution with gravity – NGC 2264

(GM/R • (r/R))1/2 ~ (G [4000 M]/3.5 pc • (0.55))1/2 ~ 1.6 km/s

faster infall at ends - focal point behavior


Open cluster kinematics: ONC


Finite sheet evolution with gravity – ONC

Orion A

Orion B


Finite sheet evolution with gravity – ONC

Orion A has a similar structure (clumps along a filament) as the Burkert-Hartmann theory predicts


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




Histogram of cluster members:

Average radial velocity is 26.6 km/s

Velocity dispersion ~ 4 km/s


ONC: triggered star formation?


NGC 1907 & 1912

age ~250 Myrdistance ~1300 pcseparation ~18 pc

supposed pair(Subramaniam & Sagar, 1999)

photometry:FLWO 48” and MiniCam

target selection for Hectochelle spectroscopy, based on CMD

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



Region C (NGC 1912)total/member 106/45mean RV -0.9 ( 0.7) km/sdispersion 3.8 km/s

Region B (bridge)total/member 57/28mean RV -0.7 ( 1.1) km/sdispersion 3.6 km/s

Region A (NGC 1907)total/member 35/10mean RV -3.3 ( 1.1) km/sdispersion 4.5 km/s



N body simulation using STARLAB: fly-by of two clusters, V=3 km/s



1 = 3 km/s

2 = 3 km/s


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?

Future Plans


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.

Future Plans: age determination


[email protected]

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