Culmination of the Culmination of the Southern Proper Motion ProgramSouthern Proper Motion Program

T. Girard(Yale University)

William van Altena Arnold Klemola Ting-Gao Yang

Carlos López Dana Casetti-Dinescu John Lee

Imants Platais René Méndez Wen-Zhang Ma

Vera-Kozhurina Platais Reed Meyer Dave Monet

David Herrera Danilo CastilloNorbert Zacharias

Kathy Vieira Jin-Fuw Lee

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A Brief History of the SPM Program

• SPM is the southern extension of the Lick NPM program (Klemola 1986).

• Both are based on W. H. Wright’s (1950) proposal of using external galaxies as a fixed reference frame for proper-motion determination.

• SPM began, formally, in 1952 as a joint project of Yale and Columbia Univ.

• El Leoncito, Argentina was selected as the site for the new observatory. Eventually, Columbia was out and Univ. of San Juan, Argentina was in.

• Observations with the 20-inch double astrograph began July 1st, 1965 when SPM field #512 (α=19h, δ=-30°) was successfully taken by Arnold Klemola.

• The first epoch was essentially completed by the end of 1973. • Sky coverage is south of δ=-20°, with some more northerly fields

providing overlap with the Lick NPM.

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A Brief History of the SPM Program (cont.)

• Second-epoch photographic observations from 1988 to 1998, then the supply of Kodak 103 emulsion plates ran out, with ~1/3 of survey repeated

• CCD cameras installed in 2000- main astrometry camera, 4Kx4K PixelVision

(yellow)- smaller 1Kx1K Apogee 8, replaced by 2Kx2K

Apogee Alta (blue)- two auxiliary SBIG ST5c cameras for focusing

• Second-epoch CCD observations from 2003 - present

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Cesco Obs: El Leoncito, Argentina

altitude = 2400 m

Astrograph: twin 51-cm, f/7

scale = 55.1 “/mm

YSO Double-Astrograph at Cesco Obs.

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Current SPM Observing Status *

* through June 2008

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SPM Catalogs

The SPM1 and SPM2 Catalogs were based on PDS measures and thus contain only a small fraction of stars down to the plate limit.

The SPM3 is based on full plate scans of the SPM plates using the PMM of USNO-FS.

SPM1

(1998)

SPM2

(1999)

SPM3

(2004)

(SPM4)

(200?)

measurements PDS PDS PMM PMM+CCD

sky coverage 720 sq deg 3,700 sq deg 3,700 sq deg 13,600 sq deg

# of objects 0.059 M 0.322 M 10.7 M ~ 100 M

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Magnitude-Equation Correction

SPM (and NPM) plates use objective gratings, producing diffraction image pairs which can be compared to the central-order image to deduce the form of the magnitude equation.

A comparison of proper motions derived from uncorrected SPM blue-plate pairs and yellow-plate pairs indicates a significant magnitude equation is present.

Using the grating images to correct each plate’s individual magnitude equation, the resulting proper motions are largely free of bias.

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SPM Catalog Estimated UncertaintiesSPM2 (pds measures) SPM3 (pmm measures)

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Harvesting the SPM

• López & Girard 1990 (PASP 102, 1018) “Accurate Positions for Variable and Suspected Variable Stars South of -67 Deg”

• Demartino et al. 1996 (IBVS 4321/4322) “Accurate Positions of Variable/Suspected Variable Stars near the South Galactic Pole”

• Bailyn et al. 2002 (Nature 37, 701) “The Optical Counterpart of the Superluminal Source GRO J1655-40”

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Harvesting the SPM• Girard et al. 1988 (AJ 95, 58) “Astrometry of SN1987A and SK-69.202°”

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Harvesting the SPM

• Platais et al. 1998 (A&A 331, 1119) “The Hipparcos Proper Motion Link to the Extragalactic Reference System using SPM and NPM”

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Harvesting the SPM

• Carraro et al. 2005 (A&A 433, 143) “Probing the Nature of Possible Open Cluster Remnants with the Southern Proper Motion Program”

• Dinescu et al. 2007 (AJ 134, 195) “Space Velocities of Southern Globular Clusters V: A Low Galactic-Latitude Sample”

• Dinescu et al. 2005 (ApJ 618L, 25) “Absolute Proper Motion of the Sagittarius Dwarf Galaxy and the Outer Regions of the Milky Way Bulge”

“To date, 53 of ~150 GGC have measured absolute proper motions, with formal errors between 0.1 and 2.0 mas/yr; mean value ~ 0.5 mas/yr. Of those measured, 33 have a single determination, and 25 were measured by the Southern Proper-Motion Program (SPM).”

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Velocity Shear of the Thick Disk using SPM3• Girard et al. 2006 (AJ 132, 1768)

◄ SPM3 stars within 15° of SGP

’s measure transverse motion ►

2MASS photometry to select preferentially thick-disk giants ►

Ngiants ~ 1200

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Velocity Shear of the Thick Disk using SPM3

Proper-motion data:

Thick-disk component shows up well, distinct from the faint, nearby dwarfs that show a much larger dispersion.

↓

Transverse Velocities

Assume an absolute magnitude distribution as a function of J-K color to convert J,K, to U,V,d. (Integrate under the assumed magnitude distributions.)

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Velocity Shear of the Thick Disk using SPM3

(Somewhat equivalent to separation using reduced proper motion.)

◄ Trim conservatively in U,V to eliminate nearby dwarfs.

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Velocity Shear of the Thick Disk using SPM3Density and Velocity profiles:

Over the range 1 < z < 4 kpc the observed sample shows an exponential form in number density and roughly linear forms of mean velocity and velocity dispersion as a function of z.

BUT we must correct for systematic biases; (Malmquist and “Lutz-Kelker”-type).

►Use knowledge of our uncertainties and selection criteria to construct Monte-Carlo simulations and derive the intrinsic Thick-disk parameters:

hz = 783 ±48 pc

dV/dz = -30 ±3 km/s/kpc

dV,U/dz = 9 ±3 km/s/kpc

(and 8 ±6 % halo contamination).

[ Figure Key: U-profiles in black, V in gray ]

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Ongoing and Future SPM Projects

• Vieira, K. 2009, Ph.D. Thesis: “Proper-Motion Study of the Magellanic Clouds Using SPM Data”

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Ongoing and Future SPM Projects

• SPM “TBD”– absolute of Sgr dSph stars along trailing and leading orbital tails– absolute of CMa overdensity over an extended area– absolute for 15 globular clusters for which CCD observations

exist– absolute for 19 more globular clusters , CCD obs are still needed– full 3-d velocity distribution of SGP thick-disk giant sample– full 3-d velocity analysis using SPM4/RAVE cross-section