Download presentation
Presentation is loading. Please wait.
Published byAnnis Hawkins Modified over 9 years ago
1
IAU Symp 248: October, 2007Proper-Motion Catalogs1 Maintenance and Densification: An Overview of Current Proper-Motion Catalogs - T. M. Girard (Yale University)
2
IAU Symp 248: October, 2007 Proper-Motion Catalogs 2 Importance of proper-motion surveys Maintain the positional accuracy of an astrometric catalog with time Provide a means of distance/luminosity estimation and thus discrimination between various classes of objects, (e.g., reduced proper motions) Provide transverse velocity components, enabling study of the kinematics and equilibrium structure of various Galactic components, (i.e., thin disk, thick disk, halo)
3
IAU Symp 248: October, 2007 Proper-Motion Catalogs 3 Maintenance: Current astrometric catalogs...
4
IAU Symp 248: October, 2007 Proper-Motion Catalogs 4 Primary reference catalogs... Hipparcos (ESA 1997): defines ICRS in the optical ►120,000 objects → ~3 /deg 2, V < 7.5 ►@1991 typical pos = 1 mas;@2007 pos = 15 mas Tycho-2 (Høg et al. 2000): Hipparcos satellite starmapper & 1 st -epoch ground-based positions ►2.5x10 6 objects → 25 to 150 /deg 2, V < 11.5 ►@2007 typical pos = 25 to 100 mas, depending on magnitude UCAC2 (Zacharias et al. 2004): USNO CCD Astrograph Catalog & 1 st -epoch astrograph data/catalogs ►48x10 6 objects, -90°< <+40° to +52°; (soon to be all-sky, UCAC3) ►R UCAC < 16, ~85% complete; (to be improved, UCAC3) ► pos = 30 to 70 mas
5
IAU Symp 248: October, 2007 Proper-Motion Catalogs 5 Currently Available Proper-Motion Catalogs CatalogNAreaDensVc (r/a) [mas/yr] Source Material / Notes Hipparcos118Kall-sky37.50.9 /0.25fully satellite-based Tycho22.5Mall-sky6211.52.5 / ?Hipparcos starmapper + ground-based cats UCAC2 [ UCAC3 ] 48M [ ? ] <+45° [ all-sky ] 1.6K16.5~3 /~3modern CCD + ground-based plate-catalogs [ available in the first half of 2008 ] “The Big Three” Some <
6
IAU Symp 248: October, 2007 Proper-Motion Catalogs 6 Currently Available Proper-Motion Catalogs (cont) CatalogNAreaDensVc (r/a) [mas/yr] Source Material / Notes USNO-B1.0 (Monet et al. 2003 & www) 1046Mall-sky25K~21~5 / -POSS1, POSS2, ESO, AAO, SERC GSC II (GSC2.3) (5.1.3 in ~45 min, & www) 945Mall-sky23K~21 † ??POSS1, POSS2, ESO, AAO, SERC SuperCOSMOS Sky Survey (Hambly et al. 2001, & www) >1000M <+3° >46K ? ~2110 – 50 / <1 ? POSS1, POSS2, UKST, ESO APM Cambridge166MNGP cap 15000 sq 11K??---POSS1, UKST APS Luyten P.-M. Project?? POSS1, POSS2, Luyten Derivative catalogs SDSS-USNOB1 (Munn et al. 2004) ~8M2099 sq3.8K19.73-3.5/ <0.5 SDSS minus USNOB1 Schmidt survey-based † from the CDS Description of Catalog I/305: “The GSC2.3 has no magnitude limit.” Some <
7
IAU Symp 248: October, 2007 Proper-Motion Catalogs 7 Currently Available Proper-Motion Catalogs (cont) CatalogNArea Den s Vc (r/a) [mas/yr] Source Material / Notes NOMAD (www) 1100Mall-sky27K~211 - 5 / 0.2 - ? HIPPARCOS+Tycho2+UCAC2+USNOB1 CatalogNAreaDensVc (r/a) [mas/yr] Source Material / Notes rNLTT (Salim & Gould 2003) 59K44% sky 3*3* ~183 - 5NLTT+POSS1+2MASS LSPM (Lépine et al. 2005) 122K[ all-sky ] 3*3* 21~5 ? >150 mas/yr, [ >100 mas/yr ] DSS’s and SUPERBLINK software (+Tycho2) Proper-motion threshold Rank merged Some <
8
IAU Symp 248: October, 2007 Proper-Motion Catalogs 8 Currently Available Proper-Motion Catalogs (cont) CatalogNAreaDensVc (r/a) [mas/yr] Source Material / Notes Astrograph-based proper-motion surveys NPM (NPM1+NPM2) (Hanson et al. 2004) 0.4M >-23° 23---~5 / ~1astrograph plates with objective grating SPM3 (Girard et al. 2004) [SPM4] 10.7M ~ -40°< <-20° 3700 sq [ <-20°] 2.9K17.53-5 /0.4astrograph plates with objective grating CdC-based PM2000 Bordeaux (Ducourant et al. 2006) 2.7M +11°< <+18° 0.5K15.4Bordeaux Meridian Circle (M2000) +CdC+AC2000+USNOA2+YS3 CdC-SF1 (Vicente et al. 2007) 503K -10.5°< <-2.5° 1080 sq 0.5K15.11.1 – 3 /?San Fernando CdC+UCAC2 commercial flatbed scanner Other useful surveys Some <
9
IAU Symp 248: October, 2007 Proper-Motion Catalogs 9 Importance of proper-motion surveys Maintain the positional accuracy of an astrometric catalog with time Provide a means of distance/luminosity estimation and thus discrimination between various classes of objects, (e.g., reduced proper motions) Provide transverse velocity components, enabling study of the kinematics and equilibrium structure of various Galactic components, (i.e., thin disk, thick disk, halo)
10
IAU Symp 248: October, 2007 Proper-Motion Catalogs 10 Detecting WD candidates in SDSS-USNOB1 (Kilic et al. 2005) Reduced Proper Motion H g = g + 5log + 5
11
IAU Symp 248: October, 2007 Proper-Motion Catalogs 11 Detecting WD candidates in SDSS-USNOB1 (Harris et al. 2005)
12
IAU Symp 248: October, 2007 Proper-Motion Catalogs 12 Detecting WD candidates in SuperCOSMOS-RECONS (Finch et al. 2007)
13
IAU Symp 248: October, 2007 Proper-Motion Catalogs 13 Importance of proper-motion surveys Maintain the positional accuracy of an astrometric catalog with time Provide a means of distance/luminosity estimation and thus discrimination between various classes of objects, (e.g., reduced proper motions) Provide transverse velocity components, enabling study of the kinematics and equilibrium structure of various Galactic components, (i.e., thin disk, thick disk, halo)
14
IAU Symp 248: October, 2007 Proper-Motion Catalogs 14 Make certain your ’s are appropriate to the task at hand The central 2° x 2° region of a sample southern-sky SPM field. The vector point diagram (VPD) constructed using proper motions from the USNO-B1 (left panel) is compared to that of the SPM3 (right panel) for stars in common. Note: The majority of the USNO-B1 proper motion values in this field are 0.
15
IAU Symp 248: October, 2007 Proper-Motion Catalogs 15 Magnitude Equation – the astrometrist’s bane 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.
16
IAU Symp 248: October, 2007 Proper-Motion Catalogs 16 Velocity shear of the thick disk using SPM3 ◄ SPM3 stars within 15° of SGP ’s measure transverse motion ► 2MASS photometry to select preferentially thick-disk giants ► N giants ~ 1200 (Girard et al. 2006)
17
IAU Symp 248: October, 2007 Proper-Motion Catalogs 17 Velocity shear of the thick disk using SPM3 (cont.) 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.)
18
IAU Symp 248: October, 2007 Proper-Motion Catalogs 18 Velocity shear of the thick disk using SPM3 (cont.) (Somewhat equivalent to separation using reduced proper motion.) ◄ Trim conservatively in U,V to eliminate nearby dwarfs.
19
IAU Symp 248: October, 2007 Proper-Motion Catalogs 19 Velocity shear of the thick disk using SPM3 (cont.) Density 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: h z = 783 ±48 pc dV/dz = -30 ±3 km/s/kpc d V,U /dz = 9 ±3 km/s/kpc (and 8 ±6 % halo contamination). [ Figure Key: U-profiles in black, V in gray ]
20
IAU Symp 248: October, 2007 Proper-Motion Catalogs 20 Velocity shear of the thick disk using SPM3 (cont.) Equilibrium analysis: Assume a relaxed population of thick-disk stars in equilibrium within the gravitational potential of the Galaxy → Jeans equation: Test five model parameters: 1.Halo potential form; Plummer vs isothermal 2.Velocity-dispersion cross-term ( ) 3.Thick-disk radial scale-length (h R =3.5 – 5.0 kpc) 4.Form of the pressure term (self-gravitating or not) 5.Thin-disk mass surface density (36 – 48 M /pc 2 )
21
IAU Symp 248: October, 2007 Proper-Motion Catalogs 21 Velocity shear of the thick disk using SPM3 (cont.) Figure. The best-fit model’s intrinsic dispersion profile (dashed curve) is convolved with the sampling statistics and proper-motion errors to produce the ±1σ predicted “observed” profile (gray area). Heavy black curve is the actual observed profile for the SGP sample.
22
IAU Symp 248: October, 2007 Proper-Motion Catalogs 22 Velocity shear from low-mass dwarfs and SDSS-USNOB1 (Bochanski et al. 2007, astro-ph) ► Spectroscopic & proper-motion data for ~7400 K and M dwarfs, (l =105°, b = -62°) ► Well-sampled out to 1 kpc Bochanski et al. Figure 8. Velocity-dispersion profiles for thick-disk stars (squares) compared to the Besançon model prediction (crosses).
23
IAU Symp 248: October, 2007 Proper-Motion Catalogs 23 A cautionary word of advice... Dimitri Pourbaix (2007-10-15) “Someone’s garbage can be science for others.” The inverse can also be true!
24
IAU Symp 248: October, 2007 Proper-Motion Catalogs 24 Your catalog will be misused...
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.