segue target selection on-going segue observations
DESCRIPTION
SEGUE Target Selection on-going SEGUE observations. SDSS/SEGUE status as of Nov. 10, 2004 Black= completed stripe or plate pair 1002/3900 sq deg imaging: 25% complete, 34/400 plates 8.5% complete. SEGUE Imaging Aug-Oct 2004: Aug 2004 1260 N 38 sq deg 291 N 104 - PowerPoint PPT PresentationTRANSCRIPT
SDSS/SEGUE status as of Nov. 10, 2004 Black= completed stripe or plate pair
1002/3900 sq deg imaging: 25% complete, 34/400 plates 8.5% complete.
SEGUE Imaging Aug-Oct 2004:
Aug 2004 1260 N 38 sq deg 291 N 104 Sep 2004 1100 N 105 1260 S 60 1100 S 107 72 S 117 72 N 62Oct 2004 72 N 55 1300 N 52 1300 S 47 --------------------- 747 sq deg + earlier scans: 255--------------------- 1002 sq deg 25% of SEGUE goal
Drillable imaging(filled Stripes N&S): 1100 N&S 200 sq. 1220 N&S 175 sq. portions of: 72 N&S 200 sq. 1300 N&S 40 sq. Stripes 1100&72were scanned in Aug/Sep and targetted/drilled for Nov/Dec observing(6 week turnaround)
SEGUE imaging sampleColor-Magnitude diagramsin 10 square degree boxestowards one direction on the sky...
Color-Magnitude (g-r,g) diagram for Strip 1260N
Dual turnoffs,indicates stream(s?) at10 and 20 kpcfrom the sun.
Thick Disk Fs
Halo or stream(s)?
Thin disk M stars
SEGUE spectroscopic sample:Radial Velocities of populationsof similar stars, Metalicity, Teff, log g determinations
Kinematic, Chemical populationstudies of the Milky Way and halo
25 WD150 A/BHB200 F 375 G III +V150 Low Metals100 K III100 K V 30 sdM (and L/T candidates) 10 AGB 10 Cool Wds
SEGUE target selection currently has 11 categories, freshly reviewed,and aims to observe a total of 240,000 stars arount the sky.Samples of the stellar categories:
Numbersindicateallocationof fibersby spectraltype perplate pair.
SEGUE spectroscopy to date:
Aug 2004: 8 Bright, 8 Faint Sep 2004: 7 Bright, 6 Faint Oct 2004: 3 Bright, 2 Faint --------------------------- 18 B 16 F 34/400 Plates done = 8.5% of SEGUE goal 43.6 plate equivalents
To date we have approx. 16,000 classified spectra, groupedin these categories (approximately):1500 A/BHBs, 3000 F, 6000 G, 150 K giants, 1500 K dwarf,300 WD, 800 M dwarf, 2500 Low Metal candidates (F-K),plus assorted QSOs and stars of unknown type.
G dwarf, largest SEGUE sample, probe disk/inner halo 1.5kpc to 8 kpc distances, Stream Giants also here
Low metalicity candidate, [Fe/H] = -2.6, g=15.8, g-r=0.47Pop III exploration, gradients in inner/outer halo
LowerMetalsthan thelowest metalicity Globular cluster!
AGB candidate, Giants in Sagittarius/Monoceros streams?g = 16.5,g-r =1.12, u-g = 3.1, RV= -72km/s d(AGB) = 18 kpc
K Giant:Narrowerlines, featuresless deep.
K dwarfStrongerfeatures,broaderlines.
How to tella (distant)K giant froma (nearby)K dwarf, usingSDSS/SEGUEspectra.
Sun
SEGUE K giant stars usedto probe halo to d> 50 kpc
Using thespectrato separategiants from dwarfs,one can explorehalo structurewith K giants.
To test ability todetermine metalicity ofstars from SDSS/SEGUEspectra, we obtainspectra of objects withknown Metals [Fe/H] = -1.6
Target cluster stars separate well fromfield stars, with spread of 1 sigma = 0.25 dex.
+1
0
-1[Fe/H]-2
-3Radial Velocity
g-r
g
With atmosphericparameters determinedfor stars, one can go fromobserved 'color-magnitude'diagrams to...
Physical Hertzsprung-Russell diagrams:
Green: cluster giantsRed: Field starsYellow: Proper motiondefinite cluster matches Teff
surface gravity
g-r
g