Gyöngyi KerekesEötvös Lóránd University, Budapest

MAGPOP 2008, Paris

István CsabaiLászló DobosMárton Trencséni

Estimate distances of stars create 3D maps

Explore the structure of Milky Way Exponencial disks + power-law halo(es) Dwarf galaxies (merging) and streams

Our goal: reproduce current distributions / find new structures

Improvements in outer regions, giants Gaia (launch around 2011)

1510

Mm

d

Polinomial fit to main sequence:

Mr=f(r-i)

Non-parametric estimator We use all magnitudes (colors) from SDSS Nearest neighbors of a point in a 5D space

Weight the estimated parameters with an exponencial distribution

Can be adopted to other photometric systems

MILES library INDO-US libraryBright stars from SDSSM67NGC 2420

Total number of stars: 3392

MILES+BaSeL

These libraries were targeted to stars with different stellar parameters

Synthetic magnitudesCrossmatched with Hipparcos catalogChallenges:

▪ wavelength coverage ofspectra is not enough ▪ normalization of synthetic

magnitudes

No bright stars in SDSS! Observations with Photometric Telescope (50

cm) to calibrate SDSS stars to USNO stars

Crossmatch with Hipparcos 117 stars

First chosen as test objects Turned out at estimation of distances

that giants are overrepresented in the training set

After applying distance modulus from (Harris et al, 1996) we added them to the TS.

Extinction

E(B-V)

Distance modulus

M67 0.3 9.61 (1)

NGC2420 0.4 12.0 (2)(1): Anthony-Twarog et al, 2006(2): An et al, 2007 b.

Mr

r-i

g-r

Mr

Blue: our estimationRed: Juric, 2008

SDSS Stripe 82 (Image coadd catalog with improved photometry)

~420,000 stars

Applying Cartesian coordinate system:

Blue: our estimationRed: Juric, 2008

Z (pc) Z (pc)

Blue: Our estimationRed: Juric, 2008

Stripe 82 in SDSS (~420,000 stars)

Apply to all SDSS dataCalculate metallicityCombine with kinematics (USNO, RAVE

…)GALEX crossmatch