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Photometric parallax estimation using the MILES catalog and BaSeL models

Photometric parallax estimation using the MILES catalog and BaSeL models. István Csabai László Dobos Márton Trencsényi Norbert Purger Géza Herczeg. Gyöngyi Kerekes MAGPOP Meeting , Malta 10 November 2014. Photometric parallax. Based on different distance measurements for stars :

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Photometric parallax estimation using the MILES catalog and BaSeL models

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  1. Photometric parallax estimation using theMILEScatalogandBaSeLmodels István Csabai László Dobos Márton Trencsényi Norbert Purger Géza Herczeg Gyöngyi Kerekes MAGPOPMeeting, Malta 10 November 2014

  2. Photometricparallax • Basedondifferentdistancemeasurementsforstars: • Trigonometricparallax (neareststars) • Mainsequencefitting (openclusters) • Cepheidvariablestars (globularclusters), etc. • Calculationofabsolutemagnitudes • Color-magnitude diagram • Mainsequencefittingwith a function • Ifweknowthecolor index of a star, wecanestimatethedistance.

  3. Photometricparallax Problems: • We can only estimate for main sequence stars • Color indices are metallicity-dependent (especially B, V) • We need continuous parameters • Hawley, 2002(spectroscopic parallax)

  4. Photometricparallaxestimations Juricetal, 2005 THE MILKY WAY TOMOGRAPHY WITH SDSS

  5. Ourconception

  6. MILES database • 985 stars • Wavelength range: 3525 – 7500 Åat 2.3 Å spectral resolution • Atmospheric data estimated using CEN01b(Teff, log g, [Fe/H])

  7. MILES database Teffvslog g Largerangeofatmosphericparameters: frommetal-rich, coolstarsto hot, metal-poorstars. Cenarro et al, 2006

  8. Hipparcos • Trigonometric parallax • About 130.000 stars • Error: 0.7-0.9 mas for stars brighter than9 mag

  9. Miles – hipparcoscrossmatch • Based on coordinates (40 arcsec)  614 stars • HRD[V>10]

  10. Miles – hipparcoscrossmatch • CMD

  11. BaSeLmodel • Usedforfitting: 2 735 spectra • Method: leastχ2 • Spectra fitted: χ2=3.578 χ2=11.886 χ2=0.344

  12. Spectra fitting • Cutatχ2 = 3 • Result:562 stars

  13. Spectrafitting

  14. Synthetic magnitudes • u’, g’, r’, i’, z’ (Sloan filters) [Fukugita et al, 1996]

  15. Synthetic magnitudes Jester et al. 2005 filter transformation equations: • g=V+0.64(B-V)-0.13 • r=V-0.46(B-V)+0.11

  16. Color-colordiagrams g – r SDSS starsselection: Relativeerrorinmagnitudes < 0.04% Magnitudesinrange [14;17] Upper CCD fromMichaelRichmond g – r vsr – i for 100 000 Sloan stars (reddots) and for MILES stars (greencrosses) r – i

  17. Color-colordiagrams u-gvsg-rfor 100 000 Sloan stars (reddots) and for MILES stars (greencrosses)

  18. OUR estimation • We have code for nonparametricestimation(multidimensional indexing integrated with databases) • It was created for photometric redshift calculation and estimation of physical parameters ofgalaxies • This code can be adapted for photometric parallax estimation: 5-D (4 CI & M) spaces  nearest neighbour searching  absolute manitude & parallax estimation

  19. Futuretasks

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