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The First DIRECT Distance to M33

The First DIRECT Distance to M33. Alceste Bonanos Carnegie - DTM March 8 th , 2006. Collaborators. Kris Stanek Tom Matheson Rolf Kudritzki Barbara Mochejska Lucas Macri Norbert Przybilla Dimitar Sasselov Andrew Szentgyorgyi

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The First DIRECT Distance to M33

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  1. The First DIRECT Distance to M33 Alceste Bonanos Carnegie - DTM March 8th, 2006

  2. Collaborators Kris Stanek Tom Matheson Rolf Kudritzki Barbara Mochejska Lucas Macri Norbert Przybilla Dimitar Sasselov Andrew Szentgyorgyi Janusz Kaluzny John Tonry David Bersier Guillermo Torres Fabio Bresolin Peter Stetson

  3. Outline • Motivation • DIRECT Project • Distance to M33 • Implications • Massive Binaries

  4. NASA/WMAP Science Team

  5. Distance Ladder Astronomy Today, Chaisson & McMillan

  6. Cepheid Period-Luminosity Relation Leavitt & Pickering (1912)

  7. Cepheid Period-Luminosity Relation Udalski et al. (1999)

  8. Anchor Galaxy Large Magellanic Cloud (LMC)

  9. Distance Modulus to the LMC HST Key Project 21 methods Benedict et al. (2002)

  10. LMC Systematic Errors • Zeropoint of P-L relation • Elongation of LMC • Variable reddening across LMC • Metallicity dependence of P-L relation • 10% - 15% uncertainty • in the LMC distance • and the distance scale! Nikolaev et al. (2004)

  11. Why Distances? Improve accuracy (currently ~ 10%) Vital for • calibrating stellar luminosities • determining H0 • constraining dark energy equation of state

  12. “… to test the cosmological constant hypothesis and measure the equation of state of the dark energy at z~0.4-0.5, the best complement to current and future CMB measurements is a measurement of the Hubble constant that is accurate at the few percent level.” -Wayne Hu (2005)

  13. The DIRECT Project • K. Stanek, J. Kaluzny, D. Sasselov, J. Tonry, M. Mateo, • M. Krockenberger, B. Mochejska, L. Macri, R. Kudritzki, • A. Bonanos • Bypass LMC • Obtain direct distance to M31 and M33 with • Detached eclipsing binaries • Baade-Wesselink method for Cepheids

  14. Detached Eclipsing Binaries Modern Astrophysics, Carroll & Ostlie

  15. Joel Hartman - CfA

  16. Detached Eclipsing Binaries Light curves: period, inclination, eccentricity, , fractional radii, flux ratio temperature ratio Spectra: radial velocity semi-amplitudes, eccentricity, , effective temperatures intrinsic color, reddening Kepler’s law: semi-major axis of orbit, radii, masses

  17. DEB Distance Observed binary flux (de-reddened) fλ = R12 F1(T1, log g1) [1 + (R2/R1)2 F2/F1] / d2 F1(T1, log g1) from model atmosphere after spectral analysis  T1 R1, R2 and F2/F1 known from light curve g1 = G M1/R12 from radial velocity curve

  18. DIRECT Observations 1996-1999:200 full/partial nights on FLWO 1.2 meter and MDM 1.3 meter 1999, 2001:27 nights on KPNO 2.1 meter 2002-2004:11half nights on Keck 10 meter 2004:17 hours on Gemini-North

  19. The DIRECT Project M31 stars visible with 1.2 meter FLWO telescope Modern Astrophysics, Carroll & Ostlie

  20. DIRECT Project M33

  21. DIRECT Project M31

  22. The DIRECT Project Results in M31 Bonanos et al. 2003

  23. The DIRECT Project From M31 field Y (Bonanos et al. 2003)

  24. DIRECT Project Macri et al., 2001  candidate found

  25. O-star binary P = 4.8938 days KPNO 2.1 m follow up data

  26. Hubble Space Telescope U-band B-band

  27. Spitzer- IRAC 3.6 m 4.5 m 5.8 m 8 m M33 Spitzer GTO team (Gerhz et al.)

  28. Lightcurve V-band 278 points KPNO 2.1m 1999, 2001

  29. Model EBOP program (Nelson & Davis 1972, Popper & Etzel 1981) Wilson-Devinney program (Wilson & Devinney 1971, Wilson 1979, 1990) Simultaneous fit of BV light curves & radial velocity curve 13 parameters: period P, time of primary eclipse T0, inclination i, eccentricity e, argument of periastron , semi-major axis a, systemic velocity , surface potentials 1, 2, mass ratio q = M2/M1, Teff2, light ratio in V and B

  30. Lightcurve B-band 83 points KPNO 2.1m 1999, 2001

  31. Radial velocity curve Keck ESI Gemini GMOS 2002: ESI broke 2003: Hurricane Jimena

  32. Keck- ESI Spectrum Oct 11, 2004 5.25 hours

  33. Keck/ESI HeI 4388 HeII 4200 H H

  34. DEB Parameters Period, P 4.89380 ±0.00003 days Inclination, i 87.2 ±0.5 deg Eccentricity, e 0.18 ±0.02 Longitude of periastron,  252.4 ±1.0 deg Light ratio L2/L1 (V) 0.492 ± 0.005 Light ratio L2/L1 (B) 0.493 ± 0.005 Mass ratio, q 0.91 ± 0.07 Systemic velocity ,  -214 ± 7km s-1 Semi-amplitude, K1 242 ± 11 km s-1 Semi-amplitude, K2 266 ± 11 km s-1 Fractional radius, r1 0.254 ± 0.002 Fractional radius, r2 0.182 ± 0.002

  35. DEB Physical Parameters Bonanos, Stanek, Kudritzki et al., in prep.

  36. Modelatmospheres • Hydrodynamic non-LTE models: • FASTWIND • including stellar winds • spherical extension • metal line blanketing • Puls, Urbaneja et al. 2005, A&A Rolf Kudritzki

  37. Spectral Fits model spectra for star 1 log g1 = 3.78, v1(rad) star 2 log g2 = 4.03, v2(rad) free parameter : T1 (F1/F2 T2) composite spectrum: Sp = R12 F1 Sp1(T1, g1, v1)+R22 F2 Sp2(T2, g2, v2) normalize by N = R12 F1 + R22 F2

  38. HeI 4026 HeII 5412 HeII 4542 HeI 4471 HeII 4200 HeI 4922

  39. H4 Star 2 Star 1 Hβ T1 =35,37,39kK

  40. HeI 4922 Star 2 Star 1 HeI λ4922 T1 =35,37,39kK

  41. HeII 5412 Star 2 Star 1 HeII λ5412 T1 =35,37,39kK

  42. Distance B - V = -0.11 (B-V)0= -0.25 E(B-V)= 0.14 ± 0.03 A(V)= Rv E(B-V)

  43. Distance 24.87 +/- 0.16 mag U B V=19.58 R I

  44. Distance Modulus

  45. Distance to DEB Distance Modulus 24.87 ± 0.16 mag m-M = 5 log (d/10pc)942 ± 73 kpc Error Budget extinction 4.4% radii 4% temperature 4% photometry 3% 8% distance to M33

  46. M33 Distance HST Key Project

  47. Implications M33 Distance Key Project, Cepheids 24.62 ± 0.15 mag Freedman et al. (2001) DIRECT Project, DEB 24.87 ± 0.16 mag Bonanos et al. (in prep) LMC: 18.75 ± 0.22 mag H0= 63 km s-1 Mpc-1 (12% decrease)

  48. HST Key Project Freedman et al. 2001

  49. Large Magellanic Cloud 43.2 ±1.8 kpc 47.0 ±2.2 kpc 50.2 ±1.2 kpc 47.5 ±1.8 kpc Fitzpatrick et al. (2003)

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