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DG Leo : a triple system with a surprising variety of physical phenomena

DG Leo : a triple system with a surprising variety of physical phenomena.

vernon-aguilar
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DG Leo : a triple system with a surprising variety of physical phenomena

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  1. DG Leo : a triple system with a surprising variety of physical phenomena P. Lampens,Y. Frémat & H. Hensberge, Royal Observatory of Belgium, Brussel, Belgium V. Tamazian, J.A. Docobo, Observatorio Astronómico R. M. Aller, Santiago de Compostela, Spain Y. Balega, Special Astrophysical Observatory, Russia Garching (ESO) - Multiple stars across the HR diagram

  2. Outline • Part I: Introduction • 1.1 The goal • 1.2 The target • Part I: Astrophysical relevance • 2.1 The close binary • 2.2 The visual binary • Part II: Orbit analyses • 3.1 New astrometric orbit • 3.2 New combined orbit • 4.Future work Garching (ESO) - Multiple stars across the HR diagram

  3. I. Introducing the project • Goal of the current project: In-depth study of a pulsating star in a binary or multiple system • Binarity/multiplicity provides “added value” wrt. the component’s physical properties in a straight-forward, independent way • Binarity/multiplicity allows to “discard” the shared characteristics between the components (distance, environment-e.g.overall chemical composition- and age) • Comparative study of the pulsational properties between components of “twin systems” is most rewarding •  Principal target = DG Leo Garching (ESO) - Multiple stars across the HR diagram

  4. 1.2 Introducing DG Leo HD 85040 = HIP 48218 = Kui 44AB Aab = inner binary (SB2) Porb1 ~ 4.15 days AB = outer binary (SB2-VB) Porb2 ~ 100-150 yr near periastron (2003) Fig. 1 The hierarchical triple system DG Leo 3 nr identical components (A8/F0 IV-III) all   Sct instability strip (+Am) (Fekel & Bopp ’77; Frémat et al. ’05) Garching (ESO) - Multiple stars across the HR diagram

  5. 2.1 The close binary Aab • Aab system: Porb= 4.15 days • From the photometry: • tidal interaction (pure ellipsoidal variation - no net “reflection”) • no eclipses (iorb<73º)*  MAa = MAb > 2.0 M • (Rosvick & Scarfe ’91; • Lampens et al. ’05) Aa Ab Fig. 2. The close binary in DG Leo A Garching (ESO) - Multiple stars across the HR diagram

  6. 2x Max 2x Min Garching (ESO) - Multiple stars across the HR diagram

  7. JD = 2452312.709 Phase = 0.748 T Min Ab Aa Aa JD = 2452313.746 Phase = 0.498 T Max Ab No phase lag between light and RV Garching (ESO) - Multiple stars across the HR diagram

  8. 2.1 The close binary Aab • From the spectroscopy: • (high S/N spectra from ELODIE@OHP, France) • spectral disentangling method(Hadrava 1995) • component spectra • comp radial velocities • (Fekel & Bopp ’77; • Frémat et al. ’05) Aa Ab Fig. 2. The close binary in DG Leo A Garching (ESO) - Multiple stars across the HR diagram

  9. Underabundance Overabundance Fe Ni Ti 5030 Sc II Chemical composition: comp Ab HD 33959 A9 IV V sin i = 29 km/s HD 88849 A7m V sin i = 29 km/s Ab Garching (ESO) - Multiple stars across the HR diagram

  10. 2.2 The visual binary AB • AB pair: Porb ~ 100–150 yr • Abrupt changes in Vr,A • & Vr,B observed (Jan.’03) • First orbit computation; confirmation of high i and e(Frémat et al. 05) •  possibility for deriving all 3 component masses… B Fig. 4. The distant companion DG Leo B Garching (ESO) - Multiple stars across the HR diagram

  11. 2forb f1, f2, f3, f4 (at least) 1 comp is multiperiodic  Sct variable Garching (ESO) - Multiple stars across the HR diagram

  12. Start of night 7 Pulsation: comp B Mean CCF Aa B Ab Garching (ESO) - Multiple stars across the HR diagram

  13. Start of night 5 Pulsation: comp B Mean CCF Ab B Aa Garching (ESO) - Multiple stars across the HR diagram

  14. Underabundance Overabundance Fe Ni Ti 5030 Sc II Chemical composition: comp B HD 33959 A9 IV V sin i = 29 km/s HD 88849 A7m V sin i = 29 km/s B Garching (ESO) - Multiple stars across the HR diagram

  15. Fundamental component parameters Garching (ESO) - Multiple stars across the HR diagram

  16. II. First (astrometric+RV) orbit (Frémat et al., 2005) Obtained with VBSB2 (global exploration of the parameter space followed by simultaneous LSQ minimiz.) (Pourbaix 1998) B A However ambiguities on KA, KB reflect on the true semi-major axes aA, aB and on the masses MA, MB Garching (ESO) - Multiple stars across the HR diagram

  17. 3.1 Improved astrometric solution (Docobo & Tamazian, submitted) A new speckle datum at epoch 2004.99 i.e. after periastron passage (6m tel@SAO) leads to: Garching (ESO) - Multiple stars across the HR diagram

  18. 3.1 Improved astrometric solution • Solution 1(Porb=101 yr) • Based on Docobo (1985) • Best agreement for all astrometric data (n=91) • Smaller errors • Efficiency = 0.10 (Pourbaix & Eichhorn 1998) Using Hipparcosparallax System mass ~ 3 M ?! Garching (ESO) - Multiple stars across the HR diagram

  19. 3.2 Combined orbital solution Including new speckle datum after periastron: New Previous (Frémat et al., 2005) (this work) Garching (ESO) - Multiple stars across the HR diagram

  20. 3.2 Combined orbital solution • Solution 2 (Porb=113 yr) • Based on Pourbaix (1998) • Incl. Vr,A and Vr,B • Excellent agreement for interferometric data only (n=41) • Efficiency = 0.16 Garching (ESO) - Multiple stars across the HR diagram

  21. 3.2 Combined orbital solution • Solution 2 (Porb=113 yr) • Includes VrA and VrB • All data (n=111) • Efficiency = 0.32 (x 2) • System parameters hold orbital parallax •  Hipparcos parallax butonlyat 1.5 σ-level (and σπ/π= 15%) B A Using orbitalparallax System mass  6 M ! Garching (ESO) - Multiple stars across the HR diagram

  22. Using Hipparcos parallax: (m-M)=-5-5.log(πHIP) Using the orbital parallax: (m-M)=-5-5.log(πOrb) Schaller et al. 2002 (Z=0.02) Garching (ESO) - Multiple stars across the HR diagram

  23. 4. What is (still) needed ? • Very high-accuracy astrometry to resolve the close binary system Aab (VLTI) for orbital inclination & accurate dynamical masses (2 mild Am) • (Very) high-accuracy astrometry to improve the system parameters/orb. parallax of AB pair (VLTI3-4m tel) for accurate third component mass(δSCT) • Additional high-S/N spectroscopy for pulsation mode identification (multi-colour photometry, line profiles, modelling)  New insights for understanding the link between pulsation - chemical composition (diffusion) - multiplicity Garching (ESO) - Multiple stars across the HR diagram

  24. To be (hopefully) cont’d Garching (ESO) - Multiple stars across the HR diagram

  25. Pulsation: comp B Night 8 • DG Leo B is a multiperiodic, small-amplitude Delta Scuti pulsating star ! Night 7 Night 6 Night 5 Garching (ESO) - Multiple stars across the HR diagram

  26. Am binaries in general • Binary frequency > 50 %(North et al. ‘98) • Orbital period distribution(Debernardi et al. ‘00) • Circularization period(Debernardi et al. ‘00) • Spin-orbit synchronization(Abt, Levato et al. ‘02) Fig. R. The (e, log P) distribution of Am binaries Fig. L. Orbital period distribution of Am bin. from CORAVEL survey Garching (ESO) - Multiple stars across the HR diagram

  27. Using the orbital parallax: (m-M) = -5 -5.log (πOrb) Schaller et al. 2002 (Z=0.02) Garching (ESO) - Multiple stars across the HR diagram

  28. Using Hipparcos parallax: (m-M)=-5-5.log(πHIP) Schaller et al. 2002 (Z=0.02) Garching (ESO) - Multiple stars across the HR diagram

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