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Gamow conference, Odessa , 2 0.08. 20 0 9

Gamow conference, Odessa , 2 0.08. 20 0 9. Ivan L. Andronov Odessa National Maritime University. Space Laboratory to Study Accretion in Magnetic Cataclysmic Variables: The Case of Exotic Newly-Discovered Polar OTJ 071126+440405.

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Gamow conference, Odessa , 2 0.08. 20 0 9

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  1. Gamow conference, Odessa, 20.08.2009 Ivan L. Andronov Odessa National Maritime University Space Laboratory to Study Accretion in Magnetic Cataclysmic Variables: The Case of Exotic Newly-Discovered Polar OTJ 071126+440405

  2. Theoretical part of the international observational campaign

  3. International collaboration • Inter-Longitude Astronomy (ILA): • Polar – photopolarimetric and spectroscopic study of gravimagnetic rotators in cataclysmic variables (in Ukraine, using the CrAO telescopes)‏ • Superhump – study of the precession of accretion disks in nova-like and dwarf nova stars • Stellar Bell – analysis of multi-component pulsations of short- and long- period variable stars based on own photometric observations and the data from the international databases of UAVSO (Ukraine), AFOEV (France) and VSOLJ (Japan). • SCJ - Star classification and justification of suspected variables from surveys (space observatories: Hipparcos-Tycho and ground-based: Sky Patrol).

  4. General classificationof non-magnetic and magnetic binary stars • non-magnetic cataclysmic binary stars (ex-Nova, dwarf Nova, Nova-like) • “semi-magnetic” cataclysmic binary stars (intermediate polars) • magnetic cataclysmic binary stars (synchronizing polars) • magnetic cataclysmic binary stars (classical polars)

  5. General modeldepends on characteristic dimensions:Rwd – radius of the white dwarfRA-Alfven Radius (magnetosphere)Rc- co-rotation radiusRd- maximum dimension of diskRL– distance to the inner Lagrangian pointa – orbital separation • Always: Rwd<Rd<RL< a, but Rwd ~RA-”non-magnetic” Rwd <RA~Rc <~Rd intermediate polars Rwd <Rc < RA~ Rd<RL asynchronous polars Rwd <Rd < Rc = RA~RL classical polars

  6. Types of Variability: Non-Magnetic Magnetic (polars) Characteristic timescale Nova-like classical Dwarf Novae asynchr IP

  7. New Year 2008/2009

  8. New Year 2008/2009

  9. Theoretical modelsof magnetic binary stars • “Asymmetric propeller" – synchronization of the spin and orbital periods of the white dwarf owed to ejection of plasma by magnetic field (additional centrifugal force)

  10. Theoretical models: “Asymmetric propeller" –ejection • Gravitation • Coriolis force • Centrifugal force • Viscosity • Gas pressure • Magnetic channeling

  11. Theoretical modelsof magnetic binary stars “Standard model" – accretion flow channelized by the magnetic field: “Magnetic valve” (dependence on the accretion flux and torque on the orientation of the magnetic axis

  12. Ivan L. Andronov, Odessa National Maritime University; Alexey V.Baklanov, Crimean Astrophysical Observatory Vadim N. Burwitz Max-Planck Institut fuer Extraterrestische Physik (Germany); Observatori Astronomic de Mallorca (Spain) A & A 2006 The unique magnetic cataclysmic system V1432 Aql: Third type of Minima, Synchronization and Capture Radius

  13. “Var-Comp” instrumental VR magnitudes choosing an optimal local constant/linear fit HJDmin = 2451492.11112(14) + 0,140235812(12) × (Е –16347).

  14. “Var-Comp” instrumental VR magnitudes The orbital “dip” was removed spin wide 1 spin narrow 2 HJDspin = 2453223.8359(13)+ 0.140585(30) *Е (2004г.)

  15. Three types of minima spin wide 1 1 orbital period 2 spin period migrating minima beat period ~60 days spin narrow 2 orbital "dips" | Andronov, Baklanov & Burwitz (2005) 4 subsequent nights from 18

  16. Synchronization of the white dwarf (acceleration of the “slow” spin rotation): • HJDspin= 2449638.327427(74) + 0.14062831(23) *Е -7.81(11) 10-10 *Е2 (1993-2004) • HJDspin = 2453223.8359(13)+ 0.140585(30) *Е(2004)

  17. Period variations: • TE= T0+P*Е +Q* Е2 • dP/dt=2Q/P, (dP/dt)/P=2Q/P2 • Q=-9.14.10-10 (Staubert et al. 2003 , 1.5s) • Q=-6.5.10-10 (Mukai et al. 2003, 9s) • Q=-7.81(11) . 10-10(all data:1993-2004 , 61s) Theory: AM Her (similar parameters) : 6<t<260 yrs (Andronov 1982) Observations: BY Cam (Silber et al. (1997), Mason et al. [1998]), V1500 Cyg (Pavlenko and Pelt (1988), Pavlenko and Shugarov 2005)

  18. Distances from the center of the white dwarf to:a – center of the secondaryRL – inner Lagrangian pointRY – Roche lobe in the orbital plane (“Y”)RHS – “hot spot” (Warner & Peters 1972)16RWD – minimal capture radius RWD – surface of the white dwarf + Andronov & Baklanov (Af 2007)

  19. Two limiting models of the accretion columns :1 - “vertical” (or height << radius) 2 - “inclined” (or height >> radius) (hope that the truth is somewhere in between): Δφ R0/ RWD (model 1) R0/ RWD (model 2) 0.42 36 16 0.43 47 21 0.44 64 28 φ+ ψ(φ)= π(1-2Δφ)/2 dipole magnetic field line white dwarf 1s "corridor" of Df model 1 model 2

  20. Results (briefly): Most precise: Orbital period Spin period Spin period variations + synchronization time Beat period of 57.201d First (observations): 3-rd type of minima 2-color (VR) photometry -> color index -> temperature First (theory): Capture radius range from the phase difference Self-consistent values of the parameters: Distance Accretion rate Capture radius Mass/Radius of the white dwarf

  21. Very new object: OTJ 0704 Discovered on December 31, 2008/January 1, 2009 Short orbital period (117 minutes) Deep eclipse (7minutes, from ~15 to ~19 magnitude) Pre-eclipse: 17 minutes before Out-of the outburst asymmetric wave Mean brightness variations: ~15 in January, ~18 in February, Maximum at the beginning of March Drastic color variations ~0.6 mag!!! Observations at 1-m Korean telescope at Mt.Lemmon (USA) March 11-19, 2009 (Yoh-Na Joon (became a father during obs)) 1-m (Slovakia), 2.6m, 1.25m (Ukraine)

  22. Crimean Astrophysical Observatory: AZT-11 S.V.Kolesnikov (reduced with MUNIpack by V.V.Breus): Faint minima missing reduced with WinFits by L.L.Chinarova: Measuring all

  23. BVRI photometry at the Korean Mt. Lemmon Observatory: 1m

  24. Crimean Astrophysical Observatory: B,I, B-I (AZT-11, K.A.Antoniuk)

  25. unfiltered photometry in Finland: changing states of luminosity & pre-dip shift

  26. unfiltered photometry in Finland: fall <5 sec

  27. Crimean Astrophysical Observatory: ZTSh (1 sec) – S.V.Kolesnikov, N.M.Shakhovskoy Reduced with ZTShServer (V.V.Breus) Wide R filter (intensities “var/comp”)

  28. These studies of the magnetic cataclysmic variables were initiated in 1978 by Prof. Vladimir P.Tsessevich (1907-1983) when I was a 3-rd year student and was interested in mathematical modeling of unstable Universe, black holes, gravitational lenses and pulsations

  29. Need for monitoring to check dynamics of the object. • Otherwise: antigravitation maybe?

  30. Arto Oksanen (Finland) : 3 unexpectedly different luminosity states

  31. Theoretical modelsof magnetic binary stars • 2D - oscillations of the orientation of the magnetic axis Red dwarf White dwarf

  32. Theoretical modelsof magnetic binary stars • 3D - oscillations of the orientation of the magnetic axis

  33. Theoretical modelsof magnetic binary stars • “Swinging dipole" – excitation of the auto-oscillations of the orientation of the magnetic axis with characteristic time of~1-10years

  34. Model of Dipole+thin disk:Dependence of the equilibrium period on the orientation (Andronov 2005)

  35. Spin phase variabilityas function of the orbital phase+correlated irregular shifts:clues for determination of the column orientation Kim, Andronov et al. (2005)

  36. Angular characteristics of the Roche lobe (Andronov, 1992) Improved expressions presented In the poster: Andronov & Breus, this conf.

  37. Dependence of the eclipse duration (in degrees) on the orbital inclination for various values of the mass of the white dwarf

  38. Dependence of the orbital inclination on the mass of the white dwarf

  39. The model of the system computed assuming the mass ratio q=0.3. The red dwarf (RD) fills its Roche lobe (RL). The plasma moves from the inner Lagrangian point (LP) initially along the ballistic (collisionless) trajectory (BT) and then captured by the magnetic field of the white dwarf (WD) and then moves along the dipole line (DL). At the low state, the thread point is close to the Lagrangian point, so the self-eclipse (SE) of the accretion column is observed closer in phase to the main eclipse of the main emission region by the red dwarf (when the line of centers (LC) is closest to the line of sight). The self-eclipse at the high state (SEH) is observed at another phase, practically corresponding to the minimal angle between the line of sight an the magnetic axis.

  40. Monitoring of selected cataclysmic variables – AM Herculis • Statistical dependence of the phase curve and characteristics of flickering on luminosity … • Changes of orientation of the accretion column (I.e. magnetic axis of the white dwarf) have been confirmed, which had been predicted by the “Swinging Dipole” model. • Unprecedented flare of the red dwarf of the UV Ceti -type • Minute-scale variability as the “Red noise”. • Fractal behaviour of luminosity variations in unprecedentally wide range from seconds to decades

  41. Theoretical modelsof magnetic binary stars • Advanced models of the “Standard” accretion column : • Non-homegeneous • Asymmetric • Inclined • “Rainbow” • “Boiling” • “Falling oscillating spaghetti”

  42. "Rainbow" Accretion Column

  43. Self-consistent model Orbital period 117.18331±0.00017minutes Duration of eclipse 433.3 seconds Distance to the system ~140 parsec Mass of the red dwarf 0.163 MSun Radius of the red dwarf 0.204RSun Mass ratio q=0.3 (assuming similarity to the magnetic system AR UMa) Mass of the white dwarf 0.543 MSun Orbital separation 0.704 RSun=4.9*108m Distance from the inner Lagrangian point to the white dwarf 3.04*108m Illumination of the red dwarf~ 1.8% emission of the white dwarf Radius of the white dwarf 0.013RSun=9.06*106m Orbital velocity 437 km/s Ascending/descending branch of the eclipse of the white dwarf: expected 20 sec, observed 3 sec Size of the main emission region 1300 km Orbital inclination 79-86 (79.1o) Angle between the line of centers and the magnetic axis 50.3o Angle between the line of centers and the accretion column’s axis in the intermediate state 38.9o Dependence of accretion geometry on luminosity !

  44. 3D Model: I.L.Andronov;animation: V.V.Breus

  45. Self-consistent mathematical model of the exotic object OTJ 071126+440405= CSS 081231:071126+440405 is discussed. The system was discovered as a polar at the New year night 31.12.2008/01.01.2009 by D.Denisenko (VSNET Circ), and we have initiated an international campaign of photometric and polarimetric observations of this object (totally ~80 runs in Ukraine, Korea, Slovakia, Finland, USA). This work is a part of the "Inter-Longitude Astronomy" (ILA) project on monitoring of variable stars of different classes (Andronov et al., 2003). Results of this campaign will be published separately (Andronov et al., 2009). Here we present the geometrical and physical model of the system. In an addition to the usual assumption that cataclysmic variables contain a Roche-lobe filling red dwarf and an accreting white dwarf, we propose an interpretation of three types of the brightness minima, as the eclipses by the red dwarf, white dwarf and the accretion column itself (self-eclipse). In the low luminosity state, when the accretion rate is suggested to vanish, a "quiescence" is observed at the light curve, i.e. the optical flux comes from the illuminated secondary star and the non-accreting side of the white dwarf. When the accretion column becomes visible, the light curve exhibits a `hump" interrupted by the main eclipse by the red dwarf. In the "intermediate" luminosity state, the brightness increases at all phases, however, the main hump shifts to smaller phases and an additional minimum (self-eclipse) is observed. In this state, the emitting accreting region becomes larger, and is not significantly eclipsed by the white dwarf. The phase difference between the preliminary and main eclipses is smaller than in the high luminosity state, what is interpreted by the dependence of the position of the thread point, where magnetic field of the white dwarf captures the (initially ballistic) accretion stream. At the high state, the thread point approaches the cross-section of the ballistic stream with the magnetic axis, whereas at the intermediate state, the thread point may lie from 70% to 100% of the distance between the white dwarf and the inner Lagrangian point. As the ballistic trajectory nearly coincides with the magnetic field lines near the inner Lagrangian point, this argues for an "energetically optimal" orientation of the magnetic axis. As the system is of ~20 mag at minimum, no spectral observations were made to determine parameters of the red dwarf. From the statistical relationship, the mass of the red dwarf is estimated to be ~0.165 solar masses, for the white dwarf (from eclipse duration) - from 0.5 to 1.76 solar masses. As the system resembles ER UMa in some characteristics, the lower value may be assumed. The inclination of the system and other physical parameters are estimated. The object is an excellent laboratory to study multiple physical processes in the magnetic systems.

  46. Thank You !

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