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Hen 3-1475: The Garden Sprinkler Nebula

Hen 3-1475: The Garden Sprinkler Nebula. Angels Riera Universitat Politècnica de Catalunya. The central star is classified as Be star (Henize 1976, Lamers et al. 1998). Evolutionary stage: transition from a AGB star to a PN (Parthasarathy & Pottasch 1989, Riera et al. 1995). Jets:

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Hen 3-1475: The Garden Sprinkler Nebula

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  1. Hen 3-1475: The Garden Sprinkler Nebula Angels Riera Universitat Politècnica de Catalunya

  2. The central star is classified as Be star (Henize 1976, Lamers et al. 1998). Evolutionary stage: transition from a AGB star to a PN (Parthasarathy & Pottasch 1989, Riera et al. 1995). Jets: • Optical imaging from the ground (Riera et al. 1995) and with the HST/WFC2 (Bobrowsky et al. 1995, Borkwoski, Blondin & Harrington 1997). • Optical spectroscopy from the ground (Bobrowsky et al. 1995, Riera et al. 1995), and with the HST/STIS (Borkowski & Harrington 2001; Riera et al. 2003). • Proper motions (Borkowski & Harrington 2001, Riera et al. 2002, 2003). • H2 2.12 m image show the presence of molecular H2 in the jet (Harrington et al. 1998 IAU Symp. 191, p. 509). • X-ray emission (knot NW1) (Guerrero, Sahai, p.c.).

  3. Central region is probably a dusty disk (or torus). • Thermal emission from hot dust in the NIR (García-Lario et al. 1997, Rodrigues et al. 2003), optical polarization (Rodrigues et al. 2003), and HI P-Cygni profilesindicate circumstellar dust close to the central star and ongoing post-AGB mass loss (Riera et al. 1995, Sánchez Contreras & Sahai 2001). • Circumstellar shell expansion: seen in CO (Knapp et al. 1995, Bujarrabal et al. 2001), andinOH maser emission (Bobrowsky et al. 1995, Zijlstra et al. 2001). • Radio continuum indicates the presence of a compact ionized region surrounding the central B star (Knapp et al. 1995).

  4. F555w blue • F502N green • F656N yellow-orange • F673N orange-red • F814W red

  5. Kinematicsof the Outflow • Large radial velocities (up to 900 km s-1). • Decrease in radial velocity moving outwards in a step-like fashion. The radial velocity decreases by 300 km s-1 from the innermost regions to the intermediate knots. • Within knot NW1, we observe an abrupt change of 145 km s-1 in just 0.90 arcsec. • Knot SE2: the spectrum displays a highly marked asymmetric shape with two intensity maxima. The high-velocity maxima occur 0.15 arcsec farther away from the central star. This is very similar to the velocity structure usually observed in HH objects. Wavelength (Å)

  6. Proper motion measurements Adopted distance 5.8 Kpc

  7. Line excitation mechanism: shocks (100 →200 km s-1) STIS G430L λc= 4300 Å G750L λc = 7751 Å

  8. Line excitation mechanism: Vs = 100 → 200 km s-1 • Emission line profiles: double-peaked profiles and extraordinarily line widths (exceeding 500 km s-1 ). • High proper motions • Step-like variations of the radial velocities along the jet ↕ HH emission is associated with shocks produced in outflows. Bow shock-like structures form as a result of a variability of the ejection velocity (Raga et al. 1990). From the observed radial velocities 1-D analytical model of Raga et al. (1990) predicts: Shock velocity Vs ~ 200 km s-1 Tangential velocities ~ 475 km s-1 Timescales for the variability of the velocity τ~ 100 years.

  9. Time-dependent ejection velocity model (poster Riera, Velázquez & Raga): 3D numerical simulations computed with YGUAZÚ-A adaptative grid code which integrates the 3D gasdynamic equation + a system of transport/rate equation for 17 atomic/ionic species. Ejection velocity variability: Vj = V0 + V1 sin (2 π (t – t0) / τ) + a t Precession: half opening angle αand period τp Parameters: V0 = 400 km s-1 V1= 150 km s-1 τ = 120 yrs a= 1 km s-1 yr-1 α= 7.5º τp = 1500 yrs

  10. Formation of highly collimated jets in PPNe: - toroidal magnetic fields? (García-Segura et al. 1999, García-Segura & López 2000) - accretion disk? (Soker & Livio 1994, Blackman et al. 2001). • Physical origin of the periodic variability: - instabilities in the gas-dust coupling in a radiation preassure-driven outflow?(Deguchi 1977) - influence of a binary companion?(Harpaz et al. 1997, Mastrodemos & Morris 1997). - magnetic cycle leading to coronal ejection-like events?(Soker 2000, Blackman et al. 2001) - MHD instabilities in a magnetized outflow (García-Segura 1997). • Origin of precession: - influence of a binary companion? - induced by irradiation of the disk by a central source?(Livio & Pringle 1997).

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