The planetary nebula M2-9: Balmer line profiles of the nuclear region Silvia Torres-Peimbert 1 Anabel Arrieta 2 Leonid Georgiev 1 1 Instituto de Astronomía, UNAM, México 2 Universidad Iberoamericana, México

M2-9, a young PN  Extreme bipolarity  Weak emission point symmetric at 60" from the nucleus  The inclination angle relative to the plane of the sky is of 15° and is located at a distance of 650 pc (Schwarz et al. 1997)  The condensations have shown motions parallel to the equatorial plane of 1“ in 10 years

Observations  2.1-m telescope San Pedro Mártir, BC f/7.5  Echelle spectrograph R=5,000 to 18,000 for Å 1024x1024 pixels Spatial resolution 0.99´´/pix Spectral resolution less than 10.6 km/s We attempt to fit the complex line profiles of the Balmer series of the central object of M2-9 This presentation

Direct image and spectroscopy [S II] 6717 [S II] 6731 [N II] 5755 He I 5876 H  [N II] 6584 H  [O III] 5007

Complex line profile of H   Extended wings can be explained by Raman scattering: Ly  photons converted to optical photons Requires column density of the scattering region of N HI ~ cm -2 (Arrieta et al. 2003) 6545A line is Raman scattered 1025A He II line (Lee, Kang & Byun 2001)  Our purpose is to explain the double profile of the core of the line

Firstly, we derive the systemic velocity Long slit spectrum of H  profile. To determine the systemic velocity it has been assumed that knots N3 and S3 are moving at V % R. A systemic velocity of 40 km/s is derived which corresponds to +61 km/s heliocentric velocity. Heliocentric velocity of km/s (Smith et al. 2005). North arcsec Intensity

Balmer and Paschen line profiles – The observed profiles are:  asymmetric  there is a decrease in the blue/red velocity difference for the higher series lines

H  /H  intensity ratios and optical depth Intensity Relative intensity uncertainty Observed H  /H  = 33.6 Derredened H  /H  = 17.4, corrected for Av = 2.7 mag, and R = 5.0, by fitting the rest of the H lines We derive  H  ~ 14

We propose a toy model to fit the profile of the core of the Balmer lines,  We derive line profiles by assuming simple geometry, density and velocity laws  We obtain the source function from Sobolev´s approximation and solve 3D radiative transfer (Georgiev & Koenigsberger 2004)  For a disk viewed in profile v % r (expanding wind)  % r -3 to r -5 (steep density gradient) Inner radius at ~10 R star Outer radius at ~1000 R star R star ~ 1 R sun

Sample of model profiles (for the core of the lines) The critical condition is a slow velocity gradient wind, not a classical radiation driven wind The profile is not sensitive to the shape of the disk (it could also be spherically symmetric) R/R star v/v infinity Radiation driven wind Slow velocity gradient wind 1

Fit to M2-9 Balmer profiles HH HH HH observedcomputed

M2-9 is not the only object with double H  & H  profiles Some examples of other young PNe and symbiotic stars

Conclusions (1) Preliminary radiative transfer models have been computed to explain the hydrogen line profiles in M2-9. They require:  disk surrounding the central star from – cm  steep density law  rather flat velocity gradient (not classical radiatively accelerated wind)

Conclusions (2) The proposed expanding wind model is compatible with:  the asymmetry of the profiles  the difference between the profiles of the Balmer series  the blue/red velocity difference between components  the optical depth of H  /H  /H  It may correspond to a transient wind in PPNe and symbiotic stars