Low-ionization Envelopes in NGC 5189: Spatially-resolved HST Observations

Talk given at CfA Postdoc Symposium, Harvard/CfA, Cambridge, USA, October 2017

Transcript

1. Low-ionization Envelopes in NGC 5189
   Low-ionization Envelopes in NGC 5189
   Spatially-resolved
   Spatially-resolved HST
   HST Observations
   Observations
   Collaborators: Margarita Karovska, W. Peter Maksym, and Rodolfo Montez Jr. (CfA)
   Collaborators: Margarita Karovska, W. Peter Maksym, and Rodolfo Montez Jr. (CfA)
   Ashkbiz Danehkar
   Ashkbiz Danehkar
   Harvard-Smithsonian Center for Astrophysic
   Harvard-Smithsonian Center for Astrophysics
   s
   ashkbiz.danehkar@cfa.harvard.edu
   ashkbiz.danehkar@cfa.harvard.edu
   

   View Slide

2. 20 October 2017 CfA Postdoc Symposium 2
   Planetary Nebulae (PNe)
   ●
   Expanding shells of H-rich material ejected by AGB star
   – Shell: Vexp ~ 10-40 km/s
   – Density: Ne ~ 100- 105 cm-3
   ●
   Central stars left the AGB phase
   – Progenitor Mass: 1 M☉ < Minit < 8 M☉
   – Current Stellar Mass: 0.5-0.9 M☉
   ●
   AGB star transited to PN phase
   ●
   UV radiation from star ionizes the shell
   Herwig 2005
   Cat's Eye
   

   View Slide

3. 20 October 2017 CfA Postdoc Symposium 3
   ●
   Round (R)
   ●
   Elliptical (E)
   ●
   Bipolar/multi-polar/ring (B)
   ●
   Point-symmetric
   Morphology of Planetary Nebula
   

   View Slide

4. 20 October 2017 CfA Postdoc Symposium 4
   NGC 5189: Complex
   HST WFC3
   ●
   F502N: [O III]
   ●
   F657N: Hα + [N II]
   ●
   F673N: [S II]
   ●
   F606W: Continuum (V)
   ●
   F814W: Continuum (I)
   PI: Zolt Levay (2012)
   ●
   Credit: NASA/ESA Hubble Space Telescope (Dec 18, 2012).
   Image with specific colors of fluorescing sulfur, hydrogen, and oxygen.
   ●
   120”
   ●
   90”
   

   View Slide

5. 20 October 2017 CfA Postdoc Symposium 5
   NGC 5189
   ●
   [O III], Hα, [S II] flux maps
   ●
   [S II]/Hα flux ratio: high in low-excitation regions
   ●
   [O III]/Hα flux ratio: high in high-excitation regions
   ●
   Diagnostic diagrams based on [O III]/Hα vs. [S II]/Hα ratios
   – Dividing Shock-ionized and Photoionized regions (Raga + 2008)
   – Similar to LINER and Seyfert regions in BPT diagrams
   (Baldwin, Phillips & Terlevich 1981; Kewley + 2006)
   

   View Slide

6. 20 October 2017 CfA Postdoc Symposium 6
   NGC 5189
   Danehkar et al. 2017 (ApJ, submitted)
   [S II]/Hα ratio [O III]/Hα ratio
   

   View Slide

7. 20 October 2017 CfA Postdoc Symposium 7
   NGC 5189
   Danehkar et al. 2017 (ApJ, submitted)
   

   View Slide

8. 20 October 2017 CfA Postdoc Symposium 8
   NGC 5189
   Danehkar et al. 2017 (ApJ, submitted)
   Photon-shock dividing line based on shock models of Raga et al. 2008
   

   View Slide

9. 20 October 2017 CfA Postdoc Symposium 9
   Conclusions
   HST WFC3 Observations of NGC 5189:
   [O III] (F502N) + Hα (F657N) + [S II] (F673N) + Continuum (F606W + F814W)
   ●
   Diagnostic diagrams based on [O III]/Hα vs. [S II]/Hα ratios:
   – Two dense low-ionization envelopes
   – A highly ionized low-density environment surrounds these two envelopes
   – Multiple low-ionization filamentary knotty structures
   – These low-ionization envelopes are likely a result of a powerful outburst
   from the post-AGB star that created shocked regions as they propagate
   through the previously expelled material
   ●
   Future Applications
   – Our diagnostic mapping provides a new powerful approach to detecting
   low-ionization regions in other PNe, especially those with a complex
   morphology (and other sources).
   

   View Slide