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
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
3. 20 October 2017 CfA Postdoc Symposium 3 • Round (R) • Elliptical (E) • Bipolar/multi-polar/ring (B) • Point-symmetric Morphology of Planetary Nebula
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”
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)
6. 20 October 2017 CfA Postdoc Symposium 6 NGC 5189 Danehkar et al. 2017 (ApJ, submitted) [S II]/Hα ratio [O III]/Hα ratio
7. 20 October 2017 CfA Postdoc Symposium 7 NGC 5189 Danehkar et al. 2017 (ApJ, submitted)
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
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).