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

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

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

Ashkbiz Danehkar

October 20, 2017
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  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
    [email protected]
    [email protected]

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  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

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  3. 20 October 2017 CfA Postdoc Symposium 3

    Round (R)

    Elliptical (E)

    Bipolar/multi-polar/ring (B)

    Point-symmetric
    Morphology of Planetary Nebula

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  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”

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  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)

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

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

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  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

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  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).

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