Effects of Preionization in Radiative Shocks. II. Application to the Herbig–Haro Objects

Journal Article · Sat Apr 01 04:00:00 EDT 2017 · Astrophysical Journal, Supplement Series

DOI:https://doi.org/10.3847/1538-4365/AA6542· OSTI ID:22872813

Dopita, Michael A.; Sutherland, Ralph S. ^[1]

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1. Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia)

In an earlier paper we treated the preionization problem in shocks over the velocity range 20 km s{sup −1 }< v{sub s}<1000 km s{sup −1 }in a fully self-consistent manner. Here we investigate in detail the effect of the upstream UV photon field generated in the radiative zone of shocks in the range in which hydrogen is only partly ionized 20 km s{sup −1 }(< v{sub s}<150 km s{sup −1}). We show that, as a result of superheating in the nonequilibrium preshock plasma, both the magnetic parameter and the Mach number of the shock are strongly affected by the preionization state of the gas, which controls to a large extent the radiative spectrum of the shock. We use these models to provide specific line diagnostics for Herbig–Haro objects, which allow us to solve for both the preshock density and shock velocity, and we present detailed models of the HH 34 jet, which allows us to derive the shock conditions, mass-loss rate, momentum flux, and chemical abundances in the jet. We show that the refractory elements Mg, Ca, Fe, and Ni are enhanced by 0.22 dex over the solar values, which provides interesting clues about the jet-launching mechanism in pre-main-sequence evolution.

• OSTI ID: 22872813
• Journal Information: Astrophysical Journal, Supplement Series, Journal Name: Astrophysical Journal, Supplement Series Journal Issue: 2 Vol. 229; ISSN 0067-0049; ISSN APJSA2
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CONTROL
DENSITY
GALACTIC EVOLUTION
HYDROGEN
MACH NUMBER
MASS TRANSFER
PHOTONS
PLASMA
REFRACTORIES
SHOCK WAVES
SPECTRA
STELLAR WINDS
SUPERHEATING
ULTRAVIOLET RADIATION