EDP Sciences
Free access
Volume 412, Number 3, December IV 2003
Page(s) 745 - 749
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20031477

A&A 412, 745-749 (2003)
DOI: 10.1051/0004-6361:20031477

Hiding the high excitation in the head of a fast Herbig-Haro jet

A. C. Raga1 and J. Cantó2

1  Instituto de Ciencias Nucleares, UNAM, Ap. 70-543, 04510 D F, México
2  Instituto de Astronomía, UNAM, Ap. 70-264, 04510 D F, México

(Received 19 May 2003 / Accepted 4 September 2003)

We propose that some low excitation HH objects might correspond to the head of a pulsed jet moving into a dense environment. We develop an analytic model showing that the head of such a jet will move slowly, producing a low excitation bow shock. At the times at which the successive pulses catch up with the jet head, high excitation emission will be produced, lasting for a time of the order of the cooling timescale of the material heated in the pulse/jet head interaction. In this way, the jet head has "flashes" of high excitation emission superimposed on a "quiescent", low excitation emission.

Key words: ISM: Herbig-Haro objects -- ISM: jets and outflows -- ISM: kinematics and dynamics -- shock waves

Offprint request: A. Raga, raga@nuclecu.unam.mx

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