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Main Author:	F. Bacciotti
Format:	Artículo científico
Language:	en
Published:	Universidad Nacional Autónoma de México 2002
Subjects:	Física, Astronomía y Matemáticas HERBIG HARO OBJECTS LINE: FORMATION ISM: JETS AND OUTFLOWS
Online Access:	https://www.redalyc.org/articulo.oa?id=57101304
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Diagnostic determination of ionization and density in stellar jets from line ratios F. Bacciotti Física, Astronomía y Matemáticas HERBIG HARO OBJECTS LINE: FORMATION ISM: JETS AND OUTFLOWS Highly collimated, supersonic Herbig-Haro (HH) jets have been recognized as an essential element of the starformation process. They show an emission-line spectrum dominated by optical red lines as [O I] 6300, H ,[N II] 6583, [S II] 6716,6731. Although it is widely accepted that such lines are produced in a gas excited bymild shocks, the detailed physical conditions of the plasma are still under debate. Observationally, the electrondensity ne is easily found from the [S II] doublet, but other crucial physical parameters, as the hydrogenionization fraction xe (and hence the total density, nH), and the average temperature of the ow, are poorlyknown. Recently, we have elaborated a new spectroscopic diagnostic technique that has allowed us to ndthese quantities in a model-independent way. Starting with an estimate of ne, the procedure combines theratios [O I]/[N II] and [S II]/[O I] to derive the ionization fraction and an estimate of the electron temperature.One can then derive the average mass loss and momentum transfer rates in the jet beam. The procedure hasbeen applied rst to a sample of HH jets and bipolar outows from T Tauri Stars, using moderate spatialresolution spectra taken from ground. The recent automation of the procedure has allowed us to analyze largehigh angular resolution ( 0:001) images and spectra taken with the Hubble Space Telescope. From the latter wehave derived for the rst time detailed maps of the physical properties both along and across the ow. Theseinvestigations have identied a number of interesting features, among which the fact that HH jets are onlypartially ionized (0:02 < xe < 0:4), and that the ionization fraction appears to increase rapidly close to thesource, to reach a plateau, and then decline gently along the beam. 2002 artículo científico 0185-1101 https://www.redalyc.org/articulo.oa?id=57101304 en http://www.redalyc.org/revista.oa?id=571 Revista Mexicana de Astronomía y Astrofísica application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Astronomía y Astrofísica (México) Vol.13

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// Anecdotal testing Today and Yesterday seems to indicate destroy() // is called by the garbage collector and everything is good. // Something to keep in mind though. return 0; } /** * Write function that is called when session data is to be saved. * * @param string $sessId The current session ID * @param string $data The session data to write * * @return bool */ public function write($sessId, $data): bool { if ($this->writesDisabled) { return true; } return $this->saveSession($sessId, $data); } /** * A function that is called internally when session data is to be saved. * * @param string $sessId The current session ID * @param string $data The session data to write * * @return bool */ abstract protected function saveSession($sessId, $data): bool; }

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