Physical conditions in the Orion Nebula and an assessment of its helium abundance

Baldwin, J. A.; Ferland, Gary J.; Martín, P. G.; Corbin, Michael R.; Cota, Stephen A.; Peterson, B. M.; Slettebak, Arne

doi:10.1086/170146

Cited by 332 publications

(451 citation statements)

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“…As a result of the metal depletion onto dust grains the gas-phase elemental abundances are altered to H: 1.00, He: 9.50 Â 10 À2 , Li: 5.40 Â 10 À11 , B: 8.90 Â 10 À11 , C: 3.00 Â 10 À4 , N: 7.00 Â 10 À5 , O: 4.00 Â 10 À4 , Ne: 6.00 Â 10 À5 , Na: 3.00 Â 10 À7 , Mg: 3.00 Â 10 À6 , Al: 2.00 Â 10 À7 , Si: 4.00 Â 10 À6 , P: 1.60 Â 10 À7 , S: 1.00 Â 10 À5 , Cl: 1.00 Â 10 À7 , Ar: 3.00 Â 10 À6 , K: 1.10 Â 10 À8 , Ca: 2.00 Â 10 À8 , Ti: 5.80 Â 10 À10 , V: 1.00 Â 10 À10 , Cr: 1.00 Â 10 À8 , Mn: 2.30 Â 10 À8 , Fe: 3.00 Â 10 À6 , Ni: 1.00 Â 10 À7 , Cu: 1.50 Â 10 À9 , and Zn: 2.00 Â 10 À8 . These depleted elemental abundances are based on results of several studies of the Orion nebula (Baldwin et al 1991;Rubin et al 1991;Rubin, Dufour, & Walter 1993;Rubin et al 1992;Osterbrock, Tran, & Veilleux 1992). Note that beryllium, fluorine, scandium, and cobalt are not included in the calculations for the dusty models.…”

Section: Methodsmentioning

confidence: 99%

Iron Is Not Depleted in High-Ionization Nuclear Emission-Line Regions of Active Galactic Nuclei

Nagao

Murayama

Shioya

et al. 2003

The Astronomical Journal

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To examine whether or not high-ionization nuclear emission-line regions (HINERs) in narrow-line regions of active galactic nuclei are dusty, we focus on two high-ionization forbidden emission lines, [Fe vii consistent with the dust-free models, while it cannot easily be explained by the dusty models. This suggests that iron is not depleted in HINERs, which implies that the HINERs are not dusty. This result is consistent with the idea that the HINERs are located closer than the dust-sublimation radius (i.e., the inner radius of dusty tori) and thus can be hidden by dusty tori when seen from a edge-on view toward the tori, which is also suggested by the AGN-type dependence of the visibility of high-ionization emission lines.

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Section: Methodsmentioning

confidence: 99%

Iron Is Not Depleted in High-Ionization Nuclear Emission-Line Regions of Active Galactic Nuclei

Nagao

Murayama

Shioya

et al. 2003

The Astronomical Journal

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“…The calcium gas-phase abundance, for example, is estimated to be ∼2×10 −8 in Orion (Baldwin et al 1991), i.e. two orders of magnitude lower than its solar abundance (∼2.04 ×10 −6 , Asplund et al 2005), and up to 4 orders of magnitude lower than solar in ζ Oph (Savage & Sembach 1996).…”

Section: Dust Reprocessing In the Jetsmentioning

confidence: 97%

“…Several theoretical studies have explored the dust content and its distribution in the interstellar medium. On the one hand both observations and theoretical models show that the gas-phase abundances of elements like iron (Fe), magnesium (Mg), silicon (Si), and calcium (Ca) are considerably depleted (by a factor of the order of 10 2 -10 4 ) with respect to their solar abundances because of the formation Article published by EDP Sciences of dust grains (Baldwin et al 1991;van Dishoek et al 1993;Savage & Sembach 1996). On the other hand the chemical composition, the size and the content of dust grains can evolve as they lose atoms to the gas phase through shocks waves.…”

Section: Introductionmentioning

confidence: 99%

Physical structure and dust reprocessing in a sample of HH jets

Podio

Medves

Bacciotti

et al. 2009

A&A

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Context. Stellar jets are an essential ingredient of the star formation process and a wealth of information can be derived from their characteristic emission-line spectra. Aims. We investigate the physical structure and dust reprocessing in the shocks along the beam of a number of classical Herbig-Haro (HH) jets in the Orion and Lupus molecular clouds (HH 111, HH 1/2, HH 83, HH 24 M/A/E/C, and Sz68). Parameters describing plasma conditions, as well as dust content, are derived as a function of distance from the source and, for HH 111, of gas velocity. Methods. Spectral diagnostic techniques are applied to obtain the jet physical conditions (the electron and total density, n e and n H , the ionisation fraction, x e , and the temperature, T e ) from the ratios of selected forbidden lines. The presence of dust grains is investigated by estimating the gas-phase abundance of calcium with respect to its solar value. Results. We find the electron density varies between 0.05-4 × 10 3 cm −3 , the ionisation fraction x e from 0.01-0.7, the temperature ranges between 0.6-3 × 10 4 K, and the hydrogen density between 0.01-6 × 10 4 cm −3 . Interestingly, in the HH 111 jet, n e , x e , and T e peak in the high velocity interval (HVI) of the strongest working surfaces, confirming a prediction from shocks models. Calcium turns out to be depleted with respect to its solar value, but its gas-phase abundance is higher than estimates for the interstellar medium in Orion. The depletion is high (up to 80%) along the low-excited jets, while low or no depletion is measured in those jets which show higher excitation conditions. Moreover, for HH 111 the depletion is lower in the HVI of the fastest shock. Conclusions. Our results confirm the shock structure predicted by models and indicate that shocks occurring along jets, and presumably those present in the launch zone, only partially destroy dust grains and that the efficiency of dust reprocessing strongly depends on shock velocity. However, the high Ca gas-phase abundance estimated in some of the knots, is not well understood in terms of existing models of dust reprocessing in shocks, and indicates that the dust must have been partially reprocessed in the region where the flow originates.

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“…These values are used in our calculation. Baldwin et al (1991) studied the Orion H ii region and obtained similar results for and f. The Infrared Space T HLG Observatory detected MIR emission from hot large grains in galaxies (Vigroux et al 1996;Dale et al 2000 unbiased Palomar Survey provides a fair representation of the local galaxy population, where old SBGs are major constituents (30%-40% in number). The spectral index lies between Ϫ2 and Ϫ3 in a(25, 60) 90% of the Palomar SBGs (Fig.…”

Section: Model Analysismentioning

confidence: 67%

Numerous Old Starburst Galaxies in the Local Universe

Mouri¹,

Taniguchi²

2000

The Astrophysical Journal

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Old starburst galaxies are deficient in O stars and hence do not exhibit strong line emission in the optical regime. However, there remain many B stars, which are expected to heat dust grains and generate strong continuum emission in the far-infrared. The IRAS data for a statistically complete sample of nearby galaxies reveal for the first time that such objects are as numerous as 30%-40% of the local galaxy population.

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Physical conditions in the Orion Nebula and an assessment of its helium abundance

Cited by 332 publications

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Iron Is Not Depleted in High-Ionization Nuclear Emission-Line Regions of Active Galactic Nuclei

Iron Is Not Depleted in High-Ionization Nuclear Emission-Line Regions of Active Galactic Nuclei

Physical structure and dust reprocessing in a sample of HH jets

Numerous Old Starburst Galaxies in the Local Universe

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