Measurements of the Singly Ionized Oxygen Auroral Doublet Lines λλ7320, 7330 Using High‐Resolution Sky Spectra

Sharpee, B. D.; Slanger, T. G.; Huestis, D. L.; Cosby, P. C.

doi:10.1086/382869

Cited by 19 publications

(31 citation statements)

References 33 publications

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“…This provides important insight into the method of analysis of the full Orion data and also provides improved values of the two energies constrained by the blue lines à la Bowen. We conclude by comparing our results with recent work by Sharpee et al (2004).…”

Section: Introductionsupporting

confidence: 71%

“…COMPARISON TO RECENT WORK OF SHARPEE ET AL. Sharpee et al (2004) have observed the four red lines (kk7319, 7320, 7330, and 7331) in sky spectra using the High Resolution Echelle Spectrograph (HIRES) on Keck I. In their determination of the O ii 2p 3 energy levels, they also make use of data sets from nebulae (Bowen 1955(Bowen , 1960de Robertis et al 1985;Baldwin et al 2000;Sharpee et al 2003).…”

Section: Constraining the Energy Levels With Thementioning

confidence: 99%

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On the OiiGround Configuration Energy Levels

Blagrave

Martín

2004

ApJ

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The most accurate way to measure the energy levels for the O ii 2p 3 ground configuration has been from the forbidden lines in planetary nebulae. We present an analysis of modern planetary nebula data that nicely constrain the splitting within the 2 D term and the separation of this term from the ground 4 S 3=2 level. We extend this method to H ii regions using high-resolution spectroscopy of the Orion Nebula, covering all six visible transitions within the ground configuration. These data confirm the splitting of the 2 D term while additionally constraining the splitting of the 2 P term. The energies of the 2 P and 2 D terms relative to the ground ( 4 S ) term are constrained by requiring that all six lines give the same radial velocity, consistent with independent limits placed on the motion of the O + gas and the planetary nebula data.

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Section: Introductionsupporting

confidence: 71%

Section: Constraining the Energy Levels With Thementioning

confidence: 99%

On the OiiGround Configuration Energy Levels

Blagrave

Martín

2004

ApJ

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“…Since the intensity ratio I(λ7320 Å)/I(λ7319 Å) = constant = 3.071 in the N e range considered here (De Robertis et al 1985;Keenan et al 1999;Sharpee et al 2004), the λ7319 Å suppression was obtained in the simple fashion illustrated in Fig. 5.…”

Section: Observations and Reductionsmentioning

confidence: 85%

The 3-D shaping of NGC 6741: A massive, fast-evolving Planetary Nebula at the recombination-reionization edge

Sabbadin¹,

Benetti²,

Ragazzoni

et al. 2005

A&A

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Abstract. We infer the gas kinematics, diagnostics and ionic radial profiles, distance and central star parameters, nebular photo-ionization model, spatial structure and evolutionary phase of the Planetary Nebula NGC 6741 by means of long-slit ESO NTT+EMMI high-resolution spectra at nine position angles, reduced and analysed according to the tomographic and 3-D methodologies developed at the Astronomical Observatory of Padua (Italy). NGC 6741 (distance 2.0 kpc, age 1400 yr, ionized mass M ion 0.06 M ) is a dense (electron density up to 12 000 cm −3 ), high-excitation, almost-prolate ellipsoid (0.036 pc×0.020 pc×0.018 pc, major, intermediate and minor semi-axes, respectively), surrounded by a sharp low-excitation skin (the ionization front), and embedded in a spherical (radius 0.080 pc), almostneutral, high-density (n(H I) 7 × 10 3 atoms cm −3 ) halo containing a large fraction of the nebular mass (M halo ≥ 0.20 M ). The kinematics, physical conditions and ionic structure indicate that NGC 6741 is in a deep recombination phase, started about 200 years ago, and caused by the rapid luminosity drop of the massive (M * = 0.66−0.68 M ), hot (log T * 5.23) and faint (log L * /L 2.75) post-AGB star, which has exhausted the hydrogen-shell nuclear burning and is moving along the white dwarf cooling sequence. The general expansion law of the ionized gas in NGC 6741, V exp (km s −1 ) = 13 × R , fails in the innermost, highest-excitation layers, which move slower than expected. The observed deceleration is ascribable to the luminosity drop of the central star (the decreasing pressure of the hot-bubble no longer balances the pressure of the ionized gas), and appears in striking contrast to recent reports inferring that acceleration is a common property of the Planetary Nebulae innermost layers. A detailed comparative analysis proves that the "U"-shaped expansion velocity field is a spurious, incorrect result due to a combination of: (a) simplistic assumptions (spherical shell hypothesis for the nebula); (b) unfit reduction method (emission profiles integrated along the slit); and (c) inappropriate diagnostic choice (λ4686 Å of He II, i.e. a thirteen finestructure components recombination line). Some general implications for the shaping mechanisms of Planetary Nebulae are discussed.

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“…The intensity ratio between the 731.9 nm and 733.0 nm O + lines has been investigated in terrestrial as well as astrophysical environments (e.g. Sharpee et al, 2004;De Robertis et al, 1985). From this reference spectrum, the ratio of these two O + emission lines is found to be 1.6.…”

Section: Methods For Separating Sif Spectral Componentsmentioning

confidence: 99%

Using spectral characteristics to interpret auroral imaging in the 731.9 nm O<sup>+</sup> line

Dahlgren¹,

Ivchenko²,

Lanchester

et al. 2008

Ann. Geophys.

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Abstract.Simultaneous observations were made of dynamic aurora during substorm activity on 26 January 2006 with three high spatial and temporal resolution instruments: the ASK (Auroral Structure and Kinetics) instrument, SIF (Spectrographic Imaging Facility) and ESR (EISCAT Svalbard Radar), all located on Svalbard (78 • N, 16.2 • E). One of the narrow field of view ASK cameras is designed to detect O + ion emission at 731.9 nm. From the spectrographic data we have been able to determine the amount of contaminating N 2 and OH emission detected in the same filter. This is of great importance to further studies using the ASK instrument, when the O + ion emission will be used to detect flows and afterglows in active aurora. The ratio of O + to N 2 emission is dependent on the energy spectra of electron precipitation, and was found to be related to changes in the morphology of the small-scale aurora. The ESR measured height profiles of electron densities, which allowed estimates to be made of the energy spectrum of the precipitation during the events studied with optical data from ASK and SIF. It was found that the higher energy precipitation corresponded to discrete and dynamic features, including curls, and low energy precipitation corresponded to auroral signatures that were dominated by rays. The evolution of these changes on time scales of seconds is of importance to theories of auroral acceleration mechanisms.

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Measurements of the Singly Ionized Oxygen Auroral Doublet Lines λλ7320, 7330 Using High‐Resolution Sky Spectra

Cited by 19 publications

References 33 publications

On the OiiGround Configuration Energy Levels

On the OiiGround Configuration Energy Levels

The 3-D shaping of NGC 6741: A massive, fast-evolving Planetary Nebula at the recombination-reionization edge

Using spectral characteristics to interpret auroral imaging in the 731.9 nm O<sup>+</sup> line

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Measurements of the Singly Ionized Oxygen Auroral Doublet Lines λλ7320, 7330 Using High‐Resolution Sky Spectra

Cited by 19 publications

References 33 publications

On the OiiGround Configuration Energy Levels

On the OiiGround Configuration Energy Levels

The 3-D shaping of NGC 6741: A massive, fast-evolving Planetary Nebula at the recombination-reionization edge

Using spectral characteristics to interpret auroral imaging in the 731.9 nm O&lt;sup&gt;+&lt;/sup&gt; line

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Using spectral characteristics to interpret auroral imaging in the 731.9 nm O<sup>+</sup> line