Oscillator Strengths for High-level Transitions in Hydrogen

Menzel, Donald H.

doi:10.1038/218756a0

Cited by 56 publications

(35 citation statements)

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“…Because the energy level spacings between adjacent RRLs for n > 50 are similar relative to the ground state, the line parameters-intensity, line width, and velocity-are nearly identical. For example, the classical oscillator strengths for the H 50 α and H 51 α RRLs differ by only 2%, so these lines should have comparable intensities (Menzel 1968). Thus at the high energy levels of our observations, to first order all transitions have the same intensity.…”

Section: Radio Recombination Linesmentioning

confidence: 99%

The Green Bank Telescope H Ii Region Discovery Survey. Ii. The Source Catalog

Anderson¹,

Bania²,

Balser³

et al. 2011

ApJS

215

312

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The Green Bank Telescope (GBT) H ii Region Discovery Survey has doubled the number of known H ii regions in the Galactic zone 343• 67• with | b | 1 • . We detected 603 discrete hydrogen radio recombination line (RRL) components at 9 GHz (3 cm) from 448 targets. Our targets were selected based on spatially coincident mid-infrared and 20 cm radio continuum emission. Such sources are almost invariably H ii regions; we detected hydrogen RRL emission from 95% of our target sample. The sensitivity of the GBT and the power of its spectrometer together made this survey possible. Here, we provide a catalog of the measured properties of the RRL and continuum emission from the survey nebulae. The derived survey completeness limit, 180 mJy at 9 GHz, is sufficient to detect all H ii regions ionized by single O-stars to a distance of 12 kpc. These recently discovered nebulae share the same distribution on the sky as does the previously known census of Galactic H ii regions. On average, however, the new nebulae have fainter continuum fluxes, smaller continuum angular sizes, fainter RRL intensities, and smaller RRL line widths. Though small in angular size, many of our new nebulae show little spatial correlation with tracers associated with extremely young H ii regions, implying that our sample spans a range of evolutionary states. We discovered 34 first quadrant negative-velocity H ii regions, which lie at extreme distances from the Sun and appear to be part of the Outer Arm. We found RRL emission from 208 Spitzer GLIMPSE 8.0 μm "bubble" sources, 65 of which have been cataloged previously. It thus appears that nearly all GLIMPSE bubbles are H ii regions and that ∼50% of all Galactic H ii regions have a bubble morphology at 8.0 μm.

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Section: Radio Recombination Linesmentioning

confidence: 99%

The Green Bank Telescope H Ii Region Discovery Survey. Ii. The Source Catalog

Anderson¹,

Bania²,

Balser³

et al. 2011

ApJS

215

312

View full text Add to dashboard Cite

show abstract

“…lines. Using the approximations for oscillator strengths given by Menzel (1968) and assuming thermodynamic equilibrium, the ratio of the intensities of the p and a. lines and of the y and a. lines may be written:…”

Section: H113p and H129i Linesmentioning

confidence: 99%

Recombination Lines near 8·9 GHz of Strong Sources in the Southern Milky Way

McGee¹,

Newton²,

Batchelor³

1975

Aust. J. Phys.

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Seventeen intense nebulae in the southern Milky Way have been surveyed for their radio recombination lines of hydrogen and helium, H 90IX, He 9OIX, H 113ft, H 129y, and of elements heavier than helium, X901X. The H901X line for 30Doradus in the Large Magellanic Cloud was also observed. Data on source size, flux density, continuum temperature, line temperature, line half-width and radial velocity are used to derive information about the sources. This information includes electron temperatures and turbulent velocities, the abundance ratio of singly ionized helium to ionized hydrogen, and the intensity ratios of ft and y lines to IX lines. The lines from elements heavier than helium are discussed.

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“…No knowledge of ion densities or kinetic temperatures is required by this method .. Using the recent formulae for oscillator strengths (Menzel 1968) their expression for the ratio may be more accurately written 1(198,8) = n~98v:oo,198x 2·633x 10-2 (1+3/198) = 0.28.…”

Section: (B) H 198f3 Linementioning

confidence: 99%

“…bn = 1), u = 0·19 (Menzel 1968), n = 158, and v = 1651·541 MHz. The equation may be solved for the electron temperature Te provided that (i) both the continuum background and the line radiation have low optical depth at this frequency;…”

Section: Recombination Line Profiles (A) H 158a: Linementioning

confidence: 99%

Recombination Lines 158a and 198ß in Nine Southern Nebulae

McGee¹,

Batchelor²,

Brooks³

et al. 1969

Aust. J. Phys.

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SummaryRecombination lines H 158", He 158", and H 198,8 (near ,\ 18 em) have been observed in the HI! regions Orion Nebula, RCW 38 and 49, "I Carinae I, RCW 57, PKS1617-5OI in Norma, NGC6334 and 63571, and Omega Nebula. Physical parameters such as ratio of line to continuum temperatures TdT c, line halfwidths, median radial velocities, and intensity ratios 1(198,8)/1(158,,) and 1(He)/1(H) are given. A lack of agreement in the measured radial velocities of the H 198,8 and H 158" lines in three nebulae is discussed.

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Oscillator Strengths for High-level Transitions in Hydrogen

Cited by 56 publications

References 0 publications

The Green Bank Telescope H Ii Region Discovery Survey. Ii. The Source Catalog

The Green Bank Telescope H Ii Region Discovery Survey. Ii. The Source Catalog

Recombination Lines near 8·9 GHz of Strong Sources in the Southern Milky Way

Recombination Lines 158a and 198ß in Nine Southern Nebulae

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