Related papers: On the O II ground configuration energy levels
This chapter presents a review on the latest advances in the computation of physical conditions and chemical abundances of elements present in photoionized gas H II regions and planetary nebulae). The arrival of highly sensitive…
Many energy levels of singly ionised iron (Fe II, $Z=26$) remain uncertain or experimentally unknown. Their identification and spectral line data are required in reliable astrophysical spectral analyses. In motivation for improving the…
We present the result of calculations to optimize the search for molecular oxygen (O2) in Earth analogs transiting around nearby, low-mass stars using ground-based, high-resolution, Doppler shift techniques. We investigate a series of…
Ultraviolet and visible spectra of the symbiotic nova RR Telescopii are used to derive reference wavelengths for many forbidden and intercombination transitions of ions +1 to +6 of elements C, N, O, Ne, Na, Mg, Al, Si, P, S, Cl, Ar, K and…
A recently generated theoretical line list of C II dielectronic recombination lines together with observational data gathered from the literature is used to investigate the electron temperature in a range of astronomical objects, mainly…
The current report presents the work to investigate the recombination lines of CII in the spectra of planetary nebulae. Two CIII targets were prepared and used to generate theoretical data required in the investigation of recombination…
In this paper we present fully reduced and dereddened emission line strengths for a sample of 45 southern Type II planetary nebulae (PNe). The spectrophotometry for these PNe covers an extended optical/near-IR range from 3600 - 9600…
We present an analysis of physical conditions in planetary nebulae (PNe) in terms of collisionally-excited line (CEL) and optical-recombination line (ORL) profiles. We aim to investigate whether line profiles could be used to study the…
In this paper we present an analysis of the physical and chemical conditions of the planetary nebula NGC 40 through spatially-resolved spectroscopic maps. We also introduce a new algorithm --2D_NEB-- based on the well-established IRAF…
Diagnostic diagrams of electron density - excitation for a sample of 613 planetary nebulae are presented. The present extensive sample allows the definition of new statistical limits for the distribution of planetary nebulae in the log…
We present high signal-to-noise spectrophotometric observations of seven luminous HII galaxies. The observations have been made with the use of a double-arm spectrograph which provides spectra with a wide wavelength coverage, from 3400 to…
Using the multiconfiguration Dirac-Hartree-Fock and the relativistic configuration interaction methods, a consistent set of transition energies and radiative transition data for the main states of the $2s^2 2p^4$, $2s 2p^5$, $2p^6$, $2s^2…
We study the oxygen abundance in five H II regions and seven planetary nebulae (PNe) located within 2 kpc from the Sun that have available spectra of high quality. Our analysis uses a similar procedure and the same atomic data to derive…
We carry out plasma diagnostic analyses for 123 planetary nebulae (PNe) and 42 H II regions using the N II and O II optical recombination lines (ORLs). New effective recombination coefficients for the N II and O II optical recombination…
We present new observations of O II recombination lines in ten bright planetary nebulae, along with spatially-resolved measurements of O II and [O III] in the Ring nebula NGC 6720, to study the discrepancy between abundances derived from O…
We present an atlas of three-dimensional (position-position-velocity) spectra of the Orion Nebula in optical emission lines from a variety of different ionization stages: [O I] 6300, [S II] 6716,6731, [N II] 6584, [S III] 6312, H alpha…
Since the last IAU symposium on planetary nebulae (PNe), several deep spectroscopic surveys of the relatively faint optical recombination lines (ORLs) emitted by heavy element ions in PNe and H II regions have been completed. New diagnostic…
This paper is the third in a series reporting on a study of carbon abundances in a carefully chosen sample of planetary nebulae representing a large range in progenitor mass and metallicity. We make use of the IUE Final Archive database…
Environmental research aimed at monitoring and predicting O2 depletion is still lacking or in need of improvement, in spite of many attempts to find a relation between atmospheric gas content and climate variability. The aim of the present…
The ground state energy per particle of a dilute, homogeneous, two-dimensional Bose gas, in the thermodynamic limit is shown rigorously to be $E_0/N = (2\pi \hbar^2\rho /m){|\ln (\rho a^2)|^{-1}}$, to leading order, with a relative error at…