Theoretical Line Intensities. I. Strong Emission Lines.

1965 ◽  
Vol 142 ◽  
pp. 724 ◽  
Author(s):  
R. Grant Athay
Keyword(s):  
Emission Lines ◽  
Strong Emission ◽  
Line Intensities ◽  
Theoretical Line

scholarly journals IUE Spectra of The by Dra/Flare Star AU Mic

1983 ◽  
Vol 71 ◽  
pp. 249-250
Author(s):  
C.J. Butler ◽  
A.D. Andrews ◽  
J.G. Doyle ◽  
P.B. Byrne ◽  
J.L. Linsky ◽  
...  
Keyword(s):  
Light Curve ◽  
Emission Line ◽  
Flare Star ◽  
Emission Lines ◽  
Spectral Variation ◽  
Strong Emission ◽  
Line Intensities ◽  
The Mean ◽  
Phase Interval

A coordinated series of ground-based optical and IUE observations of BY Dra variables was undertaken to follow the spectral variation of these stars over one cycle. In the first series 20 LWR and 19 SWP trailed spectra were taken of AU Mic over a three day period 4-6 August 1980 .In Figure 1 we show the mean integrated fluxes for the strong emission lines in the SWP spectra of AU Mic over the observed phase interval of 0.14 to 0.8 together with an approximate V light curve determined by the FES on IUE. From comparison of the emission line intensities and FES magnitudes in Figure 1 several points emerge.

EXCITATION CONDITIONS IN THE UPPER ATMOSPHERE AS DETERMINED FROM A STUDY OF ATOMIC EMISSION LINES IN THE AURORAL SPECTRUM

1947 ◽  
Vol 25a (5) ◽  
pp. 293-301 ◽  
Author(s):  
William Petrie
Keyword(s):  
Oxygen Atom ◽  
Atomic Emission ◽  
Upper Atmosphere ◽  
Emission Lines ◽  
Excitation Temperature ◽  
Auroral Region ◽  
Line Intensities ◽  
Theoretical Line ◽  
Measured Line ◽  
Excitation Conditions

Vegard's identifications of a number of lines appearing in the auroral spectrum are discussed. The conclusion is reached that a good many of these lines may be attributed to the oxygen atom in several stages of ionization. It is shown how measured line intensities and theoretical line strengths are combined to give the excitation temperature of the auroral region. Preliminary results indicate that this temperature is in the range 3000° to 6000° K. The meaning of this result is discussed briefly.

scholarly journals Long-Slit Spectroscopy of IC 5135 and NGC 4388

1989 ◽  
Vol 134 ◽  
pp. 480-481
Author(s):  
Joseph C. Shields ◽  
Alexei V. Filippenko
Keyword(s):  
Stellar Population ◽  
Emission Lines ◽  
H Ii Regions ◽  
Strong Emission ◽  
Narrow Component ◽  
Line Intensities ◽  
Relative Line ◽  
Two Component ◽  
The Galaxy ◽  
Emission Line Profile

The nucleus of the peculiar Sa galaxy IC 5135 has strong emission lines whose relative intensities resemble those of Seyfert 2 galaxies (Phillips, Charles, and Baldwin 1983). However, the galaxy exhibits relative line intensities such as [O III] λ5007/Hβ = 6.5 and He II λ4686/Hβ = 0.17 that are considerably smaller than typical Seyfert 2 values of 11 and 0.3, respectively (Koski 1978). New, high-resolution spectra (FWHM ≈ 2Å) obtained at Las Campanas Observatory reveal that the Hβ emission-line profile actually consists of a relatively strong, narrow component (FWHM ≈ 250 km s−1) superposed on a much weaker, broad base (FWHM ≈ 1000 km s−1; Fig. 1). A similar two-component profile is evident in [O I] λ6300, whose narrow core probably comes from circumnuclear H II regions that produce little [O III] and He II emission. The strong, high-order Balmer absorption lines are consistent with the presence of a young stellar population in the nucleus.

scholarly journals The SAMI Galaxy Survey: reconciling strong emission line metallicity diagnostics using metallicity gradients

2021 ◽  
Vol 502 (3) ◽  
pp. 3357-3373
Author(s):  
Henry Poetrodjojo ◽  
Brent Groves ◽  
Lisa J Kewley ◽  
Sarah M Sweet ◽  
Sebastian F Sanchez ◽  
...  
Keyword(s):  
Emission Line ◽  
Electron Temperature ◽  
Gas Phase ◽  
Mass Range ◽  
Accurate Method ◽  
Emission Lines ◽  
Mass Relation ◽  
Strong Emission ◽  
Data Release ◽  
Accurate Comparison

ABSTRACT We measure the gas-phase metallicity gradients of 248 galaxies selected from Data Release 2 of the SAMI Galaxy Survey. We demonstrate that there are large systematic discrepancies between the metallicity gradients derived using common strong emission line metallicity diagnostics. We determine which pairs of diagnostics have Spearman’s rank coefficients greater than 0.6 and provide linear conversions to allow the accurate comparison of metallicity gradients derived using different strong emission line diagnostics. For galaxies within the mass range 8.5 < log (M/M⊙) < 11.0, we find discrepancies of up to 0.11 dex/Re between seven popular diagnostics in the metallicity gradient–mass relation. We find a suggestion of a break in the metallicity gradient–mass relation, where the slope shifts from negative to positive, occurs between 9.5 < log (M/M⊙) < 10.5 for the seven chosen diagnostics. Applying our conversions to the metallicity gradient–mass relation, we reduce the maximum dispersion from 0.11 dex/Re to 0.02 dex/Re. These conversions provide the most accurate method of converting metallicity gradients when key emission lines are unavailable. We find that diagnostics that share common sets of emission line ratios agree best, and that diagnostics calibrated through the electron temperature provide more consistent results compared to those calibrated through photoionization models.

Dissecting quasars with the J-PAS narrow-band photometric survey

2019 ◽  
Vol 15 (S356) ◽  
pp. 12-16
Author(s):  
Silvia Bonoli ◽  
Giorgio Calderone ◽  
Raul Abramo ◽  
Jailson Alcaniz ◽  
Narciso Benitez ◽  
...  
Keyword(s):  
Emission Line ◽  
Wavelength Range ◽  
Software Package ◽  
Narrow Band ◽  
Active Galaxies ◽  
Emission Lines ◽  
Low Resolution ◽  
Strong Emission ◽  
Optical Wavelength ◽  
Quasar Spectra

AbstractThe J-PAS survey will soon start observing thousands of square degrees of the Northern Sky with its unique set of 56 narrow band filters covering the entire optical wavelength range, providing, effectively, a low resolution spectra for every object detected. Active galaxies and quasars, thanks to their strong emission lines, can be easily identified and characterized with J-PAS data. A variety of studies can be performed, from IFU-like analysis of local AGN, to clustering of high-z quasars. We also expect to be able to extract intrinsic physical quasar properties from the J-PAS pseudo-spectra, including continuum slope and emission line luminosities. Here we show the first attempts of using the QSFit software package to derive the properties for 22 quasars at 0.8 < z < 2 observed by the miniJPAS survey, the first deg2 of J-PAS data obtained with an interim camera. Results are compared with the ones obtained by applying the same software to SDSS quasar spectra.

scholarly journals Twenty years of observations of PM 1-188: Its chemical abundances and extraordinary kinematics

2021 ◽  
Author(s):  
Miriam Peña ◽  
Liliana Hernández-Martínez ◽  
Francisco Ruiz-Escobedo
Keyword(s):  
Chemical Composition ◽  
Planetary Nebula ◽  
Central Star ◽  
Emission Lines ◽  
Type I ◽  
Chemical Abundances ◽  
Line Intensities ◽  
Physical Conditions ◽  
The Past ◽  
Spectrophotometric Data

Abstract The analysis of 20 years of spectrophotometric data of the double shell planetary nebula PM 1-188 is presented, aiming to determine the time evolution of the emission lines and the physical conditions of the nebula, as a consequence of the systematic fading of its [WC 10] central star whose brightness has declined by about 10 mag in the past 40 years. Our main results include that the [O iii], [O ii], [N ii] line intensities are increasing with time in the inner nebula as a consequence of an increase in electron temperature from 11 000 K in 2005 to more than 14 000 K in 2018, due to shocks. The intensity of the same lines are decreasing in the outer nebula, due to a decrease in temperature, from 13 000 K to 7000 K, in the same period. The chemical composition of the inner and outer shells was derived and they are similar. Both nebulae present subsolar O, S and Ar abundances, while they are He, N and Ne rich. For the outer nebula the values are 12+log He/H = 11.13 ± 0.05, 12+log O/H = 8.04 ± 0.04, 12+log N/H = 7.87 ± 0.06, 12+log S/H = 7.18 ± 0.10 and 12+log Ar = 5.33 ± 0.16. The O, S and Ar abundances are several times lower than the average values found in disc non-Type I PNe, and are reminiscent of some halo PNe. From high resolution spectra, an outflow in the N-S direction was found in the inner zone. Position-velocity diagrams show that the outflow expands at velocities in the −150 to 100 km s−1 range, and both shells have expansion velocities of about 40 km s−1.

scholarly journals Density Diagnostics of Solar Emission Lines from the Nitrogen-like Mg VI Ion

1990 ◽  
Vol 142 ◽  
pp. 443-444
Author(s):  
P.K. Raju ◽  
R. Vasundhara
Keyword(s):  
Electron Density ◽  
Line Intensity ◽  
Emission Lines ◽  
Solar Plasma ◽  
Theoretical Line ◽  
Intensity Ratios ◽  
Density Diagnostics

The variation of theoretical line intensity ratios with electron density for Mg VI ion are presented. This study indicates that the line intensity ratios for Mg VI can be used to infer electron density for solar plasma.

scholarly journals The Statistical Equilibrium of H and He and the H/He Ratio in WR Stars

1984 ◽  
Vol 86 ◽  
pp. 88-91
Author(s):  
A.B. Underhill ◽  
A.K. Bhatia
Keyword(s):  
Electron Temperature ◽  
Statistical Equilibrium ◽  
Emission Lines ◽  
General Distribution ◽  
Strong Emission ◽  
B Stars ◽  
Effective Temperatures ◽  
The Masses ◽  
Selection Of ◽  
Made In

The mixed selection of strong emission lines present in the spectra of WR stars suggests that we are observing plasma with an electron temperature of the order of 105 K somewhere in the atmospheres of these rare stars. In the spectra of some WR stars emission lines of H are detected; this suggests that plasma with an electron temperature of the order of 104 K may be present also. Since the observations made in the last 30 years show that the masses, luminosities, effective temperatures, and general distribution in space of WR stars are similar to those of stars with spectral types in the range from about B2 to O9, a prime question is why are the spectra of WR stars so different from those of the B stars with which they are associated.

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