Wing profile measurements of the resonance emission lines of Na (5890/96Å) and Sr (4607Å) in flames

The preliminary results of a joint study of this symbiotic star with 6 Italian astronomers are reported. The relative intensities of the intercombination emission lines indicate electron densities of 1010 and an upper limit to the dilution factor between 10−4 and 10−6. The resonance emission lines give a maximum thickness in the line of sight. A hot (T between 19000° and 26000°) continuum is interpreted as coming from a hot subdwarf, but the high excitation emission lines appear to be formed near the cool giant component of what is probably a close binary.

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Effects of Eccentric Orbit of BF Cygni on IUE and Optical Spectra

International Astronomical Union Colloquium ◽

10.1017/s0252921100103719 ◽

1988 ◽

Vol 103 ◽

pp. 299-300

Author(s):

J. Mikolajewska ◽

M. Mikolajewski

Keyword(s):

Emission Measure ◽

Line Emission ◽

Optical Spectra ◽

Emission Lines ◽

Recent Analysis ◽

Emission Region ◽

Galactic Rotation ◽

Resonance Emission ◽

High Ionization ◽

Cosmic Abundance

A recent analysis of all available photometric data has resulted in a new ephemeris for BF Cyg: MIN=JD 2415058 + 756.8E. Simultaneously, optical spectra collected in 1979–1986 showed periodic changes of all emission lines (Mikolajewska 1987; Mikolajewska & lijima 1987). It is interesting that the forbidden lines of [OIII] varied in antiphase to the permitted emission lines and optical brightness.IUE spectra taken in 1979–1981 showed a strong hot continuum and high ionization resonance emission lines of NV, SilV CIV, intercombination lines of NIV], NIII], SiIII], CIII] and OIII] as well as Hell emission. The observed λ2200Å interstellar absorption band suggests E(B-V)≃0.3. Taking into account the interstellar reddening distribution in the vicinity of BF Cyg (Lucke 1978; Mikolajewska & Mikolajewski 1980), the observed extinction implies a distance d≲1.5kpc. This distance is in good agreement with the observed low value of the systemic radial velocity (∼15 km/s, Fig.1) of BF Cyg and the standard galactic rotation law. The standard extinction curve with E(B-V)=0.3 (Seaton 1979) was used for reddening correction of the spectra. The UV continuum of BF Cyg can be interpreted as a combination of a hot subdwarf (Teff≃60000K, L≃2500L⊙ for d=1.5kpc) and hydrogen bf+ff emission (Te≃10000K). The emission measure of the nebular (bf+ff) continuum varied from ∼4×1059cm−3 at maximum to ∼1059cm−3 at minimum. Assuming cosmic abundance of Si/C the observed SiIII]/CIII] line ratio implies ne≃2×l010cm−3 at the photometric maximum and ne≃3×109cm−3 at the minimum. We assume that these values are representative of the region where the bulk of the HI Balmer and intercombination line emission is produced. The ratio of NV(1240)/NIV(1720) gives Te(NV)≃11500K close to the value derived for the Balmer emission region from the UV continuum fit.

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Kernresonanz-Emissionslinien während rascher Radikalreaktionen

Zeitschrift für Naturforschung A ◽

10.1515/zna-1967-1015 ◽

1967 ◽

Vol 22 (10) ◽

pp. 1556-1562 ◽

Cited By ~ 61

Author(s):

J. Bargon ◽

H. Fischer

Keyword(s):

Nuclear Magnetic Resonance ◽

Dynamic Nuclear Polarization ◽

Nuclear Polarization ◽

Emission Lines ◽

Radical Reactions ◽

Dynamic Coupling ◽

Correct Order ◽

Chemically Induced ◽

Resonance Emission ◽

Order Of Magnitude

Previously observed nuclear magnetic resonance emission lines of products of rapid radical reactions are explained by chemically induced dynamic nuclear polarization. This polarization occurs after the production of radicals by the dynamic coupling between radical electrons and protons, and it is transfered to the products by the secondary reaction. A theoretical analysis shows that this concept leads to a correct order of magnitude calculation of the intensity of emission. New experiments are described the results of which support the explanation. It is concluded that chemically induced dynamic nuclear polarization is not restricted to the systems treated so far but may occur in other investigations also.

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Dust Formation and the Doubly-Periodic Variable Stars

International Astronomical Union Colloquium ◽

10.1017/s0252921100036976 ◽

1995 ◽

Vol 155 ◽

pp. 196-197

Author(s):

T. Lloyd Evans

Keyword(s):

Dust Cloud ◽

Variable Stars ◽

Emission Lines ◽

Circumstellar Dust ◽

Dust Formation ◽

Circumstellar Envelope ◽

Pulsation Period ◽

Deep Minimum ◽

Resonance Emission ◽

Semiregular Variable

AbstractThe doubly-periodic semiregular variable V Hydrae became redder and developed resonance emission lines and bands during the 1992-94 deep minimum, which therefore resulted from the production of a circumstellar dust cloud. This removes the need to postulate a secondary pulsation period, ten times as long as the main pulsation period, in the stellar as opposed to circumstellar envelope.

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Long-term Cyclic Variations of Prominences, Green and Red Coronae over Solar Cycles

International Astronomical Union Colloquium ◽

10.1017/s0252921100064496 ◽

2000 ◽

Vol 179 ◽

pp. 201-204

Author(s):

Vojtech Rušin ◽

Milan Minarovjech ◽

Milan Rybanský

Keyword(s):

Emission Lines ◽

High Latitudes ◽

Green Line ◽

Solar Cycles ◽

The South ◽

Coronal Emission ◽

Local Maxima ◽

The North ◽

Cyclic Variations

AbstractLong-term cyclic variations in the distribution of prominences and intensities of green (530.3 nm) and red (637.4 nm) coronal emission lines over solar cycles 18–23 are presented. Polar prominence branches will reach the poles at different epochs in cycle 23: the north branch at the beginning in 2002 and the south branch a year later (2003), respectively. The local maxima of intensities in the green line show both poleward- and equatorward-migrating branches. The poleward branches will reach the poles around cycle maxima like prominences, while the equatorward branches show a duration of 18 years and will end in cycle minima (2007). The red corona shows mostly equatorward branches. The possibility that these branches begin to develop at high latitudes in the preceding cycles cannot be excluded.

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Modeling of Hydrogen Emission Lines in the Spectrum of UX Ori in Its Bright State and during Eclipses

Astronomy Reports ◽

10.1134/s1063772920120148 ◽

2020 ◽

Vol 64 (12) ◽

pp. 1026-1041

Author(s):

L. V. Tambovtseva ◽

V. P. Grinin ◽

D. V. Dmitriev

Keyword(s):

Emission Lines ◽

Hydrogen Emission ◽

Hydrogen Emission Lines

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Line observations of the 30-Dor complex and N159A5 with the MPE imaging NIR spectrometer FAST

Symposium - International Astronomical Union ◽

10.1017/s0074180900200375 ◽

1991 ◽

Vol 148 ◽

pp. 205-206 ◽

Cited By ~ 1

Author(s):

A. Krabbe ◽

J. Storey ◽

V. Rotaciuc ◽

S. Drapatz ◽

R. Genzel

Keyword(s):

Spatial Resolution ◽

Molecular Hydrogen ◽

Near Infrared ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Emission Lines ◽

Resolving Power ◽

Max Planck ◽

First Time ◽

Infrared Array

Images with subarcsec spatial resolution in the light of near-infrared atomic (Bry) and molecular hydrogen H2 (S(1) v=1-0) emission lines were obtained for some extended, pointlike objects in the Large Magellanic Cloud (LMC) for the first time. We used the Max-Planck-Institut für extraterrestrische Physik (MPE) near-infrared array spectrometer FAST (image scale 0.8”/pix, spectral resolving power 950) at the ESO/MPI 2.2m telescope, La Silla. We present some results on the 30-Dor complex and N159A5.

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Gaia-assisted discovery of a detached low-ionisation BAL quasar with very large ejection velocities

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936957 ◽

2020 ◽

Vol 634 ◽

pp. A111 ◽

Cited By ~ 2

Author(s):

J. P. U. Fynbo ◽

P. Møller ◽

K. E. Heintz ◽

J. N. Burchett ◽

L. Christensen ◽

...

Keyword(s):

Emission Line ◽

Absorption Line ◽

Emission Lines ◽

Broad Absorption ◽

Broad Absorption Line ◽

Red Edge ◽

First Case ◽

Bl Lac ◽

Spatially Extended ◽

Extended Emission

We report on the discovery of a peculiar broad absorption line (BAL) quasar identified in our Gaia-assisted survey of red quasars. The systemic redshift of this quasar was difficult to establish because of the absence of conspicuous emission lines. Based on deep and broad BAL troughs of at least Si IV, C IV, and Al III, a redshift of z = 2.41 was established under the assumption that the systemic redshift can be inferred from the red edge of the BAL troughs. However, we observe a weak and spatially extended emission line at 4450 Å that is most likely due to Lyman-α emission, which implies a systemic redshift of z = 2.66 if correctly identified. There is also evidence for the onset of Lyman-α forest absorption bluewards of 4450 Å and evidence for Hα emission in the K band consistent with a systemic redshift of z = 2.66. If this redshift is correct, the quasar is an extreme example of a detached low-ionisation BAL quasar. The BALs must originate from material moving with very large velocities ranging from 22 000 km s−1 to 40 000 km s−1. To our knowledge, this is the first case of a systemic-redshift measurement based on extended Lyman-α emission for a BAL quasar. This method could also be useful in cases of sufficiently distant BL Lac quasars without systemic-redshift information.

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

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab205 ◽

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.

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