scholarly journals UV and optical spectroscopic observations of colliding winds in WR+O binaries

1995 ◽  
Vol 163 ◽  
pp. 388-396
Author(s):  
Nicole St-Louis
Keyword(s):  
Terminal Velocity ◽  
Emission Lines ◽  
Wind Effects ◽  
Strong Emission ◽  
Spectroscopic Evidence ◽  
Spectroscopic Observations ◽  
Colliding Winds ◽  
Optical Evidence

In this paper, a review of spectroscopic evidence for colliding wind effects in WR+O binaries is presented with a particular emphasis on variability at ultraviolet wavelengths. In the optical, evidence for colliding winds comes from extra emission formed in the region of shocked gas and superimposed on the strong emission lines formed in the WR wind. At ultraviolet wavelengths, we observe the consequences of the fact that between the two stars the winds are prevented from reaching their terminal velocity because of the wind-wind interaction.

scholarly journals Spectral variations of CI Cyg between 1980 and 1981

1982 ◽  
Vol 70 ◽  
pp. 151-152
Author(s):  
Huang Chang-Chun
Keyword(s):  
The Other ◽  
Emission Lines ◽  
Strong Emission ◽  
Spectroscopic Observations ◽  
Balmer Lines

In our paper (Ch. Fehrenbach and C.C. Huang, 1981) we have described the details of our spectroscopic observations of CI Cyg in 1980. In that year, the star showed a fair presence of bright forbidden lines of [FeV ]and very strong emission lines of high and low excitation, including forbidden [0 III ] , [Ne III], [Fe II ] and [S II] and permitted 0 III, N III as well as He I and Fe II … etc … The He II 4686 A was very strong. The Balmer lines were the strongest emission features in the spectrum and Hα and Hβ were double. There were two groups of velocities in 1980, one was positive for forbidden lines and the other was negative for the permitted lines. The displacements of Balmer lines showed a regression.

scholarly journals A review of the properties of the symbiotic star CH Cygni

1982 ◽  
Vol 70 ◽  
pp. 131-136
Author(s):  
M. Hack ◽  
P.L. Selvelli
Keyword(s):  
High Resolution ◽  
Normal Phase ◽  
Emission Lines ◽  
Symbiotic Star ◽  
Strong Emission ◽  
Spectroscopic Observations ◽  
Activity Phase ◽  
Balmer Lines

The spectrum of CH Cygni usually has the appearance of a normal M6 III star, but at intervals of several years, it has phases of activity during which it shows the characteristics of a symbiotic star, that is, a blue continuum extending shortward of the Balmer discontinuity, and strong emission lines of He I, Fe II, [Fe II] , [S II], [0 1] , [0 III]; the Balmer lines and the H and K lines of Ca II present emission wings. Outbursts were observed: 1) in September 1963; the star returned to its normal phase by August 1965 (Deutsch, 1964); 2) in June 1967 (Deutsch, 1967); the spectrum was observed by Faraggiana and Hack (1971) until December 1970, when the activity phase was over; 3) another outburst was observed in August 1977 (Morris, 1977; Fehrenbach, 1977), and at the time of our last spectroscopic observations (June 1981) it was still going on. During this last period of activity several observations were made with IUE in both the low and high resolution modes, from 1175 A to 3100 A.

Spectroscopic Observations of BF Cygni

1991 ◽  
Vol 9 (2) ◽  
pp. 293-294 ◽  
Author(s):  
C. C. Huang ◽  
L. Chen
Keyword(s):  
Emission Lines ◽  
Strong Emission ◽  
Spectroscopic Observations ◽  
Balmer Lines

AbstractSpectroscopic observations of BF Cygni performed at the Haute-Provence Observatory in 1981 August, October and November are presented. The spectrum of BF Cyg was dominated by strong emission lines of H I, He I, [O III] and [Ne III]. Emission lines of He II and N III were weak. The spectrum of the star displayed dramatic variations during our observations. The intensities of Balmer lines, Balmer continuum and He I lines clearly increased from August to October, while the lines of [Ne III] and [O III] showed inverse variability.

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 H2 Emission from External Galaxies

1992 ◽  
Vol 150 ◽  
pp. 103-107
Author(s):  
Kimiaki Kawara
Keyword(s):  
Uv Radiation ◽  
Supernova Remnants ◽  
Emission Lines ◽  
Hot Stars ◽  
Shock Excitation ◽  
X Ray ◽  
Spectroscopic Observations ◽  
Near Ir ◽  
Bare Nucleus ◽  
External Galaxies

2 μm spectroscopic observations by many authors have revealed significant rotation-vibrational H2 emission is widespread from starburst to bare nucleus galaxies. Near-IR H2 emission lines can arise from various excitation sources: UV radiation by hot stars, shock excitation by supernova remnants or AGN driven winds, and UV/X-ray radiation by an AGN. In this review recent data will be compared with such H2 excitation models.

scholarly journals Observation of Diffuse CII Emission in the Galactic Center Region

1989 ◽  
Vol 136 ◽  
pp. 145-149
Author(s):  
H. Okuda ◽  
H. Shibai ◽  
T. Nakagawa ◽  
T. Matsuhara ◽  
T. Maihara ◽  
...  
Keyword(s):  
Galactic Center ◽  
Line Emission ◽  
Wide Area ◽  
Strong Emission ◽  
Spectroscopic Observations ◽  
Center Region ◽  
Fabry Perot ◽  
Galactic Longitude

Spectroscopic observations of CII line emission at 157.7 μm have been made of the Galactic Center region with a Fabry-Perot spectrometer onboard a balloon telescope. Strong emission has been detected ubiquitously in a wide area extending between ± 0.7° in galactic longitude. A ring-like structure is suggested from the double lobed distribution of the emission around the Galactic Center.

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.

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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