scholarly journals Helium Emission Lines in the Type I[CLC]c[/CLC] Supernova 1999[CLC]cq[/CLC]

2000 ◽  
Vol 119 (5) ◽  
pp. 2303-2310 ◽  
Author(s):  
Thomas Matheson ◽  
Alexei V. Filippenko ◽  
Ryan Chornock ◽  
Douglas C. Leonard ◽  
Weidong Li
Keyword(s):  
Emission Lines ◽  
Type I ◽  
Helium Emission

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 Infrared helium emission lines from Cygnus X-3 suggesting a Wolf-Rayet star companion

Nature ◽  
1992 ◽  
Vol 355 (6362) ◽  
pp. 703-705 ◽  
Author(s):  
M. H. van Kerkwijk ◽  
P. A. Charles ◽  
T. R. Geballe ◽  
D. L. King ◽  
G. K. Miley ◽  
...  
Keyword(s):  
Emission Lines ◽  
Rayet Star ◽  
Helium Emission

scholarly journals The polarized signal from broad emission lines in AGNs

2019 ◽  
Vol 491 (1) ◽  
pp. 1-12 ◽  
Author(s):  
P Lira ◽  
R W Goosmann ◽  
M Kishimoto ◽  
R Cartier
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Position Angle ◽  
Emission Lines ◽  
Type I ◽  
Line Profiles ◽  
Scattering Media ◽  
Broad Emission ◽  
Line Region ◽  
Scattering Signal

ABSTRACT Using the stokes Monte Carlo radiative transfer code, we revisit the predictions of the spectropolarimetric signal from a disc-like broad emission line region (BLR) in type I active galactic nuclei due to equatorial scattering. We reproduce the findings of previous works, but only for a scatterer that is much more optically and geometrically thick than previously proposed. We also find that when taking into account the polarized emission from all regions of the scatterer, the swing of the polarization position angle (PA) is in the opposite direction to that originally proposed. Furthermore, we find that the presence of outflows in the scattering media can significantly change the observed line profiles, with the PA of the scattering signal being enhanced in the presence of radially outflowing winds. Finally, a characteristically different PA profile, shaped like an ‘M’, is seen when the scatterer is co-spatial with the BLR and radially outflowing.

scholarly journals The strength of the low-ionization emission lines in Type I PNe

1997 ◽  
Vol 180 ◽  
pp. 273-273
Author(s):  
A. Riera
Keyword(s):  
Statistical Analysis ◽  
Emission Line ◽  
Emission Lines ◽  
Optical Data ◽  
Type I

I have performed a statistical analysis on a group of emission line ratios of a sample of PNe. The optical data was taken from ELCAT2 Catalogue (http://www.stsci.edu/pub/elcat). Some observations of H–H objects were also included for comparison.

scholarly journals New Models for Massive Star Populations in Young Starbursts: Summary of the Models and Applications

1999 ◽  
Vol 186 ◽  
pp. 285-285
Author(s):  
Daniel Schaerer ◽  
William D. Vacca
Keyword(s):  
Emission Line ◽  
Stellar Evolution ◽  
Massive Star ◽  
Optical Emission ◽  
Emission Lines ◽  
Evolutionary Synthesis ◽  
Stellar Spectra ◽  
New Models ◽  
Helium Emission ◽  
Line Strengths

Using the latest stellar evolution models, theoretical stellar spectra, and a compilation of observed emission line strengths from Wolf-Rayet (WR) stars, we have constructed evolutionary synthesis models for young starbursts (Schaerer & Vacca 1997; see also Schaerer 1996). We provide detailed predictions of UV and optical emission line strengths for both the WR stellar lines and the major nebular hydrogen and helium emission lines, as a function of several input parameters related to the starburst episode.

scholarly journals New Chandra/HST-STIS Results on Seyfert I AGN: Photoionized Outflows

2003 ◽  
Vol 214 ◽  
pp. 259-264
Author(s):  
Barry McKernan ◽  
Tahir Yaqoob
Keyword(s):  
High Resolution ◽  
Column Density ◽  
Emission Lines ◽  
High Resolution Spectroscopy ◽  
Type I ◽  
Ionization State ◽  
X Ray ◽  
Spectral Signatures

We present soft X-ray results from observations with Chandra (HETGS) of the Seyfert I AGN NGC 4593 and Mrk 509. We discuss the photoionized outflows associated with Seyfert I AGN in terms of their absorption spectral signatures and discuss their kinematics, column density and ionization state. We discuss the link between UV and X-ray absorbers in Mrk 509 (which was simultaneously observed with Chandra and HST-STIS). We also briefly discuss the possibility of absorption due to neutral Fe embedded in the warm absorber of NGC 4593 versus an interpretation of the data in terms of soft X-ray relativistic emission lines. We conclude with a summary of what is being learnt about warm absorbers in type I AGN from high resolution spectroscopy.

scholarly journals Host galaxy properties of changing-look AGNs revealed in the MaNGA survey

2020 ◽  
Vol 498 (3) ◽  
pp. 3985-3994
Author(s):  
Xiaoling Yu ◽  
Yong Shi ◽  
Yanmei Chen ◽  
Jianhang Chen ◽  
Songlin Li ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Main Sequence ◽  
Galactic Nuclei ◽  
Axial Ratio ◽  
Emission Lines ◽  
Host Galaxy ◽  
Type I ◽  
Host Galaxies ◽  
Star Forming ◽  
Nearby Galaxies

ABSTRACT Changing-look active galactic nuclei (CL-AGNs) are a subset of AGNs in which the broad Balmer emission lines appear or disappear within a few years. We use the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey to identify five CL-AGNs. The 2D photometric and kinematic maps reveal common features as well as some unusual properties of CL-AGN hosts as compared to the AGN hosts in general. All MaNGA CL-AGNs reside in the star-forming main sequence, similar to MaNGA non-changing-look AGNs (NCL-AGNs). The $80 \pm 16{{\ \rm per\ cent}}$ of our CL-AGNs do possess pseudo-bulge features, and follow the overall NCL-AGN MBH–σ* relationship. The kinematic measurements indicate that they have similar distributions in the plane of angular momentum versus galaxy ellipticity. MaNGA CL-AGNs, however, show a higher, but not statistically significant ($20 \pm 16{{\ \rm per\ cent}}$) fraction of counter-rotating features compared to that ($1.84 \pm 0.61{{\ \rm per\ cent}}$) in general star formation population. In addition, MaNGA CL-AGNs favour more face-on (axial ratio > 0.7) than that of type I NCL-AGNs. These results suggest that host galaxies could play a role in the CL-AGN phenomenon.

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