scholarly journals Variability of the Emission-Line Spectrum of the Nucleus of the Seyfert Galaxy NGC 7469

1975 ◽  
Vol 67 ◽  
pp. 605-609
Author(s):  
I. I. Pronik
Keyword(s):  
Emission Line ◽  
Seyfert Galaxy ◽  
Emission Lines ◽  
Time Variability ◽  
Variable Time ◽  
Balmer Lines ◽  
Hα Emission ◽  
Emission Line Spectrum ◽  
Hydrogen Lines ◽  
Ngc 7469

It is shown that the emission lines of the NGC 7469 nucleus spectrum are variable. Time variability of hydrogen lines is less than 20 days. The Hα emission line is at the profile base about a factor of two narrower than the Hγ line. Estimation of the density of hydrogen envelope, where Balmer lines wings were emitted, gives the value of about 108–109 cm−3.

scholarly journals Variability of the Emission Line Spectrum of the Nucleus of Seyfert Galaxy NGC 1275

1974 ◽  
Vol 58 ◽  
pp. 341-345
Author(s):  
I. Pronik
Keyword(s):  
Emission Line ◽  
Seyfert Galaxy ◽  
Emission Lines ◽  
Line Spectrum ◽  
Spectroscopic Observations ◽  
Emission Line Spectrum ◽  
Ngc 1275

Recent spectroscopic observations of the nucleus of NGC 1275, together with results from earlier workers, confirm the variability of the emission lines and indicate corresponding variations in the electron temperatures and densities of different zones. These changes may be associated with the microwave outbursts from this source.

scholarly journals Spectral Line Variations of Symbiotic Stars EG And, AG Dra, and BX Mon and Its Interpretation

2012 ◽  
Vol 8 (S290) ◽  
pp. 353-354
Author(s):  
Tae Seog Yoon ◽  
Soo Hyun Kim ◽  
Hyeonwoo Moon ◽  
Kyu-Seob Kim ◽  
Hyungil Oh
Keyword(s):  
High Resolution ◽  
Spectral Line ◽  
Emission Line ◽  
Emission Lines ◽  
Symbiotic Stars ◽  
Astronomy Observatory ◽  
Echelle Spectrograph ◽  
Balmer Lines ◽  
Hα Emission ◽  
Optical Astronomy

AbstractWe present some results obtained by high resolution spectroscopic observations for symbiotic stars EG And, AG Dra, and BX Mon in recent years which were performed with 1.8-m reflector and echelle spectrograph BOES at Bohyunsan Optical Astronomy Observatory, Youngcheon, South Korea. The variations of Hα emission line during a night and the variations of H Balmer lines and He I emission lines among several analyzed lines over months and years are shown and discussed.

scholarly journals Hour-timescale profile variations in the broad Balmer lines of the Seyfert galaxy Hour-timescale profile variations in the broad Balmer lines of the Seyfert galaxy Markarian 6

2013 ◽  
Vol 9 (S304) ◽  
pp. 407-408
Author(s):  
Norayr S. Asatrian
Keyword(s):  
Fine Structure ◽  
Emission Line ◽  
Sampling Rate ◽  
Seyfert Galaxy ◽  
Special Astrophysical Observatory ◽  
Balmer Line ◽  
Line Profiles ◽  
Balmer Lines ◽  
Profile Changes ◽  
Hydrogen Emission Line

AbstractPart of results of the multi-epoch intranight optical spectroscopic monitoring of the Markarian 6 nucleus carried out at the telescopes of 6-m of the Special Astrophysical Observatory (Russia), 2.6-m of the Byurakan Astrophysical Observatory (Armenia) and 2-m of the Tautenburg Observatory (Germany) is presented.Observations were made in 1979, 1986, 1988-1991 and 2007-2009 during a total of 33 nights with an average sampling rate of 4 spectra per night. TV-scanner and long-slit spectrographs equipped with Image Tube and CCD detector arrays were used. Altogether we analyzed 110 Hβ and 58 Hα region spectra to search for intranight variability in the broad hydrogen emission line profiles. The typical spectral resolutions were 4 Å for scanner spectra, 6 Å for photographic spectra, and 5 Å and 10 Å for CCD spectra. The S/N ratio at the continuum level near the Hβ and Hα lines was in the range 15–50.The purpose of the search was to look for the characteristic variability signatures of different kinematical models of the broad emission-line region. We considered the centering and guiding errors which can result in differences between spectra.We found variations in the broad Balmer line difference profiles on time scale of hour with the level of significance of 3.6 σ to 5.0 σ. Variations take the form of narrow, small bumps located at the blue and red sides or only at the blue side of the lines. In the intermediate level of broad line flux, the Hβ and Hα profiles show fine structure. Detected profile changes occurred at the same radial velocity shifts as the details in the fine structure.The variability is at least 2 orders of magnitude more rapid than any observed for broad Balmer line profiles in AGNs that we are aware of in the literature.Discovered extremely rapid line-profile variability may be associated with reverberation effects. Two-sided profile changes may indicate the response of circularly rotating hydrogen clouds in the BLR to a light pulse from a central source. One-sided profile variations may be attributed to a response of a non-disk component: the subarcsec scale region of the jet.

scholarly journals The Timescales of Variations in Continuum and Hydrogen Lines During Stellar Flares

1983 ◽  
Vol 71 ◽  
pp. 239-243
Author(s):  
B.R. Pettersen
Keyword(s):  
Emission Line ◽  
Narrow Band ◽  
Light Curves ◽  
Emission Lines ◽  
Continuum Radiation ◽  
Stellar Flares ◽  
Hydrogen Lines ◽  
The Continuum

AbstractLight curves of major stellar flares have been used to study the behavior of U-B, B-V, and V-R. The majority of the flux transmitted through these filters is continuum radiation, but U and B are affected by emission lines. The variability of Ha and H$ emission lines were monitored through narrow band filters. The timescales of emission line variability are considerably longer than those for the continuum, and the emission line flare peak occurs a few minutes after the continuum flare maximum. No variability in lines at a timescale of seconds is detected in our data.

The behaviour of the hα emission line in the spectrum of Seyfert galaxy NGC4151 from 1976–1999

2001 ◽  
Vol 20 (2) ◽  
pp. 337-338 ◽  
Author(s):  
E. K. Denissyuk ◽  
R. R. Valiullin ◽  
R. W. Argyle ◽  
V. N. Gaisina ◽  
O. Karpova
Keyword(s):  
Emission Line ◽  
Seyfert Galaxy ◽  
Hα Emission

scholarly journals New Spectroscopic Observations of Dwarf Nova BZ Ursae Majoris with Extremely Unusual Emission Lines Profiles

2004 ◽  
Vol 194 ◽  
pp. 269-269 ◽  
Author(s):  
V. V. Neustroev ◽  
S. V. Zharikov ◽  
A. Medvedev ◽  
A. Shearer
Keyword(s):  
Radial Velocity ◽  
Emission Line ◽  
Velocity Curve ◽  
Emission Lines ◽  
Radial Velocity Curve ◽  
Dwarf Nova ◽  
Preliminary Results ◽  
Spectroscopic Observations ◽  
Medium Resolution ◽  
Hα Emission

We present preliminary results of new spectroscopic observations of dwarf nova BZ UMa in quiescence. Fifty medium resolution spectra allow us to reproduce the radial velocity curve from the Hα emission line. We confirm that BZ UMa shows extremely unusual emission lines profiles, Unlike the classical single or the double-peaked profiles usually observed in spectra of dwarf novae, emission lines of BZ UMa consist of at least five peaks.

scholarly journals Wolf-Rayet Phenomena

1982 ◽  
Vol 99 ◽  
pp. 3-22
Author(s):  
P. S. Conti
Keyword(s):  
Continuous Spectrum ◽  
Emission Lines ◽  
List Type ◽  
Type Number ◽  
Balmer Series ◽  
Intrinsic Absorption ◽  
Wide Range ◽  
Emission Line Spectrum ◽  
Hydrogen Lines ◽  
Future Work

I have been asked to review in broad terms the concept of Wolf-Rayet (W-R) phenomena, that is, to outline what we currently know about the properties of stars showing such phenomena and to indicate the directions in which future work is leading. I thought I would begin by listing the characteristics of W-R spectra to which probably all the participants at this Symposium will be able to agree. These can readily be adapted from Thomas (1968) who discussed them at the Boulder W-R Symposium. The characteristics of W-R spectra are as follows: (1)They are primarily an emission line spectrum superimposed on a “hot” continuous spectrum.(2)P Cygni absorption components are observed for some lines in some stars; a fact not realized in 1968 was that a very few W-R stars have intrinsic absorption lines (e.g. The Balmer series in HD 92740 — Niemela (1973).(3)The emission lines represent a wide range of excitation and ionization. This level is often higher than indicated by simple modeling of the continuous spectrum.(4)The emission lines are broad, corresponding to widths of hundreds to thousands of kilometers per second; widths often differ among various ions in the same star.(5)The W-R stars can be divided into two subtypes: These are the WN types, in which the ions of nitrogen dominate, and the WC types, in which the ions of carbon (and oxygen) dominate. Both sub-types have strong lines of helium; in a few cases, hydrogen lines, in emission, are also observed (Underbill 1968).

scholarly journals Preliminary Analysis of the Broad He I Emission Lines in R CrB

1985 ◽  
Vol 87 ◽  
pp. 199-202
Author(s):  
R. Surendiranath ◽  
K.E. Rangarajan ◽  
N. Kameswara Rao
Keyword(s):  
Emission Line ◽  
Preliminary Analysis ◽  
Emission Lines ◽  
Minimum Phase ◽  
Physical Conditions ◽  
Light Minimum ◽  
Broad Emission ◽  
Emission Line Spectrum ◽  
Intensity Ratios ◽  
Broad Emission Line

Abstract:During light minimum phase, R CrB shows a broad emission line spectrum of He I including λ10830, λ7065, λ7281, λ3889, λ6678 and λ3188. But λ5876 is very weak. The observed intensity ratios of I(λ3889)/I(λ5876) and I(λ7065)/I(λ5876) were greater than 1. The anomalous intensities of these lines appear to be due to optical depth efects. Peliminary analysis is presented to derive the physical conditions of the emitting gas.

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