On the fine structure of the Balmer lines

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.

Download Full-text

The Fine Structure of the Balmer Lines

Physical Review ◽

10.1103/physrev.45.263 ◽

1934 ◽

Vol 45 (4) ◽

pp. 263-272 ◽

Cited By ~ 33

Author(s):

W. V. Houston ◽

Y. M. Hsieh

Keyword(s):

Fine Structure ◽

Balmer Lines

Download Full-text

The Fine Structure and the Wave-Length of the Balmer Lines

The Astrophysical Journal ◽

10.1086/142989 ◽

1926 ◽

Vol 64 ◽

pp. 81 ◽

Cited By ~ 25

Author(s):

William V. Houston

Keyword(s):

Fine Structure ◽

Wave Length ◽

Balmer Lines

Download Full-text

Account of the fine structure of hydrogen atom levels in the effective emission cross sections of Balmer lines excited by electron impact in gases and plasma

Optics and Spectroscopy ◽

10.1134/1.1481126 ◽

2002 ◽

Vol 92 (5) ◽

pp. 647-657 ◽

Cited By ~ 25

Author(s):

B. P. Lavrov ◽

A. V. Pipa

Keyword(s):

Fine Structure ◽

Hydrogen Atom ◽

Electron Impact ◽

Cross Sections ◽

Balmer Lines

Download Full-text

Fine structure and spectral broadening of Balmer lines in laser-produced plasmas

Physical Review A ◽

10.1103/physreva.20.2574 ◽

1979 ◽

Vol 20 (6) ◽

pp. 2574-2581 ◽

Cited By ~ 12

Author(s):

P. Nicolosi ◽

G. Tondello ◽

E. Jannitti

Keyword(s):

Fine Structure ◽

Spectral Broadening ◽

Balmer Lines

Download Full-text

Experimental Study of the Stark Broadened Helium Ion Lines Hell 121.5, 164.0 and 468.6 nm

Zeitschrift für Naturforschung A ◽

10.1515/zna-1984-1105 ◽

1984 ◽

Vol 39 (11) ◽

pp. 1041-1048 ◽

Cited By ~ 5

Author(s):

A. Piel ◽

J. Slupek

Keyword(s):

Experimental Study ◽

Fine Structure ◽

High Purity ◽

Laser Interferometer ◽

Plasma Parameters ◽

Line Shapes ◽

Helium Ion ◽

Balmer Lines ◽

Theoretical Line ◽

Coupled Cavity

Using a pulsed linear discharge of high purity, Stark broadened profiles of the first two Balmer lines and the Paschen-α line of HeII have been investigated. The electron density (Ne = 5.5 · 1022 m-3) was measured with a coupled cavity He-Ne laser interferometer. The intensity ratio of the HeII 468.6 nm and the HeI 471.3 nm line was employed to determine the electron temperature (Te = 3.8 eV). At these plasma parameters the measured ion lines are unaffected by self absorption. This enables direct comparison with existing theories. Discrepancies between experimental and theoretical line shapes are critically discussed. Fine structure effects, usually neglected in theories, turn out to be important for the Balmer-α line.

Download Full-text