Spectroscopic monitoring of active galactic nuclei. III. Size of the broad line region in NGC 3227

• For pt.II see ibid., vol.269, no.1-2, p.39-53 (1993). The authors present the results of a five-month monitoring campaign of the active galactic nucleus in NGC 3227. The Hbeta and Halpha emission lines and the optical continuum have been analysed. The optical AGN continuum and the broad-line region (BLR) emission in NGC 3227 appear to vary by about 40% on a timescale of 1.5 month. The levels of the broad-line emission and the 675.0 nm continuum are well correlated, a fact consistent with the assumption that the BLR material is photoionised by the central continuum source. Cross-correlation analyses between the light curves of the 675.0 nm AGN continuum and the BLR H emission indicate that the lag of the BLR emission with respect to the continuum variations is 17plusmn7 days. This result suggests that the BLR clouds that are affected by the changes in the flux of the central ionising source lie about 17 light days away from it

Ämnesord

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

Nyckelord

Experimental/ astronomical photometry

astronomical spectra

galactic nuclei

visible astronomical observations/ AGN broad line region size

spectrum variations

visible

BLR clouds galactocentric distance

emission-line spectrum

BLR size-nuclear luminosity relation

AD 1990 01 to 06

light curves cross-correlation analyses

interacting galaxy

BLR clouds photoionisation

active galactic nuclei

NGC 3227

five-month monitoring campaign

active galactic nucleus

Hbeta

emission lines

optical continuum

broad-line region

675.0 nm continuum

central continuum source

BLR H emission

continuum variations

BLR clouds

central ionising source

486.1 nm

656.3 nm

675.0 nm

45 d

10 to 24 d

17 d

440 Tm

260 to 620 Tm

23 Mpc

450 to 700 nm

1158 km/s

H emission line variations time lag/ A9850R Active and peculiar galaxies A9850E Galactic structure

content and morphology A9850G Radiation and spectra of galaxies A9580J Photographic region astronomical observations/ wavelength 4.861E-07 m

wavelength 6.563E-07 m

wavelength 6.75E-07 m

time 3.9E+06 s

time 8.6E+05 to 2.1E+06 s

time 1.5E+06 s

distance 4.4E+14 m

distance 2.6E+14 to 6.2E+14 m

galactic distance 2.3E+07 pc

wavelength 4.5E-07 to 7.0E-07 m

velocity 1.158E+06 m/s/ H/el

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