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The Anisotropic Radiation Field in NGC 3516

Published online by Cambridge University Press:  19 July 2016

I. Yankulova
Affiliation:
Department of Astronomy, University of Sofia, 5 James Bourchier st., BG - 1126 Sofia, Bulgaria
V. Golev
Affiliation:
Department of Astronomy, University of Sofia, 5 James Bourchier st., BG - 1126 Sofia, Bulgaria
T. Bonev
Affiliation:
Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko chaussee blvd., BG - 1784 Sofia, Bulgaria
K. Jockers
Affiliation:
Max-Planck-Institute for Aeronomy, D - 3411 Katlenburg-Lindau, Germany

Extract

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We present new narrow-band images of the Extended Emission-Line Region (EELR) in NGC 3516 in light of [O III] λ 4959, Hα + [N II] λλ 6548, 84, [O I] λ 6364, He is/c λ 6678 and [Fe VII] + [Ca V] λ 6087. The observations were carried with the 2-m reflector of the Bulgarian National Astronomical Observatory and the Focal Reducer of the Max-Plank-Institut for Aeronomy. Our [O III] and Hα + [N II] images confirm previously reported EELR features. In contrast, the image in the high-excitation [Fe VII] + [Ca V] line shows a different structure. We identify a biconical morphology over a kiloparsec scale with peak intensities 5.9 × 10−16 ergs cm−2 s−1 arcsec−2 and 3.5 × 10−16 ergs cm−2 s−1 arcsec−2 to north and south of the nucleus, respectively. The total flux of the [Fe VII] + [Ca V] emission in 5″ and 24″ circular apertures centered at the nucleus is (9.97 ± 0.38) × 10−14 ergs cm−2 s−1 and (1.53 ± 0.15) × 10−13 ergs cm−2 s−1, respectively, which is in good agreement with measurements of Boksenberg & Netzer (1977) through the 5″ aperture. The cone axis lies at PA ∼ −10°. The continuum images (Veilleux et al., 1993, Miyaji et al., 1992) indicate a “bar” aligned along PA ∼ −10°. The velocity extrema regions revealed by Veilleux et al. (1993) are coincident with the peak intensities in our [Fe VII] + [Ca V]. We suppose that our image in [Fe VII] + [Ca V] outlines a Coronal-Line Region (CLR) of NGC 3516, which extends far beyond the classical NLR of the galaxy. Korista & Ferland (1989) have recently shown theoretically that the CLR in Seyferts may be a result of a low-density interstellar medium exposed to and photoionized by a “bare” active nucleus. A typical ISM with Ne ∼ 1–5 cm−3 may produce such an extended CLR as that observed by us.

Type
Poster Contributions: Line Studies
Copyright
Copyright © Kluwer 1994 

References

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