AAS 199th meeting, Washington, DC, January 2002
Session 50. Seyfert Galaxies
Display, Tuesday, January 8, 2002, 9:20am-6:30pm, Exhibit Hall

## [50.06] NGC 4151: Radio Morphology on the Sub-Parsec-Scale

D.S. Wong, J.S. Ulvestad, G.B. Taylor (NRAO), J.F. Gallimore (Bucknell Univ.)

The VLBA and phased-VLA were used to image Seyfert galaxy NGC~4151 at wavelengths of 3.6 and 6 cm, achieving resolutions of ~2 and 3 mas (0.16 and 0.24 pc) respectively. This marks the first time that this Seyfert has been imaged at 3.6 cm with VLBI.

At both wavelengths, two components (previously denoted as D and E) were identified. The brightness temperatures (~107-108 K) we calculated were consistent with non-thermal emission from D and E. There is no evidence for extended emission of a lower brightness temperature that might be associated with a nuclear torus. The spectral indices of the components and their subcomponents reveal no obvious flat-spectrum source, so the question of whether the nucleus is in component D or E remains unanswered. This is the second time that NGC 4151 has been imaged by the VLBA at 6 cm, enabling derivation of a tentative speed limit of \leq 0.07c on the parsec scale motion of component E with respect to component D.

NRAO is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Further support for D. S. Wong was provided by NSERC of Canada.