Nuclear Bar, Star Formation and Gas Fueling in the Active Galaxy NGC 4303

L. Colina; K. Wada

doi:10.1086/308320

paper

Nuclear Bar, Star Formation and Gas Fueling in the Active Galaxy NGC 4303

arXiv:astro-ph/9910345 · doi:10.1086/308320

Abstract

A combination of Hubble Space Telescope (HST) WFPC2 and NICMOS images are used to investigate the gas/dust and stellar structure inside the central 300 pc of the nearby active galaxy NGC 4303. The NICMOS H-band (F160W) image reveals a bright core and a nuclear elongated bar-like structure of 250 pc in diameter. The bar is centered on the bright core, and its major axis is oriented in proyection along the spin axis of the nuclear gaseous rotating disk recently detected (Colina & Arribas 1999). The V-H (F606W - F160W) image reveals a complex gas/dust distribution with a two-arm spiral structure of about 225 pc in radius. The southwestern arm is traced by young star-forming knots while the northeastern arm is detected by the presence of dust lanes. These spirals do not have a smooth structure but rather they are made of smaller flocculent spirals or filament-like structures. The magnitudes and colors of the star-forming knots are typical of clusters of young stars with masses of 0.5 to 1 x $1 0^{5} M_{so l a r}, an d a g eso f 5 t o 25 mi l l i o n y e a r s . T h eo v er a l l s t r u c t u r eo f t h e n u c l e a r s p i r a l s a s w e l l a s t h es i z e, n u mb er an d ma sseso f t h es t a r - f or min g k n o t s a r ee x pl ain e d in t h eco n t e x t o f ama ss i v e g a seo u s n u c l e a r d i s k s u bj ec tt ose l f - g r a v i t a t i o na l in s t abi l i t i es an d t o t h e g r a v i t a t i o na l f i e l d cr e a t e d b y t h e n u c l e a r ba r . A ccor d in g t o t h e m o d e l, t h e g a seo u s d i s k ha s ama sso f ab o u t 5 x 1 0^{7} M_{so l a r} in s i d e a r a d i u so f 400 p c, t h e ba r ha s a r a d i u so f 150 p c an d a p a tt er n s p ee d o f ab o u t 0.5 M y r^{- 1}, an d t h e a v er a g e ma ss a ccr e t i o n r a t e in t o t h ecor e (R < 8 p c) i s ab o u t 0.01 M_{so l a r}$ yr^{-1} for about 80 Myr.

arXiv commentApJ, in press (February 1, 2000)

Nuclear Bar, Star Formation and Gas Fueling in the Active Galaxy NGC 4303

Abstract

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