Arcsecond-scale Molecular Gas Structures in IRAS Galaxy Mrk 273
Session 23 -- Emission-Line, Starburst and Ultra-Luminous Galaxies
Oral presentation, Monday, 2:30-4:00, Wheeler Room

## [23.07] Arcsecond-scale Molecular Gas Structures in IRAS Galaxy Mrk 273

M.S.Yun, N.Z.Scoville, L.Armus, B.T.Soifer (Caltech)

The molecular gas distribution in the ultraluminous infrared galaxy Mrk 273 (UGC 8696; Log($L_{FIR}$)=12.04 $L_{\odot}$) is studied with the $2''$ spatial resolution by observing the $J=1-0$ transition of CO using the Millimeter Array at the Owens Valley Radio Observatory (OVRO). The emitting region is extended ($12''\times 7''$ or 8.9 $\times$ 5.2 kpc, assuming D = 152 Mpc) and coincides closely with the 2$\mu$m emitting region. The total detected CO flux (194 Jy km/sec; $M_{H_2}= 3.3\times 10^{10} L_{\odot}$) corresponds to 85$\%$ of the single dish flux measured by Sanders, Scoville, \& Soifer (1991, ApJ, 370, 158). One third of the total flux is concentrated in the inner 1.7 kpc region centered on the 2$\mu$m nucleus, and the brightness distribution falls off exponentially with an e-folding length of $\sim1.8$ kpc. The observed velocity gradient is along the major axis (N-S), and if interpreted as a signiture of rotation, this is consistent with the disk rotation inferred from the orientation of the prominent optical tidal feature extending due south. The associated 3mm continuum emission is not detected at the achieved sensitivity of the continuum experiment ($\sigma\sim1.3$ mJy/beam).