Hα Nuclear Geyser (Bipolar Outflow) from the Barred Galaxy NGC 1415

Abstract

A long-slit spectrum from the barred galaxy NGC 1415 (ESO 482-G033) has been obtained with the 2.1 m Guillermo Haro telescope in Cananea, México, at position angle ∼155° and shows the kinematics of Na i D lines (in absorption) and Hαλ6562.8 Å, [N ii] λ6548 Å, [N ii] λ6584 Å, [S ii] λ6716 Å, and [S ii] λ6731 Å lines in emission from the central regions and the disk. Our previous Hα continuum-free imaging of the central region showed mainly two central bright Hα knots straddling the nucleus, and Hα emission regions along the southeast and northwest inner spiral arms. Velocities of the Na i D absorption lines are taken as representative of the rotation curve of NGC 1415. Our kinematical data indicates that the central bright Hα straddling the nucleus have velocities in excess of the Na i D velocities. We interpret these velocity excesses of the central bright Hα knots as being due to a geyser (bipolar outflow) with Voutflow ∼ 140 km s−1 at a P.A.+165°. The axis of this outflow is not along the rotation axis of the disk of NGC 1415 (if it were, it would be at P.A.+238°). Additionally, we determined Ωgas, radial resonances κ(R), and estimated the value of the pattern angular speed of an inner boxy stellar bar in NGC 1415, Ωbar, from the Na i D rotation curve assuming , Ωbar ∼ 134 km s−1 kpc−1.