H12CO+ outflow and a rotating H13CO+ disk around L1551 IRS-5

High-velocity resolution (V=0.07 km s^–1) H¹²CO⁺ (J=1–0) and H¹³CO⁺ (J=1–0) observations have been carried out towards L1551 by use of the Metsähovi 14-m radio telescope. The observations reveal a bipolar H¹²CO⁺ outflow from the pre-Main-Sequence star IRS-5 which is centred on a flattened, 3 long H¹³CO⁺ cloud clump. This disk-like cloud structure has a velocity gradient ranging from 6.56 km s^–1 in the SE to 7.06 km s^–1 in the NW. It is noteworthy that the direction of the H¹²CO⁺ ion outflow is oriented E-W, and not along the NE-SW axis of the more extended CO outflow. In the disk area the H¹²CO⁺ spectra show to distinct velocity components. The right-hand H¹²CO⁺ velocity component agrees with the velocity of the H¹³CO⁺ disk. The left-hand H¹²CO⁺ component seems to belong to the outflow and the dense lobe material. The H¹²CO⁺ isovelocity contour map indicates that the dense lobe material is rotating (V _rot 0.6 km s^–1) in the same sense as the H¹³CO⁺ disk. This supports hydromagnetic outflow models.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain