No abstract

We have identified outflows and bubbles in the Taurus molecular cloud based on the ∼ 100 deg 2 Five College Radio Astronomy Observatory 12 CO(1-0) and 13 CO(1-0) maps and the Spitzer young stellar object catalogs. In the main 44 deg 2 area of Taurus we found 55 outflows, of which 31 were previously unknown. We also found 37 bubbles in the entire 100 deg 2 area of Taurus, all of which had not been found before. The total kinetic energy of the identified outflows is estimated to be ∼ 3.9 × 10 45 erg, which is 1% of the cloud turbulent energy. The total kinetic energy of the detected bubbles is estimated to be ∼ 9.2 × 10 46 erg, which is 29% of the turbulent energy of Taurus. The energy injection rate from outflows is ∼ 1.3 × 10 33 erg s −1 , 0.4 -2 times the dissipation rate of the cloud turbulence. The energy injection rate from bubbles is ∼ 6.4 × 10 33 erg s −1 , 2 -10 times the turbulent dissipation rate of the cloud. The gravitational binding energy of the cloud is ∼ 1.5 × 10 48 erg, 385 and 16 times the energy of outflows and bubbles, respectively. We conclude that neither outflows nor bubbles can provide enough energy to balance the overall gravitational binding energy and the turbulent energy of Taurus. However, in the current epoch, stellar feedback is sufficient to maintain the observed turbulence in Taurus.

We present eight epochs of 43‐GHz, dual‐polarization VLBA observations of the gravitational lens system PKS 1830‐211, made over fourteen weeks. A bright, compact ‘core’ and a faint extended ‘jet’ are clearly seen in maps of both lensed images at all eight epochs. The relative separation of the radio centroid of the cores (as measured on the sky) changes by up to 87 μ as between subsequent epochs. A comparison with the previous 43‐GHz VLBA observations made 8 months earlier shows even larger deviations in the separation of up to 201 μas. The measured changes are most likely produced by changes in the brightness distribution of the background source, enhanced by the magnification of the lens. A relative magnification matrix that is applicable on the milliarcsecond scale has been determined by relating two vectors (the ‘core–jet’ separations and the offsets of the polarized and total intensity emission) in the two lensed images. The determinant of this matrix, −1.13 ( ± 0.61), is in good agreement with the measured flux density ratio of the two images. The matrix predicts that the 10‐mas‐long jet, which is clearly seen in previous 15‐ and 8.4‐GHz VLBA observations, should correspond to a 4‐mas‐long jet trailing to the south‐east of the south‐western image. The clear non‐detection of this trailing jet is a strong evidence for substructure in the lens and may require more realistic lens models to be invoked, such as that of Nair & Garrett.