The Optical Proper Motions of HH 7–11 and Cepheus E

A key ingredient in understanding the dynamics of stellar outflows is theirproper motion. We have used optical images in the [SII] emission at 6717/31 Aand the red Digitized Palomar Observatory Sky Survey (DSS) plates to determinethe proper motion of HH 7-11 system and the optical knot of Cep E (HH 377). TheDSS plate measurements span nearly 37 years for both HH 7-11 and HH 377 andhave wide field of view, which allows an accurate determination of the propermotions despite their relatively low angular resolution. The optical images,with higher angular resolution, cover a shorter period of 7 and 4 years,respectively, and have been used to complement the DSS measurements. From theDSS plates we have found that HH 377 has a proper motion of 0.031 +/- 0.003arcsec/yr with a PA = 206 arcdeg, i.e. moving away from IRAS 230111+63, that ata distance of 730 pc corresponds to a tangential velocity of 107 +/- 14 km/s.The values obtained from the optical images are consistent with thesemeasurements. Similarly, the proper motions of HH 7-11 range from 0.015 +/-0.009 (HH 9) to 0.044 +/- 0.007 (HH 11) arcsec/yr, and the flow is moving awayfrom SVS 13 with a mean PA = 136 arcdeg. At a distance of 330 pc, these motionscorrespond to tangential velocities of 25 - 70 km/s, i.e. comparable to theoriginal values obtained by Herbig & Jones (1983). The measurements from theoptical CCD [SII] images are again consistent with these motions, although indetail there are some difference, particularly for HH 7 and HH 10.Comment: 18 pages, 6 Figures (jpgs because of their size