English

High Resolution Observations of Cepheus a

Astrophysics 2015-06-24 v1

Abstract

New high resolution 6 cm observations have been made on Cepheus A using MERLIN, and combined with new VLA observations at 3.7 cm. Angular resolution with the latter was 200 mas, and with MERLIN was 60 mas, except for isolated unresolved sources where 33 mas was achieved. Unresolved objects at 60 mas were observed in Sources 2, 3, and in particular 9 which also was not resolved at 33 mas. There is no evidence for any other object as small as this with any significant flux density, although Source 8 was quiescent at the time. The upper limit to the size of Source 9 sets a minimum brightness temperature of 4.3 ×\times 105^5K, and adds credence to a previous suggestion that it is a gyrosynchrotron source. The compact objects of Sources 2 and 3 are thought to be produced by mass outflow from stars, which could be of spectral type B0 - B1, but this is uncertain. There is a discussion regarding the powerhouse for the molecular outflow. Sources 8 and 9, which are the highly time dependent objects, appear at the centre of the disruption of the high density gas, and their estimated high temperature of 107^7 - 108^8K indicates that they could produce high velocity winds. On the other hand, the OH masers surrounding Source 2(ii) show an outward velocity of about 10 km s1{-1}, which is small, but higher velocity winds could tunnel through adjacent spaces, and even be responsible for the 300 km s1{-1} bullet of Source 7. An extrapolation of the orthogonals to the IR polarization vectors are not accurate enough to pinpoint the source of the IR radiation, but it is estimated that Sources 2(ii) and 3(d)(ii) could

Keywords

Cite

@article{arxiv.astro-ph/9402022,
  title  = {High Resolution Observations of Cepheus a},
  author = {V. A. Hughes and R. J. Cohen and S. Garrington},
  journal= {arXiv preprint arXiv:astro-ph/9402022},
  year   = {2015}
}

Comments

11 pages + 10 Figures (available by contacting HUGHESV@QUCDN.QUEENSU.CA), PostScripT file, AST-9402-7

R2 v1 2026-07-22T09:23:24.226Z