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Multi-Array λ2 and 6cm Radio Continuum Observations of Sgr A West

Published online by Cambridge University Press:  23 September 2016

F. Yusef-Zadeh ,
Mark Morris  and
Ron Ekers
F. Yusef-Zadeh
Affiliation:
LASP, Goddard Space Flight Center and Northwestern University
Mark Morris
Affiliation:
Astronomy Department, UCLA
Ron Ekers
Affiliation:
Australian Telescope, CSIRO

Abstract

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Sub-arcsecond (down to 0.1″ × 0.2″) radio continuum observations using the VLA2 in a number of configurations have been carried out in order to investigate the fine-scale morphological details of the ionized gas and the distribution of spectral index along the triskelian-shaped figure of Sgr A West. In addition to finding a number of isolated patches of thermally-emitting gas and an absorbing feature at λ6cm within three arcminutes of the Galactic center, we have observed:

1) radio continuum emission from IRS-7, implying that the stellar wind from this supergiant is externally ionized. An improved position for this object was obtained.

2) the circular mini-cavity located along the east-west bar of Sgr A West. This feature has a diameter of 2-arcseconds and may have been created by a spherical wind, the source of which is yet to be identified; the seemingly most plausible candidate, IRS-16, is offset by 3″ from the center of the cavity.

Spectral index maps having a resolution of 0.7″ × 0.3″ were made from scaled array observations at λ2cm and 6cm. They show that the eastern arm has a spectral index near −0.1, while the northern arm and the bar have positive spectral indices, indicating perhaps a partial opacity effect. The spectral index of IRS-7 is +0.6, consistent with that expected from a completely ionized stellar wind.

Type
Sagittarius A West and the Circumnuclear Disk
Information
Symposium - International Astronomical Union , Volume 136: The Galactic Center , 1989 , pp. 443 - 451
Copyright
Copyright © Kluwer 1989 

References

Aitken, D.K. 1989, this volume. Google Scholar
Allen, D.A. 1989, this volume. Google Scholar
Becklin, E., Dinerstein, H., Gatley, I., Werner, M.W. and Jones, B. 1987, The Galactic Center , ed. Backer, D.C. (New York: AIP), p162.Google Scholar
Brown, R.L. and Liszt, J.H. 1984, Ann. Rev. Astron. Astrophys. , 22, 223.CrossRefGoogle Scholar
Castor, J., McCray, R. and Weaver, R. 1975, Ap. J. Lett. , 200, L107.CrossRefGoogle Scholar
Depoy, D.L., Gatley, I., and McClean, I. 1989, this volume. Google Scholar
Ekers, R., van Gorkom, J.H., Schwarz, U.J. and Goss, W.M. 1983, Astron. Astrophys. , 122, 143.Google Scholar
Forrest, W.J., Shure, M.A., Pipher, J.L. and Woodward, C.E. 1987, The Galactic Center , ed. Backer, D.C. (New York: AIP), p153.Google Scholar
Geballe, T.R. 1987, The Galactic Center , ed. Backer, D.C. (New York: AIP), p39.Google Scholar
Geballe, T.R. 1989, this volume. Google Scholar
Hall, D.N.B., Kleinmann, S.G. and Scoville, N.Z. 1973, Ap. J. Lett. , 262, L53.Google Scholar
Lacy, J.H., Lester, D.F., Arens, J.F., Peck, M.C., Gaalema, S. 1987, The Galactic Center , ed. Backer, D.C., p142.Google Scholar
Lacy, J.H., Townes, C.H., Geballe, T.R. and Hollenbach, D.J. 1980, Ap.J. , 241, 132.CrossRefGoogle Scholar
Lo, K.Y. and Claussen, M.J. 1983, Nature , 306, 647.CrossRefGoogle Scholar
Morris, M., Jura, M. 1983, Ap.J. , 267, 179.CrossRefGoogle Scholar
Morris, M. and Yusef-Zadeh, F. 1987, The Galactic Center , ed. Backer, D.C. (New York: AIP), p127.Google Scholar
Panagia, N. and Felli, M. 1975, Astron. Astrophys. , 39, 1.Google Scholar
Sellgren, K., Hall, D.N.B., Kleinmann, S.G. and Scoville, N.Z. 1987, The Galactic Center , ed. Backer, D.C. (New York: AIP), p83.Google Scholar
Serabyn, G., Lacy, J.H., Townes, C.H. and Bharat, R. 1988, Ap.J. 326, 171.CrossRefGoogle Scholar
Rieke, G. 1989, this volume. Google Scholar
Taylor, A.R. and Seaquist, E.R. 1984, Ap.J. 286, 263.CrossRefGoogle Scholar
van Gorkom, J.H., Schwarz, U.J., and Bregman, J.D. 1984, Proceedings of IAU Symposium 106 , eds., van Woerden, , Burton and Allen, p371.Google Scholar
Werner, M.W. and Davidson, J. 198 this volume. Google Scholar
Wright, A.E. and Barlow, M.J. 1975, MNRAS , 170, 41.CrossRefGoogle Scholar
Yusef-Zadeh, F. 1989, this volume. Google Scholar