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Introductory remarks on the symbiotic star AG Draconis

Published online by Cambridge University Press:  12 April 2016

Nancy A. Oliversen  and
Christopher M. Anderson
Nancy A. Oliversen
Affiliation:
Washburn Observatory, University of Wisconsin-Madison
Christopher M. Anderson
Affiliation:
Washburn Observatory, University of Wisconsin-Madison

Extract

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AG Draconis contains a relatively early cool component. Quoted spectral types range from dG7 (Wilson 1943) to K3III (Boyarchuck 1969). Most recently Smith and Bopp (1981) adopt G7IIIe. The optical spectrum shows in emission the permitted lines of hydrogen and helium, both neutral and singly ionized. At various times the spectrum of the late type component has been heavily veiled by a blue continuum and numerous lines of various stages of ionization of iron have been seen, including the 6830 A feature which Allen (1980) attributes to Fe VI. On the other hand, on a KPNO echelle spectrum taken by one of the current authors (CMA) in 1977 August, the late giant spectrum was very sharp and no iron or forbidden lines were present. The lack of the forbidden lines identifies AG Dra as a high density case and thus it conforms to the spectral type-density correlation found by Allen (1980).

Type
Session II – Discussion on Individual Stars
Information
International Astronomical Union Colloquium , Volume 70: The Nature of Symbiotic Stars , 1982 , pp. 177 - 181
Copyright
Copyright © Reidel 1982

References

Allen, D.A. 1980 M.N.R.A.S., 190, 75.Google Scholar
Anderson, C.M., Cassinelli, J.P., and Sanders, W.T. 1981, Ap.J. 247, L1. Google Scholar
Bopp, B.W. and Evans, D.S. 1973 M.N.R.A.S., 164, 343. CrossRefGoogle Scholar
Boyarchuk, A.A. 1969 I.A.U. Coll. “Non-Periodic Phenomena in Variable Stars”, p. 395. CrossRefGoogle Scholar
Meinunger, L. 1979 I.A.U. I.B.V.S. 1611. Google Scholar
Smith, S.E. and Bopp, B.W. 1981 M.N.R.A.S., 195, 733.Google Scholar
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