Is U Aquarii a Thorne-Żytkow object?

Andrew D. Vanture*, Daniel Zucker, George Wallerstein

*Corresponding author for this work

Research output: Contribution to journalArticle

14 Citations (Scopus)


The R Coronae Borealis (RCB) star U Aqr was known to show an unusual abundance pattern with respect to the post-iron peak elements. The abundances of elements in the light s-process peak - Rb, Sr, Y, and Zr - are greatly enhanced, whereas elements representative of the heavy s-process peak, such as Ba, do not exhibit large abundance enhancements. Recent calculations of the abundances of elements formed by rapid proton capture in Thorne-Żytkow objects indicate that qualitatively the abundance pattern of post-iron peak elements in Thorne-Żytkow objects appeared to match that observed in U Aqr. New high-resolution spectra of U Aqr and two other stars are used to explore the possibility that U Aqr is a Thorne-Żytkow object. Our spectra show that on the basis of the light s-process elements, in particular the absence of an enhancement of Mo, Cu, and Zn, it does not appear that U Aqr is a good candidate for a Thorne-Żytkow object. However, the light s-process abundance pattern resembles that of Sakurai's star that has recently begun to show RCB characteristics. We suggest that these stars represent a possible source for the "weak" component of the solar system s-process distribution of heavy elements.

Original languageEnglish
Pages (from-to)932-938
Number of pages7
JournalAstrophysical Journal
Issue number2 PART 1
Publication statusPublished - 1 Apr 1999
Externally publishedYes


  • Abundances
  • Nuclear reactions
  • Nucleosynthesis
  • Stars: Abundances
  • Stars: Individual (U Aquarii)
  • Stars: Variables: Other (R Coronae Borealis)

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  • Cite this

    Vanture, A. D., Zucker, D., & Wallerstein, G. (1999). Is U Aquarii a Thorne-Żytkow object? Astrophysical Journal, 514(2 PART 1), 932-938.