  If some or all Type Ia SNe arise from accretion onto a massive WD from a
companion, then the companion will remain in some form after the SN explosion.
Tycho-B is an unusual, relatively hot star along the line of sight to Tycho's
SNR -- conclusively shown to be a Type Ia -- and has been suggested as such a
companion. If the interior of Tycho's SNR contains unshocked Fe, and if Tycho-B
is either within the SNR shell or in the background, then one might hope to see
evidence of this in the UV spectrum. Such is the case for SN\,1006, where
spectra of the background Schweizer-Middleditch star, as well as two AGNs, show
broad absorption lines of Fe II. To test this idea, we have used STIS on HST to
obtain a UV spectrum of Tycho-B. The observed spectrum, however, shows no
evidence of Fe II absorption. Furthermore, a luminosity distance estimate using
UV and optical spectra of Tycho-B suggests that the star is consistent with a
foreground interloper. We conclude either that Tycho B is nearer than Tycho's
SNR, or that all of the Fe in the interior of Tycho's SNR is more highly
ionized.
