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We analyze two binary systems containing giant stars, V723 Mon ("theUnicorn") and 2M04123153+6738486 ("the Giraffe"). Both giants orbit moremassive but less luminous companions, previously proposed to be mass-gap blackholes. Spectral disentangling reveals luminous companions with star-likespectra in both systems. Joint modeling of the spectra, light curves, andspectral energy distributions robustly constrains the masses, temperatures, andradii of both components: the primaries are luminous, cool giants ($T_{\rmeff,\,giant} = 3,800\,\rm K$ and $4,000\,\rm K$, $R_{\rm giant}=22.5\,R_{\odot}$ and $25\,R_{\odot}$) with exceptionally low masses ($M_{\rmgiant} \approx 0.4\,M_{\odot}$) that likely fill their Roche lobes. Thesecondaries are only slightly warmer subgiants ($T_{\rm eff,\,2} = 5,800\,\rmK$ and $5,150\,\rm K$, $R_2= 8.3\,R_{\odot}$ and $9\,R_{\odot}$) and thus areconsistent with observed UV limits that would rule out main-sequence stars withsimilar masses ($M_2 \approx 2.8\,M_{\odot}$ and $\approx 1.8\,M_{\odot}$). Inthe Unicorn, rapid rotation blurs the spectral lines of the subgiant, making itchallenging to detect even at wavelengths where it dominates the total light.Both giants have surface abundances indicative of CNO processing and subsequentenvelope stripping. The properties of both systems can be reproduced by binaryevolution models in which a $1-2\,M_{\odot}$ primary is stripped by a companionas it ascends the giant branch. The fact that the companions are also evolvedimplies either that the initial mass ratio was very near unity, or that thecompanions are temporarily inflated due to rapid accretion. The Unicorn andGiraffe offer a window into into a rarely-observed phase of binary evolutionpreceding the formation of wide-orbit helium white dwarfs, and eventually,compact binaries containing two helium white dwarfs.

Unicorns and Giraffes in the binary zoo: stripped giants with subgiant companions