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The halos of disk galaxies form a crucial connection between the galaxy diskand the intergalactic medium. Massive stars, HII regions, or dwarf galaxieslocated in the halos of galaxies are potential tracers of recent accretionand/or outflows of gas, and are additional contributors to the photon field andthe gas phase metallicity. We investigate the nature and origin of astar-forming dwarf galaxy candidate located in the halo of the edge-on Virgogalaxy NGC 4634 with a projected distance of 1.4 kpc and a H$\alpha$ starformation rate of $\sim 4.7 \times 10^{-3} \text{M}_\odot \text{yr}^{-1}$ inorder to increase our understanding of these disk-halo processes. With opticallong-slit spectra we measured fluxes of optical nebula emission lines to derivethe oxygen abundance 12 + log(O/H) of an HII region in the disk of NGC 4634 andin the star-forming dwarf galaxy candidate. Abundances derived from opticallong-slit data and from Hubble Space Telescope (HST) r-band data, H$\alpha$data, Giant Metrewave Radio Telescope (GMRT) HI data, and photometry of SDSSand GALEX data were used for further analysis. With additional probes of theluminosity-metallicity relation in the $B$-band from the H$\alpha$-luminosity,the HI map, and the relative velocities, we are able to constrain a possibleorigin of the dwarf galaxy candidate. The high oxygen abundance (12 + log(O/H)$\approx$ 8.72) of the dwarf galaxy candidate leads to the conclusion that itwas formed from pre-enriched material. Analysis of auxiliary data shows thatthe dwarf galaxy candidate is composed of material originating from NGC 4634.We cannot determine whether this material has been ejected tidally or throughother processes, which makes the system highly interesting for follow upobservations.

A star-forming dwarf galaxy candidate in the halo of NGC 4634