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In this work we study the striking case of a narrow blue stream around theNGC 7241 galaxy and its foreground dwarf companion. We want to figure out ifthe stream was generated by tidal interaction with NGC 7241 or it firstinteracted with the foreground dwarf companion and later both fell togethertowards NGC 7241. We use four sets of observations, including a follow-upspectroscopic study with the MEGARA instrument at the 10.4-m Gran TelescopioCanarias. Our data suggest that the compact object we detected in the stream isa foreground Milky Way halo star. Near this compact object we detect emissionlines overlapping a bluer and fainter blob of the stream that is clearlyvisible in both ultra-violet and optical deep images. From its heliocentricsystemic radial velocity (Vsyst= 1548.58+/-1.80 km s^-1) and new UV and opticalbroad-band photometry, we conclude that this over-density could be the actualcore of the stream, with an absolute magnitude of M_g ~ -10 and a (g-r) = 0.08+/- 0.11, consistent with a remnant of a low-mass dwarf satellite undergoing acurrent episode of star formation. From the width of the stream and assuming acircular orbit, we calculate that the progenitor mass can be the typical of adwarf galaxy, but it could also be substantially lower if the stream is on avery radial orbit or it was created by tidal interaction with the companiondwarf instead of with NGC 7241. Finally, we find that blue stellar streamscontaining star formation regions are commonly predicted by high-resolutioncosmological simulations of galaxies lighter than the Milky Way. This scenariois consistent with the processes explaining the bursty star formation historyof some dwarf satellites, which are followed by a gas depletion and a fastquenching once they enter within the virial radius of their host galaxies forthe first time.

Once in a blue stream: Detection of recent star formation in the NGC 7241 stellar stream with MEGARA