We present the results of VLT-MUSE integral field spectroscopy of SECCO 1 , a faint , star-forming stellar system recently discovered as the stellar counterpart of an Ultra Compact High Velocity Cloud ( HVC274.68+74.0 ) , very likely residing within a substructure of the Virgo cluster of galaxies .
We have obtained the radial velocity of a total of 38 individual compact sources identified as H ii regions in the main and secondary body of the system , and derived the metallicity for 18 of them .
We provide the first direct demonstration that the two stellar bodies of SECCO 1 are physically associated and that their velocities match the H i velocities .
The metallicity is quite uniform over the whole system , with a dispersion lower than the uncertainty on individual metallicity estimates .
The mean abundance , \langle 12 + { log ( O / H ) } \rangle = 8.44 , is much higher than the typical values for local dwarf galaxies of similar stellar mass .
This strongly suggests that the SECCO 1 stars were born from a pre-enriched gas cloud , possibly stripped from a larger galaxy .
Using archival HST images we derive a total stellar mass of \simeq 1.6 \times 10 ^ { 5 } ~ { } M _ { \sun } for SECCO 1 , confirming that it has a very high H i to stellar mass ratio for a dwarf galaxy , M _ { H { \sc i } } /M _ { * } \sim 100 .
The star formation rate , derived from the H _ { \alpha } flux is a factor of more than 10 higher than in typical dwarf galaxies of similar luminosity .