2012AJ....144..159M

H I 1225+01 is an intergalactic gas cloud located on the outskirts of Virgo cluster. Its main components are two large clumps of comparable HI masses (M_HI ∼ 10⁹M_☉) separated by about 100 kpc. One of the clumps hosts a blue low-surface-brightness galaxy J1227+0136, while the other has no identified stellar emission and is sometimes referred to as a promising candidate of a "dark galaxy," an optically invisible massive intergalactic system. We present a deep optical image covering the whole H I 1225+01 structure for the first time, as well as a collection of archival data from ultraviolet to far-infrared (IR) spectral region of the brightest knot "R1" in J1227+0136. We find that R1 has a young stellar population 10-100 Myr in age and mass ∼10⁶ M_☉, near-IR excess brightness which may point to the presence of hot dust with color temperature ∼600 K, and relatively faint mid- to far-IR fluxes corresponding to the dust mass of up to ∼100 M_☉. Overall, it seems to share the general properties with low-metallicity blue compact dwarf galaxies. On the other hand, no optical counterpart to the other clump is found in our deepest-ever image. Now the limiting surface brightness reaches down to R_AB> 28 mag/arcsec2 for any emission extended over 10'' (comparable to R1), which is more than one hundred times fainter than the brightest part of the companion galaxy J1227+0136.