We present here new observations of the eccentric debris ring surrounding the Gyr-old solar-type star HD 202628 : at millimeter wavelengths with ALMA , at far-infrared wavelengths with Herschel , and in scattered light with HST .
The ring inner edge is found to be consistent between ALMA and HST data .
As radiation pressure affects small grains seen in scattered-light , the ring appears broader at optical than at millimeter wavelengths .
The best fit to the ring seen with ALMA has inner and outer edges at 143.1 \pm 1.7 AU and 165.5 \pm 1.4 , respectively , and an inclination of 57.4 ^ { \circ } \pm 0.4 from face-on .
The offset of the ring centre of symmetry from the star allows us to quantify its eccentricity to be e = 0.09 _ { -0.01 } ^ { +0.02 } .
This eccentric feature is also detected in low resolution Herschel /PACS observations , under the form of a pericenter-glow .
Combining the infrared and millimeter photometry , we retrieve a disk grain size distribution index of \sim - 3.4 , and therefore exclude in-situ formation of the inferred belt-shaping perturber , for which we provide new dynamical constraints .
Finally , ALMA images show four point-like sources that exceed 100 \mu Jy , one of them being just interior to the ring .
Although the presence of a background object can not be excluded , we can not exclude either that this source is circumplanetary material surrounding the belt-shaper , in which case degeneracies between its mass and orbital parameters could be lifted , allowing us to fully characterize such a distant planet in this mass and age regime for the very first time .