Intertwined birth and death: a Herbig-Haro outflow resolves the distance to Vela Junior

Abstract

The distance to the Vela Junior supernova remnant (RX J0852.0-4622 or G266.2-1.2) has long remained uncertain, limiting our understanding of its physical properties. Using VLT/MUSE integral field spectroscopy, we uncover chemical and kinematic connections between the nebula surrounding its Central Compact Object (CXOU J085201.4-461753) and the nearby Herbig-Haro outflow of Ve 7-27 (Wray 16-30), indicating a shared nitrogen-rich, Fe-peak-enhanced environment. This link ties stellar birth and death, with the young star Ve 7-27 embedded in material expelled by Vela Junior's massive progenitor, and the remnant's blast wave is expanding through the same medium. Adopting the Gaia-based distance to Ve 7-27, we revise Vela Junior's distance to $1.41\pm0.14$ kpc. At this distance, the remnant's physical radius is $23.3\pm2.3$ pc, and X-ray proper motions of the northwestern rim correspond to shock speeds of $(2.8\pm0.7)\times10^3$ to $(5.6\pm1.5)\times10^3$ km s$^{-1}$. These imply an age of $\sim$1.6-3.3 kyr and a very low ambient density, indicating that Vela Junior is expanding within a highly rarefied wind-blown cavity carved by a massive progenitor -- consistent with the non-detection of strong thermal X-ray emission. This distance update also resolves long-standing inconsistencies, with major implications for its energy budget, particle acceleration efficiency, and compact object evolution.