We have for the first time detected X-ray emission associated with a protostellar jet , on the jet emanating from the L1551 IRS5 protostar .
The IRS5 protostar is hidden behind a very large absorbing column density , making the direct observation of the jet ’ s emission possible .
The observed X-ray emission is likely associated with the shock “ working surface ” , i.e .
the interface between the jet and the circumstellar medium .
The X-ray luminosity emanating from the jet is , at L _ { X } \simeq 3 \times 10 ^ { 29 } erg s ^ { -1 } , a significant fraction of the luminosity normally associated with the coronal emission from young stars .
The spectrum of the X-ray emission is compatible with thermal emission from a hot plasma , with a temperature of \simeq 0.5 MK , fully in line with the temperature expected ( on the basis of the jet ’ s velocity ) for the shock front produced by the jet hitting the circumstellar medium .