We report a new diagnostic between two different states of the local interstellar medium ( LISM ) near our solar system using a sensitivity study constrained by several distinct and complementary observations of the LISM , solar wind , and inner heliosphere .
Assuming the Interstellar Boundary Explorer ( IBEX ) He flow parameters for the LISM , we obtain a strength of \sim 2.7 \pm 0.2 \mu G and a direction pointing away from galactic coordinates ( 28 , 52 ) \pm 3 ^ { \circ } for the interstellar magnetic field as resulting from fitting Voyager 1 & 2 in situ plasma measurements and IBEX energetic neutral atoms ribbon .
When using Ulysses parameters for the LISM He flow , we recently reported the same direction but a strength of 2.2 \pm 0.1 \mu G. First , we notice that with Ulysses He flow , our solution is in the expected hydrogen deflection plane ( HDP ) .
In contrast , for the IBEX He flow , the solution is \sim 20 ^ { \circ } away from the corresponding HDP plane .
Second , the long-term monitoring of the interplanetary H I flow speed shows a value of \sim 26 km/s measured at upwind from the Doppler-shift in the strong Lyman- \alpha sky background emission line .
All elements of diagnostics seem therefore to support Ulysses He flow parameters for the interstellar state .
In that frame , we argue that reliable discrimination between superfast , subfast , or superslow states of the interstellar flow should be based on most existing in situ and remote observations used together with global modelling of the heliosphere .
For commonly accepted LISM ionization rates , we show that a fast interstellar bow-shock should be standing-off upstream of the heliopause .