Very Local Interstellar Medium Revealed by a Complete Solar Cycle of Interstellar Neutral Helium Observations with IBEX

The IBEX-Lo instrument on board the Interstellar Boundary Explorer (IBEX) mission samples interstellar neutral (ISN) helium atoms penetrating heliosphere from very local medium (VLISM). In this study, we analyze ISN observations covering a complete solar cycle, 2009 through 2020 using comprehensive uncertainty analysis including statistical and systematic sources.W e employ Warsaw Test Particle Model to simulate fluxes at IBEX, which are subsequently compared with observed count rate in three lowest energy steps of IBEX-Lo. $\chi^2$ shows that flows ecliptic $(\lambda,\beta)=(255.59^{\circ}\pm0.23^{\circ}, 5.14^{\circ}\pm0.08^{\circ})$, speed $v_\text{HP}=25.86\pm0.21$ km s$^{-1}$ temperature $T_\text{HP}=7450\pm140$ K heliopause. Accounting for gravitational attraction elastic collisions, pristine VLISM far heliopause $v_\text{VLISM}=25.9$ $T_\text{VLISM}=6150$ K, respectively. time evolution 1 au over 12 years suggests significant changes detection efficiency, higher ionization rates than assumed model, or an additional unaccounted signal source analyzed observations. Nevertheless, do not find any indication derived parameters period analyzed. Finally, argue continued operation overlap Mapping Acceleration Probe (IMAP) will be pivotal tracking possible physical VLISM.