Context. The Rosetta spacecraft followed comet 67P/Churyumov-Gerasimenko (67P) for more than two years at a slow walking pace (~1 m s ?1 ) within 1500 km from the nucleus. During one of radial movements in early phase mission, distribution plasma density could be estimated, and ionospheric was found to inversely proportional cometocentric distance r nucleus (a 1/ distribution). Aims. This study...

In this work, we study the shadow and photon sphere of black bole in clouds strings quintessence with static infalling spherical accretions. We obtain geodesics photons near a hole different impact parameters $b$. The string model influence specific intensity by affecting geodesic average radial position photons. And range parameter $a$ is constrained to ensure that can be observed. Moreover, u...