T Tauri
Jets from more evolved young stars - T Tauri stars - produce similar bow shocks, though these are visible at optical wavelengths and are called Herbig–Haro objects (HH objects). T Tauri stars are usually found in less dense environments. The absence of surrounding gas and dust means that HH objects are less effective at entraining molecular gas. Consequently, they are less likely to be associated with visible bipolar outflows.