What common feature is theorized to cause the hourglass or dumbbell shape in bipolar planetary nebulae?
Answer
A binary companion star or a dense torus near the central star
The appearance of bipolar structures strongly suggests that something is constricting the outflow near the star, commonly theorized to be a binary companion or a dense torus channeling the fast wind into two opposite directions.
Frequently Asked Questions
What drives the complex process forming a planetary nebula?Why are these objects misleadingly named 'planetary nebulae'?What final form does a star similar in mass to our Sun assume after expelling its outer layers?Which late evolutionary phase is characterized by intense instability leading to mass loss?What energy source makes the ejected gas shell of a planetary nebula visible?Approximately what speed characterizes the initial, slow stellar wind phase of mass ejection?What interaction primarily sculpts the intricate shapes seen in planetary nebulae?On cosmic timescales, how long is a planetary nebula typically in its fully illuminated state?What common feature is theorized to cause the hourglass or dumbbell shape in bipolar planetary nebulae?What is the typical mass range (in solar masses) for stars that evolve into planetary nebulae?