A "luminous shell of gas" ejected from an "old low-mass star" is called a 'planetary nebula'.
<u>Explanation:</u>
When the red giants stars are in the last stage of their life, they eject a colored ionized gas which forms a shell-like structure around the star.
This structure appears to have a ring shape. It exhibits colors like red, green and blue.
The term 'planetary' in 'Planetary Nebula' is believed to be debatable by a number of astronomers because the planetary nebulas are related to dying stars, not planets.
A warmer climate is expected to increase the risk of illnesses and death from extreme heat and poor air quality. Climate change will likely increase the frequency and strength of extreme events (such as floods, droughts, and storms) that threaten human health and safety.
