Editing Rigel (section)

=== Mass loss ===

From observations of the variable Hα spectral line, Rigel's mass-loss rate due to stellar wind is estimated be {{val|1.5|0.4|e=−7}} solar masses per year ({{solar mass|link=n}}/yr)—about ten million times more than the mass-loss rate from the [[Sun]].<ref name=chesneau2010/> More detailed optical and [[K band (infrared)|K{{nbsp}}band]] infrared spectroscopic observations, together with [[VLTI]] interferometry, were taken from 2006 to 2010. Analysis of the Hα and [[Hγ]] line profiles, and measurement of the regions producing the lines, show that Rigel's stellar wind varies greatly in structure and strength. Loop and arm structures were also detected within the wind. Calculations of mass loss from the Hγ line give {{val|9.4|0.9|e=−7|u={{solar mass}}/yr}} in 2006-7 and {{val|7.6|1.1|e=−7|u={{solar mass}}/yr}} in 2009–10. Calculations using the Hα line give lower results, around {{val|1.5|e=−7|u={{solar mass}}/yr}}. The terminal wind velocity is {{val|300|u=km/s}}.<ref name=chesneau2014/> It is estimated that Rigel has lost about three solar masses ({{solar mass}}) since beginning life as a star of {{val|24|3|u={{solar mass}}}} seven to nine million years ago.<ref name=aaa445_3_1099/>