Editing Alpha Herculis (section)

== Properties ==
[[File:AlphaHerLightCurve.png|thumb|left|A [[light curve]] for Alpha Herculis A, plotted from data published by Wasatonic (1997)<ref name=Wasatonic/>]]
Alpha Herculis A and B are more than 500 [[astronomical unit|AU]] apart, with an estimated [[orbital period]] of approximately 3600 years.{{cn|date=December 2022}} A presents as a relatively massive red [[bright giant]], but [[radial velocity]] measurements suggest a companion with a period of the order of a decade.<ref name="WDS"/> B's two components are a primary yellow [[giant star]] and a secondary, yellow-white [[dwarf star]] in a 51.578 day orbit.<ref name=deutsch/>

Alpha Herculis A is an [[asymptotic giant branch]] (AGB) star, a luminous red giant that has both hydrogen and helium shells around a degenerate carbon-oxygen core. It is the second nearest AGB star to the Sun. Its radius [[stellar pulsation|pulsates]] between 264 and 303 solar radii. At its minimum, the [[effective temperature]] is of {{convert|3155|K|C|abbr=on|lk=in}} 
and the luminosity is of 7,200 [[solar luminosity|solar luminosities]], while at its maximum the temperature is of {{convert|3365|K|C|abbr=on}} and the luminosity is of 9,330 solar luminosities.<ref name="moravveji"/> If Alpha Herculis were at the center of the [[Solar System]] its radius would extend past the orbit of [[Earth]] at 1.23{{snd}}1.4 [[astronomical unit|AU]] but not quite as far as the orbit of [[Mars]] or the [[asteroid belt]]. The red giant is estimated to have started its life with about {{solar mass|2.175-3.250}}.<ref name="moravveji"/>

The primary has been specified as a standard star for the spectral class M5 Ib-II.<ref name="moravveji"/> Like most [[Stellar classification#Class M|type M]] stars near the end of their lives, Alpha Herculis is experiencing a high degree of [[stellar mass loss]] creating a sparse, gaseous envelope that extends at least 930 AU.<ref name=deutsch/> It is a [[semiregular variable]] with complex changes in brightness with periods ranging from a few weeks to many years. The most noticeable variations occur at timescales of 80–140 days and at 1,000 - 3,000 days. The strongest detectable period is 128 days.<ref name=percy/> The full range in brightness is from magnitude 2.7 to 4.0,<ref name=gcvs/> but it usually varies over a much smaller range of around 0.6 magnitudes.<ref name=percy/>
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