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Arcturus is an orange-red giant of the spectral type K1.5 IIIpe. The star has some 24.5 times the diameter of our [[Sun]]. Like all giants, it has a low mass compared to its size, having only 1.5 times the mass of our Sun.<ref name="illinois">http://www.astro.illinois.edu/~jkaler/sow/arcturus.html</ref> Arcturus is 115 times as bright as our sun visually, although its absolute magnitude is 215 times as great counting the [[infrared]].<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2002hgs..book.....K&db_key=AST&data_type=HTML&format=&high=45e3861c6616357</ref> The star has rather low [[metallicity]], being only 17 to 32 percent as abundant as our Sun in elements heavier then [[hydrogen]], based on its abundance of [[iron]].<ref>http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1998Obs...118..299G&data_type=PDF_HIGH&type=PRINTER</ref>
Arcturus is an orange-red giant of the spectral type K1.5 IIIpe. The star has some 24.5 times the diameter of our [[Sun]]. Like all giants, it has a low mass compared to its size, having only 1.5 times the mass of our Sun.<ref name="illinois">http://www.astro.illinois.edu/~jkaler/sow/arcturus.html</ref> Arcturus is 115 times as bright as our sun visually, although its absolute magnitude is 215 times as great counting the [[infrared]].<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2002hgs..book.....K&db_key=AST&data_type=HTML&format=&high=45e3861c6616357</ref> The star has rather low [[metallicity]], being only 17 to 32 percent as abundant as our Sun in elements heavier then [[hydrogen]], based on its abundance of [[iron]].<ref>http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1998Obs...118..299G&data_type=PDF_HIGH&type=PRINTER</ref>
As a helium-burning giant star that has consumed all its [[hydrogen]] core fuel and left the main sequence, it has fully shifted to fusing [[helium]] in its core into [[carbon]] and [[oxygen]]. This stage of the star's life will only last some tens to hundreds of millions of years. Eventually the star will begin to lose its mass and the gases will puff out as a[[ planetary nebula]] containing mostly hydrogen and helium, with smaller amounts of other elements. What will be left is a [[white dwarf]] star that will gradually cool and fade over time.
As a helium-burning giant star that has consumed all its [[hydrogen]] core fuel and left the main sequence, it has fully shifted to fusing [[helium]] in its core into [[carbon]] and [[oxygen]]. Eventually the star will begin to lose its mass and the gases will puff out as a[[ planetary nebula]] containing mostly hydrogen and helium, with smaller amounts of other elements. What will be left is a [[white dwarf]] star that will gradually cool and fade over time.
There are no known substellar companions orbiting Arcturus at this time. Any world that would have been [[terrestrial planet|Earth-like]] while Arcturus was on the main sequence would have long ago been destroyed. For such a world to exist now with liquid water on its surface, it would need to be centered around 11 AU away, or between the orbital distances of [[Saturn]] and [[Uranus]] in our solar system. Such a world would be extremely difficult to detect using current methods.
There are no known substellar companions orbiting Arcturus at this time. Any world that would have been [[terrestrial planet|Earth-like]] while Arcturus was on the main sequence would have long ago been destroyed. For such a world to exist now with liquid water on its surface, it would need to be centered around 11 AU away, or between the orbital distances of [[Saturn]] and [[Uranus]] in our solar system. Such a world would be extremely difficult to detect using current methods.