Changes

| parallax        =43.46±0.28 mas<ref name=simbad/><ref name=hip/>

| parallax        =43.46±0.28 mas<ref name=simbad/><ref name=hip/>

}}

}}

'''Alpha Coronae Borealis''' (Alphecca, α Coronae Borealis, α CrB, 5 Coronae Borealis) is a [[main sequence star]] in the [[constellation]] of [[Corona Borealis]], the Northern Crown.<ref name=constellation-guide/> The star is known by several names: Alphecca (which roughly translates as “the bright one of the broken ring” in [[Arabic]]), Gemma (“jewel” in [[Latin]]), Asteroth (“idols” in [[Hebrew]]), and Gnosia (short for “Gnosia stella coronae,” or “the star of the crown of Knossos” in Latin).<ref name=constellation-guide/> The star is in fact one star in a [[binary star|binary system]] of two stars.  The brightest star in the Northern Crown, it was first catalogued in the 2nd century by the [[Ancient Greece|Greek]] astronomer, [[Ptolemy]].<ref name=osr>{{cite web|url=https://osr.org/blog/astronomy/alpha-coronae-borealis/|title=Alpha Coronae Borealis – Star Facts|accessdate=2019-04-13|publisher=osr.org|date=2016-06-01}}</ref> The star is bright enough to be seen with the unaided eye and is best observed in the mid-northern latitudes between April, May and June. It can be found by drawing an imaginairy line from [[Arcturus]] to [[Vega]].

'''Alpha Coronae Borealis''' (Alphecca, α Coronae Borealis, α CrB, 5 Coronae Borealis) is a [[main sequence star]] in the [[constellation]] of [[Corona Borealis]], the Northern Crown.<ref name=constellation-guide/> The star is known by several names: Alphecca (which roughly translates as “the bright one of the broken ring” in [[Arabic]]), Gemma (“jewel” in [[Latin]]), Asteroth (“idols” in [[Hebrew]]), and Gnosia (short for “Gnosia stella coronae,” or “the star of the crown of Knossos” in Latin).<ref name=constellation-guide/> The star is in fact one star in a [[binary star|binary system]] of two stars.  The brightest star in the Northern Crown, it was first catalogued in the 2nd century by the [[Ancient Greece|Greek]] astronomer, [[Ptolemy]].<ref name=osr>{{cite web|url=https://osr.org/blog/astronomy/alpha-coronae-borealis/|title=Alpha Coronae Borealis – Star Facts|accessdate=2019-04-13|publisher=osr.org|date=2016-06-01}}</ref> The star is bright enough to be seen with the unaided eye and is best observed in the mid-northern latitudes between April, May and June. It can be found by drawing an imaginary line from [[Arcturus]] to [[Vega]].

Situated approximately 75 [[light year]]s from [[Earth]], Alpha Coronae Borealis a white star belonging to [[spectral type|spectral class]] A0V.<ref name=osr/> Its [[spectrum]] shows a large excess of [[infrared|infrared radiation]], thought to be caused by a disk of dust and other material surrounding the star. Such a disc may contain [[planet]]s. The star is 67 times more luminous than the [[Sun]] and possess a radius 2.7 times as large.<ref name=illinois>{{cite web|url=http://stars.astro.illinois.edu/sow/alphecca.html|title=ALPHECCA|accessdate=2019-04-13|publisher=stars.astro.illinois.edu|work=Stars|author=Jim Kaler}}</ref> Its mass is estimated at 2.7 [[solar mass]]es and it has a high surface temperature of 10,000 kelvin.<ref name=illinois/> The star rotates quickly, with a speed of 110&nbsp;km/s, though other sources put it higher at 127-133&nsbp;km/s.<ref>

Situated approximately 75 [[light year]]s from [[Earth]], Alpha Coronae Borealis a white star belonging to [[spectral type|spectral class]] A0V.<ref name=osr/> Its [[spectrum]] shows a large excess of [[infrared|infrared radiation]], thought to be caused by a disk of dust and other material surrounding the star. Such a disc may contain [[planet]]s. The star is 67 times more luminous than the [[Sun]] and possess a radius 2.7 times as large.<ref name=illinois>{{cite web|url=http://stars.astro.illinois.edu/sow/alphecca.html|title=ALPHECCA|accessdate=2019-04-13|publisher=stars.astro.illinois.edu|work=Stars|author=Jim Kaler}}</ref> Its mass is estimated at 2.7 [[solar mass]]es and it has a high surface temperature of 10,000 kelvin.<ref name=illinois/> The star rotates quickly, with a speed of 110&nbsp;km/s, though other sources put it higher at 127-133&nbsp;km/s.<ref>

{{cite journal

{{cite journal

  |last1=Royer |first1=F.

  |last1=Royer |first1=F.

  |ref=harv

  |ref=harv

}}

}}

</ref> Alpha Coronae Borealis is sometimes referred to as Alphecca-A to distinguish it from the system or the companion which is then designated Alphecca-B. The average separation between the stars is 0.20&nbsp;[[AU]] (smaller than the distance between the Sun and [[Mercury]]), though the [[eccentricity]] of the [[orbit]] of ''e''=0.35 means it varies from 0.13&nsbp;AU up to 0.27&nsbp;AU.<ref name=illinois/><ref>Eccentricity computed using ''a''_min=(1-''e'')''a'', with ''a''_min=0.13&nsbp;AU, ''a''=0.2&nbsp;AU.</ref> These two stars are believed to be part of the Ursa Major Moving Group, a collection of stars in [[Ursa Major]] that share a common motion through space.

</ref> Alpha Coronae Borealis is sometimes referred to as Alphecca-A to distinguish it from the system or the companion which is then designated Alphecca-B. The average separation between the stars is 0.20&nbsp;[[AU]] (smaller than the distance between the Sun and [[Mercury]]), though the [[eccentricity]] of the [[orbit]] of ''e''=0.35 means it varies from 0.13&nbsp;AU up to 0.27&nbsp;AU.<ref name=illinois/><ref>Eccentricity computed using ''a''_min = (1-''e'')''a'', with ''a''_min = 0.13&nbsp;AU, ''a'' = 0.2&nbsp;AU.</ref> These two stars are believed to be part of the Ursa Major Moving Group, a collection of stars in [[Ursa Major]] that share a common motion through space.

Alphecca-B is a main sequence star with spectral class G5 and is an 8^th magnitude star, too dim to be seen with the naked eye.<ref>{{cite web|url=http://www.constellationsofwords.com/stars/Alphecca.html|title=Alphecca|accessdate=2019-04-13|publisher=constellationsofwords.com}}</ref> The system is classified as an [[variable star|EA variable]], meaning the brightness of Alpha Coronae Borealis varies as it is eclipsed by its companion from +2.21 up to +2.32.<ref name=constellation-guide/>  The companion star is smaller than Alpha Coronae Borealis with a mass of 0.92 [[solar mass]]es and radius of 0.9 that of Sol.<ref name=osr/> Alphecca-B is a powerful [[x-ray]] source, though to be caused by "solar-like magnetic activity".<ref name=illinois/>

Alphecca-B is a main sequence star with spectral class G5 and is an 8^th magnitude star, too dim to be seen with the naked eye.<ref>{{cite web|url=http://www.constellationsofwords.com/stars/Alphecca.html|title=Alphecca|accessdate=2019-04-13|publisher=constellationsofwords.com}}</ref> The system is classified as an [[variable star|EA variable]], meaning the brightness of Alpha Coronae Borealis varies as it is eclipsed by its companion from +2.21 up to +2.32.<ref name=constellation-guide/>  The companion star is smaller than Alpha Coronae Borealis with a mass of 0.92 [[solar mass]]es and radius of 0.9 that of Sol.<ref name=osr/> Alphecca-B is a powerful [[x-ray]] source, though to be caused by "solar-like magnetic activity".<ref name=illinois/>