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Sigma Sagittarii

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	Topics Sigma Sagittarii Topic Home Sigma Sagitarii (s Sgr / s Sagittarii) is the second brightest star systemStar system A star system or stellar system is a system comprised of a star or group of stars, and, perhaps, planetary systems of ... in the constellationConstellation A constellation is any one of the 88 areas into which the sky - or the celestial sphere - is divided.... SagittariusSagittarius (constellation) For the astrological sign, see Sagittarius.... . Its modern name Nunki is an AssyriaAssyria Assyria in earliest historical times referred to a region on the Upper Tigris river, named for its original capital, the anc... n or Babylonian name recovered by archaeologists and made public by R.H.Allen. Nunki has an apparent magnitudeApparent magnitude The apparent magnitude of a star, planet or other celestial body is a measure of its apparent brightness as seen by an obse... of +2.1 and belongs to the spectral classificationStellar classification In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associ... B3. The total luminosityLuminosity Luminosity has different meanings in several different fields of science.... of s Sgr is 3300 times that of the SunSun \|+ The Sun \|+\|-\| colspan="2" align="center" \| \|-... while it has a mass of roughly 7 solar massSolar mass The "solar mass" is the standard way to express mass in astronomy.... es. The radius of the star is equivalent to 5 Suns and it has a surface temperature of 20,000 kelvinKelvin The Kelvin scale is a temperature scale where absolute zero—the coldest possible temperature where there is no heat en... s. Sigma Sgr has a magnitude +9.5 companion, Sigma Sagitarii B, located 5.2 arcminutes away. It may also have a closer companion. Because it is close to the eclipticEcliptic The ecliptic is the apparent path the Sun traces out along the sky — independent of Earth's rotation — in the co... , Nunki can be occultedOccultation Overview An occultation is an astronomical event that occurs when one celestial object is hidden by another celestial object that pas... by the MoonMoon The Moon is Earth's only natural satellite.... and very rarely by planetFacts About Planet The International Astronomical Union , the official scientific body for astronomical nomenclature, currently defines "plane... s. The last occultation of Nunki by a planet took place on November 17, 1981, when it was occulted by Venus. Furthermore, Nunki is the brightest star that can be principally occulted by an exterior planet. However, only Mars can do this, and only rarely; the last time was on September 3rd, 423. External links