Globular star clusters in the constellation Rhododendron
47 Tucanae (NGC 104）Is aRhododendronOfGlobular cluster, DistanceearthAbout 13000Light yearWith a diameter of 120 light-years[1]。Because the brightness reaches 4.1 which can be seen by the naked eye[2], so it was marked asFranstide nomenclatureNaming.Rhododendron 47 was discovered in 1751Nicolas Louis de Lacaille It was found that because of its south position, European observers had not seen this full moon sized star cluster before.It is the second brightest globular cluster in the whole day (the brightest isCentaur omega）, and there are very bright and dense cores. Through telescope observation, we can see about 10000fixed star；22 knownMillisecond pulsarThere are at least 21 of themBlue stragglerNear the core.Many stars gather in a small and dense central core, which may contain aIntermediate-mass black hole 。Rhododendron 47 has also beenPatrick Mower Included inCodwell Deep Space AstrometerMedium, namedC106。
It was recorded as a star cluster by Nicola Louis Lacai from 1751 to 1752.Nikola Louis Lakay originally thought it was the core of a bright comet[4]。Lakay then listed it as "Lakay 1", which was the first celestial body listed in his deep space catalog. Its designated number "47" was specified in General Description and Verification of the Stars and Indexes compiled by John Elite Bode and published in Berlin in 1801.
Celestial characteristics
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Rhododendron 47 is the second brightest in the skyGlobular cluster(Next to Omega Centauri), it has a bright and dense core, and its position in the sky is close toMagellanic nebula。It isGalaxyOne of the medium and large mass globular clusters, which contains millions of stars.Under ideal observation conditions, its size in the sky is roughly the same as that of the full moon.
Multiple star clusters in the corner of 47 Rhododendron
Azalea 47 contains at least twoStellar cluster, the ages of these stars and theirAmount of metalAre different[5]。The dense core of the cluster contains many stars with strange properties[6], including at least 21Blue stragglerThese are of high scientific research value.The massive stars in the cluster are located at the center of the cluster, and the lower mass stars are located near the edge of the cluster, with orderly hierarchical division[7]。
There are hundreds of star clustersX-ray source, including some newly formedneutron starBut astronomers can observe that[8]。Rhododendron 47 has the second largest of all known star clustersPulsargroup[9], astronomers have found that several main stars areMillisecond pulsarMost of these millisecond pulsars have oneWhite dwarfCompanion stars, and constantly accrete material from their companion stars[10]。Chandra X-ray ObservatoryX-ray emitted by many millisecond pulsars has been detected from the Rhododendron 47[11]，Fermi Gamma Ray Space Telescope It was also detected from the millisecond pulsar cluster of the clusterGamma ray[12]。
Central black hole
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The evidence for the existence of a black hole at the center of Rhododendron 47 is insufficient.according toHubble Space TelescopeAccording to the analysis of a series of observed relevant data, no black hole at the center of any star cluster may exist more than 1500 timesSolar mass[13]。However, astronomers announced in February 2017 that a black hole with a mass of about 2200 times that of the sun might exist in the center of the constellation Rhododendron 47. Researchers detected the signal of a suspected black hole from the distribution and movement of pulsars in the cluster[14]However, these cannot be reliable evidence for the existence of black holes[15]。
