M15（NGC 7078）Is located inPegasusOne ofGlobular cluster。It was discovered by Jean Dominique Maraldi in 1746 and included in 1764messier Comet like objects in the catalog.It is estimated to be 12 billion years old, and is one of the oldest known globular clusters
M15 is located in the silver halo, which is nearly 150 known halos around the Milky WayGlobular clusterOne of.The brightest star is the red giant, whose orange appearance is due to its lower surface temperature than the sun.Most of the darker stars have a higher surface temperature, so they are bluish white.If we live in the core of M15, our sky will be illuminated by tens of thousands of brilliant stars no matter day or night.Nestling among countless stars (can be seen in Hubble photos) is a strange astronomical phenomenon.
A pinkish object on one side of the core of a cluster.This is the gas cloud around the dying star.It is called Kuestner 648 (also known as the Bean Nebula) and is the first one found in a globular clusterPlanetary nebula。After the discovery of Kuestner 648 in 1928, scientists identified only three other planetary nebulae in the globular cluster.
In 2002, astronomers found that there was a dark and mysterious object lurking in the center of M15 - it may be a group of darkened neutron stars, or it may be aMedium mass black hole。Of these two possibilities, black holes are much more likely.
The dark red nebula in the upper left corner is Kuestner 648
M15 is the densest knownGlobular clusterOne is that most of the mass is concentrated in the core of the cluster.Astronomers believe that clusters as dense as M15 must have experienced core collapse——Tidal gravityThe effect makes most stars migrate to the core region.
M15 is about 33600 light years away from the earth and 175 light years in diameter.itsAbsolute magnitudeIt is - 9.2, and the converted total luminosity is 360000 times that of the sun.M15 is one of the most dense globular clusters known in the Milky Way.Its core has experienced a so-called core collapse, and there is a density cusp at its center, and there may be a large number of stars around the black hole that may have a center.
Home to more than 100000 stars, this cluster contains a large number of variable stars (112) and pulsars (8), including a pair ofneutron starSystem, M15 C. M15 also contains aPlanetary nebulaPea 1 is famous for being the first one found in globular clusters.Since 1928, only three other globular clusters have been found.
Messier object M15
Amateur astronomy
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The apparent magnitude of M15 is 6.2, which is close to the limit of naked eye visibility under good conditionsBinocularsOr small telescope observation, can see like a fuzzy star.With a larger aperture (at least 6 inches/15 centimeters), some stars can be resolved, of which the brightest apparent magnitude is+12.6.The apparent diameter of the cluster is 18 minutes.
M15 position
With an 8 inch (20 cm) telescope, you can see hundreds of bright stars in its peripheral area.
It can be observed with the naked eye in the clear starry sky.The minimum aperture of the telescope needed to observe M15 is 6 cm, and a 10 cm aperture telescope can distinguish a single star.
X-ray source
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Earth orbitsatelliteUhuruandCXOTwo bright X-ray sources are detected in this cluster: M15 X-1 (4U 2129+12) and M15 X-2.The former seems to be the first astronomical X-ray source detected in Pegasus.
