Explanation cluster clusters range from rich

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Explanation: Cluster. Clusters range from rich aggregates of many thousands of stars to loose associations of only a few stars. The mutual gravitation of the stars in the larger clusters may hold them together more or less permanently; the small clusters may be held together so weakly that they will gradually dissipate into the field. A ____________ cluster is a circularly symmetrical system of stars with the highest concentration of stars near its own center. Globular. Most of the stars in the central regions of the cluster are not resolved as individual points of light, but appear as a nebulous glow. One of the most famous naked-eye globular clusters is M13 in the constellation of Hercules, which passes nearly overhead on a summer evening at most places in the United States. Below is a pic of M13:
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In contrast to the rich globular clusters, __________ clusters appear comparatively loose and "open". Explanation: Open. The open clusters contain far fewer stars than globular clusters and show little or no strong concentration of stars towards their own centers and lack the high degree of spherical symmetry that characterizes a globular cluster. They are relatively young and consist of younger, brighter, and hotter stars. Some open clusters appear irregular. Below is the Pleiades Cluster, which an open cluster: An _______________ is a group of stars that do not fall under the category of globular or open clusters. Association. Often a small open cluster can be found near the center of an association, but actually include stars that are widely spread that have a physical association or a common origin. Orion is one of the most well- known associations. The Life and Death of Stars The brightness and color of a star depend on its ____________ ______________. Explanation: Surface temperature. The hottest stars are blue, moving down the spectrum to the coolest stars, which are red.
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You can see this in the graphic below--the hottest and brightest stars are blue (upper left of the main sequence) and the coolest and least brightest stars are red (lower right of the main sequence). Note that we're talking about stars on the main sequence --we're not currently talking about red giants and white dwarves. The surface temperature may determine the brightness and color of a star, but the surface temperature itself is basically determined by the star's _______. Explanation: Mass. Given the mass of a star, we can tell a star's radius, luminosity and temperature. You can see this in the graphic below--the least massive stars are in the lower right, and as they move towards the upper-left on the main sequence, they're getting not only bigger, but hotter and brighter at the same time. Mass is really what determines a star's position on the main sequence. To summarize (for stars in the main sequence): o More mass means higher temperature o More mass means higher luminosity o More mass means bigger
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Because a star's mass determines how much fuel it has to burn and how fast it will burn that fuel, a star's mass also determines the _____________ of a star.
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