what is meant by the second exotic class?
It is a pulsar with a rotational period smaller than about 40 milliseconds.
Millisecond pulsar
A millisecond pulsar (MSP) is a pulsar with a rotational period smaller than about 40 milliseconds.
some globular clusters have three main sequence tracks. this indicates UNANSWERABLE what is this cluster? It is a spherical collection of stars that orbits a galactic core. how is this clusters formed? The formation of globular clusters remains a poorly understood phenomenon and it remains uncertain whether the stars in a globular cluster form in a single generation or are spawned across multiple generations over a period of several hundred million years. what are this composed of? Globular clusters are generally composed of hundreds of thousands of low-metal, old stars. what are its exotic components? Some exotic classes of stars, such as "blue stragglers", "millisecond pulsars", and "low-mass X-ray binaries", are much more common in globular clusters. what is the first one? A blue straggler is a main-sequence star in an open or globular cluster that is more luminous and bluer than stars at the main sequence turnoff point for the cluster. are there any other types of it? "Yellow stragglers" or "red stragglers"
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Millisecond pulsar [SEP] Introduction
A millisecond pulsar (MSP) is a pulsar with a rotational period smaller than about 40 milliseconds. Millisecond pulsars have been detected in radio, X-ray, and gamma ray parts of the electromagnetic spectrum. The leading theory for the origin of millisecond pulsars is that they are old, rapidly rotating neutron stars that have been spun up or "recycled" through accretion of matter from a companion star in a close binary system. For this reason, millisecond pulsars are sometimes called recycled pulsars. Millisecond pulsars are thought to be related to low-mass X-ray binary systems. It is thought that the X-rays in these systems are emitted by the accretion disk of a neutron star produced by the outer layers of a companion star that has overflowed its Roche lobe.