Consider the following pairs: Objects in space Description1. Cepheids Giant clouds of dust and gas in space2. Nebulae Stars which brighten and dim periodically3. Pulsars Neutron stars that are formed when massive stars run out of fuel and collapseHow many of the above pairs are correctly matched?
✓ Correct answer: a) Only one
ExplanationPair 1 is not correct: Cepheids, also known as Cepheid Variables, are stars that periodically brighten and dim.Due to their behaviour, these objects can function as cosmic indicators, extending their usefulness as yardsticks for distances up to several tens of millions of light-years away, owing to a consistent relationship between their brightness and other factors.Pair 2 is not correct: A nebula is a very large cloud of gas and dust in outer space.A dead star’s explosion, such as a supernova, releases gas and dust, which in turn forms certain nebulae (more than one nebula).Other nebulae are places where brand-new stars are only starting to develop.It is for this reason that some nebulae are referred to as “star nurseries.” Pair 3 is correct: Pulsars are extremely compact, rapidly spinning neutron stars that have a diameter of no more than 20 km (12 miles).They are virtually entirely made of neutrons that are formed when massive stars run out of fuel and collapse.101
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