quasar
quasar
Definition
☆ qua·sar (kwā′zär′, -sär′)
noun
any of a number of starlike celestial objects that emit immense amounts of light and, often, radio waves, characterized by having spectral lines with very large redshifts: quasars are thought to be the most distant and oldest observable objects in the universe
Etymology: < quas(i-stell)ar (radio source)
quasar
Usage Examples
Converse of object
- obscure: Several strong candidates for Type 2, or obscured quasars have been discovered.
- know: An example of this can be seen in the spectrum of the most distant quasar currently known.
- find: Finding the powerful quasars responsible for the X-ray background radiation.
- detect: The total number of ROSAT detected radio quasars from the above three sources is 654 objects.
- observe: Further evidence comes from astronomical observation - astronomers look into the past when they look into space and have been measuring and observing quasars.
- call: The objects called quasars are very strong point like radio sources, which can, like all radio objects, be detected in daylight.
Adjective modifier
- distant: Most types of cosmic object known to exist, from dwarf stars to the most distant quasars, are known to emit X-rays.
- bright: It is a suggestive coincidence that the space density of bright optical quasars also reached a peak sometime around z = 2-3.
- high: The low and high redshift quasars are found very similar in their emission characteristics, although differences exist.
- several: In several quasars, small, discrete sources have been found that change position from one observation to the next.
- nearby: At a distance of 1 billion light-years, Mrk 205 is a relatively nearby quasar.
Modifies a noun
- absorption: The nub of the lecture was work on the very high-resolution spectroscopy of quasar absorption lines.
- line: The nub of the lecture was work on the very high-resolution spectroscopy of quasar absorption lines.
- survey: It has also been involved with quasar surveys and more recently the discovery of over 20 planets around other stars.
- activity: Possible links between these black holes and quasar activity early in the history of the Universe.
Noun used with modifier
- redshift: The low and high redshift quasars are found very similar in their emission characteristics, although differences exist.
- radio-loud: Almost one quarter of these are members of a previously unknown class of X-ray bright, flat spectrum, radio-loud quasars.
- high-redshift: Some astronomers supported this point of view, and have sought evidence for physical associations between high-redshift quasars and low-redshift normal galaxies.
- radio: The total number of ROSAT detected radio quasars from the above three sources is 654 objects.
- background: HI can be studied in absorption against background quasars out to z 4 with the HIA.
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