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3C 48

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

3C 48 is a quasar, a highly luminous active galactic nucleus powered by a supermassive black hole at the center of a distant galaxy. It is one of the first quasars ever discovered and has been extensively studied to understand the nature of these enigmatic celestial objects.

5 Must Know Facts For Your Next Test

  1. 3C 48 was the first quasar to be identified as a distinct class of astronomical objects, separate from stars and galaxies.
  2. It was discovered in 1960 by radio astronomers, who initially thought it was a star due to its point-like appearance.
  3. The extremely high luminosity of 3C 48 is believed to be the result of the accretion of matter onto a supermassive black hole at the center of a distant galaxy.
  4. The spectrum of 3C 48 shows broad emission lines, which are characteristic of quasars and indicate the presence of high-velocity gas in the vicinity of the black hole.
  5. 3C 48 is located at a redshift of 0.367, corresponding to a distance of approximately 1.9 billion light-years from Earth.

Review Questions

  • Explain the significance of 3C 48 in the context of quasars and active galactic nuclei.
    • 3C 48 was one of the first quasars to be discovered and is considered a landmark object in the study of these highly luminous active galactic nuclei. Its identification as a distinct class of astronomical objects, separate from stars and galaxies, was a crucial step in understanding the nature of quasars. The extremely high luminosity of 3C 48 is believed to be powered by the accretion of matter onto a supermassive black hole at the center of a distant galaxy, a process that is characteristic of active galactic nuclei. The broad emission lines observed in the spectrum of 3C 48 provide further evidence of the high-velocity gas in the vicinity of the black hole, which is a key feature of quasars.
  • Describe the role of redshift in the study of 3C 48 and its implications for the distance and properties of the quasar.
    • The redshift of 3C 48, measured at 0.367, is a crucial piece of information in understanding the nature and properties of this quasar. Redshift is a measure of the expansion of the universe, and for distant objects like 3C 48, it can be used to calculate the object's distance from Earth. In the case of 3C 48, the measured redshift corresponds to a distance of approximately 1.9 billion light-years, making it one of the most distant objects known at the time of its discovery. The high redshift also indicates that 3C 48 is receding from us at a significant velocity due to the expansion of the universe, which has important implications for the luminosity and other physical characteristics of the quasar.
  • Analyze the significance of the broad emission lines observed in the spectrum of 3C 48 and how they contribute to our understanding of the quasar's structure and dynamics.
    • The broad emission lines observed in the spectrum of 3C 48 are a key feature that provides valuable insights into the structure and dynamics of this quasar. These broad lines, which are characteristic of quasars, indicate the presence of high-velocity gas in the vicinity of the supermassive black hole at the center of the host galaxy. This high-velocity gas is believed to be part of the accretion disk or the outflowing jets associated with the active galactic nucleus. By analyzing the properties of these broad emission lines, such as their width, intensity, and shift, astronomers can infer the physical conditions and kinematics of the gas, which in turn helps them better understand the complex processes driving the extreme luminosity and activity of 3C 48 and other quasars.
3C 48 Definition - Intro to Astronomy Key Term | Fiveable