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3C 273

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3C 273 is a remarkable object known as a quasar. A quasar is an extremely luminous object located at a massive astronomical distance. This specific quasar sits at the center of a giant elliptical galaxy. This host galaxy is located within the constellation of Virgo.

Quasar 3C273 Full Ground-Based Color Image
Quasar 3C273 Full Ground-Based Color Image

Because of its incredible brightness, 3C 273 is the visually brightest quasar in the sky as seen from Earth. It has an apparent visual magnitude of approximately 12.9. This brightness allows it to outshine its entire host galaxy by more than 16 times. For many amateur astronomers, it is the most distant object they are likely to see through a telescope.

The immense energy of 3C 273 comes from a central supermassive black hole. This black hole has a mass of approximately 900 million solar masses. The energy is produced through a process called accretion. Accretion occurs when the black hole pulls in nearby material. This makes 3C 273 a prototype of an Active Galactic Nucleus. This term describes a galaxy with an extremely active and bright center.

Quasar 3C 273
Quasar 3C 273

The energy produced by this process is so great that no other astrophysical source can match it. The light from this object can change at nearly every wavelength. This includes everything from radio waves to gamma rays. These changes can happen on timescales ranging from a few days to many decades.

A major feature of 3C 273 is its large-scale visible jet. This jet is made of charged particles moving at relativistic speeds. Relativistic speeds mean the particles are moving at a significant fraction of the speed of light. The jet has an apparent size of 23 arcseconds. In 1995, the Hubble Space Telescope showed that the jet has a structured morphology. This means it has a specific shape consisting of bright knots. These knots are interlaced with areas of weak emission.

Quasar 3C 273
Quasar 3C 273

The jet is viewed from Earth at an angle of about 6 degrees. In 2003, the jet was observed to change its direction by an intrinsic angle of 2 degrees. This jet also generates an expanding cocoon of heated gas. This gas may be impacting an inclined disk of gas within the central galaxy.

The history of 3C 273 is tied to the discovery of quasars. Its name comes from the Third Cambridge Catalog of Radio Sources. It was the 273rd object listed in that 1959 catalog. Astronomers like Cyril Hazard used lunar occultation to find its accurate position. This was done using the Parkes Radio Telescope. In 1963, researchers Maarten Schmidt and Bev Oke published important papers in the journal Nature. They identified that 3C 273 has a substantial redshift of 0.158. A redshift is a measurement that helps determine how far away an object is. This discovery placed the object several billion light-years away. Before this, many scientists thought such bright objects were just variable stars.

3C 273 is one of the most luminous objects known in the universe. Its absolute magnitude is -26.7. This is a measurement of its true brightness regardless of distance. To understand this scale, consider the Sun. The Sun has an absolute magnitude of 4.83. The quasar is over 4 trillion times more luminous than the Sun at visible wavelengths.

Quasar 3C 273
Quasar 3C 273

If 3C 273 were located as close as the star Pollux, it would appear nearly as bright as the Sun. It was also one of the first extragalactic X-ray sources discovered in 1970. These X-ray emissions are part of the complex radiation coming from the active nucleus.

The host galaxy of 3C 273 provides important context for the quasar. The galaxy is a giant elliptical galaxy. It is classified as E4, which means it has a moderately flattened shape. The galaxy has an estimated mass of 10^12 solar masses. It has an apparent magnitude of 16 and an apparent size of 29 arcseconds.

Quasar 3C273 Full Ground-Based Color Image
Quasar 3C273 Full Ground-Based Color Image

Because the quasar is so bright, astronomers often use a coronagraph to block its light. This allows them to see the surrounding host galaxy more easily. This technique helps scientists study how the massive black hole interacts with its environment.

3C 273 is a vital tool for modern astronomy and celestial mapping. Its position is used to help define the International Celestial Reference System. Specifically, its right ascension in the Fifth Fundamental Catalog is used to standardize 23 other radio sources. This makes it a fundamental part of how we map the positions of objects in space. By studying the synchrotron radiation from its jets, scientists learn about particle physics. Synchrotron radiation is light emitted by charged particles moving through magnetic fields. 3C 273 connects the study of individual particles to the structure of entire galaxies.

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