3C273
Encyclopedia
3C 273 is a quasar
located in the constellation
Virgo
. It was the first quasar ever to be identified.
It is the optic
ally brightest quasar in our sky (m
~12.9), and one of the closest with a redshift
, z, of 0.158. A luminosity distance of DL = 749 Mpc may be calculated from z. It is also one of the most luminous quasars known, with an absolute magnitude
of −26.7, meaning that if it was only as distant as Pollux
(~10 parsec
s) it would appear nearly as bright
in the sky as the Sun
. Its mass has been measured to be 886 ± 187 million solar mass
es through broad emission-line reverberation mapping
.
revealed a structured morphology evidenced by repeated bright knots interlaced by areas of weak emission.
) of the Third Cambridge
Catalog of Radio Sources (3C
), published in 1959. After accurate positions were obtained using lunar occultation by Cyril Hazard at the Parkes Radio Telescope,
the radio source was quickly associated with an optical counterpart, an unresolved stellar object. In 1963, Maarten Schmidt
and Bev Oke published a pair of papers in Nature
reporting that 3C 273 has a substantial redshift
, placing it several billion light-year
s away.
Prior to the discovery of 3C 273, several other radio sources had been associated with optical counterparts, the first being 3C 48. Also, many active galaxies had been misidentified as variable star
s, including the famous BL Lac
, W Com
, and AU CVn
. However, it wasn't understood what these objects were, since their spectra were unlike those of any known stars. 3C 273 was the first object to be identified as what we now know quasars to be — extremely luminous objects at cosmological distances.
3C 273 is a radio-loud quasar, and was also one of the first extragalactic X-ray
sources discovered in 1970.
However, even to this day, the process which gives rise to the X-ray emissions is controversial.
The luminosity
is variable at nearly every wavelength
from radio waves
to Gamma rays on timescales of a few days to decades.
Polarization with coincident orientation has been observed in radio, infrared, and optical light being emitted from the large-scale jet; these emissions are therefore almost certainly synchrotron
in nature, radiation that is created by a jet of charged particles moving at relativistic speeds.
Such jets are believed to be created by the interaction of the central black hole
and the accretion disk. VLBI radio observations of 3C 273 have revealed proper motion
of some of the radio emitting regions, further suggesting the presence of relativistic jets of material.
3C 273 is visible in May in both the northern hemisphere
and southern hemisphere
s. It is bright enough to be observed with larger amateur telescopes
. Its spectrum did not fit any patterns of normal stars that had been observed with normal gases.
Quasar
A quasi-stellar radio source is a very energetic and distant active galactic nucleus. Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than...
located in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Virgo
Virgo (constellation)
Virgo is one of the constellations of the zodiac. Its name is Latin for virgin, and its symbol is . Lying between Leo to the west and Libra to the east, it is the second largest constellation in the sky...
. It was the first quasar ever to be identified.
It is the optic
Optic
Optic may mean:* optic, a British term for a device for dispensing fixed amounts of alcoholic spirits* Optics, the study of the behavior and properties of light* An optical element or component, such as a lens, prism, or mirror...
ally brightest quasar in our sky (m
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
~12.9), and one of the closest with a redshift
Redshift
In physics , redshift happens when light seen coming from an object is proportionally increased in wavelength, or shifted to the red end of the spectrum...
, z, of 0.158. A luminosity distance of DL = 749 Mpc may be calculated from z. It is also one of the most luminous quasars known, with an absolute magnitude
Absolute magnitude
Absolute magnitude is the measure of a celestial object's intrinsic brightness. it is also the apparent magnitude a star would have if it were 32.6 light years away from Earth...
of −26.7, meaning that if it was only as distant as Pollux
Pollux (star)
Pollux is an orange giant star approximately 34 light-years from the Earth in the constellation of Gemini . Pollux is the brightest star in the constellation, brighter than Castor...
(~10 parsec
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
s) it would appear nearly as bright
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
in the sky as the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
. Its mass has been measured to be 886 ± 187 million solar mass
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
es through broad emission-line reverberation mapping
Reverberation mapping
Reverberation mapping is to-day a statistical method within astrophysics preferably used in connection with velocity analysis of gaseous discs around supermassive compact objects. The technique is used to measure the size of the broad emission-line region and mass of the alleged central black hole...
.
Large-scale jet
The quasar has a large-scale visible jet, which measures ~200 kly long, having an apparent size of 23″. In 1995 optical imaging of the jet using the Hubble Space TelescopeHubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
revealed a structured morphology evidenced by repeated bright knots interlaced by areas of weak emission.
History
The name signifies that it was the 273rd object (ordered by right ascensionRight ascension
Right ascension is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. The other coordinate is the declination.-Explanation:...
) of the Third Cambridge
University of Cambridge
The University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...
Catalog of Radio Sources (3C
Third Cambridge Catalogue of Radio Sources
The Third Cambridge Catalogue of Radio Sources is an astronomical catalogue of celestial radio sources detected originally at 159 MHz, and subsequently at 178 MHz. It was published in 1959 by members of the Radio Astronomy Group of the University of Cambridge...
), published in 1959. After accurate positions were obtained using lunar occultation by Cyril Hazard at the Parkes Radio Telescope,
the radio source was quickly associated with an optical counterpart, an unresolved stellar object. In 1963, Maarten Schmidt
Maarten Schmidt
Maarten Schmidt is a Dutch astronomer who measured the distances of quasars.Born in Groningen, The Netherlands, Schmidt studied with Jan Hendrik Oort. He earned his Ph.D. degree from Leiden Observatory in 1956....
and Bev Oke published a pair of papers in Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
reporting that 3C 273 has a substantial redshift
Redshift
In physics , redshift happens when light seen coming from an object is proportionally increased in wavelength, or shifted to the red end of the spectrum...
, placing it several billion light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s away.
Prior to the discovery of 3C 273, several other radio sources had been associated with optical counterparts, the first being 3C 48. Also, many active galaxies had been misidentified as variable star
Variable star
A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth...
s, including the famous BL Lac
BL Lac object
A BL Lacertae object or BL Lac object is a type of active galaxy with an active galactic nucleus and is named after its prototype, BL Lacertae. In contrast to other types of active galactic nuclei, BL Lacs are characterized by rapid and large-amplitude flux variability and significant optical...
, W Com
Coma Berenices
Coma Berenices is a traditional asterism that has since been defined as one of the 88 modern constellations. It is located near Leo, to which it formerly belonged, and accommodates the North Galactic Pole...
, and AU CVn
Canes Venatici
Canes Venatici is one of the 88 official modern constellations. It is a small northern constellation that was created by Johannes Hevelius in the 17th century. Its name is Latin for "hunting dogs", and the constellation is often depicted in illustrations as representing the dogs of Boötes the...
. However, it wasn't understood what these objects were, since their spectra were unlike those of any known stars. 3C 273 was the first object to be identified as what we now know quasars to be — extremely luminous objects at cosmological distances.
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
sources discovered in 1970.
However, even to this day, the process which gives rise to the X-ray emissions is controversial.
The luminosity
Luminosity
Luminosity is a measurement of brightness.-In photometry and color imaging:In photometry, luminosity is sometimes incorrectly used to refer to luminance, which is the density of luminous intensity in a given direction. The SI unit for luminance is candela per square metre.The luminosity function...
is variable at nearly every wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
from radio waves
Radio waves
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths from 1 millimeter to 100 kilometers. Like all other electromagnetic waves,...
to Gamma rays on timescales of a few days to decades.
Polarization with coincident orientation has been observed in radio, infrared, and optical light being emitted from the large-scale jet; these emissions are therefore almost certainly synchrotron
Synchrotron radiation
The electromagnetic radiation emitted when charged particles are accelerated radially is called synchrotron radiation. It is produced in synchrotrons using bending magnets, undulators and/or wigglers...
in nature, radiation that is created by a jet of charged particles moving at relativistic speeds.
Such jets are believed to be created by the interaction of the central black hole
Black hole
A black hole is a region of spacetime from which nothing, not even light, can escape. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole there is a mathematically defined surface called an event horizon that...
and the accretion disk. VLBI radio observations of 3C 273 have revealed proper motion
Proper motion
The proper motion of a star is its angular change in position over time as seen from the center of mass of the solar system. It is measured in seconds of arc per year, arcsec/yr, where 3600 arcseconds equal one degree. This contrasts with radial velocity, which is the time rate of change in...
of some of the radio emitting regions, further suggesting the presence of relativistic jets of material.
3C 273 is visible in May in both the northern hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
and southern hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...
s. It is bright enough to be observed with larger amateur telescopes
Amateur astronomy
Amateur astronomy, also called backyard astronomy and stargazing, is a hobby whose participants enjoy watching the night sky , and the plethora of objects found in it, mainly with portable telescopes and binoculars...
. Its spectrum did not fit any patterns of normal stars that had been observed with normal gases.
Trivia
- 'To the quasar', a song by Dutch project-band AyreonAyreonAyreon is a project by Dutch composer and musician Arjen Anthony Lucassen.Ayreon's musical style derives mostly from heavy metal and progressive rock, but combines them with genres like folk, classical and electronica...
is about quasar 3C 273. The song is found on the album 'Universal Migrator Part 2: Flight of the MigratorUniversal Migrator Part 2: Flight of the MigratorUniversal Migrator Part 2: Flight of the Migrator is a progressive metal album released in 2000 by Dutch multi-instrumentalist Arjen Lucassen, and is the fifth album of his Ayreon project....
'. - Given its distance from Earth and visual magnitude, 3C 273 is the most distant celestial object average amateur astronomers are likely to see through their telescopes.
External links
- 3C 273's Database at the INTEGRAL Science Data Centre (ESA)
- Detailed CCD image of 3C 273 based on 30 min total exposure
- Amateur 3C 273 Redshift Measurement
- NightSkyInfo.com - 3C 273
- 3C 273 at ESA/Hubble
- SKY-MAP.ORG SDSS image of 3C 273
- The Quasar 3C 273: Spring 2005 - Variable Star Of The Season AAVSO