| 3C 273 | |
|---|---|
.jpg) | |
| Observation data(EpochJ2000) | |
| Constellation | Virgo |
| Right ascension | 12h 29m 06.7s[2] |
| Declination | +02° 03′ 09″[2] |
| Redshift | 0.158339 ± 0.000067[2] |
| Distance | 2.443 Gly (749 Mpc)[3][4] (luminosity distance) 1.80+0.32 −0.28 Gly (552+97 −79 Mpc)[5] (parallax distance) |
| Type | Blazar; Sy1[2] |
| Apparent magnitude (V) | 12.9[2] |
| Notable features | optically brightest quasar, first spectrum of a quasar |
| Other designations | |
| PGC 41121[2] andHIP 60936 | |
| See also:Quasar,List of quasars | |
3C 273 is aquasar located at the center of a giantelliptical galaxy in theconstellation ofVirgo. It was the first quasar ever to be identified and is the visually brightest quasar in the sky as seen from Earth, with anapparent visual magnitude of 12.9.[2] The derived distance to this object is 749megaparsecs (2.4 billionlight-years). The mass of its centralsupermassive black hole is approximately 900 million times themass of the Sun.
3C 273 is visible from March to July in both thenorthern andsouthern hemispheres. Situated in the Virgo constellation, it is bright enough to be observed by eye with a 6-inch (150 mm)amateur telescope.[6] Due in part to its radio luminosity and its discovery as the first identified quasar, 3C 273'sright ascension in theFifth Fundamental Catalog (FK5) is used to standardize the positions of 23 extragalactic radio sources used to define theInternational Celestial Reference System (ICRS).[7]
Given its distance fromEarth and visual magnitude, 3C 273 is the most distant celestial object average amateur astronomers are likely to see through their telescopes.
This is theoptically brightest quasar in the sky from Earth with anapparent visual magnitude of ~12.9, and one of the closest with aredshift,z, of 0.158.[8] Aluminosity distance of DL = 749megaparsecs (2.4 billionlight-years) may be calculated fromz.[4] Usingparallax methods with theVery Large Telescopeinterferometer yields anangular distance estimate of DA=1.80+0.32
−0.28 Gly (552+97
−79 Mpc).[5] The latter distance is relatted to the comoving distance as.
It is one of the most luminous quasars known, with anabsolute magnitude of −26.7,[9] meaning that if it were only as distant asPollux (~10parsecs) it wouldappear nearly as bright in the sky as theSun.[10] Since the Sun'sabsolute magnitude is 4.83, it means that the quasar is over 4 trillion times moreluminous thanthe Sun at visible wavelengths.[11]
Theluminosity of 3C 273 is variable at nearly everywavelength fromradio waves togamma rays on timescales of a few days to decades.Polarization with coincident orientation has been observed with radio,infrared, and optical light being emitted from alarge-scale jet; these emissions are therefore almost certainlysynchrotron in nature.[4] The radiation is created by a jet of charged particles moving atrelativistic speeds.VLBI radio observations of 3C 273 have revealedproper motion of some of the radio emitting regions, further suggesting the presence ofrelativistic jets of material.[12][13]
This is a prototype of anActive Galactic Nucleus, demonstrating that the energy is being produced throughaccretion by asupermassive black hole (SMBH). No other astrophysical source can produce the observed energy.[14] The mass of its central SMBH has been measured to be886±187 millionsolar masses through broad emission-linereverberation mapping.[15]
The quasar has a large-scale visiblejet, which measures ~200,000 light-years (61 kpc) long, having an apparent size of 23″.[4] Such jets are believed to be created by the interaction of the centralblack hole and theaccretion disk. In 1995, optical imaging of the jet using theHubble Space Telescope revealed a structuredmorphology evidenced by repeated bright knots interlaced by areas of weak emission.[4] The viewing angle of the jet is about 6° as seen from Earth. The jet was observed to abruptly change direction by an intrinsic angle of 2° in 2003, which is larger than the jet's intrinsic opening angle of 1.1°.[16] An expanding cocoon of heated gas is being generated by the jet, which may be impacting an inclined disk of gas within the central~ 6 kpc.[14]
3C 273 lies at the center of a giantelliptical galaxy with anapparent magnitude of 16 and an apparent size of 29arcseconds. Themorphological classification of the host galaxy is E4,[17] indicating a moderately flattened elliptical shape. The galaxy has an estimated mass of~ 2×1011 M☉.[18]
The name signifies that it was the 273rd object (ordered byright ascension) of the ThirdCambridge Catalog of Radio Sources (3C), published in 1959. After accurate positions were obtained usinglunar occultation byCyril Hazard at theParkes Radio Telescope,[19] the radio source was quickly associated with anoptical counterpart, an unresolvedstellar object. In 1963,Maarten Schmidt[8] andBev Oke[20] published a pair of papers inNature reporting that 3C 273 has a substantialredshift of 0.158, placing it several billionlight-years away.
Prior to the discovery of 3C 273, several other radio sources had been associated with optical counterparts, the first being3C 48. Also, manyactive galaxies had been misidentified asvariable stars, including the famousBL Lac,W Com andAU CVn. However, it was not understood what these objects were, since their spectra were unlike those of any known stars. Its spectrum did not resemble that of any normal stars with typical stellar elements. 3C 273 was the first object to be identified as aquasar—an extremely luminous object at an astronomical distance.
3C 273 is a radio-loud quasar, and was also one of the first extragalacticX-ray sources discovered in 1970. However, the process which gives rise to the X-ray emissions was still controversial as of 2006 when new observations were reported with theSpitzer Space Telescope.[4]
