NRAO 140 | |
---|---|
Observation data (J2000.0 epoch) | |
Constellation | Perseus |
Right ascension | 03h 36m 30.1076s |
Declination | +32° 18′ 29.342″ |
Redshift | 1.265200 |
Heliocentric radial velocity | 379,297 km/s |
Distance | 8.432 Gly |
Apparent magnitude (V) | 17.50 |
Characteristics | |
Type | Opt. var, LPQ, RLQ |
Other designations | |
INTREF 154, LEDA 2820229, QSO J0336+3218, OHIO E 355, 2E 801, 1H 0332+317, 4C 32.14, DA 107, RX J0336.5+3218 |
NRAO 140 is a quasar [1] located in the constellation of Perseus, noted for its low frequency variability. [2] It has a redshift of (z) 1.258, [3] [4] first discovered in 1973 by Duncan Agnew and Halton Arp as an astronomical radio source, whom they catalogued it as 4C 32.14. [5]
NRAO 140 is classified as a radio-selected blazar (RBL) based on European X-ray Observatory Satellite (EXOSAT) observations. However the object has no presence of either long-term or rapid fluxes. Its radio spectrum is flat, making it a flat-spectrum source, [6] but also exhibiting radio and X-ray fluxes that lasted between 1979 and 1985. [7] The brightness temperature of NRAO 140 is estimated to be between 5 x 1015 and 5 x 1014 Kelvin. [8]
A low frequency outburst was detected in NRAO 140 by the Very Long Baseline Array (VLBI) observations, peaking in 1981 with the component undergoing a decrease in brightness levels as the outburst faded. [9] [10] Between August 7 and 9 in 1986, the object displayed rising levels in K flux from 1.25 ± 0.06 mJy to around 1.54 ± 0.05 mJy in a span of two days during the observation campaign. [1]
Radio imaging made by Very Large Array (VLA) at both 21 and 6 centimeters (cm) shows the structure of NRAO 140 is made up of only a single secondary component with a position angle of 150°. Other radio images made by the Westerbork Synthesis Radio Telescope shows NRAO 140 has two components located on both sides of the radio core, consisting of a southwestern component at a position angle of 149° and a northeastern component at a position angle of -31° opposed to images made by VLA. [11] VLBI observations also shows evidence of superluminal motion in several components separating at an angular rate of 0.10-0.14 milliarcseconds. [12]
The jet in NRAO 140 is found to bend slightly towards the south direction from the radio core with detections of polarized flux in its jet components. In additional, the position angle of the jet is found nearly perpendicular towards the jet's axis, with the jet itself having a faraday rotation measure gradient extended by 8 milliarcseconds from the core. By constraining the upper limits of the jet's viewing angle, the jet is confirmed to have a linear extent greater than 350 parsecs. [13]
3C 345 is a blazar/flat spectrum radio quasar located in the constellation of Hercules. It is noted for hosting a superluminal jet and its variability in almost all wave bands.
4C +71.07 known as S5 0836+71, is a quasar located in the constellation Ursa Major. Based on its high redshift, the object is located 10.7 billion light-years away from Earth and such, classified as a blazar with a flat-spectrum radio source and features a radio jet.
AO 0235+164 is a BL Lacertae object located in the constellation of Aries, 7.5 billion light years from Earth. It has a redshift of 0.94. It was first discovered as an astronomical radio source by astronomers between 1967 and 1970, and formally identified with a red stellar object in 1975. Because of its extreme variability at both radio and optical wavelengths across the electromagnetic spectrum, this BL Lac object has been referred to as a blazar.
NRAO 530 or PKS 1730-13 is a flat-spectrum radio quasar located in the southern constellation of Serpens. It has a redshift of 0.902. and was first discovered by two astronomers, W.J. Welch and Hyron Spinrad in 1973. It is classified as a blazar because of its optical variability across the electromagnetic spectrum in radio, gamma ray and X-ray bands. This quasar is also further categorized an OVV quasar.
PKS 0208-512 is a blazar located in the southern constellation of Eridanus. It has a redshift of 1.003 and was first discovered in 1975 by astronomers conducting the Parkes 2700 MHz survey in Australia as a bright astronomical radio source. This object is also classified highly polarized with the radio spectrum appearing to be flat, thus making it a flat-spectrum radio quasar.
3C 138 is a quasar located in the constellation of Taurus. It has a redshift of (z) 0.76. The radio spectrum of this source appears both compact and steep, making it a compact steep-spectrum radio quasar. It is also one of the few 3C objects showing a defined and turn-over in its electromagnetic spectrum at low frequencies.
DA 193 is a blazar located in the constellation of Auriga. It has a high redshift of 2.365. It was first discovered as an unknown astronomical radio source in 1971 by D.G. MacDonell and A.H. Bridle. This is a low polarized quasar containing a classic homogeneous synchrotron self-absorption spectrum. The radio spectrum of this source shows a turnover frequency at 5 GHz and this object has also been referred to as a gigahertz-peak spectrum source.
PKS 0537-441 is a blazar located in the constellation of Pictor. It has a redshift of 0.896 and was discovered in 1973 by an American astronomer named Olin J. Eggen, who noted it as a luminous quasar. This is a BL Lacertae object in literature because of its featureless optical spectra as well as both a possible gravitational microlensing and a gravitationally lensed candidate. Its radio source is found compact and is characterized by a spectral peak in the gigahertz range, making it a gigahertz-peaked spectrum source (GPS).
S5 1803+784 is a BL Lacertae object located in the far northern constellation of Draco. It has an estimated redshift of (z) 0.68 and was first discovered as an astronomical radio source in 1981 by a team of astronomers. This object is also classified as a blazar because of its extreme variability on the electromagnetic spectrum and a source of gamma ray activity. According to preliminary analysis in May 2011, the source of S5 1803+784 has a gamma ray flux of electron−6 photon cm−2 s−1.
PKS 0420-014 is a blazar located in the constellation of Eridanus. This is a high polarized quasar with a redshift of (z) 0.915, first discovered as an astronomical radio source by astronomers in 1975. The radio spectrum of this source appears to be flat, making it a flat-spectrum radio quasar (FRSQ).
PKS 1622-297 is a blazar located in the constellation of Scorpius. It is one of the brightest objects of its type in the gamma ray region. It has a redshift of (z) 0.815. This blazar was first discovered as a compact astronomical radio source in 1970 by astronomers who were conducting interferometer observations and identified with an optical counterpart in 1984. In addition, the radio spectrum of the source appears flat, making it a flat-spectrum radio quasar (FRSQ).
PKS 0458-020 also known as PKS 0458-02, is a quasar located in the constellation of Orion. It has a redshift of (z) 2.286 and was first identified as an astronomical radio source during the radio survey conducted by Parkes Observatory in 1966. Subsequently the source was shown to display optical behavior before being classfied as a blazar via an optical polarimetry study in 1985. This source also shows radio spectrum appearing to be flat, hence making it a flat-spectrum radio quasar (FRSQ).
PKS 1510-089 is a blazar located in the constellation of Libra, categorized as a highly polarized quasar showing fast variations in polarization angles, with a redshift of (z) 0.361. It was first discovered in 1966 as an astronomical radio source during the Parkes Observatory survey in 1966. The radio spectrum of the source appears flat, thus making it a flat-spectrum radio quasar (FRSQ).
3C 309.1 is a quasar located in the constellation of Ursa Minor. It has a redshift (z) of 0.90 and was first identified as an astronomical radio source from the Third Cambridge Catalogue of Radio Sources by in 1966. This object contains a compact steep spectrum (CSS) source, and is classified as one of the brightest and largest of its kind.
PKS 0454-234 is a blazar located in the constellation of Lepus. It is classified as a highly polarized quasar with a redshift of (z) 1.003. This object was first discovered in 1970 during a 1415 MHz continuum survey conducted by Ohio State University where it was given the designation, OF -292. The radio spectrum of this source is flat, making it a flat-spectrum radio quasar.
4C +28.07 is a blazar located in the constellation of Aries. It has a redshift of 1.213 and was first discovered in 1970 as a compact astronomical radio source during an interferometer observation and designated as CTD 20. The radio spectrum of the source is considered flat, making it a flat-spectrum radio quasar. It is one of the brightest blazars observed in the gamma ray energy band.
PKS 2255-282 is a blazar located in the constellation of Piscis Austrinus. This is a low-polarized quasar at the redshift of 0.926, first discovered in 1975 by astronomers via a spectroscopic observation. The radio spectrum of this source appears as flat, making it as a flat-spectrum quasar but also a Gigahertz Peaked Spectrum source (GPS) with turnover frequency between 22 and 37 GHz.
PKS 1127-145 is a radio-loud quasar located in the constellation of Crater. This is a Gigahertz Peaked Spectrum object with a redshift of (z) 1.187, first discovered by astronomers in 1966. Its radio spectrum appears to be flat making it a flat-spectrum radio quasar, or an FRSQ in short.
PKS 0528+134 is a distant blazar located in the Galactic anticenter towards the constellation of Orion. This is a compact radio quasar, classified as radio-loud with a redshift of (z) 2.07 yet having low polarization. It was first discovered in 1977 by astronomers as a radio source and contains a radio spectrum that appears as flat making it a flat-spectrum radio quasar. It has an optical brightness of 19.5.
PKS 1741-03 is a blazar located in the constellation of Ophiuchus. This is core-dominated quasar located at a redshift of (z) 1.054, found to be highly polarized. It was first discovered in 1970 as an extragalactic radio source by astronomers and has a radio spectrum appearing to be flat, making it a flat-spectrum source.