4C +30.31

4C +30.31
SDSS image of 4C +30.31
Observation data (J2000 epoch)
ConstellationHercules
Right ascension17h 00m 45.23s[1]
Declination+30° 08′ 12.99″[1]
Redshift0.034424[1]
Heliocentric radial velocity10320 ± 250 km/s[1]
Distance519.8 ± 40.2 Mly (159.37 ± 12.32 Mpc)[1]
magnitude (H)11.59[1]
Characteristics
TypeWLRG LINER[1]
Size~237,000 ly (72.6 kpc) (estimated)[1]
Other designations
B2 1658+30, PGC 59420, 2MASX J17004523+3008129, NSA 147601, TXS 1658+302[1]

4C +30.31 known as B2 1658+30, is a radio galaxy located in the constellation of Hercules. The redshift of the object is (z) 0.034,[1] and it was first discovered from a sample of 490 astronomical radio sources by E.T. Olsen in August 1967.[2] In October 1972, this would be identified with an elliptical galaxy counterpart.[3]

Description

4C +30.31 is categorized as an elliptical galaxy with a smooth appearance based on imaging made by Hubble Space Telescope (HST).[3][4] It is also a weak radio galaxy based on optical imaging with a companion present suggesting it is located in a rich galaxy environment.[5] The extended emission-line region of the galaxy has been described to have a complex appearance with its central source being associated with a bright region. The region is also estimated to have an extend of 6.9 kiloparsecs and has an orientation of 143°.[6] The central core region has an unresolved appearance.[4]

The galaxy has also been classified as a Fanaroff-Riley Class Type 1 radio galaxy. When observed, there is a radio jet seen on one side and embedded inside a region of diffused radio emission. Radio imaging made at 1.4 GHz frequencies also suggested the source is a double.[7] The radio spectrum is also classified initially flat in the nucleus, but however it is found steepening on the outer regions.[8] On kiloparsec scales, the morphology of the source is the same, with two resolved radio lobes that are extended. There is a main jet clearly shown and pointing in the direction of southwest. As for the counter jet on the other hand, it is embedded within the lobe's low surface brightness region.[9] A low-ionization nuclear emission-line region (LINER) is suggested to be present in the galaxy.[7] A study also found the edges of the lobes contain signs of strong polarization levels reaching between 40% and 50%.[10]

References

  1. 1 2 3 4 5 6 7 8 9 10 "NED Search results for 4C 30.31". NASA/IPAC Extragalactic Database. Retrieved 2026-04-18.
  2. ↑ Olsen, E. T. (August 1967). "Accurate positions of selected 4C sources". The Astronomical Journal. 72: 738–746. Bibcode:1967AJ.....72..738O. doi:10.1086/110302. ISSN 0004-6256.
  3. 1 2 Hazard, C.; Jauncey, D. L. (October 1972). "Identification of 4C Sources with Galaxies". The Astronomical Journal. 77: 621. Bibcode:1972AJ.....77..621H. doi:10.1086/111327. ISSN 0004-6256.
  4. 1 2 Capetti, A.; de Ruiter, H. R.; Fanti, R.; Morganti, R.; Parma, P.; Ulrich, M.-H. (October 2000). "The HST snapshot survey of the B2 sample of low luminosity radio-galaxies: a picture gallery". Astronomy and Astrophysics. 362: 871–885. arXiv:astro-ph/0009056. Bibcode:2000A&A...362..871C. ISSN 0004-6361.
  5. ↑ Carrillo, R.; Cruz-González, I.; Guichard, J. (April 1997). "Weak Radio Galaxies. I. Broad-Band Optical Imaging". Revista Mexicana de Astronomia y Astrofisica. 33: 31–57. Bibcode:1997RMxAA..33...31C. ISSN 0185-1101.
  6. ↑ Carrillo, R.; Cruz-González, I.; Guichard, J. (April 1999). "Weak Radio Galaxies. II. Narrow-Band Optical Imaging and Physical Conditions". Revista Mexicana de Astronomia y Astrofisica. 35: 45. Bibcode:1999RMxAA..35...45C. ISSN 0185-1101.
  7. 1 2 Gonçalves, A. C.; Serote Roos, M. (January 2004). "The nuclear region of low luminosity flat radio spectrum sources. II. Emission-line spectra". Astronomy and Astrophysics. 413: 97–105. arXiv:astro-ph/0309620. Bibcode:2004A&A...413...97G. doi:10.1051/0004-6361:20031494. ISSN 0004-6361.
  8. ↑ Feretti, L.; Giovannini, G.; Gregorini, L.; Parma, P. (October 1983). "WSRT observations of elliptical galaxies from the B2 catalogue". Astronomy and Astrophysics. 126: 311–319. Bibcode:1983A&A...126..311F. ISSN 0004-6361.
  9. ↑ Giovannini, G.; Taylor, G. B.; Feretti, L.; Cotton, W. D.; Lara, L.; Venturi, T. (January 2005). "The Bologna Complete Sample of Nearby Radio Sources". The Astrophysical Journal. 618 (2): 635–648. arXiv:astro-ph/0409624. Bibcode:2005ApJ...618..635G. doi:10.1086/426106. ISSN 0004-637X.
  10. ↑ Mack, K.-H.; Gregorini, L.; Parma, P.; Klein, U. (January 1994). "High-frequency radio continuum observations of radio galaxies with low and intermediate luminosity. II. Sources with sizes 4' to 5'". Astronomy and Astrophysics Supplement Series. 103: 157–182. ISSN 0365-0138.
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