UGC 8669

UGC 8669
SDSS image of UGC 8669.
Observation data (J2000.0 epoch)
ConstellationBoötes
Right ascension13h 41m 49.10s
Declination+26° 22′ 21.01″
Redshift0.075732
Heliocentric radial velocity22,704 km/s
Distance1.045 Gly
Group or clusterAbell 1775
Apparent magnitude (V)15.3
Characteristics
TypeElliptical;BrCLG
Size~330,000 ly (100 kpc) (estimated)
Notable featuresRadio galaxy
Other designations
VV 195b, MCG +05-32-063, CGCG 161-121 NED01, 2MASX J13414914+2622248, OGC 0935, KOS NP5 007, PGC 48495, 4C 26.41, B2 1339+26B

UGC 8669 known as UGC 8669 NED01 and B2 1339+26B, is a radio galaxy located in the constellation of Boötes. The redshift of the galaxy is estimated to be (z) 0.075 and it was first discovered by astronomers in 1971, later designated as 4C 26.41 in 1977. It is the brightest cluster galaxy (BCG), dominating the center of Abell 1775, an X-ray luminous and rich galaxy cluster.

Description

UGC 8669 is classified as a Fanaroff-Riley class Type I radio galaxy. Its host is an elliptical galaxy with a small dark nuclear band. It is a giant double galaxy system pairing up with another elliptical galaxy UGC 8669 NED02 or B2 1339+26A, to collectively form VV 5-32-63/64. The two nuclei of the system are estimated to display a radial velocity difference of 1700 kilometers per seconds with the separation of approximately 30 kiloparsecs from each other. The total mass of the system is 2 × 1013 M☉ making it somehow larger comparing to the low limit of double galaxies located in clusters. Both of the galaxies in the system display strong forms of isophotal twisting with ellipticity variations, suggestive of a collision.

The galaxy has head-tail radio source with an extension of 380 kiloparsecs in extent. When imaged with Very Large Array, it has a head component showing an innermost structure found detected as an off-centered nucleus with two radio jets on opposite symmetry. The northeast jet is straight in the path of the tail direction while the southwest jet mainly displays a bend at 0.7 kiloparsecs. There is a radio core located southwards from a bright hotspot. The other galaxy B2 1339+26A has been classified as a double radio galaxy.

Recent observations have showed the galaxy has an unexpected increase of surface brightness in some of the tail regions suggesting its jets display a complex bend. There was also evidence that the spectral index is rising in an unexpected manner for some of the regions ranging between 1.37 ± 0.14 and 0.88 ± 0.14. Because the regions are situated close to a fossil plasma filament with an ultra-steep spectrum, it is likely the radio emission is contaminating the galaxy.

A tail extension has been discovered in the galaxy making the source longer with a collimated structure reaching up to 400 kiloparsecs, before breaking up and becoming diffused at the spot of a cold front. This might be suggested by dormant tail electrons displaying re-acceleration.

References

  1. 1 2 3 4 5 6 7 "NED Search results for UGC 8869 NED01". NASA/IPAC Extragalactic Database. Retrieved 2025-09-01.
  2. 1 2 Chincarini, Guido; Rood, Herbert J.; Sastry, Gummuluru N.; Welch, Gary A. (August 1971). "A Supermassive Double Galaxy in the Cluster Abell 1775". The Astrophysical Journal. 168: 11. Bibcode:1971ApJ...168...11C. doi:10.1086/151055. ISSN 0004-637X.
  3. ↑ Miley, G. K.; Harris, D. E. (November 1977). "Westerbork observations of three cluster radio galaxies". Astronomy and Astrophysics. 61: L23–L26. Bibcode:1977A&A....61L..23M. ISSN 0004-6361.
  4. ↑ Liuzzo, E.; Giovannini, G.; Giroletti, M.; Taylor, G. B. (2009-08-31), "The Bologna complete sample of nearby radio sources", Astronomy & Astrophysics, 505 (2): 509–520, arXiv:0908.4391, Bibcode:2009A&A...505..509L, doi:10.1051/0004-6361/200912586
  5. ↑ Hu, Dan; Xu, Haiguang; Zhu, Zhenghao; Shan, Chenxi; Zhu, Yongkai; Fan, Shida; Zhao, Yuanyuan; Liu, Chengze; Siew, Hoongwah; Zhang, Zhongli; Gu, Liyi; Johnston-Hollitt, Melanie; Kang, Xi; Tan, Qinghua; Chang, Jiang (2021-05-01). "The Merger Dynamics of the Galaxy Cluster A1775: New Insights from Chandra and XMM-Newton for a Cluster Simultaneously Hosting a Wide-angle Tail and a Narrow-angle Tail Radio Source". The Astrophysical Journal. 913 (1): 8. arXiv:2103.03382. Bibcode:2021ApJ...913....8H. doi:10.3847/1538-4357/abf09e. ISSN 0004-637X.
  6. ↑ 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.
  7. ↑ "NED Search results for UGC 8669 NED02". NASA/IPAC Extragalactic Database. Retrieved 2025-09-01.
  8. ↑ Hintzen, P. (August 1979). "VV 5-32-63/64 - The 'supermassive double galaxy' in Abell 1775 revisited". Publications of the Astronomical Society of the Pacific. 91: 426. doi:10.1086/130514. ISSN 0004-6280.
  9. ↑ Hayes, J. J. E.; Bhattacharya, B. (November 1990). "The cD galaxy in Abell cluster 1775". NASA Conference Publication. 3098 (124): 195–199. Bibcode:1990NASCP3098..195H.
  10. 1 2 3 Botteon, A.; Giacintucci, S.; Gastaldello, F.; Venturi, T.; Brunetti, G.; Weeren, R. J. van; Shimwell, T. W.; Rossetti, M.; Akamatsu, H.; Brüggen, M.; Cassano, R.; Cuciti, V.; Gasperin, F. de; Drabent, A.; Hoeft, M. (2021-05-01). "Nonthermal phenomena in the center of Abell 1775 - An 800 kpc head-tail, revived fossil plasma and slingshot radio halo" (PDF). Astronomy & Astrophysics. 649: A37. arXiv:2103.01989. Bibcode:2021A&A...649A..37B. doi:10.1051/0004-6361/202040083. ISSN 0004-6361.
  11. ↑ Giacintucci, S.; Venturi, T.; Murgia, M.; Dallacasa, D.; Athreya, R.; Bardelli, S.; Mazzotta, P.; Saikia, D. J. (2007-10-02). "Radio morphology and spectral analysis of cD galaxies in rich and poor galaxy clusters" (PDF). Astronomy & Astrophysics. 476 (1): 99–119. arXiv:0708.4330. Bibcode:2007A&A...476...99G. doi:10.1051/0004-6361:20077918. ISSN 0004-6361.
  12. ↑ Gregory, B. Terni de; Feretti, L.; Giovannini, G.; Govoni, F.; Murgia, M.; Perley, R. A.; Vacca, V. (2017-12-01). "Narrow head-tail radio galaxies at very high resolution". Astronomy & Astrophysics. 608: A58. arXiv:1709.00223. Bibcode:2017A&A...608A..58T. doi:10.1051/0004-6361/201730878. ISSN 0004-6361.
  13. ↑ Bushi, A.; Botteon, A.; Dallacasa, D.; Weeren, R. J. van; Venturi, T.; Brüggen, M.; Gastaldello, F.; Giacintucci, S. (2025-02-01). "The head-tail radio galaxy and revived fossil plasma in Abell 1775". Astronomy & Astrophysics. 694: A317. arXiv:2502.04913. Bibcode:2025A&A...694A.317B. doi:10.1051/0004-6361/202453391. ISSN 0004-6361.