4C 38.41

4C 38.41
SDSS image of 4C 38.41
Observation data (J2000.0 epoch)
ConstellationHercules
Right ascension16h 35m 15.49s[1]
Declination+38° 08′ 04.50″[1]
Redshift1.813964[1]
Heliocentric radial velocity543,813 km/s[1]
Distance10.203 Gly
Apparent magnitude (V)17.97
Apparent magnitude (B)18.14
Characteristics
TypeFSRQ;LPQ;HPQ blazar[1]
Size~209,000 ly (64.07 kpc) (estimated)[1]
Other designations
B3 1633+382, LEDA 2820574, OS +356, NVSS J163515+380804, SDSS J163515.50+380804.4, 2MASS J16351549+3808044, S4 1633+38, VIPS 0994, WMAP 033, JVAS J1635+3808[1]

4C 38.41 known as B3 1633+382, is a quasar[2] located in the constellation of Hercules. Its redshift is estimated to lie at (z) 1.813[1] and it was first discovered in September 1973 by astronomers lead by Pauliny-Toth. They identified it as a compact 17th magnitude blue stellar object.[3] It is also a notable blazar with a flat radio spectrum, making it a flat-spectrum radio quasar.[4][5][6]

Description

4C 38.41 is optically violently variable on the electromagnetic spectrum, thus classifying it as an OVV quasar.[5][7] When observed during optical monitoring, it is known to display variations on both long-term and short-term scales, with the maximum variation in R-band magnitude reaching 0.78 and B-band 0.74.[8] A faint state was initially observed at 17.55 magnitude, before rising to 16th magnitude during the next winter.[9]

In July 2009, the object displayed gamma-ray activity when it entered a high-state with an estimated flux level of 1.38 ± 0.32 x 10-6 photons cm-2 s-1.[10] A near infrared flare was observed on 26 March, 2011.[11] On 3 September, 2018, more gamma-ray emission was noted from the blazar by the AGILE Satellite, hinting it had undergone a new active violent phrase.[12] Intraday-variability was observed in addition during the three days of observation between February 22 and 28, 2018, with it displaying a redder when brighter trend.[13]

Radio imaging made by very-long-baseline interferometry (VLBI) found 4C 38.41 has a compact core-jet morphology structure comprising at least three components. When imaged at 608 MHz frequencies, a compact radio core is revealed with an extended structure going west right up to 20 milliarcseconds.[8] Some structural extension has also been noted in other imaging, both east and towards the northwest, along a negative position angle of -35°. From the extended region of the object weak traces of radio emission are located west from the core.[14] A weak polarized component was found, described as bright with hints of further extensions.[15]

The radio jet of 4C 38.41 is described as extended by 50 milliarcseconds towards the west direction with a sharp bend at the south. This jet might be suggested weak when imaged by a 2.3 GHz radio image by VLBI.[16] Superluminal motion is also detected in the jet, given a jet component is shown moving with a proper motion of 0.14 ± 0.06 milliarcseconds per year.[17] In 2019, astronomers found the structure of the inner jet part show a semi-parabolic geometry shape. The jet regions never follow a ballistic trajectory direction, instead matching with a sinusoidal pattern. This might arise from either jet precession in helical motion or if the jet is unstable.[18]

Observations conducted in June 2023, found 4C 38.41 has evidence of quasi-periodic oscillations (QPO) with most of its activity phrases showing them with a duration period between 10 and 110 days. Further evidence also noted one of the active phases has three further subphases with the same observed oscillations lasting between 10 and 40 days. When observed in a quiescent phase, more QPO-like behavior is discovered on two time-scales. This indicates kink instability or its curved model.[19] A supermassive black hole mass of 10.1 Mʘ has been estimated for the object.[20]

References

  1. ^ a b c d e f g h "NED Search results for 4C 38.41". NASA/IPAC Extragalactic Database. Retrieved 2025-10-11.
  2. ^ Peng, B.; de Bruyn, A. G. (September 1995). "Rapid variability in the quasar 4C 38.41 at 92 cm". Astronomy and Astrophysics. 301: 25. Bibcode:1995A&A...301...25P. ISSN 0004-6361.
  3. ^ Pauliny-Toth, I. I. K.; Preuss, E.; Witzel, A.; Kellermann, K. I.; Fomalont, E. B.; Davis, M. M. (September 1973). "1633+38: A Radio Source with a Strong, Compact Component". Astronomy and Astrophysics. 27: 475–477. Bibcode:1973A&A....27..475P. ISSN 0004-6361.
  4. ^ "ATel #4448: Recent radio activity of the Fermi blazar 4C +38.41". The Astronomer's Telegram. Retrieved 2025-10-11.
  5. ^ a b Raiteri, C. M.; Villata, M.; Smith, P. S.; Larionov, V. M.; Acosta-Pulido, J. A.; Aller, M. F.; D’Ammando, F.; Gurwell, M. A.; Jorstad, S. G.; Joshi, M.; Kurtanidze, O. M.; Lähteenmäki, A.; Mirzaqulov, D. O.; Agudo, I.; Aller, H. D. (2012-09-01). "Variability of the blazar 4C 38.41 (B3 1633+382) from GHz frequencies to GeV energies" (PDF). Astronomy & Astrophysics. 545: A48. arXiv:1207.3979. Bibcode:2012A&A...545A..48R. doi:10.1051/0004-6361/201219492. ISSN 0004-6361.
  6. ^ Algaba, Juan-Carlos; Lee, Sang-Sung; Rani, Bindu; Kim, Dae-Won; Kino, Motoki; Hodgson, Jeffrey; Zhao, Guang-Yao; Byun, Do-Young; Gurwell, Mark; Kang, Sin-Cheol; Kim, Jae-Young; Kim, Jeong-Sook; Kim, Soon-Wook; Park, Jong-Ho; Trippe, Sascha (2018-06-01). "Exploring the Variability of the Flat-spectrum Radio Source 1633+382. II. Physical Properties". The Astrophysical Journal. 859 (2): 128. arXiv:1805.02849. Bibcode:2018ApJ...859..128A. doi:10.3847/1538-4357/aac2e7. ISSN 0004-637X.
  7. ^ Rantakyrö, Fredrik T.; Bååth, Lars B. (1992), "VLBI Observations of Quasars 3C 345 and CTA102 at 18 cm Wavelength", Physics of Active Galactic Nuclei, Berlin, Heidelberg: Springer Berlin Heidelberg, pp. 587–588, doi:10.1007/978-3-642-77566-6_134 (inactive 11 October 2025), ISBN 978-3-642-77568-0, retrieved 2025-10-11{{citation}}: CS1 maint: DOI inactive as of October 2025 (link) CS1 maint: work parameter with ISBN (link)
  8. ^ a b Peng, B.; Wu, J.; Zhou, X. (2003-11-19). "Optical monitoring of the quasar 4C 38.41". Monthly Notices of the Royal Astronomical Society. 346 (2): 483–488. Bibcode:2003MNRAS.346..483P. doi:10.1046/j.1365-2966.2003.07102.x. ISSN 0035-8711. Archived from the original on 2024-07-11.
  9. ^ Katajainen, S.; Takalo, L. O.; Sillanpää, A.; Nilsson, K.; Pursimo, T.; Hanski, M.; Heinämäki, P.; Kotoneva, E.; Lainela, M.; Nurmi, P.; Pietilä, H.; Rekola, R.; Riehokainen, A.; Teerikorpi, P.; Valtaoja, E. (2000-05-01). "Tuorla quasar monitoring" (PDF). Astronomy and Astrophysics Supplement Series. 143 (3): 357–368. doi:10.1051/aas:2000184. ISSN 0365-0138.
  10. ^ "ATel #2136: Fermi LAT detection of GeV flares in high redshift blazars 4C 38.41 (B2 1633+38) and PKS 0805-07". The Astronomer's Telegram. Retrieved 2025-10-11.
  11. ^ "ATel #3238: NIR Flaring of the Blazar 4C38.41". The Astronomer's Telegram. Retrieved 2025-10-11.
  12. ^ "ATel #12005: AGILE detection of a gamma-ray flare from the high-redshift FSRQ 4C +38.41". The Astronomer's Telegram. Retrieved 2025-10-11.
  13. ^ Yan, Zhang; Yue, Fang; Jiang-hua, Wu; Yan, Dai; Nan-kun, Meng (2022-01-01). "Multi-Wavelength Optical Variability of High Redshift Blazar 4C 38.41". Chinese Astronomy and Astrophysics. 46 (1): 36–48. doi:10.1016/j.chinastron.2022.02.002. ISSN 0275-1062.
  14. ^ Altschuler, D. R.; Gurvits, L. I.; Alef, W.; Dennison, B.; Graham, D.; Trotter, A. S.; Carson, J. E. (December 1995). "The centi-arcsecond structure of 16 low-frequency variable sources at 92 cm". Astronomy and Astrophysics Supplement Series. 114: 197. ISSN 0365-0138.
  15. ^ Cawthorne, T. V.; Wardle, J. F. C.; Roberts, D. H.; Gabuzda, D. C.; Brown, L. F. (October 1993). "Milliarcsecond Polarization Structure of 24 Objects from the Pearson-Readhead Sample of Bright Extragalactic Radio Sources. I. The Images". The Astrophysical Journal. 416: 496. Bibcode:1993ApJ...416..496C. doi:10.1086/173253. ISSN 0004-637X.
  16. ^ Jorstad, Svetlana G.; Marscher, Alan P.; Mattox, John R.; Wehrle, Ann E.; Bloom, Steven D.; Yurchenko, Alexei V. (June 2001). "Multiepoch Very Long Baseline Array Observations of EGRET-detected Quasars and BL Lacertae Objects: Superluminal Motion of Gamma-Ray Bright Blazars". The Astrophysical Journal Supplement Series. 134 (2): 181–240. arXiv:astro-ph/0101570. Bibcode:2001ApJS..134..181J. doi:10.1086/320858. ISSN 0067-0049.
  17. ^ Barthel, P. D.; Conway, J. E.; Myers, S. T.; Pearson, T. J.; Readhead, A. C. S. (May 1995). "New Superluminal Quasar 1633+382 and the Blazar--Gamma-Ray Connection". The Astrophysical Journal. 444: L21. Bibcode:1995ApJ...444L..21B. doi:10.1086/187850. ISSN 0004-637X.
  18. ^ Algaba, J. C.; Rani, B.; Lee, S. S.; Kino, M.; Park, Jongho; Kim, Jae-Young (2019-11-22). "Exploring the Morphology and Origins of the 4C 38.41 Jet". The Astrophysical Journal. 886 (2): 85. arXiv:1910.02661. Bibcode:2019ApJ...886...85A. doi:10.3847/1538-4357/ab4b45. ISSN 0004-637X.
  19. ^ Das, Avik Kumar; Prince, Raj; Gupta, Alok C.; Kushwaha, Pankaj (2023-06-01). "The Detection of Possible Transient Quasiperiodic Oscillations in the γ-Ray Light Curve of PKS 0244-470 and 4C+38.41". The Astrophysical Journal. 950 (2): 173. arXiv:2211.00588. Bibcode:2023ApJ...950..173D. doi:10.3847/1538-4357/acd17f. ISSN 0004-637X.
  20. ^ Liang, E. W.; Liu, H. T. (April 2003). "The masses of central supermassive black holes and the variability time-scales in gamma-ray loud blazars" (PDF). Monthly Notices of the Royal Astronomical Society. 340 (2): 632–638. Bibcode:2003MNRAS.340..632L. doi:10.1046/j.1365-8711.2003.06327.x. ISSN 0035-8711.
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