NGC 2273

NGC 2273 is a barred spiral galaxy located in the constellation Lynx. It is located at a distance of circa 95 million light years from Earth, which, given its apparent dimensions, means that NGC 2273 is about 100,000 light years across. It was discovered by Nils Dunér on September 15, 1867.[3]

NGC 2273
NGC 2273 by Hubble Space Telescope
Credit: NASA/ESA
Observation data (J2000 epoch)
ConstellationLynx
Right ascension06h 50m 08.7s[1]
Declination60° 50′ 45″[1]
Redshift0.006138 ± 0.000013 [1]
Helio radial velocity1,840 ± 4 km/s[1]
Distance94.5 ± 13 Mly (29.0 ± 4.0 Mpc)[1]
Apparent magnitude (V)11.6 [2]
Characteristics
TypeSB(r)a [1]
Apparent size (V)3′.2 × 2′.5[1]
Notable featuresSeyfert galaxy
Other designations
UGC 3546, MCG+10-10-015, PGC 19688, Mrk 620[1]

Characteristics
NGC 2273 by GALEX.

NGC 2273 has a multiring structure. The galaxy has an inner ring and two outer pseudorings formed by two sets of spiral arms. The galaxy is seen with an inclination of 41 degrees. The galaxy hosts about 1.1×109 M☉ of hydrogen gas (HI), with most of it lying at the outer pseudoring. The galaxy also hosts large amounts of molecular gas, as indicated by the CO lines, which is regarded as an indicator of active star formation.[4] The total infrared luminosity of the galaxy is 1010.25 L☉.[5] The galaxy has a bar whose radius is 40 arcseconds.[6]

Observations of the central 20 arcseconds of the galaxy by the Hubble Space Telescope showed spiral arms that corresponded to the inner ring. The central ovoid of the galaxy was found to feature a bar-like structure and two arc structures that form a partial nuclear ring. Its emission is associated with the presence of HII regions.[7] Around the nucleus lies a dusty ring-like structure, with a radius of 7 arcseconds, better seen at its northwest part. Another dusty ring is observed at 20 arcseconds radius.[8]

Nucleus

Based on the emission lines that are present in its spectrum, the nucleus of NGC 2273 has been characterised as active and it has been categorised as a type II Seyfert galaxy.[9][10] Also, a water kilomaser has been detected in the nuclear region of the galaxy. It could be created either by the active nucleus or by a prominent site of star formation.[11]

Observations by BeppoSAX, XMM Newton, and Chandra X-Ray Observatory suggested that the nucleus of NGC 2273 is obscured by a Compton thick column, with high column density,[12][13] estimated to be 1.1×1024 cm−2 as measured by ASCA,[14] or 1.5×1024 cm−2 as measured by Suzaku.[15] The harder X-Rays manage to get through and are dominated by reflection from cold material, as the Fe-K line indicates.[14] The spectrography of the nuclear regions is weakly polarised, more prominent in H-alpha.[16] The broad X-ray spectrum of NGC 2273 has been found to be composed of a thermal or scattered soft component, a reflected component, and an absorbed power law component. The 2–10 keV X-ray flux of the galaxy is estimated to be 1.7×1042 ergs−1.[15]

The nucleus also emits radiowaves. The radio source has been found to be linear and is composed of two unequal radio features separated by about 170 parsecs.[17] These two radio features have been identified as radio jets. A linear jet-like feature extending for 2 arcseconds east of the nucleus was observed in [O III] λ5007 images. It is aligned with the radio jets and is possibly of nuclear origin.[7]

The most accepted theory for the energy source of active galactic nuclei is the presence of an accretion disk around a supermassive black hole. The mass of the black hole in the centre of NGC 2273 is estimated to be between (7.5±0.4)×106 M☉ based on kinematics of the water maser circumnuclear disk. The disk appears warped.[18]

Nearby galaxies

NGC 2273 is the brightest galaxy in a galaxy group known as the NGC 2273 group. Other members of the group include the galaxies NGC 2237B and UGC 3504.[19][20] NGC 2237B lies 40 arcminutes to the south.[21]

See also
  • NGC 1386 - a similar Seyfert galaxy
  • NGC 3081 - a similar multiring Seyfert galaxy

References
  1. "NASA/IPAC Extragalactic Database". Results for NGC 2273. Retrieved 2019-01-18.
  2. "Revised NGC Data for NGC 2273". spider.seds.org. Retrieved 25 November 2018.
  3. NGC 2273 cseligman.com
  4. van Driel, W.; Buta, R. J. (1 May 1991). "A study of the ringed galaxies NGC2273, 4826, and 6217. I - H I line observations". Astronomy and Astrophysics. 245: 7–26. Bibcode:1991A&A...245....7V. ISSN 0004-6361.
  5. Sanders, D. B.; Mazzarella, J. M.; Kim, D.-C.; Surace, J. A.; Soifer, B. T. (October 2003). "The IRAS Revised Bright Galaxy Sample". The Astronomical Journal. 126 (4): 1607–1664. arXiv:astro-ph/0306263. Bibcode:2003AJ....126.1607S. doi:10.1086/376841. S2CID 14825701.
  6. Aguerri, J. A. L.; Beckman, J. E.; Prieto, M. (November 1998). "Bar Strengths, Bar Lengths, and Corotation Radii, Derived Photometrically for 10 Barred Galaxies". The Astronomical Journal. 116 (5): 2136–2153. Bibcode:1998AJ....116.2136A. doi:10.1086/300615.
  7. Ferruit, Pierre; Wilson, Andrew S.; Mulchaey, John (May 2000). "Hubble Space Telescope WFPC2 Imaging of a Sample of Early-Type Seyfert Galaxies". The Astrophysical Journal Supplement Series. 128 (1): 139–169. Bibcode:2000ApJS..128..139F. doi:10.1086/313379.
  8. Yankulova, I. M. (1 April 1999). "The circumnuclear gas and dust environment of the ringed Seyfert 2 galaxy MKN 620". Astronomy and Astrophysics. 344: 36–42. Bibcode:1999A&A...344...36Y. ISSN 0004-6361.
  9. Huchra, J. P.; Wyatt, W. F.; Davis, M. (December 1982). "New bright Seyfert Galaxies". The Astronomical Journal. 87: 1628. Bibcode:1982AJ.....87.1628H. doi:10.1086/113254.
  10. Ho, Luis C.; Filippenko, Alexei V.; Sargent, Wallace L. W. (October 1997). "A Search for "Dwarf Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies". The Astrophysical Journal Supplement Series. 112 (2): 315–390. arXiv:astro-ph/9704107. Bibcode:1997ApJS..112..315H. doi:10.1086/313041. S2CID 17086638.
  11. Zhang, J. S.; Henkel, C.; Kadler, M.; Greenhill, L. J.; Nagar, N.; Wilson, A. S.; Braatz, J. A. (19 April 2006). "Extragalactic H2O masers and X-ray absorbing column densities". Astronomy & Astrophysics. 450 (3): 933–944. Bibcode:2006A&A...450..933Z. doi:10.1051/0004-6361:20054138.
  12. Maiolino, R.; Salvati, M.; Bassani, L.; Dadina, M.; della Ceca, R.; Matt, G.; Risaliti, G.; Zamorani, G. (1 October 1998). "Heavy obscuration in X-ray weak AGNs". Astronomy and Astrophysics. 338: 781–794. arXiv:astro-ph/9806055. Bibcode:1998A&A...338..781M. ISSN 0004-6361.
  13. Guainazzi, M.; Fabian, A. C.; Iwasawa, K.; Matt, G.; Fiore, F. (1 January 2005). "On the transmission-dominated to reprocessing-dominated spectral state transitions in Seyfert 2 galaxies". Monthly Notices of the Royal Astronomical Society. 356 (1): 295–308. arXiv:astro-ph/0409689. Bibcode:2005MNRAS.356..295G. doi:10.1111/j.1365-2966.2004.08448.x.
  14. Terashima, Yuichi; Iyomoto, Naoko; Ho, Luis C.; Ptak, Andrew F. (March 2002). "X-Ray Properties of LINERs and Low-Luminosity Seyfert Galaxies Observed with ASCA. I. Observations and Results". The Astrophysical Journal Supplement Series. 139 (1): 1–36. arXiv:astro-ph/0203005. Bibcode:2002ApJS..139....1T. doi:10.1086/324373.
  15. Awaki, Hisamitsu; Terashima, Yuichi; Higaki, Yuusuke; Fukazawa, Yasushi (30 January 2009). "Detection of Hard X-Rays from the Compton-Thick Seyfert 2 Galaxy NGC 2273 with Suzaku". Publications of the Astronomical Society of Japan. 61 (sp1): S317–S325. arXiv:0810.4570. Bibcode:2009PASJ...61S.317A. doi:10.1093/pasj/61.sp1.S317. S2CID 12846803.
  16. Moran, Edward C.; Barth, Aaron J.; Kay, Laura E.; Filippenko, Alexei V. (10 September 2000). "The Frequency of Polarized Broad Emission Lines in Type 2 Seyfert Galaxies". The Astrophysical Journal. 540 (2): L73–L77. arXiv:astro-ph/0007357. Bibcode:2000ApJ...540L..73M. doi:10.1086/312876.
  17. Ulvestad, J. S.; Wilson, A. S. (October 1984). "Radio structures of Seyfert galaxies. VI - VLA observations of a nearby sample". The Astrophysical Journal. 285: 439. Bibcode:1984ApJ...285..439U. doi:10.1086/162520.
  18. Kuo, C. Y.; Braatz, J. A.; Condon, J. J.; Impellizzeri, C. M. V.; Lo, K. Y.; Zaw, I.; Schenker, M.; Henkel, C.; Reid, M. J.; Greene, J. E. (20 January 2011). "The Megamaser Cosmology Project. III. Accurate Masses of Seven Supermassive Black Holes in Active Galaxies with Circumnuclear Megamaser Disks". The Astrophysical Journal. 727 (1): 20. arXiv:1008.2146. Bibcode:2011ApJ...727...20K. doi:10.1088/0004-637X/727/1/20.
  19. Makarov, Dmitry; Karachentsev, Igor (21 April 2011). "Galaxy groups and clouds in the local (z∼ 0.01) Universe". Monthly Notices of the Royal Astronomical Society. 412 (4): 2498–2520. arXiv:1011.6277. Bibcode:2011MNRAS.412.2498M. doi:10.1111/j.1365-2966.2010.18071.x. S2CID 119194025.
  20. Garcia, A. M. (1993). "General study of group membership. II - Determination of nearby groups". Astronomy and Astrophysics Supplement Series. 100 (1): 47–90. Bibcode:1993A&AS..100...47G. ISSN 0365-0138.
  21. de Vaucouleurs, G.; de Vaucouleurs, A.; Corwin, J. R. (1976). "Second reference catalogue of bright galaxies". Second Reference Catalogue of Bright Galaxies. 1976. Bibcode:1976RC2...C......0D.


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