The galaxy was first discovered byJames Dunlop on May 10, 1826, with his 9-inch reflector telescope, who described it as exceedingly faint. The galaxy was also spotted byJohn Herschel and added to theGeneral Catalogue of Nebulae and Clusters as number 3572. The galaxy is located only 15 degrees from the galactic plane.[3]
NGC 5643 is agrand design spiral galaxy, with two well-defined, symmetric arms. In the circumnuclear region, other dust spirals are present, but the two main dust arms are wider.[4] The galaxy is seen nearly face on, at an inclination of ~ 27°.
The galaxy has a low-luminosityactive galactic nucleus of Seyfert 2 type and is also aluminous infrared galaxy. The galaxy has a double-sided diffuse radiojet. The galaxy exhibits anextended emission-line region elongated along a direction close to the radio position angle of 87°±3°. Chris Simpson et al. analysed images takes from the WFPC2 camera of theHubble Space Telescope in [O III] λ5007 and Hα and found emission extending eastward for at least 1.8 kpc and in the [O III]/Hα map a well-defined V-shaped structure that they identified as the projection of a tridimensional ionisation cone, which shares the same axis with the radio emission. A dust lane perpendicular to this axis obstructs the nucleus from direct view.[6] A disk of material was found when the data cubes of VLT were analysed. It is aligned with the nucleus, circles it, and may provide gas to the active galactic nucleus.[7] The mass of thesupermassive black hole has been estimated based on the galaxy stellar velocity dispersion to be 106.4 M⊙.[8] It has been proposed that the gas outflow has led to star formation on two locations on the bar of the galaxy which lie at the location where the gas from the nucleus encounters the dense material of the bar.[9]
Based on observations of the galaxy by theXMM Newton telescope in 2009, it was found to have a Compton–thick active galactic nucleus. Also the galaxy emits soft X-rays, mainly from photoionized matter.[10] The presence of the compton-thick column which obstructs the nucleus was confirmed from observations byNuSTAR.[11]
In 2004, Guainazzi et al. detected in the images from XMM-Newton anultraluminous X-ray source, named NGC 5643 ULX1, located within 0.8 arcminutes from the nucleus. The source outshone the nucleus in X-rays, and if it lies within NGC 5643, its luminosity exceeds 1040 erg/s. Its luminosity is variable.[12] The X-rays could be produced either by an advection dominated disc or a Comptonising corona and the X-ray source is considered to be ablack hole of stellar origin of approximately 30solar masses.[13]
Twosupernova events have been recorded within the galaxy:
SN 2013aa (TypeIa, mag. 11.9) was discovered by Stuart Parker fromNew Zealand on 13 February 2013, as part of theBackyard Observatory Supernova Search.[14][15] It was classified as a type Ia a few days before maximum brightness.[16] It got as bright as magnitude 11.3, making it the brightest supernova of the year 2013.[17]
SN 2017cbv (TypeIa, mag. 16.0451) was discovered by theDistance Less Than 40 Mpc Survey (DLT40) on 10 March 2017.[18][19] It increased in magnitude from 15.8 to 14.8 within the next day.[20] It got as bright as magnitude 11.5, making it the brightest supernova of the year 2017.[21]
^Annuar, A.; Gandhi, P.; Alexander, D. M.; Lansbury, G. B.; Arévalo, P.; Ballantyne, D. R.; Baloković, M.; Bauer, F. E.; Boggs, S. E.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Craig, W. W.; Moro, A. Del; Hailey, C. J.; Harrison, F. A.; Hickox, R. C.; Matt, G.; Puccetti, S.; Ricci, C.; Rigby, J. R.; Stern, D.; Walton, D. J.; Zappacosta, L.; Zhang, W. (4 December 2015). "NuSTAR Observations of the Compton-thick Active Galactic Nucleus and Ultraluminous X-ray Source Candidate in NGC 5643".The Astrophysical Journal.815 (1): 36.arXiv:1509.03322.Bibcode:2015ApJ...815...36A.doi:10.1088/0004-637X/815/1/36.S2CID11400958.
^Parker, S.; Amorim, A.; Parrent, J. T.; Sand, D.; Valenti, S.; Graham, M. L.; Howell, D. A. (2013). "Supernova 2013aa in NGC 5643 = PSN J14323388-4413278".Central Bureau Electronic Telegrams.3416: 1.Bibcode:2013CBET.3416....1P.
^"SN 2013aa".Transient Name Server.IAU. Retrieved6 December 2024.
