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NGC 5557
NGC 5557
	SDSS image of NGC 5557
Observation data (J2000 epoch)
Constellation	Boötes
Right ascension	14h 18m 25.708s
Declination	+36° 29′ 37.28″
Redshift	0.010764
Heliocentric radial velocity	3210 ± 28 km/s
Distance	127 Mly (38.8 Mpc)
Apparent magnitude (V)	12.2
Absolute magnitude (V)	−22.39
Characteristics
Type	E1
Other designations
	UGC 9161, MCG +06-31-093, PGC 51104

NGC 5557 is an elliptical galaxy in the constellation Boötes. It was discovered by William Herschel on May 1, 1785.^[4] The distance to NGC 5557 is not well known, but it is estimated to be about 127 million light-years (38.8 megaparsecs) away.^[3]

NGC 5557 is quite massive, with a K-band absolute magnitude of −24.8, and is a slow rotator,^[3] which suggests it gained mass through dry mergers (galaxy mergers involving galaxies significant amounts of gas).^[5] However, it has a faint tidal tail to its east, as well as a more complex structure to the west. This structure, if found to be connected to NGC 5557, would one of the largest around a galaxy, spanning about 1.1 million light-years (350,000 parsecs).^[3] This filamentary structure suggests that NGC 5557 may have formed from a more gas-rich galaxy merger a couple billion years ago.^[3] This implies that the galaxy merger would need to have a low impact parameter.^[5]

NGC 5557 is part of a galaxy group,^[3]^[4] and is the largest such galaxy in the group by far.^[3] Surrounding the galaxy near the eastern filament are several small bluish objects, which are possibly tidal dwarf galaxies.^[3]

Two supernovae have been observed in NGC 5557: SN 1996aa (type Ia, mag. 17),^[6] and SN 2013gn (type Ia, mag. 15.3).^[7]

References

^ ^a ^b Skrutskie, Michael F.; Cutri, Roc M.; Stiening, Rae; Weinberg, Martin D.; Schneider, Stephen E.; Carpenter, John M.; Beichman, Charles A.; Capps, Richard W.; Chester, Thomas; Elias, Jonathan H.; Huchra, John P.; Liebert, James W.; Lonsdale, Carol J.; Monet, David G.; Price, Stephan; Seitzer, Patrick; Jarrett, Thomas H.; Kirkpatrick, J. Davy; Gizis, John E.; Howard, Elizabeth V.; Evans, Tracey E.; Fowler, John W.; Fullmer, Linda; Hurt, Robert L.; Light, Robert M.; Kopan, Eugene L.; Marsh, Kenneth A.; McCallon, Howard L.; Tam, Robert; Van Dyk, Schuyler D.; Wheelock, Sherry L. (1 February 2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal. 131 (2): 1163–1183. Bibcode:2006AJ....131.1163S. doi:10.1086/498708. ISSN 0004-6256. S2CID 18913331.
^ ^a ^b ^c "NGC 5557". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-04-17.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Duc, Pierre-Alain; Cuillandre, Jean-Charles; Serra, Paolo; Michel-Dansac, Leo; Ferriere, Etienne; Alatalo, Katherine; Blitz, Leo; Bois, Maxime; Bournaud, Frédéric; Bureau, Martin; Cappellari, Michele; Davies, Roger L.; Davis, Timothy A.; De Zeeuw, P. T.; Emsellem, Eric; Khochfar, Sadegh; Krajnović, Davor; Kuntschner, Harald; Lablanche, Pierre-Yves; McDermid, Richard M.; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Scott, Nicholas; Weijmans, Anne-Marie; Young, Lisa M. (2011). "The ATLAS^3D project - IX. The merger origin of a fast- and a slow-rotating early-type galaxy revealed with deep optical imaging: First results". Monthly Notices of the Royal Astronomical Society. 417 (2): 863–881. arXiv:1105.5654. Bibcode:2011MNRAS.417..863D. doi:10.1111/j.1365-2966.2011.19137.x. S2CID 6762647. {{cite journal}}: |last10= has generic name (help)
^ ^a ^b ^c Seligman, Courtney. "New General Catalogue objects: NGC 5550 - 5599". cseligman.com. Retrieved 2021-04-17.
^ ^a ^b ^c Bonfini, Paolo (2014). "GALFIT-CORSAIR: Implementing the Core-Sérsic Model into GALFIT". Publications of the Astronomical Society of the Pacific. 126 (944): 935–947. arXiv:1408.6846. Bibcode:2014PASP..126..935B. doi:10.1086/678566. S2CID 119256809.
^ Transient Name Server entry for SN 1996aa. Retrieved 30 March 2023.
^ Transient Name Server entry for SN 2013gn. Retrieved 30 March 2023.