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NGC 3393 - Wikipedia

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NGC 3393
NGC 3393 by Hubble Space Telescope
Observation data (J2000 epoch)
Constellation	Hydra
Right ascension	10^h 48^m 23.5^s^[1]
Declination	−25° 09′ 43″^[1]
Redshift	0.012509 ± 0.000017 ^[1]
Heliocentric radial velocity	3,750 ± 5 km/s^[1]
Distance	181 Mly (56 Mpc)^[1]
Apparent magnitude (V)	13.1
Characteristics
Type	(R')SB(s)ab ^[1]
Apparent size (V)	2.2′ × 2.0′^[1]
Notable features	Seyfert galaxy Hosts a pair of supermassive black holes
Other designations
ESO 501-G100, MCG -04-26-011, AM 1045-245, PGC 32300^[1]

NGC 3393 is a barred spiral galaxy located in the constellation Hydra. It is located at a distance of circa 180 million light-years from Earth, which, given its apparent dimensions, means that NGC 3393 is about 140,000 light-years across. It was discovered by John Herschel on March 24, 1835.^[2] It is a Type II Seyfert galaxy, known to host two supermassive black holes, which are the nearest known pair of supermassive black holes to Earth.^[3]

Characteristics

The galaxy is characterised as a barred spiral galaxy. At both ends of the bar H II regions are present. There is also evidence of a fainter inner bar. The fainter outer arms of the galaxy form a nearly complete ring.^[4]

Active galactic nucleus

NGC 3393 has been characterised as a Seyfert galaxy, a galaxy category which features bright point-like nuclei. NGC 3393 is a type II Seyfert galaxy. Its X-ray spectrum is more consistent with a Compton-thick cold reflection source, which means that the source is hidden behind dense material, mainly gas and dust, and the X-rays observed have been reflected.^[5]

Supermassive black holes

The source of activity in the active galactic nuclei is a supermassive black hole (SMBH) lying at the centre of the galaxy. Observations by the Chandra X-ray Observatory revealed evidence for a pair of supermassive black holes in the centre of NGC 3393. The observation in hard X-rays, including emission from iron, showed two separate peaks, which were identified as black holes that are actively growing, generating X-ray emission as gas falls towards the black holes and becomes hotter. The obscured regions around both black holes block the copious amounts of optical and ultraviolet light produced by infalling material. They are the first pair of black holes found in a spiral galaxy like our Milky Way. The two black holes are separated by only 490 light years.^[3]^[6]

The two black holes in NGC 3393 are likely the remnant of a merger of two galaxies of unequal mass a billion or more years ago.^[6] Other evidence that supports the hypothesis of the galaxy merger include high pre-shock densities in the narrow-line region and low O/H and Mg/H abundances. However the N/H is more than predicted, probably due to the creation of Wolf–Rayet stars in the central region of the galaxy during the merger.^[7]

The total mass of the pair is estimated to be between 21 and 35 million M_☉.^[8]

Supernova

One supernova has been observed in NGC 3393, SN 2018aqi. The supernova was discovered by ASAS-SN on April 6, 2018, and had an apparent magnitude of 16.4 at discovery.^[9] By its spectrum, it was identified as a type Ia supernova 6 days before maximum brightness.^[10]

Nearby galaxies

NGC 3393 is the brightest galaxy in the NGC 3393 group, which also includes NGC 3369, NGC 3383, and ESO 501-086.^[11] NGC 3463 has also been proposed to be a member of the group.^[12] The group is part of the Hydra Supercluster.^[13]

References

^ ^a ^b ^c ^d ^e ^f ^g ^h "NASA/IPAC Extragalactic Database". Results for NGC 3393. Retrieved 2016-01-18.
^ NGC 3393 cseligman.com
^ ^a ^b "Spiral Galaxy NGC 3393". NASA. 24 November 2015. Retrieved 10 May 2020.
^ Alonso-Herrero, Almudena; Simpson, Chris; Ward, Martin J.; Wilson, Andrew S. (March 1998). "A Near-Infrared Imaging Study of Seyfert Galaxies with Extended Emission-Line Regions". The Astrophysical Journal. 495 (1): 196–221. Bibcode:1998ApJ...495..196A. doi:10.1086/305269.
^ Maiolino, R.; Salvati, M.; Bassani, L.; Dadina, M.; della Ceca, R.; Matt, G.; Risaliti, G.; Zamorani, G. (October 1998). "Heavy obscuration in X-ray weak AGNs". Astronomy and Astrophysics. 338: 781–794. arXiv:astro-ph/9806055. Bibcode:1998A&A...338..781M.
^ ^a ^b Fabbiano, G.; Wang, Junfeng; Elvis, M.; Risaliti, G. (31 August 2011). "A close nuclear black-hole pair in the spiral galaxy NGC 3393". Nature. 477 (7365): 431–434. arXiv:1109.0483. Bibcode:2011Natur.477..431F. doi:10.1038/nature10364. PMID 21881560. S2CID 205226065.
^ Contini, M. (11 September 2012). "Evidence of merging in the Seyfert galaxy NGC 3393, revealed by modelling the spectra". Monthly Notices of the Royal Astronomical Society. 425 (2): 1205–1214. arXiv:1206.3060. Bibcode:2012MNRAS.425.1205C. doi:10.1111/j.1365-2966.2012.21504.x.
^ Davis, Benjamin L.; Graham, Alister W.; Cameron, Ewan (6 March 2019). "Black Hole Mass Scaling Relations for Spiral Galaxies. I. I. M BH–M *,sph". The Astrophysical Journal. 873 (1): 85. arXiv:1810.04887. Bibcode:2019ApJ...873...85D. doi:10.3847/1538-4357/aaf3b8. hdl:1959.3/448397. S2CID 119211505.
^ "SN 2018aqi". Transient Name Server. wis-tns.weizmann.ac.il.
^ "ATel #11516: ePESSTO spectroscopic classification of optical transients". ATel. 8 April 2018.
^ 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.
^ A. Garcia (1993). "General study of group membership. II – Determination of nearby groups". Astronomy and Astrophysics Supplement. 100: 47–90. Bibcode:1993A&AS..100...47G.
^ "The Hydra Supercluster". www.atlasoftheuniverse.com.

External links

Wikimedia Commons has media related to NGC 3393.

NGC 3393 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images

v t e Astronomical catalogs
NGC	NGC 3388 NGC 3389 NGC 3390 NGC 3391 NGC 3392 NGC 3393 NGC 3394 NGC 3395 NGC 3396 NGC 3397 NGC 3398
PGC	PGC 32296 PGC 32297 PGC 32298 PGC 32299 PGC 32300 PGC 32301 PGC 32302 PGC 32303 PGC 32304

New General Catalogue 3000 to 3499

Constellation of Hydra

Stars

Bayer	α (Alphard) β γ δ ε (Ashlesha) ζ η θ ι (Ukdah) κ λ μ ν ξ ο π ρ σ (Minchir) τ¹ τ² υ¹ (Zhang) υ² φ¹ φ² φ³ χ¹ χ² ψ ω
Flamsteed	1 2 3 6 (a) 9 10 12 (D) 14 15 17 19 20 21 23 24 25 26 27 (P) 28 29 33 (A) 34 37 44 47 48 50 51 (k) 52 (l) 54 (m) 55 56 57 58 (E) 59 60 3 Crt (b¹) 5 Crt (b²) 6 Crt (b³) 10 Crt 17 Crt (N) 20 Crt 14 Lib 30 Mon (C) 31 Mon (F) 2 Sex
Variable	R U V W TW EX HS KU LQ V419 V421 V434 V478
HR	3378 3538 3749 (G) 3750 3858 (I) 3862 3919 3923 (Felis) 4162 4328 4339 4445 5265
HD	72659 74156 82943 86226 86264 90156
Gliese	328 357 433 453 3517 3634
Other	HE 1256-2738 HE 1327-2326 LHS 2065 LHS 3003 LTT 3780 2MASS 1114−2618 WASP-25 WASP-36 WASP-84 WISE 0855−0714

Star clusters

Open	Messier 48
Globular	Messier 68 NGC 5694

Nebulae

Planetary	Abell 33 Abell 35 NGC 3242

Galaxies

Messier	83
NGC	2617 2835 2865 2890 2936 2937 2992 3054 3081 3109 3285 3305 3307 3308 3309 3311 3312 3313 3314 3315 3316 3336 3369 3393 3402 3464 3585 3621 3717 3923 4980 4993 5078 5101 5135 5260 5264 5495
Other	3C 196.1 AM 1316-241 Arp 7 ESO 510-G13 GAMA202627 IC 535 MRC 1138-262 Peekaboo Galaxy TN J0924-2201 Tololo 1247-232

Galaxy clusters

Abell	754 3411 3412
Other	Hickson 40

Astronomical events

GW170817

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