NGC 2445 is a peculiar ring galaxy in the constellation Lynx. The galaxy lies about 200 million light years away from Earth, which means, given its apparent dimensions, that NGC 2445 is approximately 100,000 light years across.[1] It was discovered by Édouard Stephan on January 18, 1877.[2] The galaxy interacts with another galaxy, NGC 2444, and as a result its shape is distorted and new stars are formed.[3]
| NGC 2445 | |
|---|---|
 NGC 2444 (left) and NGC 2445 by Hubble Space Telescope | |
| Observation data (J2000 epoch) | |
| Constellation | Lynx |
| Right ascension | 07h 46m 55.1s[1] |
| Declination | 39° 00′ 55″[1] |
| Redshift | 4002 ± 8 km/s[1] |
| Distance | 203 ± 21 Mly (62.3 ± 6.7 Mpc)[1] |
| Apparent magnitude (V) | 13.0 |
| Characteristics | |
| Type | Im pec (Ring B) [1] |
| Apparent size (V) | 1.4′ × 1.1′[1] |
| Notable features | interacting galaxy, collisional ring |
| Other designations | |
| UGC 4017, Arp 143, VV 117, MCG +07-16-017, PGC 21776[1] | |
Characteristics
editNGC 2445 is characterised by its distorted shape and star formation which is the result of the collision with another galaxy, NGC 2444. NGC 2444 has pulled gas away from NGC 2445 and as a result a bridge of young blue stars has formed between the two galaxies that gives the latter a triangular shape.[3] The interaction has also created a ring of star clusters and HII regions around the nucleus.[4][5][6] The kinematics of the gas indicate that the ring has an age of 60 ± 15 million years.[7]
When observed in radio waves the galaxy is asymmetric, with emission being from the nucleus, three star-forming regions and a ridge towards NGC 2444. The northwestern region appears to have stronger magnetic field than the other two.[8] Two giant molecular clouds are visible in the 12CO(J=1–0) emission to the west and northwest of the nucleus.[7] In mid infrared are visible some arms connecting the ring with the nucleus.[6]
The streamers between the two galaxies are among the first in what appears to be a wave of star formation that started on the galaxy's outskirts and continued inward. Researchers estimate the streamer stars were born between 50 million and 100 million years ago.[3] The age of the star-forming knots in the ring is calculated to be 2-8 million years.[6] Stars no older than one million to two million years old are forming closer to the centre of NGC 2445.[3] Observations of carbon monoxide emission indicate that NGC 2445 still has abundant gas and star formation rates will increase.[9]
Hubble Space Telescope has uncovered dark filaments of gas in the starburst galaxy's bright core. Those features may have been formed by outbursts of material, however the dust from the outbursts blankets the nucleus in the visible spectrum.[3] When observed in radio waves the core isn't very compact and its spectrum indicates the presence of a starburst region with an age between 1.5 and 5 million years.[8]
A shell of hydrogen gas measuring 20 kiloparsecs across has been found at a projected distance of about 100 kiloparsec of the galactic system. A filament of this shells points towards the galaxies indicating that it is a superbubble associated with them[10] or a tidal tail.[8]
Supernova
editOne supernova has been observed in NGC 2444/5, SN 2016bam. The supernova occurred between the two galaxies, about 3.5 arcseconds away from a HII region of NGC 2445.[11] It was a type II supernova which had magnitude 16.1 at discovery.[12]
Nearby galaxies
editNGC 2445 and NGC 2444 (which lies about one arcminute away) form a pair, known as Arp 143. The pair is part of a galaxy group known as LGG 148. Other members of the group include the galaxies NGC 2476, NGC 2493, NGC 2524, NGC 2415, UGC 3937, and UGC 3944.[13]
References
edit- ^ a b c d e f g h "NASA/IPAC Extragalactic Database". Results for NGC 2445. Retrieved 2024-03-26.
- ^ Seligman, Courtney. "NGC 2445 (= PGC 21776, and with NGC 2444 = Arp 143)". Celestial Atlas. Retrieved 19 November 2018.
- ^ a b c d e "Hubble Looks at a 'Space Triangle' Spawned by a Galaxy Collision". www.spacetelescope.org. 22 February 2022. Retrieved 26 March 2024.
This article contains quotations from this source, which is available under the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license.
- ^ Burbidge, E. Margaret; Burbidge, G. R. (July 1959). "The Remarkable Extragalactic System NGC 2444-5". The Astrophysical Journal. 130: 12. Bibcode:1959ApJ...130...12B. doi:10.1086/146689.
- ^ Appleton, P. N.; Schombert, J. M.; Robson, E. I. (February 1992). "A multiwavelength study of the peculiar interacting galaxies ARP 143 = VV 117 - Evidence for an emerging ring galaxy?". The Astrophysical Journal. 385: 491. Bibcode:1992ApJ...385..491A. doi:10.1086/170957.
- ^ a b c Beirão, P.; Appleton, P. N.; Brandl, B. R.; Seibert, M.; Jarrett, T.; Houck, J. R. (10 March 2009). "POWERFUL H 2 EMISSION AND STAR FORMATION ON THE INTERACTING GALAXY SYSTEM Arp 143: OBSERVATIONS WITH SPITZER AND GALEX". The Astrophysical Journal. 693 (2): 1650–1665. arXiv:0812.0450. doi:10.1088/0004-637X/693/2/1650.
- ^ a b Higdon, James L.; Rand, Richard J.; Lord, Steven D. (10 November 1997). "The Detection of Massive Molecular Complexes in the Ring Galaxy System Arp 143". The Astrophysical Journal. 489 (2): L133–L136. arXiv:astro-ph/9709134. Bibcode:1997ApJ...489L.133H. doi:10.1086/310974.
- ^ a b c Nikiel-Wroczyński, B.; Jamrozy, M.; Soida, M.; Urbanik, M. (21 October 2014). "Multiwavelength study of the radio emission from a tight galaxy pair Arp 143". Monthly Notices of the Royal Astronomical Society. 444 (2): 1729–1737. arXiv:1407.7369. doi:10.1093/mnras/stu1475.
- ^ Higdon, James L.; Smith, Beverly J.; Lord, Steven D.; Rand, Richard J. (January 1995). "The detection of molecular gas in the ring galaxy ARP 143". The Astrophysical Journal. 438: L79. Bibcode:1995ApJ...438L..79H. doi:10.1086/187720.
- ^ Appleton, P. N.; Ghigo, F. D.; van Gorkom, J. H.; Schombert, James M.; Struck-Marcell, Curtis (November 1987). "A giant intergalactic H I bubble near Arpl43". Nature. 330 (6144): 140–142. Bibcode:1987Natur.330..140A. doi:10.1038/330140a0.
- ^ Taggart, K; Perley, D A (5 April 2021). "Core-collapse, superluminous, and gamma-ray burst supernova host galaxy populations at low redshift: the importance of dwarf and starbursting galaxies". Monthly Notices of the Royal Astronomical Society. 503 (3): 3931–3952. arXiv:1911.09112. doi:10.1093/mnras/stab174.
- ^ "SN 2016bam | Transient Name Server". www.wis-tns.org. Retrieved 26 March 2024.
- ^ Garcia, A. M. (1 July 1993). "General study of group membership. II. Determination of nearby groups". Astronomy and Astrophysics Supplement Series. 100: 47–90. Bibcode:1993A&AS..100...47G. ISSN 0365-0138.
External links
edit
- NGC 2445 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images