NGC 2207 and IC 2163 explained

NGC 2207 / IC 2163
Epoch:	J2000
Type:	SAB(rs)bc pec / SB(rs)c pec^[1]
Ra:	/
Dec:	/
Dist Ly:	81 ± 39 Mly ^[2]
Z:	2741 ± 15 / 2765 ± 20 km/s
Appmag V:	12.2 / 11.6
Size V:	4.3 × 2.8 / 3.0 × 1.2
Constellation Name:	Canis Major
Notes:	colliding galaxies
Names:	RR132a / RR132b, PGC 018749 / 018751, UGCA 124/125

NGC 2207 and IC 2163 are a pair of colliding spiral galaxies about 80 million light-years away^[2] in the constellation Canis Major. Both galaxies were discovered by John Herschel in 1835.

The larger spiral, NGC 2207, is classified as an intermediate spiral galaxy exhibiting a weak inner ring structure around the central bar. The smaller companion spiral, IC 2163, is classified as a barred spiral galaxy that also exhibits a weak inner ring and an elongated spiral arm that is likely being stretched by tidal forces with the larger companion. Both galaxies contain a vast amount of dust and gas, and are beginning to exhibit enhanced rates of star formation, as seen in infrared images.

NGC 2207 is in the process of colliding and merging with IC 2163. But unlike the Antennae or the Mice Galaxies, they are still two separate spiral galaxies. They are only in the first step of colliding and merging, with NGC 2207 being in the process of tidally stripping IC 2163. Soon they will collide, probably looking a bit more like the Mice Galaxies. In about a billion years time they are expected to merge and become an elliptical galaxy or perhaps a disk galaxy.^[3]

Supernovae

Five supernovae have been observed in NGC 2207:

• SN 1975A (type Ia, mag. 14.6) in January 1975^[4]
• SN 1999ec (type Ib, mag. 17.9) in October 1999^[5]
• SN 2003H (type Ib, mag. 17.8) in January 2003, discovered halfway between the two galaxies^[6]
• SN 2013ai (type II, mag. 17.4) in March 2013^[7]
• AT 2019eez (type IIn, mag. 16.7) in April 2019.^{[8] [9]}

Two supernovae have been observed in IC 2163:^[10]

• SPIRITS17lb (type unknown, mag. IR 15.6) in May 2017. ^[11]
• SN 2018lab (type II, mag. 18.5) in December 2018.^[12]

In addition, one supernova has been observed on the outskirts of the group:

• SN 2010jp (type IIn, mag. 17.2) in November 2010.^[13]

See also

• Andromeda–Milky Way collision
• Antennae Galaxies
• Arp 299
• NGC 5090 and NGC 5091
• NGC 6872 and IC 4970

External links

• HST: A grazing encounter between two spiral galaxies
• NGC 2207.
• IC 2163.

Notes and References

1. Web site: NASA/IPAC Extragalactic Database . Results for NGC 2207 / IC 2163 . 2006-11-25 .
2. Web site: Distance Results for NGC 2207 . NASA/IPAC Extragalactic Database . 2010-05-22.
3. Junko Ueda . etal . Cold molecular gas in merger remnants. I. Formation of molecular gas disks . The Astrophysical Journal Supplement Series . 214 . 1 . 1 . 2014ApJS..214....1U . 10.1088/0067-0049/214/1/1. 1407.6873 . 2014 . 716993 .
4. Kirshner, Robert P. . Arp, H.C. . Dunlap, J.R.. 1976. Observations of Supernovae - 1975a in NGC 2207 and 1975b in the Perseus Cluster. Astrophysical Journal. 207. 1. 44–52 . 1976ApJ...207...44K . 10.1086/154465 . free.
5. Jha, S. . 4 . Garnavich, P. . Challis, P. . Kirshner, R. . Berlind, P.. 1999. Supernova 1999ec in NGC 2207. IAU Circular. 7269. 2. 1999IAUC.7269....2J.
6. van den Bergh, Sidney . Li, Weidong . Filippenko, Alexei V. . Classifications of the Host Galaxies of Supernovae, Set II . The Publications of the Astronomical Society of the Pacific . 115 . 813 . 1280 - 88 . 2003 . 10.1086/379106 . 2003PASP..115.1280V . astro-ph/0308195 . 2015979 .
7. Conseil, E. . 4 . Fraser, M. . Inserra, C. . Walton, N. . Blagorodnova, N. . Nicholl, M. . Benetti, S. . Pastorello, A. . Valenti, S. . Taubenberger, S. . Smartt, S.J. . Smith, K. . Young, D. . Sullivan, M. . Gal-Yam, A. . Yaron, O.. 2013. Supernova 2013ai in NGC 2207 = Psn J06161835-2122329. Central Bureau Electronic Telegrams. 3431 . 3431. 1. 2013CBET.3431....1K.
8. Web site: Transient Name Server . Entry for AT 2019eez . 10 August 2024.
9. Web site: ATel #12706: Spectroscopic classification of ASASSN-19kz as a young Type II supernova in NGC 2207 . Strader . Jay . 30 April 2019 . The Astronomer's Telegram . 10 August 2024.
10. https://www.rochesterastronomy.org/sn2018/index.html#2018lab 2018lab
11. Web site: ATel #10489: Pre-discovery limits on SPIRITS17lb, a probable supernova in IC 2163 . Jencson . Jacob . 14 June 2017 . The Astronomer's Telegram . 10 August 2024.
12. Web site: Transient Name Server . Entry for SN 2018lab . 10 August 2024.
13. Web site: Transient Name Server . Entry for SN 2010jp . 10 August 2024.