NGC 7237

{{Short description|Galaxy in the constellation Pegasus}}

{{Infobox galaxy

| name = NGC 7237

| image = 250px

| caption = NGC 7237 by PanSTARRS

| credit =

| epoch = J2000

| type = SA0- {{cite web

| title=NASA/IPAC Extragalactic Database

| work=Results for NGC 7237

| url=http://ned.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=NGC+7237

| accessdate=2023-07-07 }}

| ra = {{RA|22|14|46.9}}

| dec = {{DEC|+13|50|27}}

| dist_ly = 371 ± 99 Mly (114 ± 30.5 Mpc)

| z = 0.026213 ± 0.000007

| h_radial_v = 7,858 ± 2 km/s

| appmag_v = 13.9{{cite web |title=Revised NGC Data for NGC 7237 |url=http://spider.seds.org/ngc/revngcic.cgi?NGC7237 |website=spider.seds.org |accessdate=25 November 2018}}

| size_v = 1.81{{prime}} × 0.72{{prime}}

| constellation name = Pegasus

| notes = Interacting galaxy, radio galaxy

| names = UGC 11958, Arp 169, II Zw 172, CGCG 428-058, MCG +02-56-024, 3C 442A, PGC 68383

}}

NGC 7237 is an interacting lenticular galaxy located in the constellation Pegasus. It is located at a distance of about 350 million light years from Earth, which, given its apparent dimensions, means that NGC 7237 is about 240,000 light years across. NGC 7237 forms a pair with NGC 7236 and is a radio galaxy. It was discovered by Albert Marth on August 25, 1864.{{cite web |last1=Seligman |first1=Courtney |title=NGC 7237 (with NGC 7236 = Arp 169) |url=https://cseligman.com/text/atlas/ngc72.htm#7237 |website=Celestial Atlas |accessdate=19 November 2018}}

NGC 7237 forms a pair with lenticular galaxy NGC 7236,{{cite journal |last1=Borne |first1=Kirk D. |last2=Hoessel |first2=John G. |title=Interacting binary galaxies. III - Observations of NGC 1587/1588 and NGC 7236/7237 |journal=The Astrophysical Journal |date=July 1988 |volume=330 |pages=51 |doi=10.1086/166454}} which lies 35 arcseconds to the northwest. The two galaxies are undergoing a merger and are surrounded by hot gas (corona) with temperature of around 1 keV. The total mass of that gas is estimated to be {{val|3|e=10|ul=M_solar}}.{{cite journal |last1=Worrall |first1=D. M. |last2=Birkinshaw |first2=M. |last3=Kraft |first3=R. P. |last4=Hardcastle |first4=M. J. |title=The Effect of a Chandra -measured Merger-related Gas Component on the Lobes of a Dead Radio Galaxy |journal=The Astrophysical Journal |date=1 April 2007 |volume=658 |issue=2 |pages=L79–L82 |doi=10.1086/513869|s2cid=15963632 |doi-access=free }} A smaller elliptical galaxy, NGC 7237C, lies 38 arcseconds southeast of NGC 7237. It is included in the Atlas of Peculiar Galaxies, in the category diffuse counter-tails. A tail is also visible in X-rays. The isophotes in the central region of NGC 7237 are irregular.{{cite journal |last1=Martel |first1=André R. |last2=Baum |first2=Stefi A. |last3=Sparks |first3=William B. |last4=Wyckoff |first4=Eric |last5=Biretta |first5=John A. |last6=Golombek |first6=Daniel |last7=Macchetto |first7=Ferdinando D. |last8=de Koff |first8=Sigrid |last9=McCarthy |first9=Patrick J. |last10=Miley |first10=George K. |title=Hubble Space Telescope Snapshot Survey of 3CR Radio Source Counterparts. III. Radio Galaxies with [FORMULA][F]z |journal=The Astrophysical Journal Supplement Series |date=May 1999 |volume=122 |issue=1 |pages=81–108 |doi=10.1086/313205|s2cid=249153931 |doi-access=free |bibcode=1999ApJS..122...81M }}

The galaxy pair is a source of radiowaves. The radio emission has a double lobe structure, with filaments, but no jets, while a weak core is identified as the nucleus of NGC 7237.{{cite journal |last1=Comins |first1=Neil F. |last2=Owen |first2=Frazer N. |title=The extraordinary radio source 3C 442 |journal=The Astrophysical Journal |date=November 1991 |volume=382 |pages=108 |doi=10.1086/170698}} The filaments could be created by the interaction of hot gas with the preexisting radio emitting plasma. Some bright radio sources are visible within the lobes but they could be background active galaxies.{{cite journal |last1=Hardcastle |first1=M. J. |last2=Kraft |first2=R. P. |last3=Worrall |first3=D. M. |last4=Croston |first4=J. H. |last5=Evans |first5=D. A. |last6=Birkinshaw |first6=M. |last7=Murray |first7=S. S. |title=The Interaction between Radio Lobes and Hot Gas in the Nearby Radio Galaxies 3C 285 and 3C 442A |journal=The Astrophysical Journal |date=10 June 2007 |volume=662 |issue=1 |pages=166–181 |doi=10.1086/517997|s2cid=18803836 |arxiv=astro-ph/0703080 |bibcode=2007ApJ...662..166H }} The core has been found to be variable source of X-rays.