View source for NGC 1637

{{short description|Galaxy in the constellation Eridanus}}
{{Sky|04|41|28.229|-|02|51|28.94}}
{{Infobox Galaxy
 | name       = [[New General Catalogue|NGC]] 1637
 | image      = Image:Spiral galaxy NGC 1637.jpg
 | caption    =[[Very Large Telescope]] image of NGC 1637.
 | credit     =
 | epoch      = [[J2000]]
 | type       = SAB(rs)c<ref name=Crowther2013/> or SBc(s)II.3<ref name=Sohn1998/>
 | ra         = {{RA|04|41|28.229}}<ref name=Skrutskie2006/>
 | dec        = {{DEC|−02|51|28.94}}<ref name=Skrutskie2006/>
 | dist_ly    = {{convert|9.77|±|1.82|Mpc|Mly|abbr=on|lk=on}}<ref name=Crowther2013/><br>{{convert|9.18|Mpc|Mly|abbr=on|lk=on}} {{hub|0.73}}<ref name="ned-distance"/>
 | z          = 0.00239<ref name=Haynes1998/>
 | h_radial_v = {{val|717.1|1.2|u=km/s}}<ref name=Haynes1998/>
 | size       = ~{{convert|17.48|kpc|ly|abbr=on|lk=on|order=flip}} (estimated)<ref name ="ned" />
 | appmag_v   = 11.5<ref name="ned" />
 | appmag_b   = 11.25<ref name=Immler2003/>
 | size_v     = 4.0{{prime}} × 3.2{{prime}}<ref name="ned" />
 | constellation name = [[Eridanus (constellation)|Eridanus]]
 | names      = {{odlist | name= AGC 440323 | PGC= 15821 | UGCA= 93 | CGCG= 393-066 | MCG= +00-12-068 | IRAS= 04389-0257}}<ref name="ned" />
}}

'''NGC 1637''' is an isolated, non-[[Interacting galaxy|interacting]]<ref name=Sohn1998/> [[intermediate spiral galaxy]] in the [[constellation]] [[Eridanus (constellation)|Eridanus]], about a degree to the WNW of the star [[Mu Eridani]].<ref name=Sinnott1997/> It was discovered by [[Germany|German-British]] astronomer [[William Herschel]] on 1 February 1786.<ref name="selig">{{cite web | url = https://cseligman.com/text/atlas/ngc16.htm#1637 | title = New General Catalogue Objects: NGC{{nbsp}}1637 | last = Seligman | first = Courtney | website = Celestial Atlas | access-date = 30 November 2024}}</ref> It is located at a distance of about {{convert|9.77|±|1.82|Mpc|Mly|abbr=on|lk=on}} from the [[Milky Way]].<ref name=Crowther2013/> The galaxy is inclined at an angle of 31.1° to the line of sight from the Earth and the long axis is oriented along a [[position angle]] of 16.3°.<ref name=Crowther2013/>

In 1991, [[Gérard de Vaucouleurs]] and associates assigned a [[galaxy morphological classification|morphological classification]] of SAB(rs)c to NGC 1637, indicating a spiral galaxy with a weak bar structure (SAB) across the nucleus, surrounded by a partial ring (rs) and somewhat loosely-wound arms (c).<ref name=Sohn1998/> While the inner section of the galaxy shows a symmetrical two-arm structure,<ref name=Immler2003/> it has a single outer spiral arm that wraps 180° around the nucleus,<ref name=Immler2003/> giving the galaxy an overall asymmetric, lopsided appearance.<ref name=Sohn1998/> The outer spiral arm has a red component that indicates a significant age.<ref name=Immler2003/> However, the existence of this structure is difficult to explain.<ref name=Sohn1998/> The galaxy shows indications of recent [[Starburst region|starburst activity]] that may have terminated around 15 million years ago.<ref name=Immler2003/>

The [[Active galactic nucleus|active central nucleus]] shows weak [[Low-ionization nuclear emission-line region|LINER]] behavior, and it may be an intermediate form between a LINER and an [[H II region]].<ref name=Sohn1998/> The luminosity of the X-ray source at the nucleus is {{val|1.2e38|u=ergs s<sup>−1</sup>}} in the 0.3–7&nbsp;keV band.<ref name=Immler2003/>

==Supernova==
One [[supernova]] has been observed in NGC 1637. [[SN 1999em]] ([[Type_II_supernova#Light_curves_for_Type_II-L_and_Type_II-P_supernovae|type II-P]], mag. 13.5) was discovered by the [[Lick Observatory]] Supernova Search (LOSS) on 29 October 1999, at an [[angular separation]] of {{val|24|ul=arcsecond}} to the southwest of the galaxy center.<ref>{{cite journal | bibcode= 1999IAUC.7294....1L| title= Supernova 1999em in NGC 1637| last1= Li| first1= W. D.| journal= International Astronomical Union Circular| date= 1999| issue= 7294| page= 1}}</ref><ref>{{cite web | website=Transient Name Server | title=SN{{nbsp}}1999em | url=https://www.wis-tns.org/object/1999em | publisher = [[International_Astronomical_Union|IAU]] | access-date=30 November 2024}}</ref> It was the brightest supernova discovered that year, reaching magnitude 13.1.<ref name=Rochester1999/> The location corresponds to a deprojected galactocentric separation of {{Convert|1.3|kpc|kly|abbr=on|lk=on}}.<ref name=Crowther2013/>

==Image and Video Gallery==
<gallery>
NGC 1637 imaged by the Hubble Space Telescope.jpg|NGC 1637 imaged by the [[Hubble Space Telescope]] 
Zooming in on the spiral galaxy NGC 1637 eso1315a.ogv|thumbtime=45|Video showing the location of NGC 1637
</gallery>

== See also ==
* [[List of NGC objects (1001–2000)]]

==References==
{{reflist|refs=

<ref name=Sinnott1997>{{cite book
 | first1=Roger W. | last1=Sinnott
 | first2=Michael A. C. | last2=Perryman
 | title=Millennium Star Atlas
 | volume=1 | year=1997 | isbn=0-933346-84-0
 | publisher=Sky Publishing Corporation and the European Space Agency }}</ref>

<ref name=Sohn1998>{{cite journal
 | title=VRI CCD Photometry of Supergiant Stars in the Barred Galaxies NGC 925 and NGC 1637
 | last1=Sohn | first1=Young-Jong | last2=Davidge | first2=T. J.
 | journal=The Astronomical Journal
 | volume=115 | issue=1 | pages=130–143 | date=January 1998
 | doi=10.1086/300163 | bibcode=1998AJ....115..130S | doi-access=free }}</ref>

<ref name=Immler2003>{{cite journal
 | title=A Deep Chandra X-Ray Observation of NGC 1637
 | last1=Immler | first1=Stefan | last2=Wang | first2=Q. Daniel
 | last3=Leonard | first3=Douglas C. | last4=Schlegel | first4=Eric M.
 | display-authors=1 | journal=The Astrophysical Journal
 | volume=595 | issue=2 | pages=727–742 | date=October 2003
 | doi=10.1086/377474 | bibcode=2003ApJ...595..727I | doi-access=free }}</ref>

<ref name=Skrutskie2006>{{cite journal |doi=10.1086/498708 |last1=Skrutskie |first1=Michael F. |last2=Cutri |first2=Roc M. |last3=Stiening |first3=Rae |last4=Weinberg |first4=Martin D. |last5=Schneider |first5=Stephen E. |last6=Carpenter |first6=John M. |last7=Beichman |first7=Charles A. |last8=Capps |first8=Richard W. |last9=Chester |first9=Thomas |last10=Elias |first10=Jonathan H. |last11=Huchra |first11=John P. |last12=Liebert |first12=James W. |last13=Lonsdale |first13=Carol J. |last14=Monet |first14=David G. |last15=Price |first15=Stephan |last16=Seitzer |first16=Patrick |last17=Jarrett |first17=Thomas H. |last18=Kirkpatrick |first18=J. Davy |last19=Gizis |first19=John E. |last20=Howard |first20=Elizabeth V. |last21=Evans |first21=Tracey E. |last22=Fowler |first22=John W. |last23=Fullmer |first23=Linda |last24=Hurt |first24=Robert L. |last25=Light |first25=Robert M. |last26=Kopan |first26=Eugene L. |last27=Marsh |first27=Kenneth A. |last28=McCallon |first28=Howard L. |last29=Tam |first29=Robert |last30=Van Dyk |first30=Schuyler D. |last31=Wheelock |first31=Sherry L. |title=The Two Micron All Sky Survey (2MASS) |journal=The Astronomical Journal |date=1 February 2006 |volume=131 |issue=2 |pages=1163–1183 |bibcode=2006AJ....131.1163S |s2cid=18913331 |issn=0004-6256 |doi-access=free }}</ref>

<ref name=Crowther2013>{{cite journal
 | title=On the association between core-collapse supernovae and H ii regions
 | last=Crowther | first=Paul A.
 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=428 | issue=3 | pages=1927–1943 | date=January 2013
 | doi=10.1093/mnras/sts145 | doi-access=free | arxiv=1210.1126
 | bibcode=2013MNRAS.428.1927C }}</ref>

<ref name=Haynes1998>{{cite journal
 | title=Asymmetry in High-Precision Global H i Profiles of Isolated Spiral Galaxies
 | display-authors=1 | last1=Haynes | first1=Martha P.
 | last2=Hogg | first2=David E. | last3=Maddalena | first3=Ronald J.
 | last4=Roberts | first4=Morton S. | last5=van Zee | first5=Liese
 | journal=The Astronomical Journal
 | volume=115 | issue=1 | pages=62–79 | date=January 1998
 | doi=10.1086/300166 | bibcode=1998AJ....115...62H | s2cid=123380349 | doi-access=free }}</ref>

<ref name="ned">{{cite web
 | title=NASA/IPAC Extragalactic Database
 | work=Results for NGC 1637
 | url=http://nedwww.ipac.caltech.edu/
 | access-date=2006-11-25 }}</ref>

<ref name="ned-distance">{{cite web
 | title=NASA/IPAC Extragalactic Database
 | work=Results for NGC 1512, Co-Moving Radial Distance
 | url=http://nedwww.ipac.caltech.edu/
 | access-date=2014-12-18 }}</ref>

<ref name=Rochester1999>{{cite web
 | title=Bright Supernovae - 1999 : SN 1999em
 | last = Bishop
 | first = David
 | publisher=Astronomy Section, Rochdale Academy of Science
 | url=https://www.rochesterastronomy.org/snimages/sn1999/#1999em
 | access-date=2024-11-30 }}</ref>

}}

== External links ==
* {{commonscat-inline}}

{{astronomical catalogs|NGC=1637|PGC=15821}}
{{Ngc20}}
{{Eridanus (constellation)}}

{{DEFAULTSORT:NGC 1637}}
[[Category:Intermediate spiral galaxies]]
[[Category:LINER galaxies]]
[[Category:Eridanus (constellation)]]
[[Category:NGC objects|1637]]
[[Category:Principal Galaxies Catalogue objects|015821]]
[[Category:Articles containing video clips]]
[[Category:UGCA objects]]
[[Category:IRAS catalogue objects|04389-0257]]
[[Category:MCG objects|+00-12-068]]
[[Category:Astronomical objects discovered in 1786|17860201]]
[[Category:Discoveries by William Herschel]]