View source for NGC 185

{{Short description|Galaxy in the constellation Cassiopeia}}
{{Infobox galaxy
| name = [[New General Catalogue|NGC]] 185
| image = Caldwell_18_%2850289818793%29.jpg
| caption = NGC 185 imaged by the [[Hubble Space Telescope]]
| type = dSph/dE3,<ref name="ned">{{cite web
 | title=NASA/IPAC Extragalactic Database
 | work=Results for NGC 185
 | url=http://nedwww.ipac.caltech.edu/
 | access-date=2006-11-29
 }}</ref> Sy2 <ref name="simbad">{{cite simbad
 |title=NGC 185 
 |access-date=2014-05-05
 }}</ref>
| epoch = [[J2000.0]]<ref name="simbad" />
| ra = {{RA|00|38|57.970}}<ref name="simbad" />
| dec = {{DEC|+48|20|14.56}}<ref name="simbad" />
| dist_ly = [[1 E22 m|2.05 ± 0.13]] [[light-year|Mly]] (630 ± 40 [[parsec|kpc]])<ref name="tonryetal2001" /><ref name="karachentsevetal2004" /><ref name="Karachentsevetal2006" />{{Ref_label|A|a|none}}
| z = −202 ± 3 [[kilometer|km]]/[[second|s]]<ref name="ned" />
| appmag_v = 10.1<ref name="ned" />
| size_v = 11.7{{prime}} × 10.0{{prime}}<ref name="ned" />
| constellation name = [[Cassiopeia (constellation)|Cassiopeia]]
| notes = [[Satellite galaxy]] of the<br/>[[Andromeda Galaxy]]
| names = [[Uppsala General Catalogue|UGC]] 396,<ref name="ned" /> [[Principal Galaxies Catalogue|PGC]] 2329,<ref name="ned" /> LEDA 2329,<ref name="simbad" /> [[Caldwell catalogue|Caldwell]]&nbsp;18
}}

'''NGC 185''' (also known as '''Caldwell 18''') is a [[dwarf spheroidal galaxy]] located [[1 E19 m|2.08 million]] [[light-year]]s from Earth, appearing in the [[constellation]] [[Cassiopeia (constellation)|Cassiopeia]]. It is a member of the [[Local Group]], and is a [[satellite galaxy|satellite]] of the [[Andromeda Galaxy]] (M31).<ref name=SEDS/> NGC 185 was discovered by [[William Herschel]] on November 30, 1787, and he cataloged it "H II.707".<ref name=SEDS>{{cite web|title=SEDS — NGC 185|url=http://spider.seds.org/spider/LG/n0185.html}}</ref> [[John Herschel]] observed the object again in 1833 when he cataloged it as "h 35", and then in 1864 when he cataloged it as "GC 90" within his ''[[General Catalogue of Nebulae and Clusters]]''.<ref name=SEDS/> NGC 185 was first photographed between 1898 and 1900 by [[James Edward Keeler]] with the [[Crossley Reflector]] of [[Lick Observatory]].<ref name=SEDS/> Unlike most dwarf elliptical galaxies, NGC 185 contains young [[stellar clusters]], and star formation proceeded at a low rate until the recent past. NGC 185 has an [[active galactic nucleus]] (AGN) and is usually classified as a type 2 [[Seyfert galaxy]],<ref name="hoetal1997">{{cite journal |last1=Ho |first1=Luis C. |last2=Filippenko |first2=Alexei V. |last3=Sargent |first3=Wallace L. W. |title=A Search for 'Dwarf' Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies  |date=October 1997 |volume=112 |issue=2 |pages=315–390 |arxiv=astro-ph/9704107 |bibcode=1997ApJS..112..315H |doi=10.1086/313041 |journal=The Astrophysical Journal Supplement Series|s2cid=17086638 }}</ref> though its status as a Seyfert is questioned.<ref name="Martins2012">{{cite journal |title=The ionization mechanism of NGC 185: How to fake a Seyfert galaxy? |first1=Lucimara P. |last1=Martins |first2=Gustavo |last2=Lanfranchi |first3=Denise R. |last3=Goncalves |first4=Laura |last4=Magrini |first5=Ana M. |last5=Teodorescu |first6=Cintia |last6=Quireza |date=February 2012 |doi=10.1111/j.1365-2966.2011.19954.x |bibcode=2012MNRAS.419.3159M |arxiv=1110.5891 |journal=Monthly Notices of the Royal Astronomical Society |volume=419 |issue=4 |pages=3159–3166|doi-access=free |s2cid=119188037 }}</ref> It is possibly the closest Seyfert galaxy to Earth, and is the only known Seyfert in the Local Group.

==Distance measurements==
At least two techniques have been used to measure distances to NGC 185. The surface brightness fluctuations distance measurement technique estimates distances to galaxies based on the graininess of their appearance. The distance measured to NGC 185 using this technique is 2.08 ± 0.15 [[light-year|Mly]] (640 ± 50 [[parsec|kpc]]).<ref name="tonryetal2001">{{cite journal |author=J. L. Tonry |display-authors=4  |author2=A. Dressler |author3=J. P. Blakeslee |author4=E. A. Ajhar |author5=A. B. Fletcher |author6=G. A. Luppino |author7=M. R. Metzger |author8= C. B. Moore | title=The SBF Survey of Galaxy Distances. IV. SBF Magnitudes, Colors, and Distances |journal=Astrophysical Journal | date=2001 |volume=546 |issue=2 | pages=681–693 |bibcode=2001ApJ...546..681T |doi=10.1086/318301 |arxiv=astro-ph/0011223|s2cid=17628238 }}</ref> However, NGC 185 is close enough that the [[tip of the red giant branch]] (TRGB) method may be used to estimate its distance. The estimated distance to NGC 185 using this technique is 2.02 ± 0.2 Mly (620 ± 60 kpc).<ref name="karachentsevetal2004">{{cite journal |author=I. D. Karachentsev |author2=V. E. Karachentseva |author3=W. K. Huchtmeier |author4=D. I. Makarov |title=A Catalog of Neighboring Galaxies |journal=Astronomical Journal |date=2004 |volume=127 |issue=4 |pages=2031–2068 |bibcode=2004AJ....127.2031K |doi=10.1086/382905|doi-access=free }}</ref><ref name="Karachentsevetal2006">{{cite journal |author=Karachentsev, I. D. |author2=Kashibadze, O. G. |title=Masses of the local group and of the M81 group estimated from distortions in the local velocity field |journal=Astrophysics |date=2006 |volume=49 |issue=1 |pages=3–18 |bibcode=2006Ap.....49....3K |doi=10.1007/s10511-006-0002-6|s2cid=120973010 }}</ref>

==Star formation==
Martínez-Delgado, Aparicio, & Gallart (1999) looked into the [[star formation]] history of NGC 185 and found that the majority of star formation in NGC 185 happened at early times.<ref name="Martins2012"/> In the last ~1 Gyr, stars have formed only near the center of this galaxy. [[Walter Baade]] discovered young blue objects within this galaxy in 1951, but these have turned out to be star clusters and not individual stars. A [[supernova remnant]] near the center was also discovered by Martínez-Delgado et al.<ref name="Bergh2000">{{Cite journal | last1 = van den Bergh | first1 = Sidney | author-link1 = Sidney van den Bergh | title = Updated Information on the Local Group 
 |date = April 2000| journal = The Publications of the Astronomical Society of the Pacific | volume = 112 | issue = 770 | bibcode = 2000PASP..112..529V | pages = 529–536 | doi = 10.1086/316548|arxiv = astro-ph/0001040 | s2cid = 1805423 }}</ref>

==See also==
* [[List of Andromeda's satellite galaxies]]
 
==References==
{{Reflist|2}}

==External links==
{{commonscat}}
* {{WikiSky}}

{{Sky|00|38|58.0|+|48|20|15|2050000}}
{{Catalogs | C = 18 | NGC = 185 | UGC = 396 | PGC = 2329}}
{{Caldwell catalogue}}
{{Andromeda galaxy}}
{{NGC5}}
{{Cassiopeia (constellation)}}

{{DEFAULTSORT:NGC 0185}}
[[Category:Dwarf galaxies]]
[[Category:Dwarf elliptical galaxies]]
[[Category:Dwarf spheroidal galaxies]]
[[Category:Local Group]]
[[Category:Andromeda Subgroup]]
[[Category:Cassiopeia (constellation)]]
[[Category:NGC objects|0185]]
[[Category:UGC objects|00396]]
[[Category:Principal Galaxies Catalogue objects|02329]]
[[Category:Caldwell objects|018b]]
[[Category:Galaxies discovered in 1787|17871130]]