View source for NGC 2438

{{short description|Planetary nebula in the constellation Puppis}}
{{Infobox nebula
 | image     = [[File:N2438s-crop.jpg|300px]]
 | caption   = 
 | credit    = 
 | name      = NGC 2438
 | epoch     = J2000.0
 | constellation  = Puppis
 | ra        = {{RA|07|41|50.51986}}<ref name="GaiaDR2" />
 | dec       = {{Dec|−14|44|07.4843}}<ref name="GaiaDR2" />
 | dist_ly   = {{Convert|420|±|40|pc|ly|order=flip|lk=on|abbr=on}}<ref name="GaiaDR2" />
 | type      = Planetary
 | appmag_v  = +10.8
 | size_v    = 1.1 [[Minute of arc|arcmins]]
 | radius_ly = 
 | absmag_v  = 
 | notes     = Superimposed on [[Messier 46]]
 | names     = {{odlist|name=H IV.39|name2=FC 87|name3=PK 231+4.2}}
}}

'''NGC 2438''' is a [[planetary nebula]] in the southern [[constellation]] of [[Puppis]].<ref name=APOD>{{Cite APOD
 | title=Planetary Nebula NGC 2438
 | access-date=2011-04-08
 | date=2011-04-07 }}</ref> [[Stellar parallax|Parallax]] measurements by [[Gaia (spacecraft)|Gaia]] put the central star at a distance of roughly 1,370&nbsp;[[light year]]s.<ref name=GaiaDR2/> It was discovered by [[William Herschel]] on March 19, 1786.<ref name="ATLAS"/> NGC 2438 appears to lie within the cluster [[Messier 46|M46]], but it is most likely unrelated since it does not share the cluster's [[radial velocity]].<ref name=majaess2007>{{cite journal
 | title=In Search of Possible Associations between Planetary Nebulae and Open Clusters
 | display-authors=1 | last1=Majaess | first1=D. J.
 | last2=Turner | first2=D. | last3=Lane | first3=D.
 | journal=Publications of the Astronomical Society of the Pacific
 | volume=119 | issue=8 | page=1349 | date=2007
 | doi=10.1086/524414 | arxiv=0710.2900 | bibcode=2007PASP..119.1349M | s2cid=18640979 }}</ref><ref name=kiss2008>{{cite journal
 | display-authors=1 | last1=Kiss | first1=L. L.
 | last2=Szabó | first2=Gy. M. | last3=Balog | first3=Z.
 | last4=Parker | first4=Q. A. | last5=Frew | first5=D. J.
 | title=AAOmega radial velocities rule out current membership of the planetary nebula NGC 2438 in the open cluster M46
 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=391 | issue=1 | pages=399–404 | date=November 2008
 | arxiv=0809.0327 | bibcode=2008MNRAS.391..399K 
 | doi=10.1111/j.1365-2966.2008.13899.x | doi-access=free | s2cid=15207860 }}</ref>

The object is a multi-shell planetary nebula with a bright inner nebula with a diameter of {{val|60|ul=arcsecond}}, consisting of two somewhat detached shells.<ref name="Öttl2014" /> It is expanding with a velocity of {{val|37|u=km/s}}.<ref name="Corradi2000" /> The structure is surrounded by a fainter, mostly circular halo that is more visible on the western half,<ref name="Öttl2014" /> and has a diameter of {{val|130|u=arcsecond}}.<ref name="Corradi2000" /> The mass of the main nebula is estimated at {{val|0.45|ul=solar mass}}, while the shell has 0.5–{{val|0.8|u=solar mass}}.<ref name="Öttl2014" /> The main nebula has a temperature of about 10–13,000&nbsp;K, rising to 15–17,000&nbsp;K at the inner edge.<ref name="Dalnodar2012" />

The nebula consists of material ejected from the central star during the [[asymptotic giant branch]] stage, beginning about 8,500 years ago. The main nebula was formed at about half that age.<ref name="Corradi2000" /> The central star of this planetary nebula is a 17.7-[[apparent magnitude|magnitude]] [[white dwarf]],<ref name="ATLAS" /> with a surface temperature of about {{convert|75000|K|°C}}.<ref name="kopernik" />

==References==

{{reflist|refs=
<ref name="GaiaDR2">{{Cite Gaia DR2|3029214290412318720}}</ref>

<ref name="Dalnodar2012">{{cite conference | title=The ionization state of the halo planetary nebula NGC 2438 | last=Dalnodar | first=Silvia | conference=Planetary Nebulae: An Eye to the Future, Proceedings of the International Astronomical Union, IAU Symposium | volume=283 | pages=338–339 | date=August 2012 | bibcode=2012IAUS..283..338D | arxiv=1109.5609 | doi=10.1017/S1743921312011313}}</ref>

<ref name="Corradi2000">{{cite journal | title=A hydrodynamical study of multiple-shell planetaries . I. NGC 2438 | last1=Corradi | first1=R. L. M. | last2=Schönberner | first2=D. | last3=Steffen | first3=M. | last4=Perinotto | first4=M. | editor1-first=A. | editor1-last=Manchado | editor2-first=L. | editor2-last=Stanghellini | editor3-first=D. | editor3-last=Schoenberner | display-authors=1 | journal=Astronomy and Astrophysics | volume=354 | pages=1071–1085 | date=February 2000 | bibcode=2000A&A...354.1071C}}</ref>

<ref name="Öttl2014">{{cite journal | title=Ionization structure of multiple-shell planetary nebulae. I. NGC 2438 | display-authors=1 | last1=Öttl | first1=S. | last2=Kimeswenger | first2=S. | last3=Zijlstra | first3=A. A. | journal=Astronomy & Astrophysics | volume=565 | id=A87 | pages=13 | date=May 2014 | doi=10.1051/0004-6361/201323205 | arxiv=1403.6715 | bibcode=2014A&A...565A..87O | s2cid=118479677}}</ref>

<ref name="ATLAS">{{cite web | title=NGC Objects: NGC 2400 - 2449 | url=http://cseligman.com/text/atlas/ngc24.htm#2438 | access-date=2011-04-08}}</ref>

<ref name="kopernik">{{cite web | title=Planetary Nebula NGC 2438 in Puppis | website=kopernik.org | date=March 13, 2000 | url=http://www.kopernik.org/images/archive/n2438.htm | access-date=2011-04-08}}</ref>
}}

==External links==
{{commonscat}}
* [http://messier.seds.org/xtra/ngc/n2438.html NGC 2438 @ SEDS NGC objects pages]


{{Ngc25}}
{{Sky|07|41|50.6|-|14|44|05|3000}}
{{puppis}}
[[Category:Planetary nebulae]]
[[Category:Puppis]]
[[Category:NGC objects|2438]]