| 词条 | NGC 2438 |
| 释义 |
| image = | caption = NGC 2438 (upper left) and the Calabash Nebula (lower right) | name = NGC 2438 | type = IV+II | epoch = J2000.0 | ra = 07h 41.8m | dec = -14° 44′ | dist_ly = 2,900 ly | appmag_v = +10.8 | size_v = 1.1 arcmins | constellation = Puppis | radius_ly = - | absmag_v = - | notes = Superimposed on Messier 46 | names = H IV.39, FC 87, PK 231+4.2 }}NGC 2438 is a planetary nebula about 3,000 light years away in the constellation Puppis.[1] It was discovered by William Herschel on March 19, 1786.[2] NGC 2438 appears to lie within the cluster M46, but it is most likely unrelated since it does not share the cluster's radial velocity.[3][4] The case is yet another example of a superposed pair, joining the famed case of NGC 2818.[3][5] Long exposures have shown that this planetary nebula has an extended double halo,[6] while the more easily visible portion probably dates to the death of the red giant in its center.[2] Central starThe central star of this planetary nebula is a 17.7-magnitude white dwarf,[2] with surface temperature of about {{convert|75000|K|°C}}.[7] It is one of the hottest stars known. GallerySee also
References1. ^{{Cite APOD|title=Planetary Nebula NGC 2438|access-date=2011-04-08|date=2011-04-07}} 2. ^1 2 {{cite web|title=NGC Objects: NGC 2400 - 2449|url=http://cseligman.com/text/atlas/ngc24.htm#2438|accessdate=2011-04-08}} 3. ^1 Majaess D. J., Turner D., Lane D. (2007). In Search of Possible Associations between Planetary Nebulae and Open Clusters, PASP, 119, 1349 4. ^Kiss, L. L., Szabó, Gy. M., Balog, Z., Parker, Q. A., Frew, D. J. (2008). [https://arxiv.org/abs/0809.0327 AAOmega radial velocities rule out current membership of the planetary nebula NGC 2438 in the open cluster M46], MNRAS 5. ^Mermilliod, J.-C., Clariá, J. J., Andersen, J., Piatti, A. E., Mayor, M. (2001). Red giants in open clusters. IX. NGC 2324, 2818, 3960 and 6259, A&A 6. ^{{cite web|title=NGC 2438|url=http://messier.seds.org/xtra/ngc/n2438.html|publisher=SEDS|accessdate=2011-04-08}} 7. ^{{cite web|title=Planetary Nebula NGC 2438 in Puppis|url=http://www.kopernik.org/images/archive/n2438.htm|accessdate=2011-04-08}} External links
3 : Planetary nebulae|Puppis|NGC objects |
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