| 词条 | NGC 2440 |
| 释义 |
| name = NGC 2440 | image = File:NGC 2440 by HST.jpg | image_size = 250px | caption = NGC 2440, as taken by the Hubble Space Telescope | type = Planetary | epoch = J2000 | ra = {{RA|07|41|54.91}}[1] | dec = {{DEC|-18|12|29.7}}[1] | dist_ly = 4.00 kly (1.23 kpc)[3] | appmag_v = 9.4[4] | size_v = 74" × 42"[4] | constellation = Puppis | radius_ly = | absmag_v = | notes = | names = ESO 560-PN9 }} NGC 2440 is a planetary nebula, one of many in our galaxy. Its central star, HD62166,[1] is possibly the hottest known white dwarf. The nebula is situated in the constellation Puppis. It was discovered by William Herschel on March 4, 1790. He described it as "a beautiful planetary nebula of a considerable degree of brightness, not very well defined."[2] The nebula is located about 1.23 kiloparsecs (3.79×1019 m) or about 4,000 light years from the Sun.[3] HD 62166HD 62166 has an exceptionally high surface temperature of about 200,000 kelvins[3] and a luminosity 1,100 times that of the Sun.[4] This dense star, with an estimated 0.6 solar mass and 0.028 solar radius,[4] has an apparent magnitude of 17.5.[5]See also
Notes1. ^1 2 {{Harv|SIMBAD|2007}} 2. ^1 2 {{Harv|O'Meara|2007}} 3. ^1 2 {{Harv|Nemiroff|Bonnell|2007}} 4. ^1 {{Harv|James|Marion|2006}} 5. ^{{Cite web | url=http://observing.skyhound.com/archives/feb/NGC_2440.html | title=Observing at Skyhound: NGC 2440}} References{{refbegin}}
| last1 = SIMBAD | title = Results for NGC 2440 | author1-link = SIMBAD | date = January 9, 2007 | publisher = SIMBAD, Centre de Données Astronomiques de Strasbourg | url = http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=NGC+2440 }}
| title = Planetary Nebula NGC 2440 | date = February 15, 2007 | access-date = }}
| last1 = James | first1 = Renée | last2 = Marion | first2 = Howie | title = X-treme Stars of the cosmos | journal = Astronomy | date = April 2006 | volume = 34 | issue = 4 | pages = 34–39 | bibcode = 2006Ast....34d..34J
| last1 = O'Meara | first1 = Stephen James | title = Albino Butterfly, Kiss Nebula, Little Lips Nebula: NGC 2440 | journal = Hidden Treasures | date = 2007 | pages = 204–208 }}{{refend}} External links
4 : Planetary nebulae|Puppis|NGC objects|ESO objects |
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