imported>InternetArchiveBot：补救4个来源，并将0个来源标记为失效。) #IABot (v2.0.9.5

2023-06-11T17:46:12Z

补救4个来源，并将0个来源标记为失效。) #IABot (v2.0.9.5

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{{Sky|17|48|08.17|+|70|52|35.3|20.259}}
{{Starbox begin
|name= G 240-72 }}
{{Starbox observe
|epoch=[[J2000]]<ref name="Simbad">{{cite web
| url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=GJ+1221
| title=GJ 1221 -- White Dwarf
| publisher=[[Centre de Données astronomiques de Strasbourg]]
| access-date=2011-10-23
| archive-date=2023-03-22
| archive-url=https://web.archive.org/web/20230322220102/http://simbad.u-strasbg.fr/simbad/sim-id?Ident=GJ+1221
| dead-url=no
}}</ref>
|equinox=[[J2000]]<ref name="Simbad"/>
|constell=[[天龍座]]
|ra={{RA|17|48|08.17}}<ref name="Simbad"/>
|dec={{DEC|+70|52|35.3}}<ref name="Simbad"/>
|appmag_v=14.15<ref name="Holberg2008">{{cite journal |last=Holberg |first=J. B. |author2=Sion |author3=Oswalt |author4=McCook |author5=Foran |author6=Subasavage |date=2008 |journal=[[The Astronomical Journal]] |volume=135 |issue=4 |pages=1225–1238 |bibcode=2008AJ....135.1225H |doi=10.1088/0004-6256/135/4/1225 |title=A New Look at the Local White Dwarf Population |s2cid=122855486 |url=https://commons.erau.edu/publication/886 |access-date=2023-03-22 |archive-date=2023-04-20 |archive-url=https://web.archive.org/web/20230420034914/https://commons.erau.edu/publication/886/ |dead-url=no }}</ref>}}
{{Starbox character
|class=DQP9.0<ref name="Holberg2008"/>
|appmag_1_passband=B
|appmag_1=14.55<ref name="Simbad"/>
|appmag_2_passband=V
|appmag_2=14.15<ref name="Simbad"/>
|appmag_3_passband=R
|appmag_3=13.5<ref name="Simbad"/>
|appmag_4_passband=I
|appmag_4=13.1<ref name="Simbad"/>
|appmag_5_passband=J
|appmag_5=12.709 ± 0.021<ref name="Simbad"/>
|appmag_6_passband=H
|appmag_6=12.528 ± 0.023<ref name="Simbad"/>
|appmag_7_passband=K
|appmag_7=12.507 ± 0.023<ref name="Simbad"/>}}
{{Starbox astrometry
|prop_mo_ra=-1261<ref name="Sion2009">
{{cite journal
| last=Sion |first=Edward M.
|author2=Holberg |author3=Oswalt |author4=McCook |author5= Wasatonic
| date=2009
| journal=[[The Astronomical Journal]]
| volume=138 |issue=6
| pages=1681–1689
| bibcode=2009AJ....138.1681S
| doi=10.1088/0004-6256/138/6/1681
|arxiv = 0910.1288 |title=The White Dwarfs within 20 Parsecs of the Sun: Kinematics and Statistics
|s2cid=119284418
}}</ref>
|prop_mo_dec=1112<ref name="Sion2009"/>
|parallax=160.9952
|p_error=0.0119
|parallax_footnote=<ref name="GaiaEDR3">{{Cite Gaia EDR3|1638979384378696704}}</ref>
| absmag_v=15.23<ref name="Holberg2008"/>{{r|van Altena1995}}<ref name="note 1" group="note">From apparent magnitude and parallax.</ref>
}}
{{Starbox detail
| mass=0.81 ± 0.01<ref name="Holberg2008"/>
| gravity=8.36 ± 0.02<ref name="Holberg2008"/>
| radius=0.00984<ref name="Holberg2008"/><ref name="note 2" group="note">From surface gravity and mass.</ref>
| temperature=5590 ± 90<ref name="Holberg2008"/>
| luminosity = 0.000085<ref name="ApJS199_2_29"/>
|rotation=>100 years<ref name=Brinkworth2013/>
| age_gyr=5.69<ref name="note 3" group="note">Cooling age, i. e. age as degenerate star (not counting duration of previous existence as main sequence star and as giant star)</ref><ref name="Sion2009"/>}}
{{Starbox catalog
|names=WD 1748+708,<ref name="Holberg2008"/><ref name="Sion2009"/> [[Luyten Half-Second catalogue|LHS]] 455,<ref name="Holberg2008"/> [[Luyten-Palomar proper motion catalogue|LP]] 44-113,<ref name="Simbad"/> [[New Luyten Two-Tenths catalogue|NLTT]] 45565,<ref name="Simbad"/> [[Gliese catalogue|GJ]] 1221,{{r|van Altena1995}} EGGR 372,<ref name="Simbad"/> [[Two Micron All-Sky Survey|2MASS]] J17480817+7052353<ref name="Simbad"/>}}
{{Starbox reference
| Simbad=GJ+1221
}}
{{Starbox image
|image={{Location map|100x100|AlternativeMap=Draco_constellation_map.svg
|alt=G 240-72 is located in the constellation Draco
|caption=G 240-72 在[[天龍座]]的位置|border=infobox|mark=Red_pog.png|width=300
|label=G 240-72
|lat=49.8
|long=36.1
}}|caption=
}}
{{Starbox end}}

'''G 240-72''' (或 '''WD 1748+708'''或 '''LHS 455'''或 '''GJ 1221''') 是一顆位於[[天龍座]]附近的白矮星，光譜等級為 DQP9.0<ref name="Holberg2008"/>。

==距離==
G 240-72 是距離第七近的白矮星（僅次於[[天狼星#天狼星B|天狼星B]]、[[南河三#伴星|南河三B]]、[[范馬南星]]、[[GJ 440]]、[[波江座40|波江座40B]]和[[施泰因2051|施泰因2051B]]）。

==特性==
G 240-72質量為0.81個[[太陽質量]]<ref name="Holberg2008"/>。

這顆白矮星的溫度相對較低，為5590K<ref name="Holberg2008"/>。由於其溫度與太陽相似，因此外觀呈白色。它有純氦大氣，自轉非常緩慢，週期可能超過100年。<ref name=Brinkworth2013>{{Cite web |url=https://iopscience.iop.org/article/10.1088/0004-637X/773/1/47/pdf |title=MEASURING THE ROTATIONAL PERIODS OF ISOLATED MAGNETIC WHITE DWARFS |access-date=2023-03-22 |archive-date=2023-03-22 |archive-url=https://web.archive.org/web/20230322054254/https://iopscience.iop.org/article/10.1088/0004-637X/773/1/47/pdf |dead-url=no }}</ref>

==參考==
{{reflist|refs=
<ref name="van Altena1995">{{cite web |url=http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-source=I/238A/picat&GCTP=2835.01 |title=GCTP 2835.01 |work=The General Catalogue of Trigonometric Stellar Parallaxes |edition=Fourth |author1=Van Altena W. F. |author2=Lee J. T. |author3=Hoffleit E. D. |year=1995 |access-date=2023-03-22 |archive-date=2022-05-23 |archive-url=https://web.archive.org/web/20220523021021/http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-source=I/238A/picat&GCTP=2835.01 |dead-url=no }}</ref>

<ref name="ApJS199_2_29">{{citation
| last1 = Giammichele
| first1 = N.
| last2 = Bergeron
| first2 = P.
| last3 = Dufour
| first3 = P.
| title = Know Your Neighborhood: A Detailed Model Atmosphere Analysis of Nearby White Dwarfs
| journal = The Astrophysical Journal Supplement
| volume = 199
| issue = 2
| page = 29
|date=April 2012
| arxiv = 1202.5581
| doi = 10.1088/0067-0049/199/2/29
| bibcode = 2012ApJS..199...29G
| s2cid = 118304737
| postscript = .
}}</ref>
}}

==註釋==
<references group="note"/>

==外部連結==
*[https://web.archive.org/web/20120513202710/http://www.chara.gsu.edu/RECONS/TOP100.posted.htm The 100 Nearest Star Systems (RECONS)]

{{Nearest star systems|5}}
{{Stars of Draco}}

{{DEFAULTSORT:G 240-72}}
[[Category:白矮星]]
[[Category:天龍座]]
[[Category:格利澤和GJ天體|1221]]
[[Category:2MASS天體|J17480817+7052353]]

G 240-72 - 版本历史

imported>InternetArchiveBot：​补救4个来源，并将0个来源标记为失效。) #IABot (v2.0.9.5

imported>InternetArchiveBot：补救4个来源，并将0个来源标记为失效。) #IABot (v2.0.9.5