# G 240-72

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Star in the constellation Draco

G 240-72 G 240-72 Location of G 240-72 in the constellation Draco Observation data Epoch J2000 Equinox J2000 Constellation Draco Right ascension 17h 48m 07.99282s[1] Declination +70° 52′ 35.9221″[1] Apparent magnitude (V) 14.15[2] Characteristics Evolutionary stage white dwarf[2] Spectral type DQP9.0[2] Apparent magnitude (B) 14.55[3] Apparent magnitude (V) 14.15[3] Apparent magnitude (R) 13.5[3] Apparent magnitude (I) 13.1[3] Apparent magnitude (J) 12.709 ± 0.021[3] Apparent magnitude (H) 12.528 ± 0.023[3] Apparent magnitude (K) 12.507 ± 0.023[3] Astrometry Proper motion (μ) RA: −1266.387 mas/yr[1] Dec.: 1108.801 mas/yr[1] Parallax (π) 160.9952±0.0119 mas[1] Distance 20.259 ± 0.001 ly (6.2114 ± 0.0005 pc) Absolute magnitude (MV) 15.23[2][4][note 1] Details Mass 0.81 ± 0.01[2] M☉ Radius 0.00984[2][note 2] R☉ Luminosity 0.000085[5] L☉ Surface gravity (log g) 8.36 ± 0.02[2] cgs Temperature 5590 ± 90[2] K Rotation >100 years[6] Age 5.69[note 3][7] Gyr Other designations GJ 1221, EGGR 372, G 240-72, LHS 455, LP 44-113, NLTT 45565, WD 1748+708, 2MASS J17480817+7052353[3] Database references SIMBAD data

**G 240-72** (or **WD 1748+708**, or **LHS 455**, or **GJ 1221**) is a nearby [white dwarf](/source/White_dwarf) (degenerate star) of spectral class DQP9.0,[2] located 20.3 [light-years](/source/Light-year) away in the constellation [Draco](/source/Draco_(constellation)).

## Distance

G 240-72 is the seventh closest white dwarf (after [Sirius B](/source/Sirius_B), [Procyon B](/source/Procyon_B), [van Maanen's star](/source/Van_Maanen's_star), [Gliese 440](/source/Gliese_440), [40 Eridani B](/source/40_Eridani_B) and [Stein 2051 B](/source/Stein_2051)). Its [trigonometric parallax](/source/Parallax), as measured by the [Gaia](/source/Gaia_(spacecraft)) space telescope, is 160.9952±0.0119 [mas](/source/Milliarcsecond),[1] corresponding to a distance of 6.2114 [parsecs](/source/Parsec) (20.259 [light-years](/source/Light-year)).

## Properties

G 240-72 has a mass of 0.81 [Solar masses](/source/Solar_mass)[2] and [surface gravity](/source/Surface_gravity) 108.36 (2.29×108) cm·s−2,[2] or approximately 234 000 of [Earth](/source/Earth's_gravity)'s, corresponding to a radius 6850 [km](/source/Kilometer), or 107% of [Earth's](/source/Earth's_radius).

This white dwarf has a relatively low temperature of 5590 [K](/source/Kelvin)[2] (slightly cooler than the [Sun](/source/Sun)), and an old cooling age, i.e. the age as a degenerate star (not counting the duration of its previous existence as a main sequence and giant star) of 5.69 [Gyr](/source/Gigayear).[7] It has a white appearance, due to its similar temperature to the [Sun](/source/Sun). It has a pure helium atmosphere and rotates very slowly, with period of possibly over 100 years.[6]

## References

1. ^ [***a***](#cite_ref-GaiaDR3_1-0) [***b***](#cite_ref-GaiaDR3_1-1) [***c***](#cite_ref-GaiaDR3_1-2) [***d***](#cite_ref-GaiaDR3_1-3) [***e***](#cite_ref-GaiaDR3_1-4) Vallenari, A.; et al. (Gaia collaboration) (2023). ["*Gaia* Data Release 3. Summary of the content and survey properties"](https://doi.org/10.1051%2F0004-6361%2F202243940). *Astronomy and Astrophysics*. **674**: A1. [arXiv](/source/ArXiv_(identifier)):[2208.00211](https://arxiv.org/abs/2208.00211). [Bibcode](/source/Bibcode_(identifier)):[2023A&A...674A...1G](https://ui.adsabs.harvard.edu/abs/2023A&A...674A...1G). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202243940](https://doi.org/10.1051%2F0004-6361%2F202243940). [S2CID](/source/S2CID_(identifier)) [244398875](https://api.semanticscholar.org/CorpusID:244398875). [Gaia DR3 record for this source](https://vizier.cds.unistra.fr/viz-bin/VizieR-4?-source=+I%2F355&-from=nav&-nav=cat%3AI%2F355%26tab%3A%7BI%2F355%2Fgaiadr3%7D%26key%3Asource%3D1355%2Fgaiadr3%26HTTPPRM%3A%26-out.add%3D.%26Source%3D%3D%3D1638979384378696704%26-go+%25%23Sesame%23%25%26) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-Holberg2008_2-0) [***b***](#cite_ref-Holberg2008_2-1) [***c***](#cite_ref-Holberg2008_2-2) [***d***](#cite_ref-Holberg2008_2-3) [***e***](#cite_ref-Holberg2008_2-4) [***f***](#cite_ref-Holberg2008_2-5) [***g***](#cite_ref-Holberg2008_2-6) [***h***](#cite_ref-Holberg2008_2-7) [***i***](#cite_ref-Holberg2008_2-8) [***j***](#cite_ref-Holberg2008_2-9) [***k***](#cite_ref-Holberg2008_2-10) [***l***](#cite_ref-Holberg2008_2-11) Holberg, J. B.; Sion; Oswalt; McCook; Foran; Subasavage (2008). ["A New Look at the Local White Dwarf Population"](https://commons.erau.edu/publication/886). *[The Astronomical Journal](/source/The_Astronomical_Journal)*. **135** (4): 1225–1238. [Bibcode](/source/Bibcode_(identifier)):[2008AJ....135.1225H](https://ui.adsabs.harvard.edu/abs/2008AJ....135.1225H). [doi](/source/Doi_(identifier)):[10.1088/0004-6256/135/4/1225](https://doi.org/10.1088%2F0004-6256%2F135%2F4%2F1225). [S2CID](/source/S2CID_(identifier)) [122855486](https://api.semanticscholar.org/CorpusID:122855486).

1. ^ [***a***](#cite_ref-Simbad_3-0) [***b***](#cite_ref-Simbad_3-1) [***c***](#cite_ref-Simbad_3-2) [***d***](#cite_ref-Simbad_3-3) [***e***](#cite_ref-Simbad_3-4) [***f***](#cite_ref-Simbad_3-5) [***g***](#cite_ref-Simbad_3-6) [***h***](#cite_ref-Simbad_3-7) ["GJ 1221 – White Dwarf"](http://simbad.u-strasbg.fr/simbad/sim-id?Ident=GJ+1221). [Centre de Données astronomiques de Strasbourg](/source/Centre_de_Donn%C3%A9es_astronomiques_de_Strasbourg). Retrieved 2011-10-23.

1. **[^](#cite_ref-van_Altena1995_4-0)** Van Altena, W. F.; Lee, J. T.; Hoffleit, E. D. (1995). [*GCTP 2835.01*](https://web.archive.org/web/20220523021021/http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-source=I/238A/picat&GCTP=2835.01). The General Catalogue of Trigonometric Stellar Parallaxes (Fourth ed.). [Bibcode](/source/Bibcode_(identifier)):[1995gcts.book.....V](https://ui.adsabs.harvard.edu/abs/1995gcts.book.....V). Archived from [the original](http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-source=I/238A/picat&GCTP=2835.01) on 2022-05-23. Retrieved 2015-10-10.

1. **[^](#cite_ref-ApJS199_2_29_7-0)** Giammichele, N.; Bergeron, P.; Dufour, P. (April 2012). "Know Your Neighborhood: A Detailed Model Atmosphere Analysis of Nearby White Dwarfs". *The Astrophysical Journal Supplement*. **199** (2): 29. [arXiv](/source/ArXiv_(identifier)):[1202.5581](https://arxiv.org/abs/1202.5581). [Bibcode](/source/Bibcode_(identifier)):[2012ApJS..199...29G](https://ui.adsabs.harvard.edu/abs/2012ApJS..199...29G). [doi](/source/Doi_(identifier)):[10.1088/0067-0049/199/2/29](https://doi.org/10.1088%2F0067-0049%2F199%2F2%2F29). [S2CID](/source/S2CID_(identifier)) [118304737](https://api.semanticscholar.org/CorpusID:118304737).

1. ^ [***a***](#cite_ref-Brinkworth2013_8-0) [***b***](#cite_ref-Brinkworth2013_8-1) Brinkworth, Carolyn S.; Burleigh, Matthew R.; Lawrie, Katherine; Marsh, Thomas R.; Knigge, Christian (August 2013). "Measuring the Rotational Periods of Isolated Magnetic White Dwarfs". *[The Astrophysical Journal](/source/The_Astrophysical_Journal)*. **773** (1): 47. [Bibcode](/source/Bibcode_(identifier)):[2013ApJ...773...47B](https://ui.adsabs.harvard.edu/abs/2013ApJ...773...47B). [doi](/source/Doi_(identifier)):[10.1088/0004-637X/773/1/47](https://doi.org/10.1088%2F0004-637X%2F773%2F1%2F47). [ISSN](/source/ISSN_(identifier)) [0004-637X](https://search.worldcat.org/issn/0004-637X).

1. ^ [***a***](#cite_ref-Sion2009_10-0) [***b***](#cite_ref-Sion2009_10-1) Sion, Edward M.; Holberg, J. B.; Oswalt, Terry D.; McCook, George P.; Wasatonic, Richard (2009). "The White Dwarfs within 20 Parsecs of the Sun: Kinematics and Statistics". *[The Astronomical Journal](/source/The_Astronomical_Journal)*. **138** (6): 1681–1689. [arXiv](/source/ArXiv_(identifier)):[0910.1288](https://arxiv.org/abs/0910.1288). [Bibcode](/source/Bibcode_(identifier)):[2009AJ....138.1681S](https://ui.adsabs.harvard.edu/abs/2009AJ....138.1681S). [doi](/source/Doi_(identifier)):[10.1088/0004-6256/138/6/1681](https://doi.org/10.1088%2F0004-6256%2F138%2F6%2F1681). [S2CID](/source/S2CID_(identifier)) [119284418](https://api.semanticscholar.org/CorpusID:119284418).

## Notes

1. **[^](#cite_ref-note_1_5-0)** From apparent magnitude and parallax.

1. **[^](#cite_ref-note_2_6-0)** From surface gravity and mass.

1. **[^](#cite_ref-note_3_9-0)** Cooling age, i. e. age as degenerate star (not counting duration of previous existence as main sequence star and as giant star)

## External links

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

v t e Constellation of Draco List of stars in Draco Draco in Chinese astronomy Stars Bayer α (Thuban) β (Rastaban) γ (Eltanin) δ (Altais) ε (Tyl) ζ (Aldhibah) η (Athebyne) θ ι (Edasich) κ λ (Giausar) μ (Alrakis) ν (Kuma) ξ (Grumium) ο π ρ σ (Alsafi) τ υ φ χ ψ1 (Dziban) ψ2 ω Flamsteed 4 6 7 (Tianyi) 8 (Taiyi) 10 (i) 15 (A) 18 (g) 19 (h) 26 36 39 (b) 42 (Fafnir) 45 (d) 50 59 64 (e) 68 Variable TW YY AG BY CL CM CX DO EK HP V581 HR 3751 4126 4934 5811 6237 6518 6618 (Alruba) 6817 7137 7783 HD 109246 (Funi) 101364 128717 147379 156279 158259 176693 191939 Other 2MASS 1237+6526 2MASS J17554042+6551277 G 240-72 GD 356 Gliese 420 Gliese 625 Gliese 687 GRW +70 8247 Kepler-4 Kepler-10 Kepler-12 Kepler-90 Kepler-296 KOI-256 LP 71-82 Qatar-1 SDSS J1240+6710 Struve 2398 TOI-1136 WD 1856+534 WISE 1647+5632 WISE 1841+7000 Exoplanets HD 139357 b HD 167042 b ι Dra b (Hypatia) Kepler-4b Kepler-10b c Kepler-12b Kepler-90e f g h i Kepler-296b c d e f TOI-1452 b TrES-2b Star clusters LAMOST 1 Nebulae Cat's Eye Nebula NGC 6742 Galaxies NGC 3147 3197 3735 4121 4125 4221 4236 4319 4331 4332 4363 4441 4513 4545 4589 5678 5777 5866 5866B 5879 5905 5907 5949 5963 5965 5982 5985 6090 6248 6285 6286 6338 6340 6365 6373 6394 6412 6503 6505 6566 6621 6622 6670 6676 6786 6789 Other 1ES 1927+654 1ES 1959+650 3C 249.1 3C 305 3C 319 3C 343 3C 343.1 3C 351 3C 356 3C 371 3C 380 3C 390.3 3C 401 4C +72.26 4C 73.08 8C 1241+735 Abell 2218 BCG Bean galaxy Beaver galaxy BZQ J1727+5510 Draco Dwarf Draco II GB 1508+5714 Goldfish galaxy H1821+643 HFLS3 IERS B1946+708 IRAS F17179+5444 IRAS 18580+6527 J120011.1+680924.8 KKR 25 Markarian 817 Markarian 876 Original TRG PGC 39058 Porphyrion QSO B1823+568 RGZ J172749.5+534647 S5 1803+784 S5 2007+777 SDSS J1715+6008 Tadpole Galaxy UGC 9391 UGC 9405 UGC 11241 UGC 11411 WISEA J145223.62+611707.5 WN B1851+5707 Galaxy clusters Abell 2218 CL1358+62 Draco Supercluster NGC 5866 Group Astronomical events SN 2003jb SN 2005B SN 2016aps Swift J1644+57 Category

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Adapted from the Wikipedia article [G 240-72](https://en.wikipedia.org/wiki/G_240-72) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/G_240-72?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.