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 |
| Declination | +70° 52′ 35.9221″ |
| Apparent magnitude (V) | 14.15 |
| Characteristics | |
| Evolutionary stage | white dwarf |
| Spectral type | DQP9.0 |
| Apparent magnitude (B) | 14.55 |
| Apparent magnitude (V) | 14.15 |
| Apparent magnitude (R) | 13.5 |
| Apparent magnitude (I) | 13.1 |
| Apparent magnitude (J) | 12.709 ± 0.021 |
| Apparent magnitude (H) | 12.528 ± 0.023 |
| Apparent magnitude (K) | 12.507 ± 0.023 |
| Astrometry | |
| Proper motion (μ) | RA: −1266.387 mas/yr Dec.: 1108.801 mas/yr |
| Parallax (π) | 160.9952±0.0119 mas |
| Distance | 20.259 ± 0.001 ly (6.2114 ± 0.0005 pc) |
| Absolute magnitude (MV) | 15.23 |
| Details | |
| Mass | 0.81 ± 0.01 M☉ |
| Radius | 0.00984 R☉ |
| Luminosity | 0.000085 L☉ |
| Surface gravity (log g) | 8.36 ± 0.02 cgs |
| Temperature | 5590 ± 90 K |
| Rotation | >100 years |
| Age | 5.69 Gyr |
| Other designations | |
| GJ 1221, EGGR 372, G 240-72, LHS 455, LP 44-113, NLTT 45565, WD 1748+708, 2MASS J17480817+7052353 | |
| Database references | |
| SIMBAD | data |
G 240-72 (or WD 1748+708, or LHS 455, or GJ 1221) is a nearby white dwarf (degenerate star) of spectral class DQP9.0, located 20.3 light-years away in the constellation Draco.
Distance
G 240-72 is the seventh closest white dwarf (after Sirius B, Procyon B, van Maanen's star, Gliese 440, 40 Eridani B and Stein 2051 B). Its trigonometric parallax, as measured by the Gaia space telescope, is 160.9952±0.0119 mas, corresponding to a distance of 6.2114 parsecs (20.259 light-years).
Properties
G 240-72 has a mass of 0.81 Solar masses and surface gravity 108.36 (2.29×108) cm·s−2, or approximately 234 000 of Earth's, corresponding to a radius 6850 km, or 107% of Earth's.
This white dwarf has a relatively low temperature of 5590 K (slightly cooler than the 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. It has a white appearance, due to its similar temperature to the Sun. It has a pure helium atmosphere and rotates very slowly, with period of possibly over 100 years.
References
- 1 2 3 4 5 6 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- 1 2 3 4 5 6 7 8 9 10 11 12 Holberg, J. B.; Sion; Oswalt; McCook; Foran; Subasavage (2008). "A New Look at the Local White Dwarf Population". The Astronomical Journal. 135 (4): 1225–1238. Bibcode:2008AJ....135.1225H. doi:10.1088/0004-6256/135/4/1225. S2CID 122855486.
- 1 2 3 4 5 6 7 8 "GJ 1221 – White Dwarf". Centre de Données astronomiques de Strasbourg. Retrieved 2011-10-23.
- ↑ Van Altena, W. F.; Lee, J. T.; Hoffleit, E. D. (1995). GCTP 2835.01. The General Catalogue of Trigonometric Stellar Parallaxes (Fourth ed.). Bibcode:1995gcts.book.....V. Archived from the original on 2022-05-23. Retrieved 2015-10-10.
- ↑ 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:1202.5581. Bibcode:2012ApJS..199...29G. doi:10.1088/0067-0049/199/2/29. S2CID 118304737.
- 1 2 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. 773 (1): 47. Bibcode:2013ApJ...773...47B. doi:10.1088/0004-637X/773/1/47. ISSN 0004-637X.
- 1 2 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. 138 (6): 1681–1689. arXiv:0910.1288. Bibcode:2009AJ....138.1681S. doi:10.1088/0004-6256/138/6/1681. S2CID 119284418.
