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GALEX J2339–0424

GALEX J2339–0424 (star in the center) as seen by GALEX Credit: NASA/JPL-Caltech GALEX
Observation data Epoch J2000      Equinox J2000
Constellation	Aquarius
Right ascension	23 39 17.03
Declination	−04° 24′ 24.67″
Characteristics
Evolutionary stage	white dwarf
Spectral type	DABZ
Apparent magnitude (G)	16.16
Astrometry
Radial velocity (Rv)	6 ±5 km/s
Proper motion (μ)	RA: 24.501 ±0.058 mas/yr Dec.: -32.293 ±0.048 mas/yr
Parallax (π)	11.2005 ± 0.0581 mas
Distance	291 ± 2 ly (89.3 ± 0.5 pc)
Details
Mass	0.548 ±0.051 M☉
Radius	0.0133 ±0.0008 R☉
Surface gravity (log g)	7.93 ±0.09 cgs
Temperature	13735 ±500 K
Age	cooling age: 241 ±6 Myr
Other designations
2MASS J23391701-0424248, GALEX J233917.0-042425, SDSS J233917.05-042425.0, TIC 136841996, USNO-A2.0 0825-19992233, Gaia DR2 2446993162322393088
Database references
SIMBAD	data

GALEX J2339–0424 (GALEX J233917.0–042425, GALEX J2339) is a white dwarf that is suspected to be polluted with material originating from an icy exomoon. This is evident from the first detection of beryllium in this white dwarf, together with GD 378.

GALEX J2339 was first identified as a possible quasar with GALEX in 2007. It was identified as a white dwarf candidate from Gaia and virtual observatory data in 2018. In 2020 it was identified as a DBAZ: white dwarf, which means that it had helium, hydrogen and metal absorption lines. In 2021 the white dwarf was observed with Lick, Magellan 1 and Keck. The observations showed that the object had absorption due to hydrogen, helium, beryllium, oxygen, magnesium, silicon, calcium, titanium, chromium, manganese and iron. The oxygen is present in excess, which indicates a water ice-rich body. The accreted parent object had a chondrite-like composition and was 85% water ice in volume. The accretion event lasted for 2–4 Million years and the parent body had a mass of 3 × 10–1 × 10 kg, or between about the mass of Vesta to about the mass of Ceres.

Exomoons as a source of white dwarf pollution has been proposed since 2016/2017 and their fate around white dwarfs was further studied later, showing that around 1% of polluted white dwarfs should be polluted with exomoons. The presence of beryllium is thought to be the result of spallation of heavier elements (especially oxygen) on the surface of an icy dust belt around a giant planet. The icy dust belts enriched in beryllium will then form exomoons, which might pollute white dwarf. These icy dust belts are comparable to Saturns rings and rings around J1407b. Other scenarios are mentioned, such as the radiation of a Wolf-Rayet star. But these environments are less favourable to produce the observed beryllium excess. The spallation should also produce lithium and boron, but (as of September 2024) these are not detected around GALEX J2339 or GD 378.

See also

• List of exoplanets and planetary debris around white dwarfs
• List of exomoon candidates

References

1. ^ Klein, Beth L.; Doyle, Alexandra E.; Zuckerman, B.; Dufour, P.; Blouin, Simon; Melis, Carl; Weinberger, Alycia J.; Young, Edward D. (2021-06-01). "Discovery of Beryllium in White Dwarfs Polluted by Planetesimal Accretion". The Astrophysical Journal. 914 (1): 61. arXiv:2102.01834. Bibcode:2021ApJ...914...61K. doi:10.3847/1538-4357/abe40b. ISSN 0004-637X.
2. ^ Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
3. ^ Doyle, Alexandra E.; Desch, Steven J.; Young, Edward D. (2021-02-01). "Icy Exomoons Evidenced by Spallogenic Nuclides in Polluted White Dwarfs". The Astrophysical Journal. 907 (2): L35. arXiv:2102.01835. Bibcode:2021ApJ...907L..35D. doi:10.3847/2041-8213/abd9ba. ISSN 0004-637X.
4. Atlee, David W.; Gould, Andrew (2007-07-01). "Photometric Selection of QSO Candidates from GALEX Sources". The Astrophysical Journal. 664 (1): 53–63. arXiv:astro-ph/0611820. Bibcode:2007ApJ...664...53A. doi:10.1086/518467. ISSN 0004-637X.
5. Jiménez-Esteban, F. M.; Torres, S.; Rebassa-Mansergas, A.; Skorobogatov, G.; Solano, E.; Cantero, C.; Rodrigo, C. (2018-11-01). "A white dwarf catalogue from Gaia-DR2 and the Virtual Observatory". Monthly Notices of the Royal Astronomical Society. 480 (4): 4505–4518. arXiv:1807.02559. Bibcode:2018MNRAS.480.4505J. doi:10.1093/mnras/sty2120. ISSN 0035-8711.
6. Kilic, Mukremin; Bergeron, P.; Kosakowski, Alekzander; Brown, Warren R.; Agüeros, Marcel A.; Blouin, Simon (2020-07-01). "The 100 pc White Dwarf Sample in the SDSS Footprint". The Astrophysical Journal. 898 (1): 84. arXiv:2006.00323. Bibcode:2020ApJ...898...84K. doi:10.3847/1538-4357/ab9b8d. ISSN 0004-637X.
7. Brouwers, Marc G.; Buchan, Andrew M.; Bonsor, Amy; Malamud, Uri; Lynch, Elliot; Rogers, Laura; Koester, Detlev (2023-02-01). "Asynchronous accretion can mimic diverse white dwarf pollutants II: water content". Monthly Notices of the Royal Astronomical Society. 519 (2): 2663–2679. arXiv:2211.05113. Bibcode:2023MNRAS.519.2663B. doi:10.1093/mnras/stac3317. ISSN 0035-8711.
8. Payne, Matthew J.; Veras, Dimitri; Holman, Matthew J.; Gänsicke, Boris T. (2016-03-01). "Liberating exomoons in white dwarf planetary systems". Monthly Notices of the Royal Astronomical Society. 457 (1): 217–231. arXiv:1603.09344. Bibcode:2016MNRAS.457..217P. doi:10.1093/mnras/stv2966. ISSN 0035-8711.
9. Payne, Matthew J.; Veras, Dimitri; Gänsicke, Boris T.; Holman, Matthew J. (2017-01-01). "The fate of exomoons in white dwarf planetary systems". Monthly Notices of the Royal Astronomical Society. 464 (3): 2557–2564. arXiv:1610.01597. Bibcode:2017MNRAS.464.2557P. doi:10.1093/mnras/stw2585. ISSN 0035-8711.
10. Trierweiler, Isabella L.; Doyle, Alexandra E.; Melis, Carl; Walsh, Kevin J.; Young, Edward D. (2022-09-01). "Exomoons as Sources of White Dwarf Pollution". The Astrophysical Journal. 936 (1): 30. arXiv:2205.07935. Bibcode:2022ApJ...936...30T. doi:10.3847/1538-4357/ac86d5. ISSN 0004-637X.

v t e Constellation of Aquarius
Aquarius in Chinese astronomy Aquarius Stream List of stars in Aquarius
Stars	Bayer α (Sadalmelik) β (Sadalsuud) γ (Sadachbia) δ (Skat) ε (Albali) ζ η θ (Ancha) ι κ (Situla) λ (Hydor) μ ν ξ (Bunda) ο π ρ σ τ τ υ φ χ ψ (91) ψ ψ ω ω A A b b b c c c d e f g g h i i i k α PsA C Flamsteed 1 4 5 7 8 9 10 11 12 14 15 16 17 18 19 20 21 24 26 28 29 30 32 35 36 37 39 40 41 42 44 45 47 49 50 51 54 56 58 60 61 64 65 67 70 72 74 75 77 78 81 82 84 85 87 94 96 97 100 Variable R U AE DV EP EW EZ FO HK IL HU IZ LL LP HR 8017 8056 8121 8263 8363 8453 8500 8507 8581 8612 8629 8645 8716 8783 8836 8856 8879 8924 9014 HD 206610 (Bosona) 210277 212771 (Lionrock) 215152 219617 220466 220689 222093 222582 Other 2MASS J21392676+0220226 BD−22 5866 Gliese 849 K2-21 K2-28 K2-58 K2-72 K2-138 LS IV-14 116 Sneden's Star TRAPPIST-1 WASP-6 (Márohu) WASP-47 WASP-69 WASP-75
Exoplanets ψ Aquarii b Gliese 849 b Gliese 876 b c d e HD 206610 b HD 210277 b HD 212771 b (Victoriapeak) HD 221416 b HD 222582 b K2-66b K2-72b c d e K2-138b TRAPPIST-1b c d e f g h WASP-6b
Star clusters Messier 2 Messier 72 Messier 73
Nebulae Helix Nebula Saturn Nebula
Galaxies	NGC 6975 7001 7010 7047 7051 7065 7069 7077 7081 7184 7222 7252 7257 7301 7302 7393 7492 7585 7592 7600 7606 7723 7727 7759 Other Aquarius Dwarf ESO 603-G21 Lyman-alpha blob 1 PGC 1228197 PHL 293B SMM J2135-0102 WISE J224607.57−052635.0 J2345-0449
Galaxy clusters Abell 2597 RXC J2211.7-0350 XMMXCS 2215-1738
Astronomical events SN 2213-1745
Category

• White dwarfs
• Aquarius (constellation)