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WD 2317+1830

Artist's impression of a white dwarf with a disk Credit: NOIRLab/NSF/AURA/J. da Silva Image processing: M. Zamani and M. Kosari (NSF NOIRLab)
Observation data Epoch J2000      Equinox J2000
Constellation	Pegasus
Right ascension	23 17 26.74
Declination	+18° 30′ 52.76″
Characteristics
Evolutionary stage	white dwarf
Spectral type	DZ
Apparent magnitude (G)	19.35
Astrometry
Radial velocity (Rv)	25 ±31 km/s
Proper motion (μ)	RA: -33.855 ±0.317 mas/yr Dec.: -452.811 ±0.263 mas/yr
Parallax (π)	26.4097 ± 0.3090 mas
Distance	123 ± 1 ly (37.9 ± 0.4 pc)
Details
Mass	1.076+0.007 −0.008 M☉
Radius	0.00793 ±0.00021 R☉
Surface gravity (log g)	8.64 ±0.03 cgs
Temperature	4557 ±63 K
Age	cooling age: 6.388 Gyr total age: 7.7+0.3 −0.4 Gyr
Other designations
SDSS J231726.72+183049.6, EQ J2317+1830, Gaia DR2 2818957013992481280
Database references
SIMBAD	data

WD 2317+1830 (SDSS J231726.72+183049.6) is one of the first white dwarfs with lithium detected in its atmosphere. The white dwarf is surrounded by a debris disk and is actively accreting material. Researchers suggest that the presence of alkali metals indicates the accretion of crust material. Another work however cautions to use alkali metals as a single indicator of crust material. They suggest that such objects could be polluted by mantle material instead. An analysis in 2024 finds that the abundance of lithium is in agreement with Big Bang nucleosynthesis (BBN) and galactic nucleosynthesis. WD 2317+1830 likely was a star with sub-solar metallicity, which is evident from its old age, as well as from its thick disk or halo kinematics. This low metallicity means that the planetesimals that formed around this old white dwarf had a composition more similar to BBN abundances. The lithium-enhancement is not in agreement with the accretion of terrestrial continental crust material. The accretion of an exotic exoplanet is not ruled out, but the accretion of a primitive planetesimal is more likely. The accretion of an exomoon as a lithium source is excluded.

WD 2317+1830 was first discovered in 2021 from Gaia and SDSS data as a candidate white dwarf. A first spectral analysis was published in 2020, identifying it as a DZ white dwarf. In 2021 observations with the Gran Telescopio Canarias were published. The white dwarf is massive and has a mass of 1.00 ± 0.02 M_☉. The cooling age was determined to be 9.5±0.2 Gyrs and the total age is 9.7±0.2 Gyrs. A more recent work found a higher temperature and younger cooling age of about 6.4 Gyrs. The researchers detected sodium, lithium and weak calcium absorption. The researchers also detected infrared excess, indicative of a debris disk, around this white dwarf. The disk is inclined by 70°, has an inner disk temperature of 1,500 K and an outer disk temperature of 500 K. In the past WD 2317+1830 had a mass of 4.8 ± 0.2 M_☉ and was likely a B-type star.

See also

• List of exoplanets and planetary debris around white dwarfs
• WD J2356−209 is another cool white dwarf with sodium detected
• LSPM J0207+3331 is another old white dwarf with a disk detected

References

1. ^ Tremblay, P. -E.; Hollands, M. A.; Gentile Fusillo, N. P.; McCleery, J.; Izquierdo, P.; Gänsicke, B. T.; Cukanovaite, E.; Koester, D.; Brown, W. R.; Charpinet, S.; Cunningham, T.; Farihi, J.; Giammichele, N.; van Grootel, V.; Hermes, J. J. (2020-09-01). "Gaia white dwarfs within 40 pc - I. Spectroscopic observations of new candidates". Monthly Notices of the Royal Astronomical Society. 497 (1): 130–145. arXiv:2006.00965. Bibcode:2020MNRAS.497..130T. doi:10.1093/mnras/staa1892. ISSN 0035-8711.
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. ^ Hollands, Mark A.; Tremblay, Pier-Emmanuel; Gänsicke, Boris T.; Koester, Detlev; Gentile-Fusillo, Nicola Pietro (2021-05-01). "Alkali metals in white dwarf atmospheres as tracers of ancient planetary crusts". Nature Astronomy. 5 (5): 451–459. arXiv:2101.01225. Bibcode:2021NatAs...5..451H. doi:10.1038/s41550-020-01296-7. ISSN 2397-3366.
4. ^ Bergeron, P.; Kilic, Mukremin; Blouin, Simon; Bédard, A.; Leggett, S. K.; Brown, Warren R. (2022-07-01). "On the Nature of Ultracool White Dwarfs: Not so Cool after All". The Astrophysical Journal. 934 (1): 36. arXiv:2206.03174. Bibcode:2022ApJ...934...36B. doi:10.3847/1538-4357/ac76c7. ISSN 0004-637X.
5. ^ Kaiser, Benjamin C.; Clemens, J. Christopher; Blouin, Simon; Dennihy, Erik; Dufour, Patrick; Hegedus, Ryan J.; Reding, Joshua S. (2024-12-02). "The Origins of Lithium Enhancement in Polluted White Dwarfs". arXiv:2412.01878 .
6. University of Warwick. "Vaporised crusts of Earth-like planets found in dying stars". warwick.ac.uk. Retrieved 2024-09-16.
7. Putirka, Keith D.; Xu, Siyi (2021-11-01). "Polluted white dwarfs reveal exotic mantle rock types on exoplanets in our solar neighborhood". Nature Communications. 12 (1): 6168. arXiv:2111.03124. Bibcode:2021NatCo..12.6168P. doi:10.1038/s41467-021-26403-8. ISSN 2041-1723. PMC 8563750. PMID 34728614.
8. info@noirlab.edu. "Rocky Exoplanets Are Even Stranger Than We Thought - A new astrogeology study suggests that most nearby rocky exoplanets are quite unlike anything in our Solar System". www.noirlab.edu. Retrieved 2024-09-16.
9. Gentile Fusillo, N. P.; Tremblay, P. -E.; Cukanovaite, E.; Vorontseva, A.; Lallement, R.; Hollands, M.; Gänsicke, B. T.; Burdge, K. B.; McCleery, J.; Jordan, S. (2021-12-01). "A catalogue of white dwarfs in Gaia EDR3". Monthly Notices of the Royal Astronomical Society. 508 (3): 3877–3896. arXiv:2106.07669. Bibcode:2021MNRAS.508.3877G. doi:10.1093/mnras/stab2672. ISSN 0035-8711.

v t e Constellation of Pegasus
Pegasus in Chinese astronomy List of stars in Pegasus
Stars	Bayer α (Markab) β (Scheat) γ (Algenib) δ (Alpheratz) ε (Enif) ζ (Homam) η (Matar) θ (Biham) ι κ λ μ (Sadalbari) ν ξ ο π π ρ σ τ (Salm) υ (Alkarab) φ χ ψ Flamsteed 1 2 3 4 5 7 9 11 12 13 14 15 16 17 18 19 20 21 23 25 28 30 31 32 33 34 35 36 37 38 39 40 41 45 51 (Helvetios) 52 55 56 57 58 59 60 61 63 64 65 66 67 69 70 71 72 73 74 75 76 77 78 79 80 82 83 85 86 87 23 Psc 34 Vul Variable R S U W Z RU RV RZ SV TW TY AG AQ AT AU AV AW BB BH BK BO BP BX BY DH DI DY EE EF EQ EZ GT GX HN HO HP HR HX II IK IM IP KT KU LL LO LS MS MT NV NZ OY PT V342 V343 V354 V363 V372 V376 V391 HR 19 49 8116 8219 8221 8231 8250 8257 8258 8274 8292 8325 8341 8348 8358 8359 8364 8372 8391 8397 8412 8415 8435 8441 8455 8456 8458 8460 8461 8466 8475 8482 8491 8503 8514 8543 8555 8564 8587 8604 8605 8608 8631 8638 8642 8737 8784 8788 8792 8824 8831 8833 8838 8839 8873 8922 8942 8953 8970 9039 9055 9078 9109 HD 434 204603 205011 205422 205603 206689 206793 208897 209709 210890 211076 213025 215549 215733 219196 219828 220288 220773 221170 221493 225292 Other BD+14 4559 (Solaris) BD +17 4708 BD +28 4211 GD 246 Gl 829 Gl 880 HAT-P-8 NGC 8 NGC 18 NGC 30 PG 2131+066 PG 2303+243 PSR B2127+11C PSR B2303+30 Q2343-BX418 WASP-10 WASP-21 (Tangra) WASP-52 (Anadolu) WASP-59 WASP-60 (Morava) X2127+119 3C 454.3
Exoplanets 51 Pegasi b (Dimidium) WASP-10b BD+14 4559 b (Pirx) TOI-5678 b HD 209458 b HR 8799 b c d e
Star clusters	Other Balbinot 1 Messier 15
Nebulae	Other Pease 1
Galaxies	NGC 1 2 9 14 15 16 22 23 26 41 42 52 7033 7034 7042 7043 7053 7056 7066 7068 7074 7085 7190 7217 7236 7237 7303 7312 7315 7317 7318 7319 7320 7320c 7331 7332 7427 7448 7454 7457 7466 7469 7479 7610 7619 7625 7673 7674 7678 7720 7726 7735 7741 7742 NGC 7752 NGC 7753 7767 7769 7773 7800 7814 Other BX442 CTA-102 Einstein Cross Huchra's lens IC 5145 IC 5337 Markarian 335 Pegasus Dwarf Irregular Galaxy Pegasus Dwarf Spheroidal Galaxy Q2343-BX418
Galaxy clusters Abell 2390 NGC 7331 Group Stephan's Quintet
Astronomical events SN 1990U SN 2008ha SN 2013fs
Category

• White dwarfs
• Circumstellar disks
• Pegasus (constellation)