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BD+05 4868

Visualization of the simulated dust tail transiting in front of the primary Credit: Hon et al.
Observation data Epoch J2000      Equinox J2000
Constellation	Pegasus
BD+05 4868A
Right ascension	21 47 26.52
Declination	+06° 36′ 17.50″
Apparent magnitude (V)	10.16
BD+05 4868B
Right ascension	21 47 26.71
Declination	+06° 36′ 18.38″
Characteristics
Evolutionary stage	main-sequence star
Spectral type	mid-K+M
Astrometry
BD+05 4868A
Radial velocity (Rv)	–25.56 ±0.15 km/s
Proper motion (μ)	RA: 205.593 ±0.017 mas/yr Dec.: 106.359 ±0.012 mas/yr
Parallax (π)	22.9322 ± 0.0163 mas
Distance	142.2 ± 0.1 ly (43.61 ± 0.03 pc)
BD+05 4868B
Radial velocity (Rv)	–24.62 ±1.60 km/s
Proper motion (μ)	RA: 212.158 ±0.064 mas/yr Dec.: 112.173 ±0.049 mas/yr
Parallax (π)	23.1585 ± 0.0629 mas
Distance	140.8 ± 0.4 ly (43.2 ± 0.1 pc)
Details
BD+05 4868A
Mass	0.70 ±0.02 M☉
Radius	0.69 ±0.02 R☉
Luminosity	0.192 ±0.005 L☉
Surface gravity (log g)	4.60+0.03 −0.02 cgs
Temperature	4540 ±110 K
Metallicity	−0.07 ±0.09 dex
Age	11.1+1.7 −3.0 Gyr
BD+05 4868B
Mass	0.43 ±0.03 M☉
Radius	0.42 ±0.02 R☉
Luminosity	0.023 ±0.001 L☉
Surface gravity (log g)	4.83 ±0.03 cgs
Temperature	3480 ±70 K
Position (relative to BD+05 4868A)
Component	BD+05 4868B
Epoch of observation	October 2024
Angular distance	3″
Projected separation	132.037 ±0.002 AU
Other designations
BD+05 4868A: HIP 107587, G 93-37, LSPM J2147+0636, LTT 18540, 2MASS J21472654+0636178, TIC 466376085, TYC 556-856-1, UCAC2 34205672, WISE J214726.69+063618.9, Gaia DR3 2700378125204437760
BD+05 4868B: Gaia DR3 2700378125203895808
Database references
BD+05 4868A
SIMBAD	data
BD+05 4868B
SIMBAD	data

BD+05 4868 is a binary star consisting of a K-dwarf and an M-dwarf. Around the primary one rocky planet is detected. This planet, called BD+05 4868Ab orbits the star so close that it disintegrates, creating a large comet-like tail, seen in transits.

BD+05 4868 was first cataloged in the Bonner Durchmusterung and in 1961 the star was identified as a proper motion star by Giclas et al. In 1984 its spectrum was observed for the first time, identifying it as a K5: type star. The star was first identified as a binary from Gaia data. The common proper motion and parallax indicate that the pair is physically bound. The binary was also detected with the Las Cumbres Observatory Global Telescope (LCOGT) 2 m Faulkes Telescope North and with Keck NIRC2.

Planetary system

The planet BD+05 4868Ab was discovered with TESS in transits. The transits are unusually deep with variable depth of 0.8-2.0%. The transits are also asymmetric with a short ingress followed by a long egress. The researchers were also are able to detect the transits in ground-bases ASAS-SN and LCOGT 2m telescope data. Seven spectra of the primary were obtained with the WIYN 3.5m Telescope, detecting no radial velocity signal larger than a few m/s. The researchers interpret the transits as a disintegrating rocky planet, similar to Kepler-1520b, KOI-2700b and K2-22b. The difference is that BD+05 4868Ab is around a relative bright (V=10.16 mag) host star and the transits are consistently deep. Other disintegrating rocky planets show weaker transits (~0.5% transit depth) that are also variable. This makes BD+05 4868Ab a compelling target for transmission spectroscopy, which could characterize exoplanet mineralogy. The planet also has a relative low equilibrium temperature of 1820±45 Kelvin, which could lead to differences in dust properties, when compared to other disintegrating planets. Comparisons to models suggest that the planet began with a mass larger than Mercury, but lost mass over several billion years. The mass of the planet is not known, but the researchers assume a mass of about 0.02 M_E (about lunar-mass) in their modelling. Currently the mass-loss rate is at 10 M_E per billion years, meaning it will evaporate in several million years.

References

1. ^ Hon, Marc; Rappaport, Saul; Shporer, Avi; Vanderburg, Andrew; Collins, Karen A.; Watkins, Cristilyn N.; Schwarz, Richard P.; Barkaoui, Khalid; Yee, Samuel W. (2025-01-09). "A Disintegrating Rocky Planet with Prominent Comet-like Tails Around a Bright Star". arXiv:2501.05431 .
2. 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.
3. 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.
4. Argelander, Friedrich Wilhelm August (1903-01-01). "Bonner Durchmusterung des nordlichen Himmels". Eds Marcus and Weber's Verlag: 0. Bibcode:1903BD....C......0A.
5. Giclas, Henry L.; Burnham, Robert; Thomas, Norman Gene (1961-01-01). "Lowell proper motions III : proper motion survey of the Northern Hemisphere with the 13-inch photographic telescope of the Lowell Observatory". Lowell Observatory Bulletin. 6: 61–132. Bibcode:1961LowOB...5...61G.
6. Lee, S. -G. (1984-05-01). "Spectral classification of high-proper-motion stars". The Astronomical Journal. 89: 702–719. Bibcode:1984AJ.....89..702L. doi:10.1086/113569. ISSN 0004-6256.

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+05 4868 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

• Durchmusterung objects
• Exoplanets discovered in 2024
• Pegasus (constellation)
• Transiting exoplanets
• Exoplanets discovered by TESS
• Sub-Earth exoplanets