ASASSN-24fw
| Observation data Epoch J2000.0 Equinox ICRS | |
|---|---|
| Constellation | Monoceros |
| Right ascension | 07h 51m 41.996s[1] |
| Declination | +09° 23′ 9.79″[1] |
| Characteristics | |
| Evolutionary stage | Main-sequence |
| Spectral type | F8IV[2] |
| Astrometry | |
| Radial velocity (Rv) | 36.87 [3] km/s |
| Proper motion (μ) | RA: -3.75[3] mas/yr Dec.: -7.612[3] mas/yr |
| Distance | 3,260[4] ly |
| Details[4][2] | |
| Mass | 1.40+0.07 −0.11 M☉ |
| Radius | 1.95+0.05 −0.06 R☉ |
| Age | 2.75 ± 0.24 Gyr |
| Other designations | |
| ASASSN-24fw, 2MASS J07051897+0612195, WISE J070518.97+061219.5, UCAC4 482-031200, Gaia DR3 3152916838954800512[3] | |
| Database references | |
| SIMBAD | data |
ASASSN-24fw is a F-type main-sequence star that underwent a rare, prolonged occultation event detected by the All Sky Automated Survey for SuperNovae (ASAS-SN), resulting in a deep dimming of approximately 4.1 magnitudes in the g-band lasting about 8–9 months from late September 2024 to late May or June 2025.[5][6]
Observation
[edit]The star is located approximately 3,260 light-years away in the constellation of Monoceros. It has an estimated mass of about 1.4 M☉ and exhibits an infrared excess indicative of circumstellar dust, with pre-event photometry showing stability over more than a decade of ASAS-SN monitoring.[4]
One model attributes the occultation to optically thick rings or a circumplanetary disk surrounding either a red dwarf[7] or a substellar companion[8][9] (brown dwarf or massive gas giant, minimum mass around 3–3.4 MJ), with ring radius ~0.17 AU forming a large structure at ~14 AU orbital separation.[4][10]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (years) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| Ab (unconfirmed) | 3.4 MJ | 14.0 | 16060.0 | 0.88±0.07 | — | — |
See also
[edit]References
[edit]- 1 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.
- 1 2 3 Martin, Pierre-Yves (2025). "Planet ASASSN-24fw Ab". exoplanet.eu. Retrieved 2026-03-06.
- 1 2 3 4 "UCAC4 482-031200". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2026-03-01.
- 1 2 3 4 Zakamska, Nadia L.; Pallathadka, Gautham Adamane; Bizyaev, Dmitry; Merc, Jaroslav; Owen, James E.; Reggiani, Henrique; Schlaufman, Kevin C.; Bąkowska, Karolina; Bednarz, Sławomir; Bernacki, Krzysztof; Gurgul, Agnieszka; Hall, Kirsten R.; Hambsch, Franz-Josef; Joachimczyk, Barbara; Kotysz, Krzysztof (2026-02-02). "ASASSN-24fw: Candidate Gas-rich Circumsecondary Disk Occultation of a Main-sequence Star". The Astronomical Journal. 171 (2): 95. arXiv:2507.05367. Bibcode:2026AJ....171...95Z. doi:10.3847/1538-3881/ae1fd9. ISSN 0004-6256.
- ↑ Forés-Toribio, Raquel; JoHantgen, B.; Kochanek, C. S.; Jorstad, S. G.; Hermes, J. J.; Armstrong, J. D.; Ashall, C.; Burns, C. R.; Gaidos, E.; Hoogendam, W. B.; Hsiao, E. Y.; Medler, K.; Morrell, N.; Pfeffer, C.; Shappee, B. J. (2025-08-07). "ASASSN-24fw: An 8-month long, 4.1 mag, optically achromatic and polarized dimming event". The Open Journal of Astrophysics. 8: 114. arXiv:2507.03080. Bibcode:2025OJAp....8E.114F. doi:10.33232/001c.143105. ISSN 2565-6120.
- ↑ Shah, Sarang; Marshall, Jonathan P; del Burgo, Carlos; Hajdu, Gergely; Rebollido, Isabel; Pilecki, Bogumił; Mahabal, Ashish; Zeegers, Sascha T; Reddy, Bacham Eswar; Kemper, Francisca; Kasliwal, Mansi M; Karambelkar, Viraj; Graham, Matthew J; Djorgovski, S G; Stern, Daniel (2026-02-03). "The nature of ASASSN-24fw's occultation: modelling the event as dimming by optically thick rings around a substellar companion". Monthly Notices of the Royal Astronomical Society. 546 (3) staf2251. arXiv:2511.02581. doi:10.1093/mnras/staf2251. ISSN 0035-8711.
- ↑ Simion @Yonescat, Florin (2026-02-12). "Unseen planet or brown dwarf may have hidden 'rare' fading star". The Royal Astronomical Society. Retrieved 2026-03-08.
- ↑ "Dusty structure explains near vanishing of faraway star | Department of Astronomy". astronomy.osu.edu. Retrieved 2026-03-06.
- ↑ Tomaswick, Andy (2026-01-26). "Investigating the Star That Almost Vanished for Eight Months". Universe Today. Retrieved 2026-03-06.
- ↑ Thompson, Mark (2026-02-15). "The Mystery of the Fading Star". Universe Today. Retrieved 2026-03-02.