Saved in:
| Main Authors: | , , , , , , , , , , , , , , |
|---|---|
| Format: | Preprint |
| Published: |
2026
|
| Subjects: | |
| Online Access: | https://arxiv.org/abs/2604.15207 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866918461686415360 |
|---|---|
| author | Tian, Jun Li, Bin Liu, Y. J. Xu, Z. J. Zhai, R. Y. Zhao, H. B. Pomazan, Anton Li, Fan Abdelaziz, A. M. Ping, Y. D. Liu, Wei Mao, Y. D. Chen, Jian Shokry, Ahmed. Ismail, Mohamed |
| author_facet | Tian, Jun Li, Bin Liu, Y. J. Xu, Z. J. Zhai, R. Y. Zhao, H. B. Pomazan, Anton Li, Fan Abdelaziz, A. M. Ping, Y. D. Liu, Wei Mao, Y. D. Chen, Jian Shokry, Ahmed. Ismail, Mohamed |
| contents | We present comprehensive photometric characterisation of 2025 FA$_{22}$, a Potentially Hazardous Asteroid (PHA) discovered on 29 March 2025 and observed during the seventh International Asteroid Warning Network (IAWN) coordinated campaign. The asteroid's close approach at 2 lunar distances on 18 September 2025 provided an opportunity for rapid physical characterisation in a simulated virtual impactor scenario. Photometric observations were conducted from 17 September to 1 October 2025, during which 2025 FA$_{22}$ traversed a $150^{\circ}$ arc and spanned solar phase angles from $\sim20^{\circ}$ to $\sim70^{\circ}$. This geometry enabled detailed physical characterisation, including determination of the spin axis and shape. Convex inversion yields a sidereal rotation period of $P_{\mathrm{sid}} = 13.07366 \pm 0.00076$ h and a spin axis at ecliptic coordinates $(λ, β) = (246^{\circ} \pm 9^{\circ}, 60^{\circ} \pm 9^{\circ})$. The absolute magnitude was derived as $H_{\mathrm{V}} = 21.39^{+0.07}_{-0.08}$ mag ($G_1 = 0.8228$, $G_2 = 0.0194$), with colour indices $B-V = 0.71 \pm 0.05$ mag, $V-R = 0.39 \pm 0.03$ mag, and $R-I = 0.39 \pm 0.04$ mag, consistent with X-complex classification in the Bus--DeMeo taxonomy. Assuming a geometric albedo of $p_v = 0.15^{+0.05}_{-0.04}$, representative of the moderate-albedo X-complex asteroids, we estimate $D_{\mathrm{eff}} = 181^{+31}_{-25}$ m, consistent with "China Compound Eye" radar dimensions of ${\sim}100 \times 320$ m ($D_{\mathrm{eff}} \sim 186$ m), which also reveal a contact-binary morphology consistent with the axis ratios $a:b:c \sim 2.68:1.96:1.00$ derived from our photometric shape model. The bilobate morphology is consistent with YORP-driven spin-up and deformation during a previous YORP cycle, with the current slow rotation possibly explained by internal reconfiguration or tidal braking during close Earth encounters. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_15207 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Photometry and physical characterization of near-Earth asteroid 2025 FA22 from one apparition Tian, Jun Li, Bin Liu, Y. J. Xu, Z. J. Zhai, R. Y. Zhao, H. B. Pomazan, Anton Li, Fan Abdelaziz, A. M. Ping, Y. D. Liu, Wei Mao, Y. D. Chen, Jian Shokry, Ahmed. Ismail, Mohamed Earth and Planetary Astrophysics We present comprehensive photometric characterisation of 2025 FA$_{22}$, a Potentially Hazardous Asteroid (PHA) discovered on 29 March 2025 and observed during the seventh International Asteroid Warning Network (IAWN) coordinated campaign. The asteroid's close approach at 2 lunar distances on 18 September 2025 provided an opportunity for rapid physical characterisation in a simulated virtual impactor scenario. Photometric observations were conducted from 17 September to 1 October 2025, during which 2025 FA$_{22}$ traversed a $150^{\circ}$ arc and spanned solar phase angles from $\sim20^{\circ}$ to $\sim70^{\circ}$. This geometry enabled detailed physical characterisation, including determination of the spin axis and shape. Convex inversion yields a sidereal rotation period of $P_{\mathrm{sid}} = 13.07366 \pm 0.00076$ h and a spin axis at ecliptic coordinates $(λ, β) = (246^{\circ} \pm 9^{\circ}, 60^{\circ} \pm 9^{\circ})$. The absolute magnitude was derived as $H_{\mathrm{V}} = 21.39^{+0.07}_{-0.08}$ mag ($G_1 = 0.8228$, $G_2 = 0.0194$), with colour indices $B-V = 0.71 \pm 0.05$ mag, $V-R = 0.39 \pm 0.03$ mag, and $R-I = 0.39 \pm 0.04$ mag, consistent with X-complex classification in the Bus--DeMeo taxonomy. Assuming a geometric albedo of $p_v = 0.15^{+0.05}_{-0.04}$, representative of the moderate-albedo X-complex asteroids, we estimate $D_{\mathrm{eff}} = 181^{+31}_{-25}$ m, consistent with "China Compound Eye" radar dimensions of ${\sim}100 \times 320$ m ($D_{\mathrm{eff}} \sim 186$ m), which also reveal a contact-binary morphology consistent with the axis ratios $a:b:c \sim 2.68:1.96:1.00$ derived from our photometric shape model. The bilobate morphology is consistent with YORP-driven spin-up and deformation during a previous YORP cycle, with the current slow rotation possibly explained by internal reconfiguration or tidal braking during close Earth encounters. |
| title | Photometry and physical characterization of near-Earth asteroid 2025 FA22 from one apparition |
| topic | Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2604.15207 |