A satellite orbit drift in binary near-Earth asteroids (66391) 1999 KW4 and (88710) 2001 ...

@article{58641,
   author = {Scheirich, P. and Pravec, P. and Kusnirak, P. and Hornoch, K. and McMahon, J. and Scheeres, D. J. and Capek, D. and Pray, D. P. and Kučáková, Hana and Galad, A. and Vrastil, J. and Krugly, Yu N. and Moskovitz, N. and Avner, L. D. and Skiff, B. and McMillan, R. S. and Larsen, J. A. and Brucker, M. J. and Tubbiolo, A. F. and Cooney, W. R. and Gross, J. and Terrell, D. and Burkhonov, O. and Ergashev, K. E. and Ehgamberdiev, A. and Fatka, P. and Durkee, R. and Schunova, E. Lilly and Inasaridze, R. Ya and Ayvazian, V. R. and Kapanadze, G. and Gaftonyuk, N. M. and Sanchez, J. A. and Reddy, V. and McGraw, L. and Kelley, M. S. and Molotov, I. E.},
   article_number = {May},
   doi = {http://dx.doi.org/10.1016/j.icarus.2021.114321},
   keywords = {Asteroids;Dynamics;Near-Earth objects;Photometry},
   language = {eng},
   issn = {0019-1035},
   journal = {Icarus},
   title = {A satellite orbit drift in binary near-Earth asteroids (66391) 1999 KW4 and (88710) 2001 SL9-Indication of the BYORP effect},
   url = {https://www.sciencedirect.com/science/article/pii/S0019103521000208?via%3Dihub},
   volume = {360},
   year = {2021}
}

TY  - JOUR
ID  - 58641
AU  - Scheirich, P. - Pravec, P. - Kusnirak, P. - Hornoch, K. - McMahon, J. - Scheeres, D. J. - Capek, D. - Pray, D. P. - Kučáková, Hana - Galad, A. - Vrastil, J. - Krugly, Yu N. - Moskovitz, N. - Avner, L. D. - Skiff, B. - McMillan, R. S. - Larsen, J. A. - Brucker, M. J. - Tubbiolo, A. F. - Cooney, W. R. - Gross, J. - Terrell, D. - Burkhonov, O. - Ergashev, K. E. - Ehgamberdiev, A. - Fatka, P. - Durkee, R. - Schunova, E. Lilly - Inasaridze, R. Ya - Ayvazian, V. R. - Kapanadze, G. - Gaftonyuk, N. M. - Sanchez, J. A. - Reddy, V. - McGraw, L. - Kelley, M. S. - Molotov, I. E.
PY  - 2021
TI  - A satellite orbit drift in binary near-Earth asteroids (66391) 1999 KW4 and (88710) 2001 SL9-Indication of the BYORP effect
JF  - Icarus
VL  - 360
IS  - May
SP  - "114321-1"-"114321-13"
EP  - "114321-1"-"114321-13"
SN  - 00191035
KW  - Asteroids;Dynamics;Near-Earth objects;Photometry
UR  - https://www.sciencedirect.com/science/article/pii/S0019103521000208?via%3Dihub
N2  - We obtained thorough photometric observations of two binary near-Earth asteroids (66391) Moshup = 1999 KW4 and (88710) 2001 SL9 taken from 2000 to 2019. We modeled the data and derived physical and dynamical properties of the binary systems. For (66391) 1999 KW4, we derived its mutual orbit's pole, semimajor axis and eccentricity that are in agreement with radar-derived values (Ostro et al., 2006. Science, 314, 1276-1280). However, we found that the data are inconsistent with a constant orbital period and we obtained unique solution with a quadratic drift of the mean anomaly of the satellite of -0.65 +/- 0.16 deg./yr2 (all quoted uncertainties correspond to 3 sigma). This means that the semimajor axis of the mutual orbit of the components of this binary system, determined a = 2.548 +/- 0.015 km by Ostro et al. (2006), increases in time with a mean rate of 1.2 +/- 0.3 cm/yr. For (88710) 2001 SL9, we determined that the mutual orbit has a pole within 10. of (L, B) = (302 degrees, 73 degrees) (ecliptic coordinates), and is close to circular (eccentricity < 0.07). The data for this system are also inconsistent with a constant orbital period and we obtained two solutions for the quadratic drift of the mean anomaly: 2.8 +/- 0.2 and 5.2 +/- 0.2 deg./yr(2), implying that the semimajor axis of the mutual orbit of the components (estimated a similar to 1.6 km) decreases in time with a mean rate of 2.8 +/- 0.2 or 5.1 +/- 0.2 cm/yr for the two solutions, respectively. The expanding orbit of (66391) 1999 KW4 may be explained by mutual tides interplaying with binary YORP (BYORP) effect (McMahon and Scheeres, 2010a. Icarus 209, 494-509). However, a modeling of the BYORP drift using radar-derived shapes of the binary components predicted a much higher value of the orbital drift than the observed one. It suggests that either the radar-derived shape model of the secondary is inadequate for computing the BYORP effect, or the present theory of BYORP overestimates it. It is possible that the BYORP coefficient has instead an opposite sign than predicted; in that case, the system may be moving into an equilibrium between the BYORP and the tides. In the case of (88710) 2001 SL9, the BYORP effect is the only known physical mechanism that can cause the inward drift of its mutual orbit. Together with the binary (175706) 1996 FG3 which has a mean anomaly drift consistent with zero, implying a stable equilibrium between the BYORP effect and mutual body tides (Scheirich et al., 2015. Icarus 245, 56-63), we now have three distinct cases of well observed binary asteroid systems with their long-term dynamical models inferred. They indicate a presence of all the three states of the mutual orbit evolution - equilibrium, expanding and contracting - in the population of near-Earth binary asteroids.
ER  - 

SCHEIRICH, P., P. PRAVEC, P. KUSNIRAK, K. HORNOCH, J. MCMAHON, D. J. SCHEERES, D. CAPEK, D. P. PRAY, Hana KUČÁKOVÁ, A. GALAD, J. VRASTIL, Yu N. KRUGLY, N. MOSKOVITZ, L. D. AVNER, B. SKIFF, R. S. MCMILLAN, J. A. LARSEN, M. J. BRUCKER, A. F. TUBBIOLO, W. R. COONEY, J. GROSS, D. TERRELL, O. BURKHONOV, K. E. ERGASHEV, A. EHGAMBERDIEV, P. FATKA, R. DURKEE, E. Lilly SCHUNOVA, R. Ya INASARIDZE, V. R. AYVAZIAN, G. KAPANADZE, N. M. GAFTONYUK, J. A. SANCHEZ, V. REDDY, L. MCGRAW, M. S. KELLEY and I. E. MOLOTOV. A satellite orbit drift in binary near-Earth asteroids (66391) 1999 KW4 and (88710) 2001 SL9-Indication of the BYORP effect. \textit{Icarus}. 2021, vol.~360, May, p.~''114321-1''-''114321-13'', 13 pp. ISSN~0019-1035. Available from: https://dx.doi.org/10.1016/j.icarus.2021.114321.