Constraining the orientation of the spin axes of extrasolar minor bodies 1I/2017 U1 (‘Oumuamua) and 2I/Borisov

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Context. The orientation of the spin axis of a comet is defined by the values of its equatorial obliquity and its cometocentric longitude of the Sun at perihelion. These parameters can be computed from the components of the nongravitational force caused by outgassing if the cometary activity is well characterized. The trajectories of known interstellar bodies passing through the Solar System show nongravitational accelerations. Aims. The spin-axis orientation of 1I/2017 U1(‘Oumuamua) remains to be determined; for 2I/Borisov, the already released results are mutually exclusive. In both cases, the values of the components of the nongravitational force are relatively well constrained. Here, we investigate —within the framework of the forced precession model of a nonspherical cometary nucleus— the orientation of the spin axes of ‘Oumuamua and 2I/Borisov using public orbit determinations that consider outgassing. Methods. We applied a Monte Carlo simulation using the covariance matrix method together with Monte Carlo random search techniques to compute the distributions of equatorial obliquities and cometocentric longitudes of the Sun at perihelion of ‘Oumuamua and 2I/Borisov from the values of the nongravitational parameters. Results. We find that the equatorial obliquity of ‘Oumuamua could be about 93◦ , if it has a very prolate (fusiform) shape, or close to 16◦ , if it is very oblate (disk-like). Different orbit determinations of 2I/Borisov gave obliquity values of 59◦ and 90◦ . The distributions of cometocentric longitudes were in general multimodal. Conclusions. Our calculations suggest that the most probable spin-axis direction of ‘Oumuamua in equatorial coordinates is (280◦ , +46◦ ) if very prolate or (312◦ , −50◦ ) if very oblate. Our analysis favors a prolate shape. For the orbit determinations of 2I/Borisov used here, we find most probable poles pointing near (275◦ , +65◦ ) and (231◦ , +30◦ ), respectively. Although our analysis favors an oblate shape for 2I/Borisov, a prolate one cannot be ruled out.
A’Hearn, M. F., Belton, M. J. S., Delamere, W. A., et al. 2011, Science, 332,1396 Amarante, A. & Winter, O. C. 2020, MNRAS, 496, 4154 Astropy Collaboration, Robitaille, T. P., Tollerud, E. J., et al. 2013, A&A, 558,A33 Astropy Collaboration, Price-Whelan, A. M., Sipocz, B. M., et al. 2018, AJ, 156, ˝123 Avdyushev, V. A. & Banshchikova, M. A. 2007, Solar System Research, 41, 413 Belton, M. J. S., Hainaut, O. R., Meech, K. J., et al. 2018, ApJ, 856, L21 Bodewits, D., Noonan, J. W., Feldman, P. D., et al. 2020, Nature Astronomy, 4,867 Bolin, B. T., Weaver, H. A., Fernandez, Y. R., et al. 2018, ApJ, 852, L2 Bolin, B. T. & Lisse, C. M. 2020, MNRAS, 497, 4031 Bolin, B. T., Bodewits, D., Lisse, C. M., et al. 2020a, The Astronomer’s Telegram13613, 1 Bolin, B. T., Lisse, C. M., Kasliwal, M. M., et al. 2020b, AJ, 160, 26 Bordovitsyna, T., Avdyushev, V., & Chernitsov, A. 2001, Celestial Mechanics and Dynamical Astronomy, 80, 227 Box, G. E. P. & Muller, M. E. 1958, The Annals of Mathematical Statistics, 29,610 Bruck Syal, M., Schultz, P. H., Sunshine, J. M., et al. 2013, Icarus, 222, 610 Cordiner, M. A., Milam, S. N., Biver, N., et al. 2020, Nature Astronomy, 4, 861 Cremonese, G., Fulle, M., Cambianica, P., et al. 2020, ApJ, 893, L12 de la Fuente Marcos, C. & de la Fuente Marcos, R. 2015, MNRAS, 453, 1288 de la Fuente Marcos, C. & de la Fuente Marcos, R. 2017a, Res. Notes Am. Astron. Soc., 1, 5 de la Fuente Marcos, C. & de la Fuente Marcos, R. 2017b, Res. Notes Am. Astron. Soc., 1, 9 de León, J., Licandro, J., Serra-Ricart, M., et al. 2019, Res. Notes Am. Astron. Soc., 3, 131 de León, J., Licandro, J., de la Fuente Marcos, C., et al. 2020, MNRAS, 495,2053 Drahus, M., Guzik, P., Waniak, W., et al. 2018, Nature Astronomy, 2, 407 Drahus, M., Guzik, P., Udalski, A., et al. 2020, The Astronomer’s Telegram13549, 1 Farnham, T. L., Wellnitz, D. D., Hampton, D. L., et al. 2007, Icarus, 187, 26 Farnham, T. L., Bodewits, D., Li, J.-Y., et al. 2013, Icarus, 222, 540 Fitzsimmons, A., Snodgrass, C., Rozitis, B., et al. 2018, Nature Astronomy, 2,133 Fitzsimmons, A., Hainaut, O., Meech, K. J., et al. 2019, ApJ, 885, L9 Flekkøy, E. G., Luu, J., & Toussaint, R. 2019, ApJ, 885, L41 Fraser, W. C., Pravec, P., Fitzsimmons, A., et al. 2018, Nature Astronomy, 2, 383 Freedman, D. & Diaconis, P. 1981, Probability Theory and Related Fields, 57,453 Ginsburg, A., Sipocz, B. M., Brasseur, C. E., et al. 2019, AJ, 157, 98 ˝ Giorgini, J. D. 2015, IAUGA, 22, 2256293 Gladman, B., Boley, A., & Balam, D. 2019, Res. Notes Am. Astron. Soc., 3, 187 Guzik, P., Drahus, M., Rusek, K., et al. 2020, Nature Astronomy, 4, 53 Hainaut, O. R., Meech, K. J., Micheli, M., et al. 2018, The Messenger, 173, 13 Hoang, T. & Loeb, A. 2020, ApJ, 899, L23 Hui, M.-T. & Knight, M. M. 2019, AJ, 158, 256 Hui, M.-T., Ye, Q.-Z., Föhring, D., et al. 2020, AJ, 160, 92 Hunter, J. D. 2007, Computing in Science and Engineering, 9, 90 Jewitt, D., Mutchler, M., Kim, Y., et al. 2020a, The Astronomer’s Telegram 13611, 1 Jewitt, D., Hui, M.-T., Kim, Y., et al. 2020b, ApJ, 888, L23 Jewitt, D., Kim, Y., Mutchler, M., et al. 2020c, ApJ, 896, L39 Kareta, T., Andrews, J., Noonan, J. W., et al. 2020, ApJ, 889, L38 Kidger, M. R., & Manteca, J. 2002, Earth Moon and Planets, 90, 153 Kim, Y., Jewitt, D., Mutchler, M., et al. 2020, ApJ, 895, L34 Knight, M. M., Protopapa, S., Kelley, M. S. P., et al. 2017, ApJ, 851, L31 Knollenberg, J., Lin, Z. Y., Hviid, S. F., et al. 2016, A&A, 596, A89 Krolikowska, M., Sitarski, G., & Szutowicz, S. 1998, A&A, 335, 757 Lin, H. W., Lee, C.-H., Gerdes, D. W., et al. 2020, ApJ, 889, L30 Manzini, F., Oldani, V., Ochner, P., et al. 2020, MNRAS, 495, L92 Marsden, B. G., Sekanina, Z., & Yeomans, D. K. 1973, AJ, 78, 211 Mashchenko, S. 2019, MNRAS, 489, 3003 McKay, A. J., Cochran, A. L., Dello Russo, N., et al. 2020, ApJ, 889, L10 Meech, K. J., Weryk, R., Micheli, M., et al. 2017, Nature, 552, 378 Micheli, M., Farnocchia, D., Meech, K. J., et al. 2018, Nature, 559, 223 Mommert, M., Kelley, M., de Val-Borro, M., et al. 2019, The Journal of Open Source Software, 4, 1426 Opitom, C., Fitzsimmons, A., Jehin, E., et al. 2019, A&A, 631, L8’Oumuamua ISSI Team, Bannister, M. T., Bhandare, A., et al. 2019, Nature Astronomy, 3, 594 Rafikov, R. R. 2018, ApJ, 867, L17 Rinaldi, G., Formisano, M., Kappel, D., et al. 2019, A&A, 630, A21 Rudenko, M. 2016, Asteroids: New Observations, New Models, Proceedings of the International Astronomical Union, IAU Symposium, Volume 318, pp. 265-269 Samarasinha, N. H., Mueller, B. E. A., Belton, M. J. S., et al. 2004, Comets II (Cambridge, UK: Cambridge University Press), 281 Scargle, J. D., Norris, J. P., Jackson, B., et al. 2013, ApJ, 764, 167 Scott, D. W. 1992, Multivariate Density Estimation: Theory, Practice, and Visualization (John Wiley & Sons, New York, Chicester) Sekanina, Z. 1981, ARA&A, 9, 113 Sekanina, Z. 1984, AJ, 89, 1573 Sekanina, Z. 1997, A&A, 318, L5 Sekanina, Z. 2019, arXiv e-prints, arXiv:1911.06271 Seligman, D., Laughlin, G., & Batygin, K. 2019, ApJ, 876, L26 Seligman, D. & Laughlin, G. 2020, ApJ, 896, L8 Sitarski, G. 1990, Acta Astron., 40, 405 Sitarski, G. 1996, Acta Astron., 46, 29 Trilling, D. E., Mommert, M., Hora, J. L., et al. 2018, AJ, 156, 261 Vazan, A. & Sari, R. 2020, MNRAS, 493, 1546 Virtanen, P., Gommers, R., Oliphant, T. E., et al. 2020, Nature Methods, 17, 261 Whipple, F. L. 1950, ApJ, 111, 375 Xing, Z., Bodewits, D., Noonan, J., et al. 2020, ApJ, 893, L48 Yabushita, S. 1996, MNRAS, 283, 347 Yang, B., Kelley, M. S. P., Meech, K. J., et al. 2020, A&A, 634, L6 Ye, Q., Kelley, M. S. P., Bolin, B. T., et al. 2020, AJ, 159, 77 Yeomans, D. K., Chodas, P. W., Sitarski, G., et al. 2004, Comets II (Cambridge, UK: Cambridge University Press), 137 Zhang, Q., Ye, Q., & Kolokolova, L. 2020, The Astronomer’s Telegram 13618,1 Zhang, Y. & Lin, D. N. C. 2020, Nature Astronomy, 4, 852 Zhou, W. H. 2019, arXiv e-prints, arXiv:1911.12228v2 Zhou, W. H. 2020, ApJ, 899, 42