Focus on slow rotators - first results from stellar occultations campaign on long-period asteroids

• DOI: 10.5194/epsc2022-224
• Publication Date: 2022-09-23T12:06:09Z
• Authors: Anna Marciniak; Josef Durech; Antoine Choukroun; Eric Frappa; Wolfgang Beisker
• Keywords: Adenine nucleotide; AMP deaminase

<p><strong>Most asteroids are slow rotators  </strong>                                                                                                                                                              <br />Results from space missions like Kepler and TESS (Molnar et al. 2018; Pal 2020), but also ground-based surveys e.g. ATLAS ZTF (Erasmus 2021) reveal unexpectedly large numbers of slowly rotating in the main belt, with periods reaching up to a few thousand hours. Actually majority rotate slowly, impossible be fully covered during one night. As consequence, their spin shape models mostly missing, skewing big picture spins, shapes, sizes other properties.    <br />                                                                                                                                                                                        />Our long-term project (see Marciniak 2015; targets tens 60 hours, obtain full lightcurves an efficient world-wide observing scheme. Dense then serve for reconstructions via lightcurve inversion. Recently we launched special campaign among stellar occultation observers<sup>1,2</sup>, put these into scale, verify solutions, often allowing break mirror-pole ambiguity.              </p> <p>                                    /><strong>Sample result</strong>                                                                       survey resulted rich enough dataset create unique model asteroid (439) Ohio, challenging rotator displaying 37-hours period. At same time, two successful, multi-chord occultations by this have been registered within "slow rotators" March 2022. Together archival PDS database (Herald al., 2019) they allowed us precisely scale our Ohio using method Durech (2011). This has independently confirmed size location features down single kilometers on 74-km body figure below). </p> <p><img src="" alt="" width="1026" height="259" /></p> <p><strong>Fig. 1.</strong> Shape (blue contours) fitted chords three (black lines). Grey segments denote timing uncertainties. North is west right. Volume equivalent diameter: 74 +/- 2 km.</p> <p><strong>Conclusions future prospects </strong>                  />Presented scheme recently obtaining quality 15 rotators, most them first time. Sizes determined fitting agree infrared WISE (Wright 2010), IRAS (Neugebauer 1984), AKARI (Usui 2011), yet providing better accuracy, or resolving previous inconsistencies determinations some cases. That stems creating robust instead spherical approximation unknown used Simple Thermal Model (Harris & Lagerros 2002). For roughly half reject mirror pole clearly pointing preferred one, thus removing ambiguity inherent Such well scaled shapes will constitute solid basis precise density determinations, once masses available (for expected already Gaia mission). Spin general keep filling gap caused various biases. </p> <p><em>Acknowledgements:</em> work was supported National Science Centre, Poland, through grant no. 2020/39/O/ST9/00713.</p> <p>                                                                                                   /><strong>References: </strong>                                                                                               />Durech, J., Kaasalainen, M., Herald, D. 2011, Icarus 214, 652 />Erasmus, N., Kramer, D., McNeill, A. 2021, MNRAS 505, 3872 />Harris, W., Lagerros, J. S. V. 2002, Asteroids III, 205 />Herald, Frappa, E., Gault, 2019, Asteroid Occultations V3.0, NASA Planetary Data System />Marciniak, A., Pilcher, F., Oszkiewicz, 2015, Planet. Space Sci., 118, 256 Durech, Ali-Lagoa, V., A&A, 657, A87 />Molnar, L., Pal, Sarneczky, K., 2018, ApJS, 234, 37 />Neugebauer, G., Habing, H. van Duinen, R., 1984, ApJ, 278, L1 />Pal, Szakats, Kiss, C., 2020, 247, 26 />Usui, Kuroda, Mueller, T. PASJ, 63, 1117 />Wright, E. Eisenhardt, P. R. Mainzer, 2010, AJ, 140, 1868</p> <p><sup>1</sup>https://www.iota-es.de/neglected_asteroids.html /><sup>2</sup>https://cloud.occultwatcher.net/campaigns</p>