S/2012 (2577) 1
Abstract
W. J. Merline, Southwest Research Institute (together with P. M. Tamblyn, B. D. Warner, P. Pravec, J. P. Tamblyn, C. Neyman, A. R. Conrad, W. M. Owen, B. Carry, J. D. Drummond, C. R. Chapman, B. L. Enke, W. M. Grundy, C. Veillet, S. B. Porter, C. Arcidiacono, J. C. Christou, D. D. Durda, A. W. Harris, H. A. Weaver, C. Dumas, D. Terrell, and P. Maley) reports the discovery, using the Keck II telescope (+ NIRC2 Laser-Guide-Star adaptive-optics system), of a second satellite of the Hungaria-type minor planet (2577) Litva. On 2012 June 22.3 UT, the satellite was found at p.a. 89 deg and separation 0".229 (projected separation 230 km). At that time, (2577) was 1.39 AU from the earth at magnitude V = 16.6. The satellite has been imaged in the K_p, H, and J bands. It was also detected on 2012 June 27, Aug. 11, and Aug. 16. Failure to detect it on 2012 July 15 is now seen to be due to being in conjunction with the primary. Follow-up observations were made at the Keck II telescope on 2013 Aug. 25 and 26 by Merline, Tamblyn, Conrad, and Tamblyn. Additional detections were made at the Large Binocular Telescope by Veillet and Arcidiacono on Oct. 12 and at the Keck II telescope by Grundy and Porter on Oct. 25, giving a total baseline of 490 days. The best-fit orbit analysis indicates that the third component has a semi-major axis of 378 km and an orbital period of 214 days; a period of half this length cannot be ruled out. Either orbit would be among the longest periods known for main-belt multiple systems and would be the most loosely bound. It resembles other wide binary systems discovered by this same group (cf. Durda et al. 2010, Proc. Lunar and Planet. Sci. Conf. 41, 2558; Jacobson et al., Ap.J., submitted). The third component is about 2.6 mag fainter than the combined brightness of the close inner pair. Using H magnitudes to scale the size of (2577) from other E-type objects of better-known size, the diameter of (2577) is estimated to be about 4 km, implying a size for the new satellite of 1.2 km. The first satellite of (2577) was inferred by Warner et al. (CBET 1715) in 2009 via lightcurve analysis; their estimate of the size ratio was 0.35, meaning that the second component would be 1.4 km diameter, based on the 4-km assumption for (2577), above. This close inner pair is unresolvable in the imaging data reported above. Warner et al. (2009, Minor Planet Bull. 36, 165) suggested that a residual 5.7-hr lightcurve period may be due to rotation by a third body -- an idea bolstered by Pravec et al. (2012, Icarus 218, 125), who found that this period was still evident even when the secondary object was in eclipse. To the authors' knowledge, S/2012 (2577) 1 is the only satellite to have been predicted prior to being found by targeted imaging. Additional information is provided on CBET 3765.
- Publication:
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International Astronomical Union Circular
- Pub Date:
- December 2013
- Bibcode:
- 2013IAUC.9267....1M