# Summary of K2 Program GO14059

Title: Physical studies of asteroids with Kepler

PI: Marciniak, Anna (Adam Mickiewicz University)
CoIs: Szabo, Robert; Szakats, Robert; Kiss, Csaba; Mueller, Thomas G

As it has been demonstrated in some recent papers, the Kepler Space Telescope in the K2 mission is an excellent tool to observe asteroids and obtain accurate lightcurves even if the targets are relatively fast-moving main belt asteroids (Szabo et al., 2015, 2016a) or Jovian Trojans (Szabo et al., 2016b).  

While in the case of trans-Neptunian bodies the lightcurve information is available for a limited sample only (see e.g. Kiss et al., 2015), the general spin characteristics of main belt asteroids are relatively well know due to their proximity and relatively short (~few years) orbital periods that allows us to observe these bodies at various spin axis aspect angles during their motion around the Sun. The sufficient orbital phase coverage also allows us to apply lightcurve inversion techniques to obtain detailed shape models for these targets (Kaasalainen et al., 2002). 

In this proposal our goal is to obtain lightcurves of slowly rotating asteroids with low amplitudes, to decrease the strong selection effects in spin and shape studies of asteroids. Currently spin and shape models are mainly available for targets with relatively short rotation periods and substantial elongations of their shapes that results in a biased sample of asteroids with known physical properties (Marciniak et al. 2015). Consequently, our knowledge on spin vs. diameter, the internal cohesion and strength or the non-gravitational effects are biased, too. Data from asteroids observed in the K2 mission can substantially increase the data pool for asteroids omitted in previous studies, enabling continuous observations of targets with periods of the order of days. 

We also investigate small asteroids with spin axes close to the ecliptic plane. Some studies suggest their non-existence due to non-gravitational YORP effect (Durech et al. 2016). However, such lack can be a selection effect, because such targets often display very small amplitudes when viewed pole-on. Kepler/K2 data will allow us to decide whether the low amplitude of these targets are due to close to pole-on configurations.  

We propose to observe a set of main belt asteroids for which additional high-quality lightcurve data obtained with K2 would enable us to obtain spin and shape models for the first time. Some of the targets, (203) Pompeja, (566) Stereoskopia and (308) Polyxo have rotation periods close to 12h or 24h and have small, <0.1 mag lightcurve amplitudes. These targets are difficult to observe from ground due to daily gaps and aliases, and would require coordinated observations from many observing sites, typically flawed by weather conditions. The Kepler Space Telescope is able to perform these observations alone. (525) Adelaide is a target with highly inclined spin axis and strongly variable amplitudes, sometimes being as low as 0.02 mag. Obtaining full, composite lightcurve of this P=19.967 h target would be very difficult from the ground, as the period exceeds the length of the average observing night. In practice, only continuous data from a space-based observatory can provide meaningful data for this target. (437) Rhodia is a very slow rotator with a period of ~56 hours, and variable, usually very low amplitudes. A sufficiently long, continuous measurement of this target would allow us to determine the orientation of its (likely) multiple spin axes.  

All our 14 targets will spend enough time on silicon (typically ~5 days) that a sufficient light curve coverage can be guaranteed. 

References:

- Durech et al., 2016, A&A, 587, A48
- Kaasalainen, et al., 2002, "Asteroid Models from Disk-integrated Data", in Asteroids III, Univ. of Arizona Press
- Kiss, Cs. et al., "Trans-Neptunian objects with K2: targeting our own Solar System", 2015, K2 White Paper
- Marciniak et al., 2015, P&SS, 118, 256
- Szabo, R., et al., 2015, AJ, 149, 112
- Szabo, R., et al., 2016a, arXiv:1609.02759, A&A, accepted
- Szabo, Gy.M., et al., 2016b, arXiv:1609.02760, A&A, accepted

# Targets requested by this program that have been observed (190)
EPIC ID, RA (J2000) [deg], Dec (J2000) [deg], magnitude, Investigation IDs
200180071, , , , GO14059_LC|373-LC-SSO_TILE
200180072, , , , GO14059_LC|373-LC-SSO_TILE
200180073, , , , GO14059_LC|373-LC-SSO_TILE
200180074, , , , GO14059_LC|373-LC-SSO_TILE
200180075, , , , GO14059_LC|373-LC-SSO_TILE
200180076, , , , GO14059_LC|373-LC-SSO_TILE
200180077, , , , GO14059_LC|373-LC-SSO_TILE
200180078, , , , GO14059_LC|373-LC-SSO_TILE
200180079, , , , GO14059_LC|373-LC-SSO_TILE
200180080, , , , GO14059_LC|373-LC-SSO_TILE
200180081, , , , GO14059_LC|373-LC-SSO_TILE
200180082, , , , GO14059_LC|373-LC-SSO_TILE
200180083, , , , GO14059_LC|373-LC-SSO_TILE
200180084, , , , GO14059_LC|373-LC-SSO_TILE
200180085, , , , GO14059_LC|373-LC-SSO_TILE
200180086, , , , GO14059_LC|373-LC-SSO_TILE
200180087, , , , GO14059_LC|373-LC-SSO_TILE
200180088, , , , GO14059_LC|373-LC-SSO_TILE
200180089, , , , GO14059_LC|373-LC-SSO_TILE
200180090, , , , GO14059_LC|373-LC-SSO_TILE
200180091, , , , GO14059_LC|373-LC-SSO_TILE
200180092, , , , GO14059_LC|373-LC-SSO_TILE
200180093, , , , GO14059_LC|373-LC-SSO_TILE
200180094, , , , GO14059_LC|373-LC-SSO_TILE
200180095, , , , GO14059_LC|373-LC-SSO_TILE
200180096, , , , GO14059_LC|373-LC-SSO_TILE
200180097, , , , GO14059_LC|373-LC-SSO_TILE
200180098, , , , GO14059_LC|373-LC-SSO_TILE
200180099, , , , GO14059_LC|373-LC-SSO_TILE
200180100, , , , GO14059_LC|373-LC-SSO_TILE
200180101, , , , GO14059_LC|373-LC-SSO_TILE
200180102, , , , GO14059_LC|373-LC-SSO_TILE
200180103, , , , GO14059_LC|373-LC-SSO_TILE
200180104, , , , GO14059_LC|373-LC-SSO_TILE
200180105, , , , GO14059_LC|373-LC-SSO_TILE
200180106, , , , GO14059_LC|373-LC-SSO_TILE
200180107, , , , GO14059_LC|373-LC-SSO_TILE
200180108, , , , GO14059_LC|373-LC-SSO_TILE
200180109, , , , GO14059_LC|373-LC-SSO_TILE
200180110, , , , GO14059_LC|373-LC-SSO_TILE
200180111, , , , GO14059_LC|373-LC-SSO_TILE
200180112, , , , GO14059_LC|373-LC-SSO_TILE
200180113, , , , GO14059_LC|373-LC-SSO_TILE
200180114, , , , GO14059_LC|373-LC-SSO_TILE
200180115, , , , GO14059_LC|373-LC-SSO_TILE
200180116, , , , GO14059_LC|373-LC-SSO_TILE
200180117, , , , GO14059_LC|373-LC-SSO_TILE
200180118, , , , GO14059_LC|373-LC-SSO_TILE
200180119, , , , GO14059_LC|373-LC-SSO_TILE
200180120, , , , GO14059_LC|373-LC-SSO_TILE
200180121, , , , GO14059_LC|373-LC-SSO_TILE
200180122, , , , GO14059_LC|373-LC-SSO_TILE
200180123, , , , GO14059_LC|373-LC-SSO_TILE
200180124, , , , GO14059_LC|373-LC-SSO_TILE
200180125, , , , GO14059_LC|373-LC-SSO_TILE
200180126, , , , GO14059_LC|373-LC-SSO_TILE
200180127, , , , GO14059_LC|373-LC-SSO_TILE
200180128, , , , GO14059_LC|373-LC-SSO_TILE
200180129, , , , GO14059_LC|373-LC-SSO_TILE
200180130, , , , GO14059_LC|373-LC-SSO_TILE
200180131, , , , GO14059_LC|373-LC-SSO_TILE
200180132, , , , GO14059_LC|373-LC-SSO_TILE
200180133, , , , GO14059_LC|373-LC-SSO_TILE
200180134, , , , GO14059_LC|373-LC-SSO_TILE
200180135, , , , GO14059_LC|373-LC-SSO_TILE
200180136, , , , GO14059_LC|373-LC-SSO_TILE
200180137, , , , GO14059_LC|373-LC-SSO_TILE
200180138, , , , GO14059_LC|373-LC-SSO_TILE
200180139, , , , GO14059_LC|373-LC-SSO_TILE
200180140, , , , GO14059_LC|373-LC-SSO_TILE
200180141, , , , GO14059_LC|373-LC-SSO_TILE
200180142, , , , GO14059_LC|373-LC-SSO_TILE
200180143, , , , GO14059_LC|373-LC-SSO_TILE
200180144, , , , GO14059_LC|373-LC-SSO_TILE
200180145, , , , GO14059_LC|373-LC-SSO_TILE
200180146, , , , GO14059_LC|373-LC-SSO_TILE
200180147, , , , GO14059_LC|373-LC-SSO_TILE
200180148, , , , GO14059_LC|373-LC-SSO_TILE
200180149, , , , GO14059_LC|373-LC-SSO_TILE
200180150, , , , GO14059_LC|373-LC-SSO_TILE
200180151, , , , GO14059_LC|373-LC-SSO_TILE
200180152, , , , GO14059_LC|373-LC-SSO_TILE
200180153, , , , GO14059_LC|373-LC-SSO_TILE
200180154, , , , GO14059_LC|373-LC-SSO_TILE
200180155, , , , GO14059_LC|373-LC-SSO_TILE
200180156, , , , GO14059_LC|373-LC-SSO_TILE
200180157, , , , GO14059_LC|373-LC-SSO_TILE
200180158, , , , GO14059_LC|373-LC-SSO_TILE
200180159, , , , GO14059_LC|373-LC-SSO_TILE
200180160, , , , GO14059_LC|373-LC-SSO_TILE
200180161, , , , GO14059_LC|373-LC-SSO_TILE
200180162, , , , GO14059_LC|373-LC-SSO_TILE
200180163, , , , GO14059_LC|373-LC-SSO_TILE
200180164, , , , GO14059_LC|373-LC-SSO_TILE
200180165, , , , GO14059_LC|373-LC-SSO_TILE
200180166, , , , GO14059_LC|373-LC-SSO_TILE
200180167, , , , GO14059_LC|373-LC-SSO_TILE
200180168, , , , GO14059_LC|373-LC-SSO_TILE
200180169, , , , GO14059_LC|373-LC-SSO_TILE
200180170, , , , GO14059_LC|373-LC-SSO_TILE
200180171, , , , GO14059_LC|373-LC-SSO_TILE
200180172, , , , GO14059_LC|373-LC-SSO_TILE
200180173, , , , GO14059_LC|373-LC-SSO_TILE
200180174, , , , GO14059_LC|373-LC-SSO_TILE
200180175, , , , GO14059_LC|373-LC-SSO_TILE
200180176, , , , GO14059_LC|373-LC-SSO_TILE
200180177, , , , GO14059_LC|373-LC-SSO_TILE
200180178, , , , GO14059_LC|373-LC-SSO_TILE
200180179, , , , GO14059_LC|373-LC-SSO_TILE
200180180, , , , GO14059_LC|373-LC-SSO_TILE
200180181, , , , GO14059_LC|373-LC-SSO_TILE
200180182, , , , GO14059_LC|373-LC-SSO_TILE
200180183, , , , GO14059_LC|373-LC-SSO_TILE
200180184, , , , GO14059_LC|373-LC-SSO_TILE
200180185, , , , GO14059_LC|373-LC-SSO_TILE
200180186, , , , GO14059_LC|373-LC-SSO_TILE
200180187, , , , GO14059_LC|373-LC-SSO_TILE
200180188, , , , GO14059_LC|373-LC-SSO_TILE
200180189, , , , GO14059_LC|373-LC-SSO_TILE
200180190, , , , GO14059_LC|373-LC-SSO_TILE
200180191, , , , GO14059_LC|373-LC-SSO_TILE
200180192, , , , GO14059_LC|373-LC-SSO_TILE
200180193, , , , GO14059_LC|373-LC-SSO_TILE
200180194, , , , GO14059_LC|373-LC-SSO_TILE
200180195, , , , GO14059_LC|373-LC-SSO_TILE
200180196, , , , GO14059_LC|373-LC-SSO_TILE
200180197, , , , GO14059_LC|373-LC-SSO_TILE
200180198, , , , GO14059_LC|373-LC-SSO_TILE
200180199, , , , GO14059_LC|373-LC-SSO_TILE
200180200, , , , GO14059_LC|373-LC-SSO_TILE
200180201, , , , GO14059_LC|373-LC-SSO_TILE
200180202, , , , GO14059_LC|373-LC-SSO_TILE
200180203, , , , GO14059_LC|373-LC-SSO_TILE
200180204, , , , GO14059_LC|373-LC-SSO_TILE
200180205, , , , GO14059_LC|373-LC-SSO_TILE
200180206, , , , GO14059_LC|373-LC-SSO_TILE
200180207, , , , GO14059_LC|373-LC-SSO_TILE
200180208, , , , GO14059_LC|373-LC-SSO_TILE
200180209, , , , GO14059_LC|373-LC-SSO_TILE
200180210, , , , GO14059_LC|373-LC-SSO_TILE
200180211, , , , GO14059_LC|373-LC-SSO_TILE
200180212, , , , GO14059_LC|373-LC-SSO_TILE
200180213, , , , GO14059_LC|373-LC-SSO_TILE
200180214, , , , GO14059_LC|373-LC-SSO_TILE
200180215, , , , GO14059_LC|373-LC-SSO_TILE
200180216, , , , GO14059_LC|373-LC-SSO_TILE
200180217, , , , GO14059_LC|373-LC-SSO_TILE
200180218, , , , GO14059_LC|373-LC-SSO_TILE
200180219, , , , GO14059_LC|373-LC-SSO_TILE
200180220, , , , GO14059_LC|373-LC-SSO_TILE
200180221, , , , GO14059_LC|373-LC-SSO_TILE
200180222, , , , GO14059_LC|373-LC-SSO_TILE
200180223, , , , GO14059_LC|373-LC-SSO_TILE
200180224, , , , GO14059_LC|373-LC-SSO_TILE
200180225, , , , GO14059_LC|373-LC-SSO_TILE
200180226, , , , GO14059_LC|373-LC-SSO_TILE
200180227, , , , GO14059_LC|373-LC-SSO_TILE
200180228, , , , GO14059_LC|373-LC-SSO_TILE
200180229, , , , GO14059_LC|373-LC-SSO_TILE
200180230, , , , GO14059_LC|373-LC-SSO_TILE
200180231, , , , GO14059_LC|373-LC-SSO_TILE
200180232, , , , GO14059_LC|373-LC-SSO_TILE
200180233, , , , GO14059_LC|373-LC-SSO_TILE
200180234, , , , GO14059_LC|373-LC-SSO_TILE
200180235, , , , GO14059_LC|373-LC-SSO_TILE
200180236, , , , GO14059_LC|373-LC-SSO_TILE
200180237, , , , GO14059_LC|373-LC-SSO_TILE
200180238, , , , GO14059_LC|373-LC-SSO_TILE
200180239, , , , GO14059_LC|373-LC-SSO_TILE
200180240, , , , GO14059_LC|373-LC-SSO_TILE
200180241, , , , GO14059_LC|373-LC-SSO_TILE
200180242, , , , GO14059_LC|373-LC-SSO_TILE
200180243, , , , GO14059_LC|373-LC-SSO_TILE
200180244, , , , GO14059_LC|373-LC-SSO_TILE
200180245, , , , GO14059_LC|373-LC-SSO_TILE
200180246, , , , GO14059_LC|373-LC-SSO_TILE
200180247, , , , GO14059_LC|373-LC-SSO_TILE
200180248, , , , GO14059_LC|373-LC-SSO_TILE
200180249, , , , GO14059_LC|373-LC-SSO_TILE
200180250, , , , GO14059_LC|373-LC-SSO_TILE
200180251, , , , GO14059_LC|373-LC-SSO_TILE
200180252, , , , GO14059_LC|373-LC-SSO_TILE
200180253, , , , GO14059_LC|373-LC-SSO_TILE
200180254, , , , GO14059_LC|373-LC-SSO_TILE
200180255, , , , GO14059_LC|373-LC-SSO_TILE
200180256, , , , GO14059_LC|373-LC-SSO_TILE
200180257, , , , GO14059_LC|373-LC-SSO_TILE
200180258, , , , GO14059_LC|373-LC-SSO_TILE
200180259, , , , GO14059_LC|373-LC-SSO_TILE
200180260, , , , GO14059_LC|373-LC-SSO_TILE