2012/10/30 by Hilke E. Schlichting, Eran O. Ofek, Re'em Sari +6 · 1 citation
Physics and Astronomy · #Astro and Planetary Science #Astronomy and Astrophysical Research #Stellar, planetary, and galactic studies #astro-ph.EP
paper · pdf · doi:10.1088/0004-637x/761/2/150
Accepted for publication in the Astrophysical Journal, 32 pages, 15 figures. arXiv admin note: text overlap with arXiv:0912.2996
arxiv created 2012/10/30 · openalex publication_date 2012/12/04 · arxiv updated 2015/06/11 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We present here the analysis of about 19,500 new star hours of low ecliptic latitude observations (|b| < 20 deg) obtained by the Hubble Space Telescope's FGS over a time span of more than nine years; which is an addition to the 12,000 star hours previously analyzed by Schlichting et al. (2009). Our search for stellar occultations by small Kuiper belt objects (KBOs) yielded one new candidate event corresponding to a body with a 530 +/-70m radius at a distance of about 40AU. Using bootstrap simulations, we estimate a probability of approx 5%, that this event is due to random statistical fluctuations within the new data set. Combining this new event with the single KBO occultation reported by Schlichting et al. (2009) we arrive at the following results: 1) The ecliptic latitudes of 6.6 deg and 14.4 deg of the two events are consistent with the observed inclination distribution of larger, 100km-sized KBOs. 2) Assuming that small, sub-km sized KBOs have the same ecliptic latitude distribution as their larger counterparts, we find an ecliptic surface density of KBOs with radii larger than 250m of N(r>250m) = 1.1+1.5-0.7 x 107 deg-2; if sub-km sized KBOs have instead a uniform ecliptic latitude distribution for -20 deg < b< 20 deg then N(r>250m) = 4.4+5.8-2.8 x 106 deg-2. This is the best measurement of the surface density of sub-km sized KBOs to date. 3) Assuming the KBO size distribution can be well described by a single power law given by N(>r) ∝ r1-q, where N(>r) is the number of KBOs with radii greater than r, and q is the power law index, we find q=3.8+/-0.2 for a KBO ecliptic latitude distribution that follows the observed distribution for larger, 100-km sized KBOs. 4) Regardless of the exact power law, our results suggest that small KBOs are numerous enough to satisfy the required supply rate for the Jupiter family comets. (Abridged)