We present variability measurements and partial light curves of Trans-Neptunian Objects (TNOs) from a two-night pilot study using Hyper Suprime-Cam (HSC) on the Subaru Telescope (Maunakea, Hawai'i, USA). Subaru's large aperture (8-m) and HSC's large field of view (1.77 deg 2 ) allow us to obtain measurements of multiple objects with a range of magnitudes in each telescope pointing. We observed 65 objects with m r = 22.6-25.5 mag in just six pointings, allowing 20-24 visits of each pointing over the two nights. Our sample, all discovered in the recent Outer Solar System Origins Survey (OSSOS), span absolute magnitudes H r = 6.2-10.8 mag and thus investigates smaller objects than previous light curve projects have typically studied. Our data supports the existence of a correlation between light curve amplitude and absolute magnitude seen in other works, but does not support a correlation between amplitude and orbital inclination. Our sample includes a number of objects from different dynamical populations within the trans-Neptunian region, but we do not find any relationship between variability and dynamical class. We were only able to estimate periods for 12 objects in the sample and found that a longer baseline of observations is required for reliable period analysis. We find that 31 objects (just under half of our sample) have variability ∆ mag greater than 0.4 mag during all of the observations; in smaller 1.25 hr, 1.85 hr and 2.45 hr windows, the median ∆ mag is 0.13, 0.16 and 0.19 mags, respectively. The fact that variability on this scale is common for small TNOs has important implications for discovery surveys (such as OSSOS or the Large Synoptic Survey Telescope) and color measurements.
We present photometric observations and numerical simulations of 2016 SD106, a low-inclination (i = 4.°8) extreme trans-Neptunian Object with a large semimajor axis (a = 350 au) and perihelion (q = 42.6 au). This object possesses a peculiar neutral color of g − r = 0.45 ± 0.05 and g − i = 0.72 ± 0.06, in comparison with other distant trans-Neptunian objects, all of which have moderate-red to ultra-red colors. A numerical integration based on orbital fitting on astrometric data covering eight years of arc confirms that 2016 SD106 is a metastable object without significant scattering evolution. Each of the clones survived at the end of the 1 Gyr simulation. However, very few neutral objects with inclinations <5° have been found in the outer solar system, even in the main Kuiper Belt. Furthermore, most mechanisms that lift perihelion distances are expected to produce a very low number of extreme objects with inclinations <5°. We thus explored the possibility that a hypothetical distant planet could increase the production of such objects. Our simulations show that no 2016 SD106–like orbits can be produced from three Kuiper Belt populations tested (i.e., plutinos, twotinos, and the Haumea Family) without the presence of a hypothetical planet, while a few similar orbits can be obtained with it; however, the presence of the additional planet produces a wide range of large semimajor-axis/large perihelion objects, in apparent contradiction with the observed scarcity of objects in those regions of phase space. Future studies may determine if there is a connection between the existence of a perihelion gap and a particular orbital configuration of a hypothetical distant planet.
The recalibration of the sunspot number series has established a new standard version for sunspot time series that requires updating of prior results based on the calibration. These recent sunspot number corrections mean a change in the results of the previous correlational studies of ISSN with geomagnetic indices, such as the aa-index. In this paper, we investigate the correlation between the old and new sunspot numbers ISSN and SN and their relationship with the aa index through time series, using the methods of Echer et. al (2004), Verma & Trippathi (2016), Stamper et. al (1996), and Feynman (1982).
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