We present our analysis on new limits of the dark matter (DM) halo consisting of primordial black holes (PBHs) or massive compact halo objects. We present a search of the first two yr of publicly ...available Kepler mission data for potential signatures of gravitational microlensing caused by these objects as well as an extensive analysis of the astrophysical sources of background error. These include variable stars, flare events, and comets or asteroids that are moving through the Kepler field. We discuss the potential of detecting comets using the Kepler light curves, presenting measurements of two known comets and one unidentified object, most likely an asteroid or comet. After removing the background events with statistical cuts, we find no microlensing candidates. We therefore present our Monte Carlo efficiency calculation in order to constrain the PBH DM with masses in the range of 2 x 10 super(-9) M sub(middot in circle) to 10 super(-7) M sub(middot in circle). We find that PBHs in this mass range cannot make up the entirety of the DM, thus closing a full order of magnitude in the allowed mass range for PBH DM.
The recent discovery by Pan-STARRS1 of 1I/2017 U1 ('Oumuamua), on an unbound and hyperbolic orbit, offers a rare opportunity to explore the planetary formation processes of other stars and the effect ...of the interstellar environment on a planetesimal surface. 1I/'Oumuamua's close encounter with the inner solar system in 2017 October was a unique chance to make observations matching those used to characterize the small-body populations of our own solar system. We present near-simultaneous g′, r′, and J photometry and colors of 1I/'Oumuamua from the 8.1 m Frederick C. Gillett Gemini-North Telescope and gri photometry from the 4.2 m William Herschel Telescope. Our g′r′J observations are directly comparable to those from the high-precision Colours of the Outer Solar System Origins Survey (Col-OSSOS), which offer unique diagnostic information for distinguishing between outer solar system surfaces. The J-band data also provide the highest signal-to-noise measurements made of 1I/'Oumuamua in the near-infrared. Substantial, correlated near-infrared and optical variability is present, with the same trend in both near-infrared and optical. Our observations are consistent with 1I/'Oumuamua rotating with a double-peaked period of 8.10 0.42 hr and being a highly elongated body with an axial ratio of at least 5.3:1, implying that it has significant internal cohesion. The color of the first interstellar planetesimal is at the neutral end of the range of solar system g − r and r − J solar-reflectance colors: it is like that of some dynamically excited objects in the Kuiper Belt and the less-red Jupiter Trojans.
The Colours of the Outer Solar System Origins Survey is acquiring near-simultaneous g, r, and J photometry of unprecedented precision with the Gemini North Telescope, targeting nearly 100 ...trans-Neptunian objects (TNOs) brighter than mr = 23.6 mag discovered in the Outer Solar System Origins Survey. Combining the optical and near-infrared photometry with the well-characterized detection efficiency of the Colours of the Outer Solar System Origins Survey target sample will provide the first flux-limited compositional dynamical map of the outer solar system. In this paper, we describe our observing strategy and detail the data reduction processes we employ, including techniques to mitigate the impact of rotational variability. We present optical and near-infrared colors for 35 TNOs. We find two taxonomic groups for the dynamically excited TNOs, the neutral and red classes, which divide at g − r 0.75. Based on simple albedo and orbital distribution assumptions, we find that the neutral class outnumbers the red class, with a ratio of 4:1 and potentially as high as 11:1. Including in our analysis constraints from the cold classical objects, which are known to exhibit unique albedos and r − z colors, we find that within our measurement uncertainty our observations are consistent with the primordial solar system protoplanetesimal disk being neutral class dominated, with two major compositional divisions in grJ color space.
The Outer Solar System Origins Survey (OSSOS), a wide-field imaging program in 2013-2017 with the Canada-France-Hawaii Telescope, surveyed 155 deg2 of sky to depths of mr = 24.1-25.2. We present 838 ...outer solar system discoveries that are entirely free of ephemeris bias. This increases the inventory of trans-Neptunian objects (TNOs) with accurately known orbits by nearly 50%. Each minor planet has 20-60 Gaia/Pan-STARRS-calibrated astrometric measurements made over 2-5 oppositions, which allows accurate classification of their orbits within the trans-Neptunian dynamical populations. The populations orbiting in mean-motion resonance with Neptune are key to understanding Neptune's early migration. Our 313 resonant TNOs, including 132 plutinos, triple the available characterized sample and include new occupancy of distant resonances out to semimajor axis a ∼ 130 au. OSSOS doubles the known population of the nonresonant Kuiper Belt, providing 436 TNOs in this region, all with exceptionally high-quality orbits of a uncertainty a ≤ 0.1%; they show that the belt exists from a 37 au, with a lower perihelion bound of 35 au. We confirm the presence of a concentrated low-inclination a 44 au "kernel" population and a dynamically cold population extending beyond the 2:1 resonance. We finely quantify the survey's observational biases. Our survey simulator provides a straightforward way to impose these biases on models of the trans-Neptunian orbit distributions, allowing statistical comparison to the discoveries. The OSSOS TNOs, unprecedented in their orbital precision for the size of the sample, are ideal for testing concepts of the history of giant planet migration in the solar system.
Several different classes of trans-Neptunian objects (TNOs) have been identified based on their optical and near-infrared colors. As part of the Colours of the Outer Solar System Origins Survey ...(Col-OSSOS), we have obtained g-, r-, and z-band photometry of 26 TNOs using Subaru and Gemini Observatories. Previous color surveys have not utilized z-band reflectance, and the inclusion of this band reveals significant surface reflectance variations between sub-populations. The colors of TNOs in g − r and r − z show obvious structure, and appear consistent with the previously measured bi-modality in g − r. The distribution of colors of the two dynamically excited surface types can be modeled using the two-component mixing models from Fraser & Brown. With the combination of g − r and r − z, the dynamically excited classes can be separated cleanly into red and neutral surface classes. In g − r and r − z, the two dynamically excited surface groups are also clearly distinct from the cold classical TNO surfaces, which are red, with and r − z 0.6, while all dynamically excited objects with similar g − r colors exhibit redder r − z colors. The z-band photometry makes it possible for the first time to differentiate the red excited TNO surfaces from the red cold classical TNO surfaces. The discovery of different r − z colors for these cold classical TNOs makes it possible to search for cold classical surfaces in other regions of the Kuiper Belt and to completely separate cold classical TNOs from the dynamically excited population, which overlaps in orbital parameter space.
Social deficits are a core symptom of autism spectrum disorder; however, the perturbed neural mechanisms underpinning these deficits remain unclear. It has been suggested that social prediction ...errors-coding discrepancies between the predicted and actual outcome of another's decisions-might play a crucial role in processing social information. While the gyral surface of the anterior cingulate cortex signalled social prediction errors in typically developing individuals, this crucial social signal was altered in individuals with autism spectrum disorder. Importantly, the degree to which social prediction error signalling was aberrant correlated with diagnostic measures of social deficits. Effective connectivity analyses further revealed that, in typically developing individuals but not in autism spectrum disorder, the magnitude of social prediction errors was driven by input from the ventromedial prefrontal cortex. These data provide a novel insight into the neural substrates underlying autism spectrum disorder social symptom severity, and further research into the gyral surface of the anterior cingulate cortex and ventromedial prefrontal cortex could provide more targeted therapies to help ameliorate social deficits in autism spectrum disorder.
Both physical and dynamical properties must be considered to constrain the origins of the dynamically excited distant solar system populations. We present high-precision (g-r) colors for 25 small (Hr ...> 5) dynamically excited trans-Neptunian objects (TNOs) and centaurs acquired as part of the Colours of the Outer Solar System Origins Survey. We combine our data set with previously published measurements and consider a set of 229 colors of outer solar system objects on dynamically excited orbits. The overall color distribution is bimodal and can be decomposed into two distinct classes, termed gray and red, that each has a normal color distribution. The two color classes have different inclination distributions: red objects have lower inclinations than the gray ones. This trend holds for all dynamically excited TNO populations. Even in the worst-case scenario, biases in the discovery surveys cannot account for this trend; it is intrinsic to the TNO population. Considering that TNOs are the precursors of centaurs, and that their inclinations are roughly preserved as they become centaurs, our finding solves the conundrum of centaurs being the only outer solar system population identified so far to exhibit this property. The different orbital distributions of the gray and red dynamically excited TNOs provide strong evidence that their colors are due to different formation locations in a disk of planetesimals with a compositional gradient.
Abstract
Using the high-cadence lightcurves collected from the FOSSIL survey, rotation periods of 17 small (diameter 1 km <
D
< 3 km) Hilda asteroids (hereinafter Hildas) were obtained. Combined with ...the previously measured rotation periods of Hildas, a spin-rate limit appears at around 3 hr. Assuming rubble-pile structures for the Hildas, a bulk density of ∼1.5 g cm
−3
is required to withstand this spin-rate limit. This value is similar to that of the C-type asteroids (1.33 g cm
−3
) and higher than the ∼1 g cm
−3
bulk density of the Jupiter Trojans. This suggests that the Hildas population may contain more C-type asteroids than expected, and the limit at 3 hr simply reflects the spin-rate limit for C-type asteroids. In addition, a Hilda superfast rotator was found, which has a rotation period of 1.633 hr and an estimated diameter of 0.7 km. This object is unlikely to be explained by a rubble-pile or monolithic structure.
ABSTRACT Although the majority of Centaurs are thought to have originated in the scattered disk, with the high-inclination members coming from the Oort cloud, the origin of the high-inclination ...component of trans-Neptunian objects (TNOs) remains uncertain. We report the discovery of a retrograde TNO, which we nickname "Niku," detected by the Pan-STARRS 1 Outer Solar System Survey. Our numerical integrations show that the orbital dynamics of Niku are very similar to that of 2008 KV42 (Drac), with a half-life of ∼500 Myr. Comparing similar high-inclination TNOs and Centaurs (q > 10 au, a < 100 au, and i > 60°), we find that these objects exhibit a surprising clustering of ascending node, and occupy a common orbital plane. This orbital configuration has high statistical significance: 3.8- . An unknown mechanism is required to explain the observed clustering. This discovery may provide a pathway to investigating a possible reservoir of high-inclination objects.
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, Hawaii, ...USA). Subaru’s large aperture (8 m) and HSC’s large field of view (1.77 deg2) 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), spans absolute magnitudes of 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 the light curve amplitude and absolute magnitude seen in other works but does not support a correlation between the 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 the 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 a reliable period analysis. We find that 31 objects (just under half of our sample) have variability of \({{\rm{\Delta }}}_{\mathrm{mag}}\) 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 \({{\rm{\Delta }}}_{\mathrm{mag}}\) is 0.13, 0.16, and 0.19 mag, 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.
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