arXiv subjects

Patryk Sofia Lykawka

Publications and source records attributed to Patryk Sofia Lykawka.

At least 19 recordsLinked to original sources

arXiv2026

On the Long-Term Orbital Behaviour of Hilda Asteroids - I. Global Stability Patterns and Catalogue

The Hildas are objects trapped in 3:2 mean-motion resonance (MMR) with Jupiter, and are a fascinating window into the Solar system's formation and evolution. We present the results of detailed dynamical integrations of 2,699 numbered asteroids in the Hilda region, following 243 clones of each Hilda for 1 Gyr under the influence of the giant planets and the Sun; 54.7% of our sample exhibit extreme dynamical stability, with all clones of 1,475 Hildas remaining trapped in the 3:2 MMR for the full 1 Gyr of our integrations. A further 408 Hildas (15.1% of the sample) see more than 50% of their clones surviving within the MMR at the end of the simulations. Of the remaining 30.2% of the population, 327 objects (12.1%) lose 50% of their clones at some point between the 100 Myr and 1 Gyr point, leading to dynamical half-lives measured in hundreds of millions of years -- a result compatible with those objects being members of a once larger population of Hildas trapped since the Solar system's youth. The final 489 objects (18.12\%) prove highly unstable -- and may well be interlopers, captured to the Hilda population in the relatively recent past. Overall, our results suggest that the Hilda population was larger in the past, while its remarkably high stability over Gyr timescales is consistent with a primordial origin.

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arXiv2026

Kuiper Belt Formation via Grainy Planetary Migration

We used N-body simulations to model the 4.5 Gyr orbital evolution of the early Kuiper Belt, incorporating a massive protoplanetary disk, the four giant planets, and 1500 primordial Pluto-class bodies ("Plutos") that drove Neptune's grainy migration. The analysis of 67 simulated systems revealed key insights: (1) All systems featured the primary trans-Neptunian object (TNO) populations: cold/hot classical, resonant, scattered, and detached; (2) Captures into stable resonant orbits favored close Neptunian mean motion resonances (MMRs; e.g., 3:2, 2:1), while distant ones beyond 50 au (e.g., 5:2 MMR) were underpopulated; (3) Optimal matches to observed resonant fractions and the classical region (including the kernel) arose from models considering a jumping Neptune, self-gravitating Plutos, and an initial disk edge at 45-47 au; (4) Models including primordial scattered disks boosted distant MMR captures but overproduced scattered objects; (5) All models were inefficient at producing the detached (q > 40 au) and high-i (i > 45 deg) populations and failed to populate observed niches, such as distant detached (a > 245 au), low-i detached (i < 20 deg), low-i scattered with q = 37-40 au (i < 20 deg), and extreme (q > 50 au or i > 50 deg) TNOs; (6) Grainy migration effects peaked early, fading as the Plutos were removed; (7) With a few primordial Plutos surviving inside 50 au, the initial population was estimated at ~150-500 to explain Pluto's solitary status. Although our four-giant-planet models reasonably replicate the trans-Neptunian structure within 50 au, they fail to account for detached, high-i, and extreme TNOs. Additional processes (e.g., a distant undiscovered planet) are required for a comprehensive outer solar system framework.

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arXiv2026

Formation of the four terrestrial planets in the Jupiter-Saturn chaotic excitation scenario: fundamental properties and water delivery

The Jupiter-Saturn chaotic excitation (JSCE) scenario proposes that the protoplanetary disk was dynamically excited and depleted beyond ~1-1.5 au in a few Myr, offering a new and plausible explanation for several observed properties of the inner solar system. Here, we expanded our previous work by conducting a comprehensive analysis of 37 optimal terrestrial planet systems obtained in the context of the JSCE scenario. Each optimal system harbored exactly four terrestrial planets analogs to Mercury, Venus, Earth, and Mars. We further investigated water delivery, feeding zones, and accretion history for the planet analogs, which allowed us to better constrain the water distribution in the disk. The main findings of this work are as follows: 1) the formation of four terrestrial planets with orbits and masses similar to those observed in our solar system in most of our sample, as evidenced by the dynamically colder and hotter orbits of Venus-Earth and Mercury-Mars analogs, and the high success rates of similar mutual orbital separations (~40-85%) and mass ratios of the planets (~70-90%) among the 37 systems; and 2) water was delivered to all terrestrial planets during their formation through the accretion of water-bearing disk objects from beyond ~1-1.5 au. The achievement of Earth's estimated bulk water content required the disk to contain sufficient water mass distributed within those objects initially. This requirement implies that Mercury, Venus, and Mars acquired water similar to the amount on Earth during their formation. Several of our planet analogs also matched additional constraints, such as the timing of Moon formation by a giant impact, Earth's late accretion mass and composition, and Mars's formation timescale.

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arXiv2025

Discovery and dynamics of a Sedna-like object with a perihelion of 66 au

Trans-Neptunian objects (TNOs) with large perihelion distances ($q > 60$ au) and semi-major axes ($a > 200$ au) provide insights into the early evolution of the solar system and the existence of a hypothetical distant planet. These objects are still rare and their detection is challenging, yet they play a crucial role in constraining models of solar system formation. Here we report the discovery of a Sedna-like TNO, 2023\,KQ$_{14}$, nicknamed `Ammonite', with $q = 66$ au, $a = 252$ au, and inclination $i=11^\circ$. Ammonite's orbit does not align with those of the other Sedna-like objects and fills the previously unexplained `$q$-gap' in the observed distribution of distant solar system objects. Simulations demonstrate that Ammonite is dynamically stable over 4.5 billion years. % with less than 1\% variation in its semi-major axis. Our analysis suggests that Ammonite and the other Sedna-like objects may have shared a primordial orbital clustering around 4.2 billion years ago. Furthermore, Ammonite's stable orbit favors larger orbits ($\sim$ 500 au) rather than closer ones for a large hypothetical planet in present-day trans-Neptunian space.

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arXiv2024

New Moons of Uranus and Neptune from Ultra-Deep Pencil Beam Surveys

We have conducted extremely ultra-deep pencil beam observations for new satellites around both Uranus and Neptune. Tens of images on several different nights in 2021, 2022 and 2023 were obtained and shifted and added together to reach as faint as 26.9 and 27.2 magnitudes in the r-band around Uranus and Neptune, respectively. One new moon of Uranus, S/2023 U1, and two new moons of Neptune, S/2021 N1 and S/2002 N5, were found. S/2023 U1 was 26.6 mags, is about 7 km in diameter and has a distant, eccentric and inclined retrograde orbit similar to Caliban and Stephano, implying these satellites are fragments from a once larger parent satellite. S/2023 U1 almost completely overlaps Stephano in orbital phase space. S/2021 N1 was 26.9 mags, about 14 km in size and has a retrograde orbit similar to Neso and Psamathe, indicating they are a dynamical family. We find S/2021 N1 is in a Kozai-Lidov orbital resonance. S/2002 N5 was 25.9 mags, is about 23 km in size and it makes a family of distant prograde satellites with Sao and Laomedeia. All three new moons show for the first time dynamical groups of moons exist around both Uranus and Neptune. The creation of these groups likely produced dust that could be the source of red material seen on the leading hemispheres of some larger inner satellites like Titania, Oberon and Umbriel. We also detected all known outer moons of Uranus and Neptune on multiple nights. This survey mostly completes the outer satellites of Uranus to about 8 km and Neptune to about 14 km in diameter. The size distributions of satellite dynamical families around the giant planets shows a strong steepening in the power law size distribution smaller than 5 km in diameter. The satellites of a family become much more common smaller than 5 km and their size distribution is consistent with a collisional break-up of a once larger parent satellite.

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arXiv2023

Is There an Earth-like Planet in the Distant Kuiper Belt?

The orbits of trans-Neptunian objects (TNOs) can indicate the existence of an undiscovered planet in the outer solar system. Here, we used N-body computer simulations to investigate the effects of a hypothetical Kuiper Belt planet (KBP) on the orbital structure of TNOs in the distant Kuiper Belt beyond ~50 au. We used observations to constrain model results, including the well-characterized Outer Solar System Origins Survey (OSSOS). We determined that an Earth-like planet (m ~ 1.5-3 Earth masses) located on a distant (semimajor axis a ~ 250-500 au, perihelion q ~ 200 au) and inclined (i ~ 30 deg) orbit can explain three fundamental properties of the distant Kuiper Belt: a prominent population of TNOs with orbits beyond Neptune's gravitational influence (i.e., detached objects with q > 40 au), a significant population of high-i objects (i > 45 deg), and the existence of some extreme objects with peculiar orbits (e.g., Sedna). Furthermore, the proposed KBP is compatible with the existence of identified Gyr-stable TNOs in the 2:1, 5:2, 3:1, 4:1, 5:1, and 6:1 Neptunian mean motion resonances. These stable populations are often neglected in other studies. We predict the existence of an Earth-like planet and several TNOs on peculiar orbits in the outer solar system, which can serve as observationally testable signatures of the putative planet's perturbations.

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arXiv2023

Terrestrial planet and asteroid belt formation by Jupiter-Saturn chaotic excitation

The terrestrial planets formed by accretion of asteroid-like objects within the inner solar system's protoplanetary disk. Previous works have found that forming a small-mass Mars requires the disk to contain little mass beyond ~1.5 au (i.e., the disk mass was concentrated within this boundary). The asteroid belt also holds crucial information about the origin of such a narrow disk. Several scenarios may produce a narrow disk. However, simultaneously replicating the four terrestrial planets and the inner solar system properties remains elusive. Here, we found that chaotic excitation of disk objects generated by a near-resonant configuration of Jupiter-Saturn can create a narrow disk, allowing the formation of the terrestrial planets and the asteroid belt. Our simulations showed that this mechanism could typically deplete a massive disk beyond ~1.5 au on a 5-10 Myr timescale. The resulting terrestrial systems reproduced the current orbits and masses of Venus, Earth and Mars. Adding an inner region disk component within ~0.8-0.9 au allowed several terrestrial systems to simultaneously form analogues of the four terrestrial planets. Our terrestrial systems also frequently satisfied additional constraints: Moon-forming giant impacts occurring after a median ~30-55 Myr, late impactors represented by disk objects formed within 2 au, and effective water delivery during the first 10-20 Myr of Earth's formation. Finally, our model asteroid belt explained the asteroid belt's orbital structure, small mass and taxonomy (S-, C- and D/P-types).

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arXiv2021

FOSSIL: I. The Spin Rate Limit of Jupiter Trojans

Rotation periods of 53 small (diameters $2 < D < 40$ km) Jupiter Trojans (JTs) were derived using the high-cadence light curves obtained by the FOSSIL phase I survey, a Subaru/Hyper Suprime-Cam intensive program. These are the first reported periods measured for JTs with $D < 10$ km. We found a lower limit of the rotation period near 4 hr, instead of the previously published result of 5 hr (Ryan et al. 2017; Szabo et al. 2017, 2020) found for larger JTs. Assuming a rubble-pile structure for JTs, a bulk density of 0.9 gcm$^{-3}$ is required to withstand this spin rate limit, consistent with the value $0.8-1.0$ gcm$^{-3}$ (Marchis et al. 2006; Mueller et al. 2010; Buie et al. 2015; Berthier et al. 2020) derived from the binary JT system, (617) Patroclus-Menoetius system.

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arXiv2021

OSSOS: The Eccentricity and Inclination Distributions of the Stable Neptunian Trojans

The minor planets on orbits that are dynamically stable in Neptune's 1:1 resonance on Gyr timescales were likely emplaced by Neptune's outward migration. We explore the intrinsic libration amplitude, eccentricity, and inclination distribution of Neptune's stable Trojans, using the detections and survey efficiency of the Outer Solar System Origins Survey (OSSOS) and Pan-STARRS1. We find that the libration amplitude of the stable Neptunian Trojan population can be well modeled as a Rayleigh distribution with a libration amplitude width $σ_{A_phi}$ of 15$^\circ$. When taken as a whole, the Neptune Trojan population can be acceptably modeled with a Rayleigh eccentricity distribution of width $σ_e$ of 0.045 and a typical sin(i) x Gaussian inclination distribution with a width $σ_i$ of 14 +/- 2 degrees. However, these distributions are only marginally acceptable. This is likely because, even after accounting for survey detection biases, the known large Hr < 8 and small Hr >= 8 Neptune Trojans appear to have markedly different eccentricities and inclinations. We propose that like the classical Kuiper belt, the stable intrinsic Neptunian Trojan population have dynamically `hot' and dynamically `cold' components to its eccentricity/inclination distribution, with $σ_{e-cold}$ ~ 0.02 / $σ_{i-cold}$ ~ 6$^\circ$ and $σ_{e-hot}$~ 0.05 / $σ_{i-hot}$ ~ 18$^\circ$. In this scenario, the `cold' L4 Neptunian Trojan population lacks the Hr >= 8 members and has 13 +11/-6 `cold' Trojans with Hr < 8. On the other hand, the `hot' L4 Neptunian Trojan population has 136 +57/-48 Trojans with Hr < 10 -- a population 2.4 times greater than that of the L4 Jovian Trojans in the same luminosity range.

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arXiv2020

Can narrow disks in the inner solar system explain the four terrestrial planets?

A successful solar system model must reproduce the four terrestrial planets. Here, we focus on 1) the likelihood of forming Mercury and the four terrestrial planets in the same system (a 4-P system); 2) the orbital properties and masses of each terrestrial planet; and 3) the timing of Earth's last giant impact and the mass accreted by our planet thereafter. Addressing these constraints, we performed 450 N-body simulations of terrestrial planet formation based on narrow protoplanetary disks with mass confined to 0.7-1.0 au. We identified 164 analogue systems, but only 24 systems contained Mercury analogues, and eight systems were 4-P ones. We found that narrow disks containing a small number of embryos with individual masses comparable to that of Mars and the giant planets on their current orbits yielded the best prospects for satisfying those constraints. However, serious shortcomings remain. The formation of Mercury analogues and 4-P systems was too inefficient (5% and 2%, respectively), and most Venus-to-Earth analogue mass ratios were incorrect. Mercury and Venus analogues also formed too close to each other (~0.15-0.21 au) compared to reality (0.34 au). Similarly, the mutual distances between the Venus and Earth analogues were greater than those observed (0.34 vs. 0.28 au). Furthermore, the Venus-Earth pair was not reproduced in orbital-mass space statistically. Overall, our results suggest serious problems with using narrow disks to explain the inner solar system. In particular, the formation of Mercury remains an outstanding problem for terrestrial planet formation models.

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arXiv2019

OSSOS XVIII: Constraining migration models with the 2:1 resonance using the Outer Solar System Origins Survey

Resonant dynamics plays a significant role in the past evolution and current state of our outer Solar System. The population ratios and spatial distribution of Neptune's resonant populations are direct clues to understanding the history of our planetary system. The orbital structure of the objects in Neptune's 2:1 mean-motion resonance (\emph{twotinos}) has the potential to be a tracer of planetary migration processes. Different migration processes produce distinct architectures, recognizable by well-characterized surveys. However, previous characterized surveys only discovered a few twotinos, making it impossible to model the intrinsic twotino population. With a well-designed cadence and nearly 100\% tracking success, the Outer Solar System Origins Survey (OSSOS) discovered 838 trans-Neptunian objects, of which 34 are securely twotinos with well-constrained libration angles and amplitudes. We use the OSSOS twotinos and the survey characterization parameters via the OSSOS Survey Simulator to inspect the intrinsic population and orbital distributions of twotino. The estimated twotino population, 4400$^{+1500}_{-1100}$ with $H_r<8.66$ (diameter$\sim$100km) at 95\% confidence, is consistent with the previous low-precision estimate. We also constrain the width of the inclination distribution to a relatively narrow value of $σ_i$=6$^\circ$$^{+1}_{-1}$, and find the eccentricity distribution is consistent with a Gaussian centered on $e_\mathrm{c}=0.275$ with a width $e_\mathrm{w}=0.06$. We find a single-slope exponential luminosity function with $α=0.6$ for the twotinos. Finally, we for the first time meaningfully constrain the fraction of symmetric twotinos, and the ratio of the leading asymmetric islands; both fractions are in a range of 0.2--0.6. These measurements rule out certain theoretical models of Neptune's migration history.

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arXiv2019

Constraining the Formation of the Four Terrestrial Planets in the Solar System

To reproduce the orbits and masses of the terrestrial planets (analogs) of the solar system, most studies scrutinize simulations for success as a batch. However, there is insufficient discussion in the literature on the likelihood of forming planet analogs simultaneously in the same system (analog system). To address this issue, we performed 540 N-body simulations of protoplanetary disks representative of typical models in the literature. We identified a total of 194 analog systems containing at least three analogs, but only 17 systems simultaneously contained analogs of the four terrestrial planets. From an analysis of our analog systems, we found that, compared to the real planets, truncated disks based on typical outcomes of the Grand Tack model produced analogs of Mercury and Mars that were too dynamically cold and located too close to the Venus and Earth analogs. Additionally, all the Mercury analogs were too massive, while most of the Mars analogs were more massive than Mars. Furthermore, the timing of the Moon-forming impact was too early in these systems, and the amount of additional mass accreted after the event was too great. Therefore, such truncated disks cannot explain the formation of the terrestrial planets. Our results suggest that forming the four terrestrial planets requires disks with the following properties: 1) Mass concentrated in narrow core regions between ~0.7-0.9 and ~1.0-1.2 au; 2) an inner region component starting at ~0.3-0.4 au; 3) a less massive component beginning at ~1.0-1.2 au; 4) embryos rather than planetesimals carrying most of the disk mass; and 5) Jupiter and Saturn placed on eccentric orbits.

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arXiv2018

Colors of Centaurs observed by the Subaru/Hyper Suprime-Cam and implications for their origin

Centaurs have orbits between Jupiter and Neptune and are thought to originate from the trans-Neptunian region. Observations of surface properties of Centaurs and comparison with those of trans-Neptunian objects (TNOs) would provide constraints on their origin and evolution. We analyzed imaging data of nine known Centaurs observed by the Hyper Suprime-Cam (HSC) installed on the Subaru Telescope with the g and i band filters. Using the data available in the public HSC data archive as well as those obtained by the HSC Subaru Strategic Program (HSC-SSP) by the end of June, 2017, we obtained the g-i colors of the nine Centaurs. We compared them with those of known TNOs in the HSC-SSP data obtained by Terai et al. (2018). We found that the color distribution of the nine Centaurs is similar to that of those TNOs with high orbital inclinations, but distinct from those TNOs with low orbital inclinations. We also examined correlations between the colors of these Centaurs and their orbital elements and absolute magnitude. The Centaurs' colors show a moderate positive correlation with semi-major axis, while no significant correlations between the color and other orbital elements or absolute magnitude were found for these Centaurs. On the other hand, recent studies on Centaurs with larger samples show interesting correlations between their color and absolute magnitude or orbital inclination. We discuss how our data fit in these previous studies, and also discuss implications of these results for their origin and evolution.

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arXiv2018

OSSOS. VII. 800+ trans-Neptunian objects - the complete data release

The Outer Solar System Origins Survey (OSSOS), a wide-field imaging program in 2013-2017 with the Canada-France-Hawaii Telescope, surveyed 155 deg$^{2}$ of sky to depths of $m_r = 24.1$-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 semi-major axis $a \sim 130$ au. OSSOS doubles the known population of the non-resonant Kuiper belt, providing 436 TNOs in this region, all with exceptionally high-quality orbits of $a$ uncertainty $σ_{a} \leq 0.1\%$; they show the belt exists from $a \gtrsim 37$ au, with a lower perihelion bound of $35$ au. We confirm the presence of a concentrated low-inclination $a\simeq 44$ 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.

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arXiv2018

OSSOS IX: two objects in Neptune's 9:1 resonance -- implications for resonance sticking in the scattering population

We discuss the detection in the Outer Solar System Origins Survey (OSSOS) of two objects in Neptune's distant 9:1 mean motion resonance at semimajor axis $a\approx~130$~au. Both objects are securely resonant on 10~Myr timescales, with one securely in the 9:1 resonance's leading asymmetric libration island and the other in either the symmetric or trailing asymmetric island. These objects are the largest semimajor axis objects with secure resonant classifications, and their detection in a carefully characterized survey allows for the first robust resonance population estimate beyond 100~au. The detection of these objects implies a 9:1 resonance population of $1.1\times10^4$ objects with $H_r<8.66$ ($D~\gtrsim~100$~km) on similar orbits (95\% confidence range of $\sim0.4-3\times10^4$). Integrations over 4~Gyr of an ensemble of clones spanning these objects' orbit fit uncertainties reveal that they both have median resonance occupation timescales of $\sim1$~Gyr. These timescales are consistent with the hypothesis that these objects originate in the scattering population but became transiently stuck to Neptune's 9:1 resonance within the last $\sim1$~Gyr of solar system evolution. Based on simulations of a model of the current scattering population, we estimate the expected resonance sticking population in the 9:1 resonance to be 1000-4500 objects with $H_r<8.66$; this is marginally consistent with the OSSOS 9:1 population estimate. We conclude that resonance sticking is a plausible explanation for the observed 9:1 population, but we also discuss the possibility of a primordial 9:1 population, which would have interesting implications for the Kuiper belt's dynamical history.

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arXiv2017

Multi-band Photometry of Trans-Neptunian Objects in the Subaru Hyper Suprime-Cam Survey

We present a visible multi-band photometry of trans-Neptunian objects (TNOs) observed by the Subaru Telescope in the framework of Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) from March in 2014 to September in 2016. We measured the five broad-band (g, r, i, z, and Y) colors over the wavelength range from 0.4 um to 1.0 um for 30 known TNOs using the HSC-SSP survey data covering ~500 deg2 of sky within +/-30 deg of ecliptic latitude. This dataset allows us to characterize the dynamical classes based on visible reflectance spectra as well as to examine the relationship between colors and the other parameters such as orbital elements. Our results show that the hot classical and scattered populations share similar color distributions, while the cold classical population has a reflective decrease toward shorter wavelength below the i band. Based on the obtained color properties, we found that the TNO sample examined in the present work can be separated into two groups by inclination (I), the low-I population consisting of cold classical objects and high-I population consisting of hot classical and scattered objects. The whole sample exhibits an anti-correlation between colors and inclination, but no significant correlation between colors and semi-major axis, perihelion distance, eccentricity, or absolute magnitude. The color-inclination correlation does not seem to be continuous over the entire inclination range. Rather, it is seen only in the high-I population. We found that the low- and high-I populations are distinguishable in the g-i vs. eccentricity plot, but four high-I objects show g-i colors similar to those of the low-I population. If we exclude these four objects, the high-I objects show a positive correlation between g-i and eccentricity and a negative correlation between g-i and inclination with high significance levels.

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arXiv2017

Terrestrial Planet Formation: Constraining the Formation of Mercury

The formation of the four terrestrial planets of the solar system is one of the most fundamental problems in the planetary sciences. However, the formation of Mercury remains poorly understood. We investigated terrestrial planet formation by performing 110 high-resolution N-body simulation runs using more than 100 embryos and 6000 disk planetesimals representing a primordial protoplanetary disk. To investigate the formation of Mercury, these simulations considered an inner region of the disk at 0.2-0.5 au (the Mercury region) and disks with and without mass enhancements beyond the ice line location, aIL, in the disk, where aIL = 1.5, 2.25, and 3.0 au were tested. Although Venus and Earth analogs (considering both orbits and masses) successfully formed in the majority of the runs, Mercury analogs were obtained in only nine runs. Mars analogs were also similarly scarce. Our Mercury analogs concentrated at orbits with a ~ 0.27-0.34 au, relatively small eccentricities/inclinations, and median mass m ~ 0.2 Earth masses. In addition, we found that our Mercury analogs acquired most of their final masses from embryos/planetesimals initially located between 0.2 and ~1-1.5 au within 10 Myr, while the remaining mass came from a wider region up to ~3 au at later times. Although the ice line was negligible in the formation of planets located in the Mercury region, it enriched all terrestrial planets with water. Indeed, Mercury analogs showed a wide range of water mass fractions at the end of terrestrial planet formation.

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arXiv2016

OSSOS: IV. Discovery of a dwarf planet candidate in the 9:2 resonance with Neptune

We report the discovery and orbit of a new dwarf planet candidate, 2015 RR$_{245}$, by the Outer Solar System Origins Survey (OSSOS). 2015 RR$_{245}$'s orbit is eccentric ($e=0.586$), with a semi-major axis near 82 au, yielding a perihelion distance of 34 au. 2015 RR$_{245}$ has $g-r = 0.59 \pm 0.11$ and absolute magnitude $H_{r} = 3.6 \pm 0.1$; for an assumed albedo of $p_V = 12$% the object has a diameter of $\sim670$ km. Based on astrometric measurements from OSSOS and Pan-STARRS1, we find that 2015 RR$_{245}$ is securely trapped on ten-Myr timescales in the 9:2 mean-motion resonance with Neptune. It is the first TNO identified in this resonance. On hundred-Myr timescales, particles in 2015 RR$_{245}$-like orbits depart and sometimes return to the resonance, indicating that 2015 RR$_{245}$ likely forms part of the long-lived metastable population of distant TNOs that drift between resonance sticking and actively scattering via gravitational encounters with Neptune. The discovery of a 9:2 TNO stresses the role of resonances in the long-term evolution of objects in the scattering disk, and reinforces the view that distant resonances are heavily populated in the current Solar System. This object further motivates detailed modelling of the transient sticking population.

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