Cold Objects Research Articles

Magneto-convection ?ow of Nano-encapsulated phase change material (NEPCM) confined within a trapezoidal porous enclosure

This research attempts to study the thermal activity of suspension consisting of water and NEPCM elements inside a cavity with a trapezoidal cross-section. In addition, the cavity center contains a cold circular object rotating at a constant speed. The cavity is thermally characterized by the following: the upper and lower walls are thermally insulated (adiabatic), while the two lateral walls have a high temperature. The purpose of this study is to find out how the suspension interferes with the transfer of heat from hot walls to the cold body through the intervention of some initial conditions, which are: The effects of rotating cylinder speed (Re = 1 -500), medium permeability (Da = 10-5 – 10-2) and the magnetic field strength (Ha= 0 -100). The study used a digital simulation by solving the differential equations related to fluid mechanics and heat transfer using the Galerkin finite element (GFEM) method.to understand the influences of studied parameters (Re, Da and Ha numbers), the contours of isotherms, heat capacity and pathlines are presented in terms of these parameters. The findings indicated that as the rotation speed of the obstacle increased, the forced convection became dominant, and the thermal transmission rate improved. The improvement of the thermal transfer rate was also observed for higher Da numbers. Increasing the strength of the magnetic field hiders the fluid motion and reduces the thermal activity. At the highest studied Re, increasing Da from 10-5 to 10-2 augmented the Nusselt number by 10 times, while augmenting Ha from 0 to 100 reduced the Nu by 46%.

Evolution of Chemistry in the envelope of HOt CorinoS (ECHOS). II. The puzzling chemistry of isomers as revealed by the HNCS/HSCN ratio

The observational detection of some metastable isomers in the interstellar medium with abundances comparable to those of the most stable isomer, or even when the stable isomer is not detected, highlights the importance of non-equilibrium chemistry. This challenges our understanding of the interstellar chemistry and shows the need to study isomeric forms of molecular species to constrain chemical processes occurring in the interstellar medium. Our goal is to study the chemistry of isomers through the sulphur isomer pair HNCS and HSCN, since HSCN has been observed in regions where its stable isomer has not been detected, and the observed HNCS/HSCN ratio seems to significantly vary from cold to warm regions. We used the Nautilus time-dependent gas-grain chemical code to model the formation and destruction paths of HNCS and HSCN in different astrochemical scenarios, as well as the time evolution of the HNCS/HSCN ratio. We also analysed the influence of the environmental conditions on their chemical abundances. We present an observational detection of the metastable isomer HSCN in the Class I object B1-a ($N$=(1.1pm 0.6)times 1012 cm$^ $), but not of the stable isomer HNCS, despite HNCS lying 3200 K lower in energy than HSCN. Our theoretical results show an HNCS/HSCN ratio sensitive to the gas temperature and the evolutionary time, with the highest values obtained at early stages ($t$lesssim 10$^4$ yr) and low ($T_ g $lesssim 20 K) temperatures. A more detailed analysis also shows that the main mechanism forming HNCS in young ($t$$<$10$^5$ yr) and cold ($T_ g $$=$10 K) objects at moderate-low densities ($n$$_ H $leq 10$^5$ cm$^ $) is a grain surface reaction (the chemical desorption reaction N$_ solid $+HCS$_ solid $rightarrow HNCS), unlike previous predictions that suggest only gas-phase chemistry for its formation. However, for the formation of its metastable isomer HSCN, over the same time range and physical conditions, we find that both surface and gas-phase reactions (through the ion H$_2$NCS$^+$) play important roles. In warmer ($T_ g $geq 50 K) regions, the formation of this isomer pair is only dominated by gas-phase chemistry through the ions H$_2$NCS$^+$ (mainly at low densities) and HNCSH$^+$ (mainly at high densities). The results suggest a different efficiency of the isomerisation processes depending on the source temperature. The progressive decrease of HNCS/HSCN with gas temperature at early evolutionary times derived from our theoretical results indicates that this ratio may be used as a tracer of cold young objects. This work also demonstrates the key role of grain surface chemistry in the formation of the isomer pair HNCS and HSCN in cold regions, as well as the importance of the ions H$_2$NCS$^+$ and HNCSH$^+$ in warm/hot regions. Since most of the interstellar regions where HSCN is detected are cold regions (starless cores, Class 0/I objects), a larger sample including sources characterised by high temperatures (e.g. hot cores) are needed to corroborate the theoretical results.

Entropy generation analysis of natural convection flow in porous diamond-shaped cavity

This study investigates the entropy generation analysis of natural convection flow within a diamond-shaped cavity filled with porous media. The research focuses on understanding the effects of a chamfered vertex and the introduction of one or two circular cold objects within the cavity. Using COMSOL Multiphysics software, the study examines various Rayleigh (Ra) and Darcy (Da) numbers to analyze the flow dynamics, heat transfer (HT), and entropy generation (Egen). Results indicate that the presence of cold objects significantly influences the flow patterns, enhances HT, and increases Egen due to fluid friction (FF). Higher Ra values lead to more vigorous convective currents, while lower Da values indicate a transition to conduction-dominated regimes. In addition, the heat transfer rate increases by 5 % by introducing a single cold cylinder inside the cavity for Da = 10−2 and Ra = 106. This enhancement rises to 16 % when two cold cylinders are introduced. The study provides valuable insights into optimizing cooling processes within diamond-shaped cavities by identifying key parameters that affect HT and irreversibility.

Comparative study of neonatal hypothermia and associated factors among neonates in rural and urban areas of the Shebadino Woreda, Sidama region, Southern Ethiopia: a community-based comparative cross-sectional study

BackgroundHypothermia is one of the major causes of newborn death, particularly in low-income nations. This was due to poor thermal care in most of the rural communities. Recent studies show that there was a prevalence discrepancy between urban and rural communities where economic, educational, and life standard differences exist. Therefore, this study aimed to assess the prevalence and factors associated with neonatal hypothermia among neonates in rural and urban areas of the Shebadino woreda, Sidama region, Ethiopia.MethodA comparative community-based cross-sectional study was performed on 682 neonates in the Shebadino Woreda, Sidama Region, southern Ethiopia, in 2023. A multistage sampling technique was used, and the collected data were manually cleaned, coded, and entered into Epi Data version 4.6 before being exported to SPSS version 26 software for analysis. Variables with a p-value < 0.25 in the bivariate logistic regression were further analyzed using multivariable logistic regression. The odds ratio (OR) with 95% CI was used as a measure of association, and variables that had a p-value less than 0.05 in the multivariable logistic regression were considered significantly associated variables.ResultsThe overall prevalence of neonatal hypothermia in this study was 51.8% (95% CI: 47.2%-56.3%). It was greater among rural neonates (55.1%) than among urban neonates (48.6%). Bathing before 24 h. (AOR = 3.64, 95% CI: 1.39, 7.16), Placing a cold object near babies’ head (AOR = 2.97, 95% CI: 1.75, 5.03), Neonates who were given traditional medication (Amessa) (AOR = 1.83% CI; 1.04–3.20) and, not separated humans and animals house (AOR = 1.75, 95%, 1.05–2.91) were significantly associated with neonatal hypothermia in rural, while Night time delivery (AOR = 1.81, CI: 1.01–5.62), Neonates who were given traditional medication (Amessa) (AOR = 3.11% CI; 1.85–5.21), and Placing a cold object near babies’ head (AOR = 2.40, 95% CI: 1.37, 3.29 were significantly associated with neonatal hypothermia among urban neonates.ConclusionThe Prevalence of neonatal hypothermia in the study area was relatively greater in rural areas than in urban areas. Cost-effective thermal care such as separating humans from animal houses, teaching not to put cold objects near babies, giving special care to newborns for those delivered from women with medical problems, and giving priority to those delivered at night, is needed.

Dynamic temperature control in microfluidics for in vivo imaging of cold-sensing in C. elegans

The ability to perceive temperature is crucial for most animals. It enables them to maintain their body temperature and swiftly react to noxiously cold or hot objects. Caenorhabditis elegans is a powerful genetic model for the study of thermosensation as its simple nervous system is well characterized and its transparent body is suited for in vivo functional imaging of neurons. The behavior triggered by experience-dependent thermosensation has been well studied in C. elegans under temperature-gradient environments. However, how C. elegans senses temperature via its nervous system is not well understood due to the limitations of currently available technologies. One major bottleneck is the difficulty in creating fast temperature changes, especially cold stimuli. Here, we developed a microfluidic-based platform that allowed the in vivo functional imaging of C. elegans responding to well-controlled temporally varying temperature stimulation by rapidly switching fluid streams at different temperatures. We used computational models to enable rational design and optimization of experimental conditions. We validated the design and utility of our system with studies of the functional role of thermosensory neurons. We showed that the responses of PVD polymodal nociceptor neurons observed in previous studies can be recapitulated. Further, we highlighted how this platform may be used to dissect neuronal circuits with an example of activity recording in PVC interneurons. Both of these neuron types show sensitization phenotypes. We envision that both the engineered system and the findings in this work will spur further studies of molecular and cellular mechanisms underlying cold-sensing through the nervous system.

Infrared thermal imaging camera to measure low temperature thermal fields.

To measure low-temperature thermal fields, we have developed a single-element cooled thermal imaging camera for a spectral range of 8-14μm with an internal shutter for radiometric calibration. To improve the accuracy of measuring the temperature of cold objects, we used a shutter with a combined emissivity as an internal reference source of radiation at the input of the device optical unit. With this aim a small mirror was fixed in the center on its surface covered black, thereby ensuring an efficient reflection of radiation in a wide spectral range of wavelengths. When processing the signal for each pixel of the thermal image, the differential value of the detector response to the shutter blackened and mirror areas was used as a reference. A relative measurement error of 3% was obtained for the studied objects with a temperature of -150 °C. The device was successfully used for remote study of thermal field dynamics during freeze-thawing of biological tissues in vivo.

The DECam Ecliptic Exploration Project (DEEP). III. Survey Characterization and Simulation Methods

We present a detailed study of the observational biases of the DECam Ecliptic Exploration Project’s B1 data release and survey simulation software that enables direct statistical comparisons between models and our data. We inject a synthetic population of objects into the images, and then subsequently recover them in the same processing as our real detections. This enables us to characterize the survey’s completeness as a function of apparent magnitudes and on-sky rates of motion. We study the statistically optimal functional form for the magnitude, and develop a methodology that can estimate the magnitude and rate efficiencies for all survey’s pointing groups simultaneously. We have determined that our peak completeness is on average 80% in each pointing group, and our magnitude drops to 25% of this value at m 25 = 26.22. We describe the freely available survey simulation software and its methodology. We conclude by using it to infer that our effective search area for objects at 40 au is 14.8 deg2, and that our lack of dynamically cold distant objects means that there at most 8 × 103 objects with 60 < a < 80 au and absolute magnitudes H ≤ 8.

Comparison of reality and illusion of wetness on soft materials and the multisensory perceptual space of wetness illusion

Skin contact with cold objects can induce the perception of wetness, known as the wetness illusion, even in the absence of actual moisture. However, the differences between wetness perceived from moisture and cooled-dry soft materials and how the material parameters affect the wetness illusion from cooled-dry soft materials remain unclear. This study recruited 12 women and 12 men to touch paired moisture and dry fabrics to compare the prescription and intensity of wetness, suggesting that the wetness illusion focused more on roughness and stickiness while the wetness of moisture fabrics sensed more on coldness. Another 12 women touched cooled-dry materials with different temperatures (10°C and 15°C), thicknesses (0.75/0.73 and 1.99/1.96 mm), and dynamic friction coefficients (mean coefficient of friction) (0.17 and 1.88), rating on wetness dissimilarity and intensity of wetness, coldness, softness, and roughness. Data were illustrated in a two-dimensional space by multidimensional scaling, in which dimension 1 represented the haptic perception in wetness, most related to the mean coefficient of friction, and dimension 2 represented the coldness perception in wetness, most related to temperature. Overall, the mean coefficient of friction and the temperature of the material had a strong influence on the wetness illusion, while the thickness had less impact. This study improves the understanding of wetness illusion and sheds light on the reproduction of wetness perception in multisensory augmented virtual reality, such as immersive gaming and virtual dress fitting.

Revised gas-phase formation network of methyl cyanide: the origin of methyl cyanide and methanol abundance correlation in hot corinos

ABSTRACT Methyl cyanide (CH3CN) is one of the most abundant and widely spread interstellar complex organic molecules (iCOMs). Several studies found that, in hot corinos, methyl cyanide and methanol abundances are correlated suggesting a chemical link, often interpreted as a synthesis of them on the interstellar grain surfaces. In this article, we present a revised network of the reactions forming methyl cyanide in the gas phase. We carried out an exhaustive review of the gas-phase CH3CN formation routes, propose two new reactions, and performed new quantum mechanics calculations of several reactions. We found that 13 of the 15 reactions reported in the databases KIDA and UDfA have incorrect products and/or rate constants. The new corrected reaction network contains 10 reactions leading to methyl cyanide. We tested the relative importance of those reactions in forming CH3CN using our astrochemical model. We confirm that the radiative association of CH3+ and HCN, forming CH3CNH+, followed by the electron recombination of CH3CNH+, is the most important CH3CN formation route in both cold and warm environments, notwithstanding that we significantly corrected the rate constants and products of both reactions. The two newly proposed reactions play an important role in warm environments. Finally, we found a very good agreement between the CH3CN predicted abundances with those measured in cold (∼10 K) and warm (∼90 K) objects. Unexpectedly, we also found a chemical link between methanol and methyl cyanide via the CH$_{3}^{+}$ ion, which can explain the observed correlation between the CH3OH and CH3CN abundances measured in hot corinos.

Evoking natural thermal perceptions using a thin-film thermoelectric device with high cooling power density and speed.

Multimodal sensory feedback from upper-limb prostheses can increase their function and usability. Here we show that intuitive thermal perceptions during cold-object grasping with a prosthesis can be restored in a phantom hand through targeted nerve stimulation via a wearable thin-film thermoelectric device with high cooling power density and speed. We found that specific regions of the residual limb, when thermally stimulated, elicited thermal sensations in the phantom hand that remained stable beyond 48 weeks. We also found stimulation sites that selectively elicited sensations of temperature, touch or both, depending on whether the stimulation was thermal or mechanical. In closed-loop functional tasks involving the identification of cold objects by amputees and by non-amputee participants, and compared with traditional bulk thermoelectric devices, the wearable thin-film device reliably elicited cooling sensations that were up to 8 times faster and up to 3 times greater in intensity while using half the energy and 1/600th the mass of active thermoelectric material. Wearable thin-film thermoelectric devices may allow for the non-invasive restoration of thermal perceptions during touch.

Cold-induced urticaria after black ant bite anaphylaxis.

Acquired cold-induced urticaria is a form of physical urticaria that is usually spontaneous. However, reports have shown that bees, wasps, or jellyfish stings can trigger it. We report the first case of cold-induced urticaria following black ant bite-induced anaphylaxis. A 41-year-old lady with no chronic illness with a known black ant bite allergy history. Three years ago, she sustained a black ant bite that required an emergency room visit to treat anaphylaxis. A few days later, she developed attacks of generalized hives on exposure to cold air and objects. She was started on desloratadine tablets which controlled her symptoms. The patient was given EpiPen and instructed to avoid black ants' approach and exposure to cold. She was then followed up in our clinic. Acquired cold-induced urticaria is a form of physical chronic inducible urticaria. Physical urticarias account for 25 % of chronic urticarias. The patient can have wheals, angioedema, or both in response to the cold exposure. Symptoms can be mild or severe, limiting the patient's quality of life. Acquired cold urticaria is idiopathic; however, cases have been reported after different triggers, such as insect stings (bees, wasps, and jellyfish). The black Samsum ant is a recognized trigger of allergic reactions in Qatar and the Gulf region. In a study done in Qatar, 23.5% of anaphylaxis cases were due to black ant stings. There are no validated or standardized skin tests or immunotherapy for the black Samsum ant, which necessitates physicians to be careful in assessing such patients and focus on taking a detailed history. The limitation of testing and immune therapy makes history the tool for diagnosis, and avoidance is the mainstay of treatment.

English

The issue of water scarcity in many parts of the world, especially in arid and semi-arid regions, is a major dilemma. The amount of moisture for plants is not comparable to rain, but in arid areas, it is a huge contribution to plant water supply. In this research, the effect of using Peltier to improve soil condensation by performing several tests was studied in order to investigate the possibility of increasing soil capacity and reducing surface evaporation. Due to the Peltier cooling effect, with copper, iron and aluminium plates, results were evaluated in normal water, saline water and soil texture. The results showed that by using the copper plates in Peltier module, temperature dropped and it was 10% more than iron and aluminium one. It showed that there were significant differences in the results. &nbsp; Key words: Aluminium, cold objects, copper, iron, moisture, refrigerants.

OSSOS. XXVI. On the Lack of Catastrophic Collisions in the Present Kuiper Belt

We investigate different conditions, including the orbital and size–frequency distribution (SFD) of the early Kuiper Belt, that can trigger catastrophic planetesimal destruction. The goal of this study is to test if there is evidence for collisional grinding in the Kuiper Belt that has occurred since its formation. This analysis has important implications for whether the present-day SFD of the cold classical trans-Neptunian objects (TNOs) is a result of collisional equilibrium or if it reflects the primordial stage of planetesimal accretion. As an input to our modeling, we use the most up-to-date debiased OSSOS++ ensemble sample of the TNO population and orbital model based on the present-day architecture of the Kuiper Belt. We calculate the specific impact energies between impactor–target pairs from different TNO groups and compare our computed energies to catastrophic disruption results from smoothed particle hydrodynamics simulations. We explore different scenarios by considering different total primordial Kuiper Belt masses and power slopes of the SFD and allowing collisions to take place over different timescales. The collisional evolution of the Kuiper Belt is a strong function of the unknown initial mass in the trans-Neptunian region, where collisional grinding of planetesimals requires a total primordial Kuiper Belt mass of M > 5 M ⊕, collision speeds as high as 3 km s−1, and collisions over at least 0.5 Gyr. We conclude that presently, most of the collisions in the trans-Neptunian region are in the cratering rather than disruption regime. Given the low collision rates among the cold classical Kuiper Belt objects, their SFD most likely represents the primordial planetesimal accretion.

CLASSIC PRESENTATION OF SCLERODERMA-RELATED INTERSTITIAL LUNG DISEASE IN A YOUNG FEMALE

CLASSIC PRESENTATION OF SCLERODERMA-RELATED INTERSTITIAL LUNG DISEASE IN A YOUNG FEMALE

Honor by Thrity Umrigar

Reviewed by: Honor by Thrity Umrigar Jaid Wehrenberg Thrity Umrigar. Honor. Chapel Hill: Algonquin Books, 2022. 336 p. Thrity Umrigar's Honor explores the consequences of impossible love in the midst of honor killings and a divided India. A journalist herself, Umrigar provides a unique perspective of India through two protagonists: Smita Agarwal, a reluctant Indian American journalist sent to capture the story, and Meena, whose forbidden love resulted in her husband's murder at the hands of her own brothers. Umrigar's past as an immigrant from India undoubtedly provides authority for this difficult yet important work. In an unlikely triumph, Umrigar unites the romance genre, complete with an enemies-to-lovers trope, with the voiceless victims of honor killings. Unflinching in its portrayal of the complicated race relations of Muslims and Hindus, the novel uses the framework of romance to expose Old India's presence in New India's reality. Honor tells two parallel love stories, one doomed and one privileged, while simultaneously exploring a love-hate relationship with India as a complicated and complex mother country. Smita, whose specialty involves women's issues in foreign countries, has a troubled and mysterious history with India that is teased and eventually revealed towards the novels' close. Meena, a Hindu woman who is suing her [End Page 354] brothers for the death of her Muslim husband, is the subject of the seasoned journalist's endeavors. Smita is hesitant to form an attachment with Meena. However, Smita's own trauma with India makes her usual cold objectivity impossible. Although the stories of women killed for honor are numerous, they often feature the men who kill women to preserve their own reputation and honor. Most of Meena's story, told in italicized sections in her own voice, is the tender love story between her and her lover. The honor present in their love restores meaning to the term and results in the naming of their child. Not flinching away from Meena's horrific treatment, Umrigar tactfully tells her story as a victim without victimizing her. Meena's final act of bravery to protect her daughter and cruel mother-in-law demonstrates the active rather than passive position she plays. Meena's choice to sue her brothers draws media attention, and subsequently, the interaction with Smita and the progression of the plot. Honor killings in India are well documented, yet Umrigar's positioning of Meena solidifies the importance of her work. Meena and Smita take center stage, but India's presence is never absent. Smita's disgust towards India is personified in her developing relationship with Mohan. Mohan, a kind and proud son of gold miners, often argues that India is a beautiful place. Smita's frequent biting remarks against India are met with well-argued rebuttals by Mohan, causing readers to side with Mohan's seemingly more understanding approach. However, the author cleverly forces readers and Mohan to confront the realities of India through both women's stories. Meena's treatment by the chief of her village and her brothers begins to unravel Mohan. Later, Smita reveals her backstory, partly for her own relief, but also so that Mohan could finally see some of her own repulsion with India. Smita's family is forced to convert to Hinduism after a mob drags her and her brother, young children at the time, into the street and sexually assaults both of them while their neighbors do nothing. Smita's earlier comments about India no longer ring as harsh, and Mohan's defenses of India suddenly sound weak and uninformed. Rather than demonize and condemn India, however, Smita's confession and solace in Mohan allows her to appreciate India again. Mohan represents all of the best of India, and in his loving embrace, Smita can begin to form healthy attachments again. Honor does exactly what it sets out to do: restore honor not [End Page 355] just to victims of honor killings, but to India. By describing India as a home, a place where food and people are united under the dust that permeates everywhere, Umrigar allows readers, through Smita's own reunification with India, to see what Mohan and others see: the possibility of...

Mechanism of tangential Knudsen force at different Knudsen numbers

In a rarefied gas with a non-uniform temperature field, one phenomenon that arises is the tangential Knudsen force. Various research studies have investigated the tangential Knudsen force but have been limited to specific cases. In this study, we investigated the mechanism of the thermally induced tangential Knudsen force, using theoretical analysis under fully diffusive conditions and for a range of Knudsen numbers. Specifically, we formulated a theoretical expression to describe the tangential Knudsen stress by considering the two kinds of momentum fluxes transferred on a surface of interest. One is brought by molecules directly coming from the other surface without experiencing intermolecular collisions, and the other is brought by molecules coming from the bulk region after experiencing intermolecular collisions there. As a reference, we used a channel where the lower surface is a hot ratchet structure and the upper surface is a flat cold object. The tangential Knudsen force on the object obtained by the theoretical analysis was compared with the results from our previous work where we performed numerical experiments by the direct simulation Monte Carlo method. Based on the comparison, it is found that the tangential Knudsen force is caused by three mechanisms. First is the contribution of impinging molecules coming from the other surface with different temperature. Second is the contribution of viscous effect of thermally driven flows, while the third is the contribution of thermal stress, which is noticeable in small Knudsen numbers.

Finch–Skea gravastar model in [formula omitted] theory

This work presents the existence of a cold and compact object known as gravastar in f(R,T) theory of gravity. The Finch–Skea function f(r)=1+ar2 with a being an arbitrary constant is assumed corresponding to radial metric coefficient. The solution of the field equations for f(R,T)=R+γT yields the gravastar analytical solutions surrounded by the perfect fluid. We interpret the Schwarzschild geometry in exterior as absolutely vacuumed region. The arbitrary constant involved in Finch–Skea metric potential is derived through matching condition. Conclusively, we obtain such a sensational gravitational collapse model that is thermodynamically stable and clear from issues in the theory of black holes.

An improved network-based recommendation model via inhibiting algorithm bias

As an effective tool of information filtering, the network-based recommendation algorithms encounter the challenging problem of recommendation bias induced by the object heterogeneity. Previous solutions usually make the improvement based on some specific algorithm, however, are difficult to generalize to different algorithms. In this article, we propose an improved model with a general formula, by inhibiting recommendation bias described by the eigenvalue and eigenvectors of the algorithm similarity matrix, and applied the model into ten different algorithms. Based on four real recommender systems, the experimental results show that nearly all the algorithms are improved in three aspects of recommendation accuracy, diversity and novelty, for all the four datasets. The recommendation accuracy of cold objects is also elevated. Especially, two excellent algorithms are further improved without introducing any other parameter. Our work may shed a new light on developing general recommendation algorithms from the perspective of revealing intrinsic feature in recommender systems.

Dynamical Implantation of Blue Binaries in the Cold Classical Kuiper Belt

Abstract Colors and binarity provide important constraints on the Kuiper Belt formation. The cold classical objects at radial distance r = 42–47 au from the Sun are predominantly very red (spectral slope s &gt; 17%) and often exist as equal-size binaries (∼30% observed binary fraction). This has been taken as evidence for the in situ formation of cold classicals. Interestingly, a small fraction (∼10%) of cold classicals is less red with s &lt; 17%, and these “blue” bodies are often found in wide binaries. Here we study the dynamical implantation of blue binaries from r &lt; 42 au. We find that they can be implanted into the cold classical belt from a wide range of initial radial distances, but the survival of the widest blue binaries—2001 QW322 and 2003 UN284—implies formation at r &gt; 30 au. This would be consistent with the hypothesized less-red to very-red transition at 30 &lt; r &lt; 40 au. For any reasonable choice of parameters (Neptune’s migration history, initial disk profile, etc.), however, our model predicts a predominance of blue singles, rather than blue binaries, which contradicts existing observations. We suggest that wide blue binaries formed in situ at r = 42–47 au and their color reflects early formation in a protoplanetary gas disk. The predominantly VR colors of cold classicals may be related to the production of methanol and other hydrocarbons during the late stages of the disk, when the temperature at 45 au dropped to ≃20 K and carbon monoxide was hydrogenated.

Discovery of 16 New Members of the Solar Neighborhood Using Proper Motions from CatWISE2020

Abstract In an effort to identify nearby and unusual cold objects in the solar neighborhood, we searched for previously unidentified moving objects using CatWISE2020 proper motion data combined with machine learning methods. We paired the motion candidates with their counterparts in 2MASS, UHS, and VHS. Then we searched for white dwarf, brown dwarf, and subdwarf outliers on the resulting color–color diagrams. This resulted in the discovery of 16 new dwarfs, including 2 nearby M dwarfs (&lt;30 pc), a possible young L dwarf, a high-motion early-T dwarf, and 3 later-T dwarfs. This research represents a step forward in completing the census of the Sun’s neighbors.