scholarly journals Mean plane of the Kuiper belt beyond 50 AU in the presence of Planet 9

2020 ◽  
Vol 637 ◽  
pp. A87
Author(s):  
Jian Li ◽  
Zhihong Jeff Xia
Keyword(s):  
Numerical Simulations ◽  
Theoretical Approach ◽  
Kuiper Belt ◽  
Kuiper Belt Objects ◽  
The Real ◽  
Relative Angle ◽  
Upper Limit ◽  
The Mean ◽  
Measurement Uncertainties ◽  
Invariable Plane

Context. A recent observational census of Kuiper belt objects (KBOs) has unveiled anomalous orbital structures. This has led to the hypothesis that an additional ∼5 − 10 m⊕ planet exists. This planet, known as Planet 9, occupies an eccentric and inclined orbit at hundreds of astronomical units. However, the KBOs under consideration have the largest known semimajor axes at a >  250 AU; thus they are very difficult to detect. Aims. In the context of the proposed Planet 9, we aim to measure the mean plane of the Kuiper belt at a >  50 AU. In a comparison of the expected and observed mean planes, some constraints would be put on the mass and orbit of this undiscovered planet. Methods. We adopted and developed the theoretical approach of Volk & Malhotra (2017, AJ, 154, 62) to the relative angle δ between the expected mean plane of the Kuiper belt and the invariable plane determined by the eight known planets. Numerical simulations were constructed to validate our theoretical approach. Then similar to Volk & Malhotra (2017, AJ, 154, 62), we derived the angle δ for the real observed KBOs with 100 <  a <  200 AU, and the measurement uncertainties were also estimated. Finally, for comparison, maps of the theoretically expected δ were created for different combinations of possible Planet 9 parameters. Results. The expected mean plane of the Kuiper belt nearly coincides with the said invariable plane interior to a = 90 AU. But these two planes deviate noticeably from each other at a >  100 AU owing to the presence of Planet 9 because the relative angle δ could be as large as ∼10°. Using the 1σ upper limit of δ <  5° deduced from real KBO samples as a constraint, we present the most probable parameters of Planet 9: for mass m9 = 10 m⊕, orbits with inclinations i9 = 30°, 20°, and 15° should have semimajor axes a9 >  530 AU, 450 AU, and 400 AU, respectively; for m9 = 5 m⊕, the orbit is i9 = 30° and a9 >  440 AU, or i9 <  20° and a9 >  400 AU. In this work, the minimum a9 increases with the eccentricity e9 (∈[0.2, 0.6]) but not significantly.

scholarly journals Linking the Origin of Asteroids to Planetesimal Formation in the Solar Nebula

2015 ◽  
Vol 10 (S318) ◽  
pp. 1-8 ◽  
Author(s):  
Hubert Klahr ◽  
Andreas Schreiber
Keyword(s):  
Numerical Simulations ◽  
Turbulent Flows ◽  
Kuiper Belt ◽  
Asteroid Belt ◽  
Kuiper Belt Objects ◽  
Physical Size ◽  
Zonal Flows ◽  
Numerical Resolution ◽  
Streaming Instability ◽  
Current Paradigm

AbstractThe asteroids (more precisely: objects of the main asteroid belt) and Kuiper Belt objects (more precisely: objects of the cold classical Kuiper Belt) are leftovers of the building material for our earth and all other planets in our solar system from more than 4.5 billion years ago. At the time of their formation those were typically 100 km large objects. They were called planetesimals, built up from icy and dusty grains. In our current paradigm of planet formation it was turbulent flows and metastable flow patterns, like zonal flows and vortices, that concentrated mm to cm sized icy dust grains in sufficient numbers that a streaming instability followed by a gravitational collapse of these particle clump was triggered. The entire picture is sometimes referred to as gravoturbulent formation of planetesimals. What was missing until recently, was a physically motivated prediction on the typical sizes at which planetesimals should form via this process. Our numerical simulations in the past had only shown a correlation between numerical resolution and planetesimal size and thus no answer was possible (Johansen et al.2011). But with the lastest series of simulations on JUQUEEN (Stephan & Doctor 2015), covering all the length scales down to the physical size of actual planetesimals, we were able to obtain values for the turbulent particle diffusion as a function of the particle load in the gas. Thus, we have all necessary data at hand to feed a 'back of the envelope' calculation that predicts the size of planetesimals as result of a competition between gravitational concentration and turbulent diffusion. Using the diffusion values obtained in the numerical simulations it predicts planetesimal sizes on the order of 100 km, which suprisingly coincides with the measured data from both asteroids (Bottke et al.2005) as well from Kuiper Belt objects (Nesvorny et al.2011).

scholarly journals Early Activity in Comet C/2014 UN271 Bernardinelli–Bernstein as Observed by TESS

2021 ◽  
Vol 2 (6) ◽  
pp. 236
Author(s):  
Tony L. Farnham ◽  
Michael S. P. Kelley ◽  
James M. Bauer
Keyword(s):  
Production Rate ◽  
Kuiper Belt ◽  
Kuiper Belt Objects ◽  
Upper Limit ◽  
Long Duration ◽  
Combining Data ◽  
Early Activity

Abstract We used long duration observations from the Transient Exoplanet Survey Satellite (TESS) to investigate the behavior of comet C/2014 UN271 Bernardinelli–Bernstein at large heliocentric distances. By combining data from sector 03 (976 30 minute exposures from 2018), and sectors 29 and 30 (3585 and 3410 10 minute exposures, respectively, from 2020), we produced deep coadded images of the comet. A comparison of these results with similarly processed images of inactive Kuiper Belt objects and asteroids reveals that the comet was already exhibiting coma at heliocentric distances 23.8 and 21.2 au, making this one of the most distant comets for which preperihelion activity has been directly detected. A simple syndyne analysis of asymmetries in the coma suggests that activity probably started several years prior to these observations, and likely arose from emission in roughly the sunward direction. The images were used to produce photometric lightcurves, though no rotational variability was detected. We used NEOWISE observations from 2020 November 26–28 to place an upper limit of 2 × 1028 molecules s−1 (3σ) on the CO production rate.

scholarly journals Fractional polarization of extragalactic sources in the 500 deg2 SPTpol survey

2019 ◽  
Vol 490 (4) ◽  
pp. 5712-5721 ◽  
Author(s):  
N Gupta ◽  
C L Reichardt ◽  
P A R Ade ◽  
A J Anderson ◽  
M Archipley ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Power Spectra ◽  
Galactic Nuclei ◽  
Weighted Mean ◽  
Full Sample ◽  
The Real ◽  
Upper Limit ◽  
Upper Limits ◽  
The Mean ◽  
Polarization Fraction

ABSTRACT We study the polarization properties of extragalactic sources at 95 and 150 GHz in the SPTpol 500 deg2 survey. We estimate the polarized power by stacking maps at known source positions, and correct for noise bias by subtracting the mean polarized power at random positions in the maps. We show that the method is unbiased using a set of simulated maps with similar noise properties to the real SPTpol maps. We find a flux-weighted mean-squared polarization fraction 〈p2〉 = [8.9 ± 1.1] × 10−4 at 95 GHz and [6.9 ± 1.1] × 10−4 at 150 GHz for the full sample. This is consistent with the values obtained for a subsample of active galactic nuclei. For dusty sources, we find 95 per cent upper limits of 〈p2〉95 &lt; 16.9 × 10−3 and 〈p2〉150 &lt; 2.6 × 10−3. We find no evidence that the polarization fraction depends on the source flux or observing frequency. The 1σ upper limit on measured mean-squared polarization fraction at 150 GHz implies that extragalactic foregrounds will be subdominant to the CMB E and B mode polarization power spectra out to at least ℓ ≲ 5700 (ℓ ≲ 4700) and ℓ ≲ 5300 (ℓ ≲ 3600), respectively, at 95 (150) GHz.

scholarly journals Resonant Gaps in the Scattered Cometary Population of the Trans-Neptunian Region

2002 ◽  
Vol 12 ◽  
pp. 251-252
Author(s):  
Tanya Taidakova ◽  
Leonid M. Ozernoy ◽  
Nick N. Gorkavyi
Keyword(s):  
Numerical Simulations ◽  
Kuiper Belt ◽  
Giant Planets ◽  
Kuiper Belt Objects ◽  
Mean Motion Resonances ◽  
Mean Motion ◽  
Scattered Population

AbstractOur numerical simulations of the Edgeworth-Kuiper Belt objects gravitationally scattered by the four giant planets accounting for mean motion resonances reveal numerous resonant gaps in the distribution of the scattered population.

U-Band Photometry of Kuiper Belt Objects

2007 ◽  
Vol 134 (5) ◽  
pp. 2046-2053 ◽  
Author(s):  
David Jewitt ◽  
Nuno Peixinho ◽  
Henry H. Hsieh
Keyword(s):  
Kuiper Belt ◽  
Kuiper Belt Objects

Prolactin Screening in a Cohort of Schizophrenia Patients in Birmingham

2009 ◽  
Vol 24 (S1) ◽  
pp. 1-1
Author(s):  
I. Waheed ◽  
A. Khan
Keyword(s):  
Health Centre ◽  
Drug Dosage ◽  
Oral Risperidone ◽  
Clinical Symptomatology ◽  
Upper Limit ◽  
Routine Monitoring ◽  
Current Medication ◽  
The Mean ◽  
Unselected Group

Aim:To establish the numerical prevalence and severity of raised prolactin levels in patients apparently asymptomatic.Method:All outpatients with schizophrenia receiving antipsychotics at Small Heath Health Centre had routine annual prolactin measurements. the sampling was done 0900-1300 either in clinic or at patient's homes. the Upper Limit of Normal (ULN) for prolactin was set by the hospital pathology service at 324 mIU/L (males) and 496 mIU/L (females). Sampling was done 0900-1200 either in clinic or at patient's homes. We recorded the patient's name, age, unit number, ethnicity, details of current medication, recent changes to medication and symptoms of hyperprolactinaemia.Results:Prolactin levels were obtained for 43 patients (M: 24 F:19). All of these patients had no clinical symptomatology that had led to prolactin measurements previously. Abnormal values were found in 47 per cent of females and 58 per cent of males, or 56 per cent (n=24) of the whole cohort. the mean prolactin was 789 mIU/L with a mean of 497 mIU/L in males and 1100 mIU/L in females. All patients on oral risperidone had hyperprolactinaemia.Conclusion:Routine prolactin screening showed abnormal values in 56 per cent of patients and significantly abnormal levels (>1000 mIU/L) that should lead to consideration of drug/dosage alterations in 26% of patients. the prevalence of hyperprolactinaemia in an unselected group of outpatients with schizophrenia suggests that consideration may be given to routine monitoring.

scholarly journals Rotation of Galaxy Dark Matter Halos

2006 ◽  
Vol 2 (S235) ◽  
pp. 104-104
Author(s):  
Stéphane Herbert-Fort ◽  
Dennis Zaritsky ◽  
Yeun Jin Kim ◽  
Jeremy Bailin ◽  
James E. Taylor
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Numerical Simulations ◽  
Galaxy Formation ◽  
Spiral Galaxy ◽  
Observational Studies ◽  
Spiral Galaxies ◽  
Satellite System ◽  
Dark Matter Halos ◽  
The Mean

AbstractThe degree to which outer dark matter halos of spiral galaxies rotate with the disk is sensitive to their accretion history and may be probed with associated satellite galaxies. We use the Steward Observatory Bok telescope to measure the sense of rotation of nearby isolated spirals and combine these data with those of their associated satellites (drawn from SDSS) to directly test predictions from numerical simulations. We aim to constrain models of galaxy formation by measuring the projected component of the halo angular momentum that is aligned with that of spiral galaxy disks, Jz. We find the mean bulk rotation of the ensemble satellite system to be co-rotating with the disk with a velocity of 22 ± 13 km/s, in general agreement with previous observational studies and suggesting that galaxy disks could be formed by halo baryons collapsing by a factor of ≈10. We also find a prograde satellite fraction of 51% and Jz, of the satellite system to be positively correlated with the disk, albeit at low significance (2655 ± 2232 kpc km/s).

Analysis of the Real Area of Contact Between a Polymeric Magnetic Medium and a Rigid Surface

1984 ◽  
Vol 106 (1) ◽  
pp. 26-34 ◽  
Author(s):  
Bharat Bhushan
Keyword(s):  
Complex Modulus ◽  
Critical Value ◽  
Computer Applications ◽  
Hard Material ◽  
Rigid Surface ◽  
Magnetic Medium ◽  
The Real ◽  
Real Area Of Contact ◽  
The Mean ◽  
Real Area

The statistical analysis of the real area of contact proposed by Greenwood and Williamson is revisited. General and simplified equations for the mean asperity real area of contact, number of contacts, total real area of contact, and mean real pressure as a function of apparent pressure for the case of elastic junctions are presented. The critical value of the mean asperity pressure at which plastic flow starts when a polymer contacts a hard material is derived. Based on this, conditions of elastic and plastic junctions for polymers are defined by a “polymer” plasticity index, Ψp which depends on the complex modulus, Poisson’s ratio, yield strength, and surface topography. Calculations show that most dynamic contacts that occur in a computer-magnetic tape are elastic, and the predictions are supported by experimental evidence. Tape wear in computer applications is small and decreases Ψp by less than 10 percent. The theory presented here can also be applied to rigid and floppy disks.

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