712 research outputs found
Potential for Solar System Science with the ngVLA
Radio wavelength observations of solar system bodies are a powerful method of
probing many characteristics of those bodies. From surface and subsurface, to
atmospheres (including deep atmospheres of the giant planets), to rings, to the
magnetosphere of Jupiter, these observations provide unique information on
current state, and sometimes history, of the bodies. The ngVLA will enable the
highest sensitivity and resolution observations of this kind, with the
potential to revolutionize our understanding of some of these bodies. In this
article, we present a review of state-of-the-art radio wavelength observations
of a variety of bodies in our solar system, varying in size from ring particles
and small near-Earth asteroids to the giant planets. Throughout the review we
mention improvements for each body (or class of bodies) to be expected with the
ngVLA. A simulation of a Neptune-sized object is presented in Section 6.
Section 7 provides a brief summary for each type of object, together with the
type of measurements needed for all objects throughout the Solar System
Thermal Properties of the Icy Galilean Satellites from Millimeter ALMA Observations
We present spatially-resolved maps of the leading and trailing hemispheres of Europa, Ganymede, and Callisto from ALMA millimeter wavelength observations
A Nearby M Star with Three Transiting Super-Earths Discovered by K2
Small, cool planets represent the typical end-products of planetary formation. Studying the architectures of these systems, measuring planet masses and radii, and observing these planets' atmospheres during transit directly informs theories of planet assembly, migration, and evolution. Here we report the discovery of three small planets orbiting a bright (K_s = 8.6 mag) M0 dwarf using data collected as part of K2, the new ecliptic survey using the re-purposed Kepler spacecraft. Stellar spectroscopy and K2 photometry indicate that the system hosts three transiting planets with radii 1.5–2.1 R_⊕, straddling the transition region between rocky and increasingly volatile-dominated compositions. With orbital periods of 10–45 days the planets receive just 1.5–10× the flux incident on Earth, making these some of the coolest small planets known orbiting a nearby star; planet d is located near the inner edge of the system's habitable zone. The bright, low-mass star makes this system an excellent laboratory to determine the planets' masses via Doppler spectroscopy and to constrain their atmospheric compositions via transit spectroscopy. This discovery demonstrates the ability of K2 and future space-based transit searches to find many fascinating objects of interest
Systematic construction of qualitative physics-based rules for process diagnostics
A novel first-principles-based expert system is proposed for on-line detection and identification of faulty component candidates during incipient off-normal process operations. The system performs function-oriented diagnostics and can be reused for diagnosing single-component failures in different processes and different plants through the provision of the appropriate process schematics information. The function-oriented and process-independent diagnostic features of the proposed expert system are achieved by constructing a knowledge base containing three distinct types of information, qualitative balance equation rules, functional classification of process components, and the process piping and instrumentation diagram. The various types of qualitative balance equation rules for processes utilizing single-phase liquids are derived and their usage is illustrated through simulation results of a realistic process in a nuclear power plant
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Diagnosis and Threat Detection Capabilities of the SERENITY Monitoring Framework
The SERENITY monitoring framework offers mechanisms for diagnosing the causes of violations of security and dependability (S&D) properties and detecting potential violations of such properties, called “threats”. Diagnostic information and threat detection are often necessary for deciding what an appropriate reaction to a violation is and taking pre-emptive actions against predicted violations, respectively. In this chapter, we describe the mechanisms of the SERENITY monitoring framework which generate diagnostic information for violations of S&D properties and detecting threats
Analysis of Neptune's 2017 Bright Equatorial Storm
We report the discovery of a large (8500 km diameter) infrared-bright
storm at Neptune's equator in June 2017. We tracked the storm over a period of
7 months with high-cadence infrared snapshot imaging, carried out on 14 nights
at the 10 meter Keck II telescope and 17 nights at the Shane 120 inch reflector
at Lick Observatory. The cloud feature was larger and more persistent than any
equatorial clouds seen before on Neptune, remaining intermittently active from
at least 10 June to 31 December 2017. Our Keck and Lick observations were
augmented by very high-cadence images from the amateur community, which
permitted the determination of accurate drift rates for the cloud feature. Its
zonal drift speed was variable from 10 June to at least 25 July, but remained a
constant m s from 30 September until at least 15
November. The pressure of the cloud top was determined from radiative transfer
calculations to be 0.3-0.6 bar; this value remained constant over the course of
the observations. Multiple cloud break-up events, in which a bright cloud band
wrapped around Neptune's equator, were observed over the course of our
observations. No "dark spot" vortices were seen near the equator in HST imaging
on 6 and 7 October. The size and pressure of the storm are consistent with
moist convection or a planetary-scale wave as the energy source of convective
upwelling, but more modeling is required to determine the driver of this
equatorial disturbance as well as the triggers for and dynamics of the observed
cloud break-up events.Comment: 42 pages, 14 figures, 6 tables; Accepted to Icaru
A Prograde, Low-Inclination Orbit for the Very Hot Jupiter WASP-3b
We present new spectroscopic and photometric observations of the transiting
exoplanetary system WASP-3. Spectra obtained during two separate transits
exhibit the Rossiter-McLaughlin (RM) effect and allow us to estimate the
sky-projected angle between the planetary orbital axis and the stellar rotation
axis, lambda = 3.3^{+2.5}_{-4.4} degrees. This alignment between the axes
suggests that WASP-3b has a low orbital inclination relative to the equatorial
plane of its parent star. During our first night of spectroscopic measurements,
we observed an unexpected redshift briefly exceeding the expected sum of the
orbital and RM velocities by 140 m/s. This anomaly could represent the
occultation of material erupting from the stellar photosphere, although it is
more likely to be an artifact caused by moonlight scattered into the
spectrograph.Comment: 23 pages, 4 figures, Accepted for publication in The Astrophysical
Journal, Replacement includes revised citation
Thermal Properties of the Icy Galilean Satellites from Millimeter ALMA Observations
We present spatially-resolved maps of the leading and trailing hemispheres of Europa, Ganymede, and Callisto from ALMA millimeter wavelength observations
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