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J. Bailey

Publications and source records attributed to J. Bailey.

At least 19 recordsLinked to original sources

Advances in aviation radiation mitigation were demonstrated during the Gannon storm

A validation strategy for aviation radiation hazard mitigation has been completed using two commercial airline flights in 2024 and 2025. We review the strategy primary elements, including the emergence of aviation radiation awareness and collaborative efforts by global aviation and radiological bodies that established mitigation standards. The article highlights biological effects of radiation exposure influenced by altitude, latitude, and geomagnetic conditions, upon aircrew, frequent flyers, and commercial space travelers. It recognizes the SWAG user needs survey report that identifies the need for continuous monitoring and predictive models to ensure long-term occupational and public health safety. The ALARA strategy validation was completed using two UAL 990 flights on B777 200 aircraft between San Francisco and Paris. Each carried the same ARMAS FM7 radiation monitoring unit. One flight occurred during the Gannon storm May 10 and 11, 2024 and one flight occurred during quiet geomagnetic conditions June 8 and 9, 2025. The flight results validated the strategy during extreme space weather, i.e., apply operational controls for shielding to reduce dose. One approach is fly lower magnetic latitudes to gain more Earth magnetic field shielding and the other is fly lower altitudes to use atmosphere depth shielding. Both ALARA shielding methods are controllable in airline operations and air traffic management. This study shows the effectiveness to deviate flight paths to lower magnetic latitude routes and lower altitudes during major geomagnetic storms. Not only does this approach mitigate HF communication outages but it also reduces risks from increased GNSS errors for takeoff and landing navigation. Magnetic field shielding is a major risk reduction factor for radiation, communication, and navigation while altitude shielding reduces radiation hazard risks.

physics.space-ph

HD 222237 b: a long period super-Jupiter around a nearby star revealed by radial-velocity and Hipparcos-Gaia astrometry

Giant planets on long period orbits around the nearest stars are among the easiest to directly image. Unfortunately these planets are difficult to fully constrain by indirect methods, e.g., transit and radial velocity (RV). In this study, we present the discovery of a super-Jupiter, HD 222237 b, orbiting a star located $11.445\pm0.002$ pc away. By combining RV data, Hipparcos and multi-epoch Gaia astrometry, we estimate the planetary mass to be ${5.19}_{-0.58}^{+0.58}\,M_{\rm Jup}$, with an eccentricity of ${0.56}_{-0.03}^{+0.03}$ and a period of ${40.8}_{-4.5}^{+5.8}$ yr, making HD 222237 b a promising target for imaging using the Mid-Infrared Instrument (MIRI) of JWST. A comparative analysis suggests that our method can break the inclination degeneracy and thus differentiate between prograde and retrograde orbits of a companion. We further find that the inferred contrast ratio between the planet and the host star in the F1550C filter ($15.50\,\mu \rm m$) is approximately $1.9\times10^{-4}$, which is comparable with the measured limit of the MIRI coronagraphs. The relatively low metallicity of the host star ($\rm-0.32\,dex$) combined with the unique orbital architecture of this system presents an excellent opportunity to probe the planet-metallicity correlation and the formation scenarios of giant planets.

astro-ph.EP

3-D selection of 167 sub-stellar companions to nearby stars

We analyze 5108 AFGKM stars with at least five high precision radial velocity points as well as Gaia and Hipparcos astrometric data utilizing a novel pipeline developed in previous work. We find 914 radial velocity signals with periods longer than 1000\,d. Around these signals, 167 cold giants and 68 other types of companions are identified by combined analyses of radial velocity, astrometry, and imaging data. Without correcting for detection bias, we estimate the minimum occurrence rate of the wide-orbit brown dwarfs to be 1.3\%, and find a significant brown dwarf valley around 40 $M_{\rm Jup}$. We also find a power-law distribution in the host binary fraction beyond 3 au similar to that found for single stars, indicating no preference of multiplicity for brown dwarfs. Our work also reveals nine sub-stellar systems (GJ 234 B, GJ 494 B, HD 13724 b, HD 182488 b, HD 39060 b and c, HD 4113 C, HD 42581 d, HD 7449 B, and HD 984 b) that have previously been directly imaged, and many others that are observable at existing facilities. Depending on their ages we estimate that an additional 10-57 sub-stellar objects within our sample can be detected with current imaging facilities, extending the imaged cold (or old) giants by an order of magnitude.

astro-ph.EP

A multiple planet system of super-Earths orbiting the brightest red dwarf star GJ887

The nearest exoplanets to the Sun are our best possibilities for detailed characterization. We report the discovery of a compact multi-planet system of super-Earths orbiting the nearby red dwarf GJ 887, using radial velocity measurements. The planets have orbital periods of 9.3 and 21.8~days. Assuming an Earth-like albedo, the equilibrium temperature of the 21.8 day planet is approx 350 K; which is interior, but close to the inner edge, of the liquid-water habitable zone. We also detect a further unconfirmed signal with a period of 50 days which could correspond to a third super-Earth in a more temperate orbit. GJ 887 is an unusually magnetically quiet red dwarf with a photometric variability below 500 parts-per-million, making its planets amenable to phase-resolved photometric characterization.

astro-ph.EP

Solar System Physics for Exoplanet Research

Over the past three decades, we have witnessed one of the great revolutions in our understanding of the cosmos - the dawn of the Exoplanet Era. Where once we knew of just one planetary system (the Solar system), we now know of thousands, with new systems being announced on a weekly basis. Of the thousands of planetary systems we have found to date, however, there is only one that we can study up-close and personal - the Solar system. In this review, we describe our current understanding of the Solar system for the exoplanetary science community - with a focus on the processes thought to have shaped the system we see today. In section one, we introduce the Solar system as a single well studied example of the many planetary systems now observed. In section two, we describe the Solar system's small body populations as we know them today - from the two hundred and five known planetary satellites to the various populations of small bodies that serve as a reminder of the system's formation and early evolution. In section three, we consider our current knowledge of the Solar system's planets, as physical bodies. In section four, we discuss the research that has been carried out into the Solar system's formation and evolution, with a focus on the information gleaned as a result of detailed studies of the system's small body populations. In section five, we discuss our current knowledge of planetary systems beyond our own - both in terms of the planets they host, and in terms of the debris that we observe orbiting their host stars. As we learn ever more about the diversity and ubiquity of other planetary systems, our Solar system will remain the key touchstone that facilitates our understanding and modelling of those newly found systems, and we finish section five with a discussion of the future surveys that will further expand that knowledge.

astro-ph.EP

Cool Jupiters greatly outnumber their toasty siblings: Occurrence rates from the Anglo-Australian Planet Search

Our understanding of planetary systems different to our own has grown dramatically in the past 30 years. However, our efforts to ascertain the degree to which the Solar system is abnormal or unique have been hindered by the observational biases inherent to the methods that have yielded the greatest exoplanet hauls. On the basis of such surveys, one might consider our planetary system highly unusual - but the reality is that we are only now beginning to uncover the true picture. In this work, we use the full eighteen-year archive of data from the Anglo-Australian Planet Search to examine the abundance of 'Cool Jupiters' - analogs to the Solar system's giant planets, Jupiter and Saturn. We find that such planets are intrinsically far more common through the cosmos than their siblings, the hot Jupiters. We find that the occurrence rate of such 'Cool Jupiters' is $6.73^{+2.09}_{-1.13}$\%, almost an order of magnitude higher than the occurrence of hot Jupiters (at $0.84^{+0.70}_{-0.20}$\%). We also find that the occurrence rate of giant planets is essentially constant beyond orbital distances of $\sim$1\,au. Our results reinforce the importance of legacy radial velocity surveys for the understanding of the Solar system's place in the cosmos.

astro-ph.EP

MASCARA-4 b/bRing-1b - A retrograde hot Jupiter around the bright A3V star HD 85628

In this paper, we aim to characterize a transiting planetary candidate in the southern skies found in the combined MASCARA and bRing data sets of HD 85628, an A3V star of V = 8.2 mag at a distance 172 pc, to confirm its planetary nature. The candidate was originally detected in data obtained jointly with the MASCARA and bRing instruments using a BLS search for transit events. Further photometry was taken by the 0.7 m CHAT, and radial velocity measurements with FIDEOS on the ESO 1.0 m Telescope. High resolution spectra during a transit were taken with CHIRON on the SMARTS 1.5 m telescope to target the Doppler shadow of the candidate. We confirm the existence of a hot Jupiter transiting the bright A3V star HD 85628, which we co-designate as MASCARA-4b and bRing-1b. It is in a 2.824 day orbit, with an estimated planet radius of $1.53 ^{0.07}_{0.04}$ $R_{\rm{Jup}}$ and an estimated planet mass of $3.1 \pm 0.9$ $M_{\rm{Jup}}$, putting it well within the planet mass regime.. The CHAT observations show a partial transit, reducing the probability that the transit was around a faint background star. The CHIRON observations show a clear Doppler shadow, implying that the transiting object is in a retrograde orbit with $|\lambda| = 247.5 \pm 1.6 $\textdegree. The planet orbits at at a distance of 0.047 $\pm$ 0.004 AU from the star and has a zero-albedo equilibrium temperature of 2100 $\pm$ 100 K. In addition, we find that HD 85628 has a previously unreported stellar companion star in the Gaia DR2 data demonstrating common proper motion and parallax at 4.3 arcsecond separation (projected separation $\sim$740 AU), and with absolute magnitude consistent with being a K/M dwarf.

astro-ph.EP

Nanoscale X-Ray Imaging of Spin Dynamics in Yttrium Iron Garnet

Time-resolved scanning transmission x-ray microscopy (TR-STXM) has been used for the direct imaging of spin wave dynamics in thin film yttrium iron garnet (YIG) with spatial resolution in the sub 100 nm range. Application of this x-ray transmission technique to single crystalline garnet films was achieved by extracting a lamella (13x5x0.185 $\mathrm{\mu m^3}$) of liquid phase epitaxy grown YIG thin film out of a gadolinium gallium garnet substrate. Spin waves in the sample were measured along the Damon-Eshbach and backward volume directions of propagation at gigahertz frequencies and with wavelengths in a range between 100~nm and 10~$\mathrm{\mu}$m. The results were compared to theoretical models. Here, the widely used approximate dispersion equation for dipole-exchange spin waves proved to be insufficient for describing the observed Damon-Eshbach type modes. For achieving an accurate description, we made use of the full analytical theory taking mode-hybridization effects into account.

cond-mat.mes-hall

Secondary eclipses of WASP-18b -- Near Infrared observations with the Anglo Australian Telescope, the Magellan Clay Telescope and the LCOGT network

We present new eclipse observations for one of the hottest "hot Jupiters" WASP-18b, for which previously published data from HST WFC3 and Spitzer have led to radically conflicting conclusions about the composition of this planet's atmosphere. We measure eclipse depths of $0.15\pm0.02\%$ at $Ks$ and $0.07\pm0.01\%$ at $z'$ bands. Using the VSTAR line-by-line radiative transfer code and both these new observations with previously published data, we derive a new model of the planetary atmosphere. We have varied both the metallicity and C/O ratio in our modelling, and find no need for the extreme metallicity suggested by Sheppard et al.(2017). Our best fitting models slightly underestimate the emission at $z'$ band and overestimate the observed flux at $Ks$-band. To explain these discrepancies, we examine the impact on the planetary emission spectrum of the presence of several types of hazes which could form on the night-side of the planet. Our $Ks$ band eclipse flux measurement is lower than expected from clear atmosphere models and this could be explained by a haze particles larger than 0.2 $\mu$m with the optical properties of Al$_{2}$O$_{3}$, CaTiO$_{3}$ or MgSiO$_{3}$. We find that $z'$ band measurements are important for understanding the contribution of photochemical hazes with particles smaller than 0.1 $\mu$m at the top of the atmosphere.

astro-ph.EP

HATS-70b: A 13 Mjup brown dwarf transiting an A star

We report the discovery of HATS-70b, a transiting brown dwarf at the deuterium burning limit. HATS-70b has a mass of Mp=12.9 +1.8/-1.6 Mjup and a radius of Rp=1.384 +0.079/-0.074 Rjup, residing in a close-in orbit with a period of 1.89 days. The host star is a M*=1.78 +/- 0.12 Msun A star rotating at vsini=40.61 +0.32/-0.35 km/s, enabling us to characterize the spectroscopic transit of the brown dwarf via Doppler tomography. We find that HATS-70b, like other massive planets and brown dwarfs previously sampled, orbits in a low projected-obliquity orbit with lambda=8.9 +5.6/-4.5 deg. The low obliquities of these systems is surprising given all brown dwarf and massive planets with obliquities measured orbit stars hotter than the Kraft break. This trend is tentatively inconsistent with dynamically chaotic migration for systems with massive companions, though the stronger tidal influence of these companions makes it difficult to draw conclusions on the primordial obliquity distribution of this population. We also introduce a modeling scheme for planets around rapidly rotating stars, accounting for the influence of gravity darkening on the derived stellar and planetary parameters.

astro-ph.EP

Mapping the Interstellar Magnetic Field Around the Heliosphere with Polarized Starlight

Starlight that becomes linearly polarized by magnetically aligned dust grains provides a viable diagnostic of the interstellar magnetic field (ISMF). A survey is underway to map the local ISMF using data collected at eight observatories in both hemispheres. Two approaches are used to obtain the magnetic structure: statistically evaluating magnetic field directions traced by multiple polarization position angles, and least-squares fits that provide the dipole component of the magnetic field. We find that the magnetic field in the circumheliospheric interstellar medium (CHM), which drives winds of interstellar gas and dust through the heliosphere, drapes over the heliopause and influences polarization measurements. We discover a polarization band that can be described with a great circle that traverses the heliosphere nose and ecliptic poles. A gap in the band appears in a region coinciding both with the highest heliosheath pressure, found by IBEX, and the center of the Loop I superbubble. The least-squares analysis finds a magnetic dipole component of the polarization band with the axis oriented toward the ecliptic poles. The filament of dust around the heliosphere and the warm helium breeze flowing through the heliosphere trace the same magnetic field directions. Regions along the polarization band near the heliosphere nose have magnetic field orientations within 15 degrees of sightlines. Regions in the IBEX ribbon have field directions within 40 degrees of the plane of the sky. Several spatially coherent magnetic filaments are within 15 pc. Most of the low frequency radio emissions detected by the two Voyager spacecraft follow the polarization band. The geometry of the polarization band is compared to the Local Interstellar Cloud, the Cetus Ripple, the BICEP2 low opacity region, Ice Cube IC59 galactic cosmic ray data, and Cassini results.

astro-ph.GA

Fast C-V method to mitigate effects of deep levels in CIGS doping profiles

In this work, methods to determine more accurate doping profiles in semiconductors is explored where trap-induced artifacts such as hysteresis and doping artifacts are observed. Specifically in CIGS, it is shown that this fast capacitance-voltage (C-V) approach presented here allows for accurate doping profile measurement even at room temperature, which is typically not possible due to the large ratio of trap concentration to doping. Using deep level transient spectroscopy (DLTS) measurement, the deep trap responsible for the abnormal C-V measurement above 200 K is identified. Importantly, this fast C-V can be used for fast evaluation on the production line to monitor the true doping concentration, and even estimate the trap concentration. Additionally, the influence of high conductance on the apparent doping profile at different temperature is investigated.

physics.ins-det

The 2~$\mu$m spectrum of the auroral emission in the polar regions of Jupiter

We report observations of the high (R$\sim$18000) and medium (R$\sim$5900) resolution, near-infrared spectra of Jupiter's polar regions with the GNIRS instrument at the Gemini North telescope. The observations correspond to the area of main auroral oval in the South and the main spot of the Io footprint in the North. We detected and assigned 18 emission lines of the H$_{3}^{+}$, 2$\nu_{2}\rightarrow 0$ overtone band in the region from 4800 to 4980 cm$^{-1}$ and 5 additional lines in the extended low-resolution spectrum. We use our new modelling scheme, ATMOF to remove telluric absorption bands of CO$_2$ that feature strongly in the 2 $\mu$m region. The H${_2}$ 1-0 S(1), S(2) and S(3) emission lines are also detected in the observed spectral region. We found the rotational temperature and column density of H$_{3}^{+}$ emission at the peak intensity for both northern and southern auroral regions to be the same within the measurement errors (T$_{rot} \sim950$K and N(H$_{3}^{+}$) $\sim$ 4.5$\times10^{16}$m$^{-2}$). The estimates of T$_{rot}$ from H$_{2}$ are consistent within much higher uncertainties with temperatures derived from H$_{3}^{+}$ emissions. We derived the profiles of the H$_{3}^{+}$ emissivity and ion density for both auroral regions providing the first such measurement for the emission associated with the main spot of the Io footprint. We also found a number of weaker lines in the high-resolution spectra that could be associated with emission from high excitation levels in neutral iron, which could be deposited in Jupiter's atmosphere as a result of meteor ablation.

astro-ph.EP

The Anglo-Australian Planet Search XXV: A Candidate Massive Saturn Analog Orbiting HD 30177

We report the discovery of a second long-period giant planet orbiting HD 30177, a star previously known to host a massive Jupiter analog (HD 30177b: a=3.8$\pm$0.1 au, m sin $i=9.7\pm$0.5 Mjup). HD 30177c can be regarded as a massive Saturn analog in this system, with a=9.9$\pm$1.0 au and m sin $i=7.6\pm$3.1 Mjup. The formal best fit solution slightly favours a closer-in planet at $a\sim$7 au, but detailed n-body dynamical simulations show that configuration to be unstable. A shallow local minimum of longer-period, lower-eccentricity solutions was found to be dynamically stable, and hence we adopt the longer period in this work. The proposed $\sim$32 year orbit remains incomplete; further monitoring of this and other stars is necessary to reveal the population of distant gas giant planets with orbital separations $a\sim$10 au, analogous to that of Saturn.

astro-ph.EP

HATS-31b Through HATS-35b: Five Transiting Hot Jupiters Discovered by the HATSouth Survey

We report the discovery of five new transiting hot Jupiter planets discovered by the HATSouth survey: HATS-31b through HATS-35b. These planets orbit moderately bright stars with V magnitudes within the range 11.9-14.4mag while the planets span a range of masses 0.88-1.22MJ, and have somewhat inflated radii between 1.23-1.64RJ.These planets can be classified as typical hot Jupiters, with HATS-31b and HATS-35b being moderately inflated gas giant planets with radii of $1.64 \pm 0.22$ RJ and 1.464+0.069-0.044RJ, respectively, that can be used to constrain inflation mechanisms. All five systems present a higher Bayesian evidence for a fixed circular orbit model than for an eccentric orbit. The orbital periods range from $1.8209993 \pm 0.0000016$ day for HATS-35b) to $3.377960 \pm 0.000012$ day for HATS-31b. Additionally, HATS-35b orbits a relatively young F star with an age of $2.13 \pm 0.51$ Gyr. We discuss the analysis to derive the properties of these systems and compare them in the context of the sample of well characterized transiting hot Jupiters known to date.

astro-ph.EP

Polarization measurements of hot dust stars and the local interstellar medium

Debris discs are typically revealed through excess emission at infrared wavelengths. Most discs exhibit excess at mid- and far-infrared wavelengths, analogous to the solar system's Asteroid and Edgeworth-Kuiper belts. Recently, stars with strong (1 per cent) excess at near-infrared wavelengths were identified through interferometric measurements. Using the HIgh Precision Polarimetric Instrument (HIPPI), we examined a sub-sample of these hot dust stars (and appropriate controls) at parts-per-million sensitivity in SDSS g' (green) and r' (red) filters for evidence of scattered light. No detection of strongly polarized emission from the hot dust stars is seen. We therefore rule out scattered light from a normal debris disk as the origin of this emission. A wavelength dependent contribution from multiple dust components for hot dust stars is inferred from the dispersion (difference in polarization angle in red and green) of southern stars. Contributions of 17 ppm (green) and 30 ppm (red) are calculated, with strict 3 sigma upper limits of 76 and 68 ppm, respectively. This suggests weak hot dust excesses consistent with thermal emission, although we cannot rule out contrived scenarios, e.g. dust in a spherical shell or face on discs. We also report on the nature of the local interstellar medium, obtained as a byproduct of the control measurements. Highlights include the first measurements of the polarimetric colour of the local interstellar medium and discovery of a southern sky region with a polarization per distance thrice the previous maximum. The data suggest the wavelength of maximum polarization is bluer than typical.

astro-ph.EP

Simultaneous infrared and optical observations of the transiting debris cloud around WD 1145+017

We present multi-wavelength photometric monitoring of WD 1145+017, a white dwarf exhibiting periodic dimming events interpreted to be the transits of orbiting, disintegrating planetesimals. Our observations include the first set of near-infrared light curves for the object, obtained on multiple nights over the span of one month, and recorded multiple transit events with depths varying between ~20 to 50 per cent. Simultaneous near-infrared and optical observations of the deepest and longest duration transit event were obtained on two epochs with the Anglo-Australian Telescope and three optical facilities, over the wavelength range of 0.5 to 1.2 microns. These observations revealed no measurable difference in transit depths for multiple photometric pass bands, allowing us to place a 2 sigma lower limit of 0.8 microns on the grain size in the putative transiting debris cloud. This conclusion is consistent with the spectral energy distribution of the system, which can be fit with an optically thin debris disc with minimum particle sizes of 10 +5/-3 microns.

astro-ph.EP

The Anglo-Australian Planet Search XXIV: The Frequency of Jupiter Analogs

We present updated simulations of the detectability of Jupiter analogs by the 17-year Anglo-Australian Planet Search. The occurrence rate of Jupiter-like planets that have remained near their formation locations beyond the ice line is a critical datum necessary to constrain the details of planet formation. It is also vital in our quest to fully understand how common (or rare) planetary systems like our own are in the Galaxy. From a sample of 202 solar-type stars, and correcting for imperfect detectability on a star-by-star basis, we derive a frequency of $6.2^{+2.8}_{-1.6}$% for giant planets in orbits from 3-7 AU. When a consistent definition of "Jupiter analog" is used, our results are in agreement with those from other legacy radial velocity surveys.

astro-ph.EP