Many problems in the experimental estimation of parameters for models can be solved through use of the likelihood ratio test. Applications of the likelihood ratio, with particular attention to photon counting experiments, are discussed. The procedures presented solve a greater range of problems than those currently in use, yet are no more difficult to apply. The procedures are proved analytically, and examples from current problems in astronomy are discussed.

Parameter estimation in astronomy through application of the likelihood ratio. [satellite data analysis techniques

Data Reduction And Error Analysis For The Physical Sciences

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Radiative Processes In Astrophysics

High-contrast adaptive optics imaging is a powerful technique to probe the architectures of planetary systems from the outside-in and survey the atmospheres of self-luminous giant planets. Direct imaging has rapidly matured over the past decade and especially the last few years with the advent of high-order adaptive optics systems, dedicated planet-finding instruments with specialized coronagraphs, and innovative observing and post-processing strategies to suppress speckle noise. This review summarizes recent progress in high-contrast imaging with particular emphasis on observational results, discoveries near and below the deuterium-burning limit, and a practical overview of large-scale surveys and dedicated instruments. I conclude with a statistical meta-analysis of deep imaging surveys in the literature. Based on observations of 384 unique and single young ($\approx$5--300~Myr) stars spanning stellar masses between 0.1--3.0~\Msun, the overall occurrence rate of 5--13~\Mjup \ companions at orbital distances of 30--300~AU is 0.6$^{+0.7}_{-0.5}$\% assuming hot-start evolutionary models. The most massive giant planets regularly accessible to direct imaging are about as rare as hot Jupiters are around Sun-like stars. Dividing this sample into individual stellar mass bins does not reveal any statistically-significant trend in planet frequency with host mass: giant planets are found around 2.8$^{+3.7}_{-2.3}$\% of BA stars, $<$4.1\% of FGK stars, and $<$3.9\% of M dwarfs. Looking forward, extreme adaptive optics systems and the next generation of ground- and space-based telescopes with smaller inner working angles and deeper detection limits will increase the pace of discovery to ultimately map the demographics, composition, evolution, and origin of planets spanning a broad range of masses and ages.

https://iopscience.iop.org/article/10.1088/1538-3873/128/968/102001/pdf

Imaging Extrasolar Giant Planets

With the advent of the Heliophysics/Geospace System Observatory (H/GSO), a complement of multi-spacecraft missions and ground-based observatories to study the space environment, data retrieval, analysis, and visualization of space physics data can be daunting. The Space Physics Environment Data Analysis System (SPEDAS), a grass-roots software development platform (
 www.spedas.org
 ), is now officially supported by NASA Heliophysics as part of its data environment infrastructure. It serves more than a dozen space missions and ground observatories and can integrate the full complement of past and upcoming space physics missions with minimal resources, following clear, simple, and well-proven guidelines. Free, modular and configurable to the needs of individual missions, it works in both command-line (ideal for experienced users) and Graphical User Interface (GUI) mode (reducing the learning curve for first-time users). Both options have “crib-sheets,” user-command sequences in ASCII format that can facilitate record-and-repeat actions, especially for complex operations and plotting. Crib-sheets enhance scientific interactions, as users can move rapidly and accurately from exchanges of technical information on data processing to efficient discussions regarding data interpretation and science. SPEDAS can readily query and ingest all International Solar Terrestrial Physics (ISTP)-compatible products from the Space Physics Data Facility (SPDF), enabling access to a vast collection of historic and current mission data. The planned incorporation of Heliophysics Application Programmer’s Interface (HAPI) standards will facilitate data ingestion from distributed datasets that adhere to these standards. Although SPEDAS is currently Interactive Data Language (IDL)-based (and interfaces to Java-based tools such as Autoplot), efforts are under-way to expand it further to work with python (first as an interface tool and potentially even receiving an under-the-hood replacement). We review the SPEDAS development history, goals, and current implementation. We explain its “modes of use” with examples geared for users and outline its technical implementation and requirements with software developers in mind. We also describe SPEDAS personnel and software management, interfaces with other organizations, resources and support structure available to the community, and future development plans.

/pdf/the-space-physics-environment-data-analysis-system-spedas-dm12usgumn.pdf

The Space Physics Environment Data Analysis System (SPEDAS)

DH Cephei is a prominent O+O-type binary system in the NGC 7380 open cluster. Our high-precision multi-band polarimetry demonstrates synchronous linear polarization variations with the orbital period. Using Stokes parameters, we derived the binary system's orbital inclination, orientation, and rotation direction. To estimate interstellar polarization, we observed neighboring stars in NGC 7380. Utilizing Dipol-2 polarimeter and T60 telescope, we measured linear polarization in the $B$, $V$, and $R$ bands with $\sim$0.003% accuracy. Lomb-Scargle period search revealed a dominant frequency at 1.055 d, corresponding to half of the 2.11 d orbital period. The $B$ passband showed a non-periodic component, while the $V$ passband provided reliable values for inclination ($46^{\circ}+11^{\circ}/-46^{\circ}$) and orbital orientation ($\Omega = 105^{\circ} \pm 55^{\circ}$). Using these values, we estimated a mass loss of $\sim$$3.4 \times 10^{-7}M_{\rm \odot} ; \rm yr^{-1}$. The binary system's rotation on the sky is clockwise. Polarimetric observations of neighboring stars indicate interstellar dust causing cluster star polarization.

High-precision broadband linear polarimetry of early-type binaries IV. Binary system of DH Cephei in the open cluster of NGC 7380

Comparative study of optical designs of ultraviolet spectrometers onboard spaceborne telescopes

The fact that the O-type close binary star system AO~Cassiopeiae exhibits variable phase-locked linear polarization has been known since the mid-1970s. In this work, we re-observe the polarization arising from this system more than 50 years later to better estimate the interstellar polarization and to independently derive the orbital parameters, such as inclination, $i$, orientation, $\Omega$, and the direction of the rotation for the inner orbit from the phase-folded polarization curves of the Stokes $q$ and $u$ parameters. The Dipol-2 polarimeter was used to obtain linear polarization measurements of AO~Cassiopeiae in the $B$, $V$, and $R$ passbands with the T60 remotely controlled telescope at an unprecedented accuracy level of $\sim$0.003\%. We have obtained the first proper quantification of the interstellar polarization in the direction heading towards AO~Cas by observing the polarization of three neighboring field stars. We employed a Lomb-Scargle algorithm and detected a clear periodic signal for the orbital period of AO~Cas. The standard analytical method based on a two-harmonics Fourier fit was used to obtain the inclination and orientation of the binary orbit. Our polarimetric data exhibited an unambiguous periodic signal at 1.76 days, thus confirming the orbital period of the binary system of 3.52 days. Most of the observed polarization is of interstellar origin. The de-biased values of the orbital inclination are $i = 63^{\circ} +2^{\circ}/ -3^{\circ}$ and orientation of $\Omega = 29^{\circ} (209^{\circ}) \pm 8^{\circ}$. The direction of the binary system rotation on the plane of the sky is clockwise.

/pdf/high-precision-broadband-linear-polarimetry-of-early-type-2t5ao0yo.pdf

High-precision broadband linear polarimetry of early-type binaries. III. AO Cassiopeiae revisited

The presence of the dawn‐to‐dusk electric field of about 4 mV/m in the Jovian inner magnetosphere and its response to the enhancement of the solar wind dynamic pressure are still a mystery of the rotation‐dominated Jovian magnetosphere. Previous studies have suggested that magnetosphere‐ionosphere (M‐I) coupling via Region 2‐like (R2‐like) field‐aligned current (FAC) could be the origin of the Jovian dawn‐to‐dusk electric field. This study investigates whether the dawn‐to‐dusk electric field is formed from this scenario by using a Jovian ionosphere model and a two‐dimensional ionospheric potential solver. Our results show that the dawn‐dusk asymmetry in the ionospheric potential form even at middle latitudes and that the dawn‐to‐dusk electric field is induced in the inner magnetosphere if the electric potential is mapped to the magnetospheric equatorial plane. Around the Io orbit, the calculated electric field strength for the ionosphere without meteoroid influx is too large, 200 mV/m at dawn and 88 mV/m at dusk. One of the solutions is to consider long‐lived meteoric ions in the Jovian ionosphere, which reduce the electric field strength to 15 mV/m at dawn and 12 mV/m at dusk. The model also shows that the electric field strength increases with the intensity of R2‐like FAC, consistent with its response to the solar wind dynamic pressure observed by the Hisaki satellite.

Masato Kagitani

Papers

High-precision broadband linear polarimetry of early-type binaries IV. Binary system of DH Cephei in the open cluster of NGC 7380

Comparative study of optical designs of ultraviolet spectrometers onboard spaceborne telescopes

High-precision broadband linear polarimetry of early-type binaries. III. AO Cassiopeiae revisited

Simulation of Dawn‐To‐Dusk Electric Field in the Jovian Inner Magnetosphere via Region 2‐Like Field‐Aligned Current

time variation of 130.4nm atomic oxygen emission near Io observed by hisaki/EXCEED