Mapping Exoplanets

The varied surfaces and atmospheres of planets make them interesting places to live, explore, and study from afar. Unfortunately, the great distance to exoplanets makes it impossible to resolve their disk with current or near-term technology. It is still possible, however, to deduce spatial inhomogeneities in exoplanets provided that different regions are visible at different times---this can be due to rotation, orbital motion, and occultations by a star, planet, or moon. Astronomers have so far constructed maps of thermal emission and albedo for short period giant planets. These maps constrain atmospheric dynamics and cloud patterns in exotic atmospheres. In the future, exo-cartography could yield surface maps of terrestrial planets, hinting at the geophysical and geochemical processes that shape them.Comment: Updated chapter for Handbook of Exoplanets, eds. Deeg & Belmonte. 17 pages, including 6 figures and 4 pages of reference

Exoplanet phase curves: observations and theory

Phase curves are the best technique to probe the three dimensional structure of exoplanets' atmospheres. In this chapter we first review current exoplanets phase curve observations and the particular challenges they face. We then describe the different physical mechanisms shaping the atmospheric phase curves of highly irradiated tidally locked exoplanets. Finally, we discuss the potential for future missions to further advance our understanding of these new worlds.Comment: Fig.5 has been updated. Table 1 and corresponding figures have been updated with new values for WASP-103b and WASP-18b. Contains a table sumarizing phase curve observation

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified

Photoionization and photofragmentation of the C60+ molecular ion

Cross-section measurements are reported for single and double photoionization of C60+ ions in the photon energy range 18-150 eV accompanied by the loss of zero to seven pairs of carbon atoms, as well as for fragmentation without ionization resulting in loss of two to eight pairs of C atoms in the photon energy range 18-65 eV. Absolute measurements were performed by merging a beam of C60+ molecular ions with a beam of monochromatized synchrotron radiation. Product channels involving dissociation yielding smaller fullerene fragment ions account for nearly half of the total measured oscillator strength in this energy range. The sum of cross sections for the measured product channels is compared to a published calculation of the total photoabsorption cross section of neutral C60 based on time-dependent density-functional theory. This comparison and an accounting of oscillator strengths indicate that with the exception of C58+, the most important product channels resulting from photoabsorption were accounted for in the experiment. Threshold energies for the successive removal of carbon atom pairs accompanying photoionization are also determined from the measurements

Cross sections for photoionization of fullerene molecular ions Cn+ with n = 40, 50, 70, 76, 78, and 84

© 2017 American Physical Society. Absolute cross-section measurements are reported for single photoionization of Cn+ fullerene molecular ions (n=40, 50, 70, 76, 78, and 84) in the photon-energy range 18-70 eV. The experiments were performed by merging a mass and charge selected beam of Cn+ molecular ions with a beam of monochromatized synchrotron radiation and measuring the yield of Cn2+ product ions as a function of the photon energy. Oscillator strengths determined by integrating the measured cross sections over this energy range exhibit a linear dependence on n. The cross sections are parametrized by fits to three Lorentzian functions to represent plasmon excitations and a linear function for direct ionization. The highest-energy resonance in the data near 46 eV is similar to that previously observed in single photoionization of C60 and may be attributable to a harmonic of the dominant surface-plasmon resonance near 23 eV

Cross sections for photoionization of fullerene molecular ions Cn+ with n = 40, 50, 70, 76, 78, and 84

© 2017 American Physical Society. Absolute cross-section measurements are reported for single photoionization of Cn+ fullerene molecular ions (n=40, 50, 70, 76, 78, and 84) in the photon-energy range 18-70 eV. The experiments were performed by merging a mass and charge selected beam of Cn+ molecular ions with a beam of monochromatized synchrotron radiation and measuring the yield of Cn2+ product ions as a function of the photon energy. Oscillator strengths determined by integrating the measured cross sections over this energy range exhibit a linear dependence on n. The cross sections are parametrized by fits to three Lorentzian functions to represent plasmon excitations and a linear function for direct ionization. The highest-energy resonance in the data near 46 eV is similar to that previously observed in single photoionization of C60 and may be attributable to a harmonic of the dominant surface-plasmon resonance near 23 eV