We present radial velocities and metallicities for a sample of 39 open clusters with ages greater than about 700 million years. For 24 clusters new moderate-resolution spectroscopic data obtained with multiobject spectrographs on the Kitt Peak National Observatory and the Cerro Tololo Inter-American Observatory 4 m telescopes are used to determine radial velocities and mean cluster metallicities. These new results are combined with data published previously by Friel & Janes to provide a sample of 459 giants in 39 old open clusters, which are used to investigate radial abundance gradients in the Galactic disk. Based on an updated abundance calibration of spectroscopic indices measuring Fe and Fe-peak element blends, this larger sample yields an abundance gradient of À0.06 AE 0.01 dex kpc À1 over a range in Galactocentric radius of 7 to 16 kpc. There is a slight suggestion of a steepening of the abundance gradient with increasing cluster age in this sample, but the significance of the result is limited by the restricted distance range for the youngest clusters. The clusters show no correlation of metallicity with age in the solar neighborhood. Consistent with the evidence for a steepening of the gradient with age, the clusters in the outer disk beyond 10 kpc show a suggestion at the 1.5 level of a dependence of metallicity on age.

RIP1 regulates necroptosis and inflammation and may play an important role in contributing to a variety of human pathologies, including immune-mediated inflammatory diseases. Small-molecule inhibitors of RIP1 kinase that are suitable for advancement into the clinic have yet to be described. Herein, we report our lead optimization of a benzoxazepinone hit from a DNA-encoded library and the discovery and profile of clinical candidate GSK2982772 (compound 5), currently in phase 2a clinical studies for psoriasis, rheumatoid arthritis, and ulcerative colitis. Compound 5 potently binds to RIP1 with exquisite kinase specificity and has excellent activity in blocking many TNF-dependent cellular responses. Highlighting its potential as a novel anti-inflammatory agent, the inhibitor was also able to reduce spontaneous production of cytokines from human ulcerative colitis explants. The highly favorable physicochemical and ADMET properties of 5, combined with high potency, led to a predicted low oral dose in humans.

We report on a 67 ks High-Energy Transmission Grating observation of the optically brightest early O star z Puppis (O4 f). Many resolved X-ray lines are seen in the spectra over a wavelength range of 5-25 Å . Chandra has sufficient spectral resolution to study the velocity structure of isolated X-ray line profiles and to distinguish the individual forbidden, intercombination, and resonance (fir) emission lines in several He-like ions, even where the individual components are strongly Doppler-broadened. In contrast to X-ray line profiles in other hot stars, z Pup shows blueshifted and skewed line profiles, providing the clearest and most direct evidence that the Xray sources are embedded in the stellar wind. The broader the line, the greater the blueward centroid shift tends to be. The N vii line at 24.78 Å is a special case, showing a flat-topped profile. This indicates that it is formed in regions beyond most of the wind attenuation. The sensitivity of the He-like ion fir lines to a strong UV radiation field is used to derive the radial distances at which lines of S xv, Si xiii, Mg xi, Ne ix, and O vii originate. The formation radii correspond well with a continuum optical depth of unity at the wavelength of each line complex, indicating that the X-ray line emission is distributed throughout the stellar wind. However, the S xv emission lines form deeper in the wind than expected from standard wind-shock models.

The Chandra spectrum of Ori A shows emission lines from hydrogen-and helium-like states of Si, Mg, Ne, and O, along with N vii Ly and lines from ions in the range Fe xvii-Fe xxi. In contrast to the broad lines seen in Pup and Ori (850 AE 40 and 1000 AE 240 km s À1 half-width at half-maximum [HWHM], respectively), these lines are broadened to only 430 AE 60 km s À1 HWHM. This is much lower than the measured wind terminal velocity of 2000 km s À1. The forbidden, intercombination, and resonance (fir) lines from He-like ions indicate that the majority of the X-ray line emission does not originate at the base of the wind, in agreement with the standard wind shock models for these objects. However, in that model the X-ray emission is distributed throughout an expanding, X-ray-absorbing wind, and it is therefore surprising that the emission lines appear relatively narrow, unshifted, and symmetric. We compare the observed line profiles to recent detailed models for X-ray line profile generation in hot stars, but none of them offers a fully satisfactory explanation for the observed line profiles.

Despite extensive study, the mechanisms by which Be star disks acquire high densities and angular momentum while displaying variability on many timescales are still far from clear. In this paper, we discuss how magnetic torquing may help explain disk formation with the observed quasi-Keplerian (as opposed to expanding) velocity structure and their variability. We focus on the effects of the rapid rotation of Be stars, considering the regime where centrifugal forces provide the dominant radial support of the disk material. Using a kinematic description of the angular velocity, v ðrÞ, in the disk and a parametric model of an aligned field with a strength BðrÞ, we develop analytic expressions for the disk properties that allow us to estimate the stellar surface field strength necessary to create such a disk for a range of stars on the main sequence. The fields required to form a disk are compared with the bounds previously derived from photospheric limiting conditions. The model explains why disks are most common for main-sequence stars at about spectral class B2 V. The earlier type stars with very fast and high-density winds would require unacceptably strong surface fields (>10 3 G) to form torqued disks, while the late B stars (with their low mass-loss rates) tend to form disks that produce only small fluxes in the dominant Be diagnostics. For stars at B2 V the average surface field required is about 300 G. The predicted disks provide an intrinsic polarization and a flux at H comparable to observations. The radial extent of our dense quasi-Keplerian disks is compatible with typical estimates. We also discuss whether the effect on field containment of the time-dependent accumulation of matter in the flux tubes/disk can help explain some of the observed variability of Be star disks.