Abstract We present the first results of the JWST program PROJECT-J (PROtostellar JEts Cradle Tested with JWST), designed to study the Class I source HH46 IRS and its outflow through NIRSpec and MIRI ...spectroscopy (1.66–28 μ m). The data provide line images (∼6.″6 in length with NIRSpec, and up to ∼20″ with MIRI) revealing unprecedented details within the jet, the molecular outflow, and the cavity. We detect, for the first time, the redshifted jet within ∼90 au from the source. Dozens of shock-excited forbidden lines are observed, including highly ionized species such as Ne iii 15.5 μ m, suggesting that the gas is excited by high velocity (>80 km s −1 ) shocks in a relatively high-density medium. Images of H 2 lines at different excitations outline a complex molecular flow, where a bright cavity, molecular shells, and a jet-driven bow shock interact with and are shaped by the ambient conditions. Additional NIRCam 2 μ m images resolve the HH46 IRS ∼110 au binary system and suggest that the large asymmetries observed between the jet and the H 2 wide-angle emission could be due to two separate outflows being driven by the two sources. The spectra of the unresolved binary show deep ice bands and plenty of gaseous lines in absorption, likely originating in a cold envelope or disk. In conclusion, JWST has unraveled for the first time the origin of the HH46 IRS complex outflow demonstrating its capability to investigate embedded regions around young stars, which remain elusive even at near-IR wavelengths.
Nematicity, defined as broken rotational symmetry, has recently been observed in competing phases proximate to the superconducting phase in the cuprate high-temperature superconductors. Similarly, ...the new iron-based high-temperature superconductors exhibit a tetragonal-to-orthorhombic structural transition (i.e., a broken C₄ symmetry) that either precedes or is coincident with a collinear spin density wave (SDW) transition in undoped parent compounds, and superconductivity arises when both transitions are suppressed via doping. Evidence for strong in-plane anisotropy in the SDW state in this family of compounds has been reported by neutron scattering, scanning tunneling microscopy, and transport measurements. Here, we present an angle-resolved photoemission spectroscopy study of detwinned single crystals of a representative family of electron-doped iron-arsenide superconductors, Ba(Fe1-xCox)₂As₂ in the underdoped region. The crystals were detwinned via application of in-plane uniaxial stress, enabling measurements of single domain electronic structure in the orthorhombic state. At low temperatures, our results clearly demonstrate an in-plane electronic anisotropy characterized by a large energy splitting of two orthogonal bands with dominant dxz and dyz character, which is consistent with anisotropy observed by other probes. For compositions x > 0, for which the structural transition (Ts) precedes the magnetic transition (TSDW), an anisotropic splitting is observed to develop above TSDW, indicating that it is specifically associated with TS. For unstressed crystals, the band splitting is observed close to Ts. whereas for stressed crystals, the splitting is observed to considerably higher temperatures, revealing the presence of a surprisingly large in-plane nematic susceptibility in the electronic structure.
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We present the results of a radial velocity survey of young stellar objects (YSOs) in early stages of evolution in the core of the L1688 molecular cloud. New and archival spectra obtained with four ...high-resolution infrared spectrographs were analyzed using Markov chain Monte Carlo techniques that simultaneously fit for the radial velocity, Teff, v sin i, and veiling by comparison with synthetic spectra. The radial velocity distribution for 32 objects, most with Class I or flat-spectrum spectral energy distributions, is marginally Gaussian, with a higher dispersion relative to optical surveys at the 2 level. When comparing the results from both proper-motion and radial velocity surveys in L1688, there is a trend for the 1D dispersions to be higher for samples of Class I/flat-spectrum YSOs that reside in the cloud core compared to Class II/III dominated samples, which are located in the lower extinction periphery. In addition, there is a velocity gradient along the major axis of the cloud core that appears more pronounced than that derived from optically visible objects at the cloud edges. If these higher dispersions for Class I/flat-spectrum objects are confirmed by future surveys, this could imply a supervirial state for the less evolved objects in the cloud core and be a signature of the initial collapse and rebound of the cluster as suggested by recent simulations of cluster evolution.
We present a model for the rotational evolution of a young, solar mass star interacting with an accretion disk. The model incorporates a description of the angular momentum transfer between the star ...and the disk due to a magnetic connection, and includes changes in the star's mass and radius and a decreasing accretion rate. The model also includes, for the first time in a spin evolution model, the opening of the stellar magnetic field lines, as expected to arise from twisting via star-disk differential rotation. In order to isolate the effect that this has on the star-disk interaction torques, we neglect the influence of torques that may arise from open field regions connected to the star or disk. For a range of magnetic field strengths, accretion rates, and initial spin rates, we compute the stellar spin rates of pre-main-sequence stars as they evolve on the Hayashi track to an age of 3 Myr. How much the field opening affects the spin depends on the strength of the coupling of the magnetic field to the disk. For the relatively strong coupling (i.e., high magnetic Reynolds number) expected in real systems, all models predict spin periods of less than {approx}3 days, in the age range of 1-3 Myr. Furthermore, these systems typically do not reach an equilibrium spin rate within 3 Myr, so that the spin at any given time depends upon the choice of initial spin rate. This corroborates earlier suggestions that, in order to explain the full range of observed rotation periods of approximately 1-10 days, additional processes, such as the angular momentum loss from powerful stellar winds, are necessary.
We present new observations of the multiplanet system HIP 41378, a bright star (V = 8.9, Ks = 7.7) with five known transiting planets. Previous K2 observations showed multiple transits of two ...Neptune-sized bodies and single transits of three larger planets (RP = 0.33RJ, 0.47RJ, 0.88RJ). K2 recently observed the system again in Campaign 18 (C18). We observe one new transit each of two of the larger planets d/f, giving maximal orbital periods of 1114/1084 days, as well as integer divisions of these values down to a lower limit of about 50 days. We use all available photometry to determine the eccentricity distributions of HIP 41378 d & f, finding that periods 300 days require non-zero eccentricity. We check for overlapping orbits of planets d and f to constrain their mutual periods, finding that short periods (P < 300 days) for planet f are disfavored. We also observe transits of planets b and c with Spitzer/Infrared Array Camera (IRAC), which we combine with the K2 observations to search for transit timing variations (TTVs). We find a linear ephemeris for planet b, but see a significant TTV signal for planet c. The ability to recover the two smaller planets with Spitzer shows that this fascinating system will continue to be detectable with Spitzer, CHEOPS, TESS, and other observatories, allowing us to precisely determine the periods of d and f, characterize the TTVs of planet c, recover the transits of planet e, and further enhance our view of this remarkable dynamical laboratory.
Abstract
We report observations of the recently discovered warm Neptune TOI-674 b (5.25
R
⊕
, 23.6
M
⊕
) with the Hubble Space Telescope’s Wide Field Camera 3 instrument. TOI-674 b is in the Neptune ...desert, an observed paucity of Neptune-size exoplanets at short orbital periods. Planets in the desert are thought to have complex evolutionary histories due to photoevaporative mass loss or orbital migration, making identifying the constituents of their atmospheres critical to understanding their origins. We obtained near-infrared transmission spectroscopy of the planet’s atmosphere with the G141 grism. After extracting, detrending, and fitting the spectral light curves to measure the planet’s transmission spectrum, we used the petitRADTRANS atmospheric spectral synthesis code to perform retrievals on the planet’s atmosphere to identify which absorbers are present. These results show moderate evidence for increased absorption at 1.4
μ
m due to water vapor at 2.9
σ
(Bayes factor = 15.8), as well as weak evidence for the presence of clouds at 2.2
σ
(Bayes factor = 4.0). TOI-674 b is a strong candidate for further study to refine the water abundance, which is poorly constrained by our data. We also incorporated new TESS short-cadence optical photometry, as well as Spitzer/IRAC data, and refit the transit parameters for the planet. We find the planet to have the following transit parameters:
R
p
/
R
*
= 0.1135 ± 0.0006,
T
0
= 2458544.523792 ± 0.000452 BJD, and
P
= 1.977198 ± 0.00007 day. These measurements refine the planet radius estimate and improve the orbital ephemerides for future transit spectroscopy observations of this highly intriguing warm Neptune.
We present the results of a program that monitored the near-IR spectroscopic variability of a sample of 19 embedded protostars. We found that the spectra of all targets are variable and that every ...emission feature observed is also variable (although not for all targets). This analysis focuses on understanding the connection between accretion (traced by H Br gamma and CO) and the wind (traced by He I, FeII, and sometimes H sub(2)). For both accretion and wind tracers, the median variability was constant versus the time interval between observations; however, the maximum variability that we observed increased with the time interval between observations. The variability of Br gamma , FeII, and H sub(2) always lies on a plane, although the orientation of the plane in three dimensions depends on the target. While we do not understand all interactions behind the variability that we observed, we have shown that spectroscopic variability is a powerful tool toward understanding the star formation process.
Our Interprofessional Education and Collaborative Practice (IPECP) Nexus previously reported significant reductions in Emergency Department (ED) visits, hospitalizations, hemoglobin A1c levels, and ...patient charges. This study examines sustainability of these results over two additional years and replication in two subsequent independent patient cohorts. Participants in the sustainability cohort (N = 276) met ≥1 of the following criteria: (a) ≥3 ED visits in first or second half of the year, (b) hemoglobin A1c level ≥ 9, or (c) Length of Stay, Acuity, Comorbidities, and ER (Emergency Room) Visits (LACE) score ≥ 10. Participants in two replicability cohorts (N = 255) and (N = 160) met the same criteria, but the LACE criterion was changed to ≥3 hospitalizations in baseline years. The Nexus, housed in a family medicine (FM) residency clinic, included professionals and students from multiple disciplines. IPECP skills and interventions included communication, team building, and conflict engagement skills training, daily huddles and pre-visit planning, immediate consultations, small teamlet IPECP interactions, and weekly IPECP case conferences for complex patients. Original health improvements and charge reductions were sustained for two additional years for ED visits, hospitalizations, A1c, and patient charges, and replicated in two additional patient cohorts. The IPECP Nexus interventions were associated with Quadruple Aim outcomes while training the next generation of health care professionals.
Abstract
We use JWST NIRCam short-wavelength photometry to capture a transit lightcurve of the exoplanet HAT-P-14 b to assess performance as part of instrument commissioning. The short-wavelength ...precision is 152 ppm per 27 s integration as measured over the full time series compared to a theoretical limit of 107 ppm, after corrections to spatially correlated 1/f noise. Persistence effects from charge trapping are well fit by an exponential function with short characteristic timescales, settling on the order of 5–15 minutes. The short-wavelength defocused photometry is also uniquely well suited to measure the real-time wave-front error of JWST. Analysis of the images and reconstructed wave-front maps indicates that two different hexagonal primary mirror segments exhibited “tilt events,” where they changed orientation rapidly in less than ∼1.4 s. In some cases, the magnitude and timing of the flux jumps caused by tilt events can be accurately predicted with a telescope model. These tilt events can be sensed by simultaneous longer-wavelength NIRCam grism spectral images alone in the form of changes to the point-spread function, diagnosed from the full width at half maximum. They can also be sensed with the fine guidance sensor instrument from difference images. Tilt events possibly from sudden releases of stress in the backplane structure behind the mirrors were expected during the commissioning period because they were found in ground-based testing. Tilt events have shown signs of decreasing in frequency but have not disappeared completely. The detectors exhibit some minor (less than 1%) deviations from linear behavior in the first few groups of each integration, potentially impacting absolute fluxes and transit depths on bright targets, where only a handful of groups are possible. Overall, the noise is within 50% of the theoretical photon noise and read noise. This bodes well for high-precision measurements of transiting exoplanets and other time variable targets.
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