Fire is a crucial event regulating the structure and functioning of many ecosystems. Yet few studies have focused on how fire affects taxonomic and functional diversities of soil microbial communities, along with changes in plant communities and soil carbon (C) and nitrogen (N) dynamics. Here, we analyze these effects in a grassland ecosystem 9 months after an experimental fire at the Jasper Ridge Global Change Experiment site in California, USA. Fire altered soil microbial communities considerably, with community assembly process analysis showing that environmental selection pressure was higher in burned sites. However, a small subset of highly connected taxa was able to withstand the disturbance. In addition, fire decreased the relative abundances of most functional genes associated with C degradation and N cycling, implicating a slowdown of microbial processes linked to soil C and N dynamics. In contrast, fire stimulated above- and belowground plant growth, likely enhancing plant-microbe competition for soil inorganic N, which was reduced by a factor of about 2. To synthesize those findings, we performed structural equation modeling, which showed that plants but not microbial communities were responsible for significantly higher soil respiration rates in burned sites. Together, our results demonstrate that fire 'reboots' the grassland ecosystem by differentially regulating plant and soil microbial communities, leading to significant changes in soil C and N dynamics.

A method for measuring oxygen abundances using optical and far-infrared emission lines provides absolute metallicities of the interstellar gas in Markarian 71 and could be applied across cosmic history.

We describe new JWST/NIRSpec observations of galaxies at z greater than or similar to 7 taken from the CEERS survey. Previous observations of this area have revealed associations of Ly alpha emitters at redshifts (z = 7.5, 7.7, and 8.7) where the intergalactic medium (IGM) is thought to be mostly neutral, leading to suggestions that these systems are situated in large ionized bubbles. We identify 21 z greater than or similar to 7 galaxies with robust redshifts in the CEERS data set, including 10 in the Ly alpha associations. Their spectra are indicative of very highly ionized and metal poor gas, with line ratios (O32 = 17.84 and Ne3O2 = 0.89, linear scale) and metallicity (12 + log (O/H) = 7.84) that are rarely seen at lower redshifts. We find that the most extreme spectral properties are found in the six z greater than or similar to 7 Ly alpha emitters in the sample. Each has a hard ionizing spectrum indicating that their visibility is likely enhanced by efficient ionizing photon production. Ly alpha velocity offsets are found to be very large (greater than or similar to 300 km s(-1)), likely also contributing to their detectability. We find that Ly alpha in z greater than or similar to 7 galaxies is 6-12 x weaker than in lower redshift samples with matched rest-optical spectral properties. If the bubbles around the Ly alpha emitters are relatively small (less than or similar to 0.5-1 pMpc), we may expect such significant attenuation of Ly alpha in these ionized regions. We discuss several other effects that may contribute to weaker Ly alpha emission at z greater than or similar to 7. Deep spectroscopy of fainter galaxies in the vicinity of the Ly alpha emitters will better characterize the physical scale of the ionized bubbles in this field.

We describe new JWST/NIRSpec observations of galaxies at z greater than or similar to 7 taken from the CEERS survey. Previous observations of this area have revealed associations of Ly alpha emitters at redshifts (z = 7.5, 7.7, and 8.7) where the intergalactic medium (IGM) is thought to be mostly neutral, leading to suggestions that these systems are situated in large ionized bubbles. We identify 21 z greater than or similar to 7 galaxies with robust redshifts in the CEERS data set, including 10 in the Ly alpha associations. Their spectra are indicative of very highly ionized and metal poor gas, with line ratios (O32 = 17.84 and Ne3O2 = 0.89, linear scale) and metallicity (12+log (O/H)=7.84) that are rarely seen at lower redshifts. We find that the most extreme spectral properties are found in the six z greater than or similar to 7 Ly alpha emitters in the sample. Each has a hard ionizing spectrum indicating that their visibility is likely enhanced by efficient ionizing photon production. Ly alpha velocity offsets are found to be very large (greater than or similar to 300 km s(-1)), likely also contributing to their detectability. We find that Ly alpha in z greater than or similar to 7 galaxies is 6-12 x weaker than in lower redshift samples with matched rest-optical spectral properties. If the bubbles around the Ly alpha emitters are relatively small (less than or similar to 0.5-1 pMpc), we may expect such significant attenuation of Ly alpha in these ionized regions. We discuss several other effects that may contribute to weaker Ly alpha emission at z greater than or similar to 7. Deep spectroscopy of fainter galaxies in the vicinity of the Ly alpha emitters will better characterize the physical scale of the ionized bubbles in this field.

Local Volume Mapper Spectrograph Control Package (LVMSCP) is the software that controls three spectrographs to acquire science spectral data cubes automatically. The software architecture design based on Python 3.9 follows a hierarchical structure of Actors, the unit that controls each piece of hardware. We used the software framework Codified Likeness Utility to implement each Actor. The Actors communicate with each other through RabbitMQ, which implements the Advanced Message Queuing Protocol. The Actor applies asynchronous programming with non-blocking procedures as the three spectrographs should operate simultaneously. For the requirement of incremental code change and management in the collaboration of the developers, we adopted the SDSS Github Action, which supports continuous integration/continuous deployment. As a result, unit testing with Pytest tested the individual components of the software, respectively, and lab testing with LVMSCP provided the spectra data for the spectrograph calibration. The LVMSCP provides the application programming interface to the Robotic Observation Package to fulfill the required scientific survey execution for the spectrographs.(c) 2023 Society of Photo-Optical Instrumentation Engineers (SPIE)

We consider the general problem of a Parker-type non-relativistic isothermal wind from a rotating and magnetic star. Using the magnetohydrodynamics code athena++, we construct an array of simulations in the stellar rotation rate omega* and the isothermal sound speed cT, and calculate the mass, angular momentum, and energy loss rates across this parameter space. We also briefly consider the 3D case, with misaligned magnetic and rotation axes. We discuss applications of our results to the spin-down of normal stars, highly irradiated exoplanets, and to nascent highly magnetic and rapidly rotating neutron stars born in massive star core-collapse.

Rapidly rotating magnetars have been associated with gamma-ray bursts (GRBs) and superluminous supernovae (SLSNe). Using a suite of two-dimensional magnetohydrodynamic simulations at fixed neutrino luminosity and a couple of evolutionary models with evolving neutrino luminosity and magnetar spin period, we show that magnetars are viable central engines for powering GRBs and SLSNe. We also present analytical estimates of the energy outflow rate from the proto-neutron star (PNS) as a function of polar magnetic field strength B-0, PNS angular velocity Omega(star), PNS radius R-star, and mass outflow rate (M)over dot. We show that rapidly rotating magnetars with spin periods P-star less than or similar to 4 ms and polar magnetic field strength B-0 greater than or similar to 10(15) G can release 10(50) to 5 x 10(51) erg of energy during the first similar to 2 s of the cooling phase. Based on this result, it is plausible that sustained energy injection by magnetars through the relativistic wind phase can power GRBs. We also show that magnetars with moderate field strengths of B-0 less than or similar to 5 x 10(14) G do not release a large fraction of their rotational kinetic energy during the cooling phase and, hence, are not likely to power GRBs. Although we cannot simulate to times greater than similar to 3-5 s after a supernova, we can hypothesize that moderate field strength magnetars can brighten the supernova light curves by releasing their rotational kinetic energy via magnetic dipole radiation on time-scales of days to weeks, since these do not expend most of their rotational kinetic energy during the early cooling phase.

M dwarfs are common host stars to exoplanets but often lack atmospheric abundance measurements. Late-M dwarfs are also good analogs to the youngest substellar companions, which share similar T-eff similar to 2300-2800 K. We present atmospheric analyses for the M7.5 companion HIP 55507 B and its K6V primary star with Keck/KPIC high-resolution (R similar to 35,000) K-band spectroscopy. First, by including KPIC relative radial velocities between the primary and secondary in the orbit fit, we improve the dynamical mass precision by 60% and find M-B=88.0(-3.2)(+3.4 )M(Jup), putting HIP 55507 B above the stellar-substellar boundary. We also find that HIP 55507 B orbits its K6V primary star with a=38(-3)(+4) au and e = 0.40 +/- 0.04. From atmospheric retrievals of HIP 55507 B, we measure [C/H] = 0.24 +/- 0.13, [O/H] = 0.15 +/- 0.13, and C/O = 0.67 +/- 0.04. Moreover, we strongly detect (CO)-C-13 (7.8 sigma significance) and tentatively detect (H2O)-O-18 (3.7 sigma significance) in the companion's atmosphere and measure (CO)-C-12/(CO)-C-13=98(-22)(+28 )and (H2O)-O-16/(H2O)-O-18=240(-80)(+145) after accounting for systematic errors. From a simplified retrieval analysis of HIP 55507 A, we measure (CO)-C-12/(CO)-C-13=79(-16)(+21) and (CO)-O-16/(CO)-O-18=288(-70)(+125) for the primary star. These results demonstrate that HIP 55507 A and B have consistent C-12/C-13 and O-16/O-18 to the <1 sigma level, as expected for a chemically homogeneous binary system. Given the similar flux ratios and separations between HIP 55507 AB and systems with young substellar companions, our results open the door to systematically measuring (CO)-C-13 and (H2O)-O-18 abundances in the atmospheres of substellar or even planetary-mass companions with similar spectral types.