We have measured the orbital parameters of seven close binaries, including six new objects, in a radial velocity survey of 38 objects comprising a hot subdwarf star with orbital periods ranging from ...∼0.17 to 3 d. One new system, GALEX J2205−3141, shows reflection on an M dwarf companion. Three other objects show significant short-period variations, but their orbital parameters could not be constrained. Two systems comprising a hot subdwarf paired with a bright main-sequence/giant companion display short-period photometric variations possibly due to irradiation or stellar activity and are also short-period candidates. All except two candidates were drawn from a selection of subluminous stars in the Galaxy Evolution Explorer ultraviolet sky survey. Our new identifications also include a low-mass subdwarf B star and likely progenitor of a low-mass white dwarf (GALEX J0805−1058) paired with an unseen, possibly substellar, companion. The mass functions of the newly identified binaries imply minimum secondary masses ranging from 0.03 to 0.39 M⊙. Photometric time series suggest that, apart from GALEX J0805−1058 and J2205−3141, the companions are most likely white dwarfs. We update the binary population statistics: close to 40 per cent of hot subdwarfs have a companion. Also, we found that the secondary mass distribution shows a low-mass peak attributed to late-type dwarfs, and a higher mass peak and tail distribution attributed to white dwarfs and a few spectroscopic composites. Also, we found that the population kinematics imply an old age and include a few likely halo population members.
We assembled a catalogue of bright, hot subdwarf and white dwarf stars extracted from a joint ultraviolet, optical and infrared source list. The selection is secured using colour criteria that ...correlate well with effective temperatures T
eff≳ 12 000 K. We built a N
UV− V versus V − J diagram for ≳60 000 bright sources using the Galaxy Evolution Explorer (GALEX) N
UV magnitude (N
UV < 14), the associated Guide Star Catalog (GSC2.3.2) photographic quick-V magnitude and the Two-Micron All-Sky Survey J and H magnitudes. This distillation process delivered a catalogue of ≈700 sources with N
UV− V < 0.5 comprising ∼160 known hot subdwarf stars and another ∼60 known white dwarf stars. A reduced proper-motion diagram built using the proper-motion measurements extracted from the Naval Observatory Merged Astrometric Dataset allowed us to identify an additional ∼120 new hot subdwarf candidates and ∼10 hot white dwarf candidates. We present a spectroscopic study of a subset of 52 subdwarfs, 48 of them analysed here for the first time, and with nine objects brighter than V ∼ 12. Our sample of spectroscopically confirmed hot subdwarfs comprises 10 sdO-type stars and 42 sdB-type stars suitable for pulsation and binary studies. We also present a study of 50 known white dwarfs selected in the GALEX survey and six new white dwarfs from our catalogue of subluminous candidates. Ultraviolet, optical and infrared synthetic magnitudes employed in the selection and analysis of white dwarf stars are listed in appendix.
Interleukin-1 (IL-1) signaling is important for multiple potentially pathogenic processes in the central nervous system (CNS), but the cell-type-specific roles of IL-1 signaling are unclear. We used ...a genetic knockin reporter system in mice to track and reciprocally delete or express IL-1 receptor 1 (IL-1R1) in specific cell types, including endothelial cells, ventricular cells, peripheral myeloid cells, microglia, astrocytes, and neurons. We found that endothelial IL-1R1 was necessary and sufficient for mediating sickness behavior and drove leukocyte recruitment to the CNS and impaired neurogenesis, whereas ventricular IL-1R1 was critical for monocyte recruitment to the CNS. Although microglia did not express IL-1R1, IL-1 stimulation of endothelial cells led to the induction of IL-1 in microglia. Together, these findings describe the structure and functions of the brain’s IL-1R1-expressing system and lay a foundation for the dissection and identification of IL-1R1 signaling pathways in the pathogenesis of CNS diseases.
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•Brain IL-1R1 is found in endothelial and ventricular cells, astrocytes, and DG neurons•Ventricular IL-1R1 regulates monocyte recruitment•Endothelial and ventricular IL-1R1 regulates IL-1-induced microglial activation•Endothelial IL-1R1 mediates sickness behavior, leukocyte recruitment, and neurogenesis
Liu et al. employ a genetic knockin reporter system in mice to track and reciprocally delete and/or express IL-1 receptor 1 (IL-1R1) in specific CNS cell types. They define cell-type-specific roles for IL-1 signaling, including an essential role for endothelial IL-1R1 in mediating sickness behavior, and provide a foundation for the dissection of IL-1R1 signaling pathways in the pathogenesis of CNS disease.
Subluminous Type Ia supernovae, such as the Type Iax–class prototype SN 2002cx, are described by a variety of models such as the failed detonation and partial deflagration of an accreting ...carbon-oxygen white dwarf star or the explosion of an accreting, hybrid carbon-oxygen-neon core. These models predict that bound remnants survive such events with, according to some simulations, a high kick velocity. We report the discovery of a high proper motion, low-mass white dwarf (LP 40-365) that travels at a velocity greater than the Galactic escape velocity and whose peculiar atmosphere is dominated by intermediate-mass elements. Strong evidence indicates that this partially burnt remnant was ejected following a subluminous Type Ia supernova event. This supports the viability of single-degenerate supernova progenitors.
Chronic stress contributes to the development of psychiatric disorders including anxiety and depression. Several inflammatory-related effects of stress are associated with increased interleukin-1 ...(IL-1) signaling within the central nervous system and are mediated by IL-1 receptor 1 (IL-1R1) on several distinct cell types. Neuronal IL-1R1 is prominently expressed on the neurons of the dentate gyrus, but its role in mediating behavioral responses to stress is unknown. We hypothesize that IL-1 acts on this subset of hippocampal neurons to influence cognitive and mood alterations with stress. Here, mice subjected to psychosocial stress showed reduced social interaction and impaired working memory, and these deficits were prevented by global IL-1R1 knockout. Stress-induced monocyte trafficking to the brain was also blocked by IL-1R1 knockout. Selective deletion of IL-1R1 in glutamatergic neurons (nIL-1R1
) abrogated the stress-induced deficits in social interaction and working memory. In addition, viral-mediated selective IL-1R1 deletion in hippocampal neurons confirmed that IL-1 receptor in the hippocampus was critical for stress-induced behavioral deficits. Furthermore, selective restoration of IL-1R1 on glutamatergic neurons was sufficient to reestablish the impairments of social interaction and working memory after stress. RNA-sequencing of the hippocampus revealed that stress increased several canonical pathways (TREM1, NF-κB, complement, IL-6 signaling) and upstream regulators (INFγ, IL-1β, NF-κB, MYD88) associated with inflammation. The inductions of TREM1 signaling, complement, and leukocyte extravasation with stress were reversed by nIL-1R1
. Collectively, stress-dependent IL-1R1 signaling in hippocampal neurons represents a novel mechanism by which inflammation is perpetuated and social interactivity and working memory are modulated.
In A Comparative Analysis of Cicero and Aquinas, Charles P. Nemeth investigates how, despite their differences, these two figures may be the most compatible brothers in ideas ever conceived in the ...theory of natural law. Looking to find common threads that run between the philosophies of these two great thinkers of the Classical and Medieval periods, this book aims to determine whether or not there exists a common ground whereby ethical debates and dilemmas can be evaluated. Does comparison between Cicero and Aquinas offer a new pathway for moral measure, based on defined and developed principles? Do they deliver certain moral and ethical principles for human life to which each agree? Instead of a polemical diatribe, comparison between Cicero and Aquinas may edify a method of compromise and afford a more or less restrictive series of judgments about ethical quandaries.
Aims.
The long-period sdOB+G1V type spectroscopic binary SB 744 reveals strong lines of fluorine and lead in the optical spectrum of the sdOB star and subsolar metallicity in the G1V companion thanks ...to a radial velocity follow-up study. Using high-quality observations and
Gaia
astrometric data, we aim to measure the chemical composition and Galactic kinematics of the system to put it into context with known populations of hot subdwarfs. Such binary systems have great potential to provide insights into the late stages of binary evolution as well as into the mysterious formation of stripped-core helium-burning stars.
Methods.
We analyzed the optical spectra with homogeneous atmospheric models to derive the surface parameters of the binary members from a direct wavelength space decomposition. Then, we independently measured the atmospheric properties of the cool companion. The two independent methods achieved consistent results, which were amended with constraints from spectral energy distributions to provide a subdwarf mass. In addition,
Gaia
astrometry allowed us to derive the Galactic kinematics of the system.
Results.
SB 744 turned out to be an old, Population II system that has gone through dramatic events. The hot subdwarf star belongs to the heavy-metal subclass of sdOB stars and we report super-solar abundances of lead, based on Pb
III/IV
lines. The He abundance of the hot subdwarf is the lowest among the known heavy-metal sdOB stars. The presence of fluorine implies that SB 744 was once a hierarchical triple system and the inner binary has merged in the near past. As an alternative scenario, single-star evolution through late core helium flash and atmospheric mixing can also produce the observed fluorine abundances. The atmospheric metal overabundances that are currently observed may perhaps be the result of a combination of mixing processes during formation and radiative support.
We present a detailed model atmosphere analysis of high-dispersion and high signal-to-noise ratio spectra of the heavily polluted DAZ white dwarf GALEX J1931+0117. The spectra obtained with the Very ...Large Telescope (VLT)-Kueyen/UV-Visual Echelle Spectrograph show several well-resolved Si ii spectral lines enabling a study of pressure effects on line profiles. We observed large Stark shifts in silicon lines in agreement with theoretical predictions and laboratory measurements. Taking into account Stark shifts in the calculation of synthetic spectra, we reduced the scatter in individual line radial velocity measurements from ∼3 to ≲1 km s−1. We present revised abundances of O, Mg, Si, Ca and Fe based on a critical review of line-broadening parameters and oscillator strengths. The new measurements are generally in agreement with our previous analysis with the exception of magnesium with a revised abundance of a factor of 2 lower than previously estimated. The magnesium, silicon and iron abundances exceed solar abundances, but the oxygen and calcium abundances are below solar. Also, we compared the observed line profiles to synthetic spectra computed with variable accretion rates and vertical abundance distributions assuming diffusive steady state. The inferred accretion rates vary from
for calcium to 2 × 109 g s−1 for oxygen. We find that the accretion flow must be oxygen rich while being deficient in calcium relative to solar abundances. The lack of radial velocity variations between two measurement epochs suggests that GALEX J1931+0117 is probably not in a close binary and that the source of the accreted material resides in a debris disc.
ABSTRACT
Magnetic fields can play an important role in stellar evolution. Among white dwarfs, the most common stellar remnant, the fraction of magnetic systems is more than 20 per cent. The origin of ...magnetic fields in white dwarfs, which show strengths ranging from 40 kG to hundreds of MG, is still a topic of debate. In contrast, only one magnetic hot subdwarf star has been identified out of thousands of known systems. Hot subdwarfs are formed from binary interaction, a process often associated with the generation of magnetic fields, and will evolve to become white dwarfs, which makes the lack of detected magnetic hot subdwarfs a puzzling phenomenon. Here we report the discovery of three new magnetic hot subdwarfs with field strengths in the range 300–500 kG. Like the only previously known system, they are all helium-rich O-type stars (He-sdOs). We analysed multiple archival spectra of the three systems and derived their stellar properties. We find that they all lack radial velocity variability, suggesting formation via a merger channel. However, we derive higher than typical hydrogen abundances for their spectral type, which are in disagreement with current model predictions. Our findings suggest a lower limit to the magnetic fraction of hot subdwarfs of $0.147^{+0.143}_{-0.047}$ per cent, and provide evidence for merger-induced magnetic fields which could explain white dwarfs with field strengths of 50–150 MG, assuming magnetic flux conservation.
ABSTRACT
We present an update on the variable star survey performed on the TESS 30 min Full Frame Image (FFI) data reported by our first two papers in this series. This update includes a ...contamination analysis in order to identify false positives and analysis of the TESS 10 min FFI data collected during Years 3 and 4 of the mission. We clarify the variability status of 2 995 targets identifying 1 403 variable stars. In addition, we spectroscopically classify 24 pre-filtered targets sampled with the 10 min FFI data and discover 11 new sdB pulsators. Future follow-up space- and/or ground-based data of variables reported here, to identify the nature of their variability and reveal spectroscopic parameters of the stars, would complement this work.
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