Type Stars Research Articles

Non-LTE abundance analysis of A-B stars with low rotational velocities – II. Do A-B stars with normal abundances exist?

ABSTRACT We present chemical composition and fundamental parameters (the effective temperature, surface gravity, and radius) for four sharp-lined A-type stars γ Gem (HD 41705), o Peg (HD 214994), θ Vir (HD 114330), and ν Cap (HD 193432). Our analysis is based on a self-consistent model fitting of high-resolution spectra and spectrophotometric observations over a wide wavelength range. We refined the fundamental parameters of the stars with the sme (Spectroscopy Made Easy) package and verified their accuracy by comparing with the spectral energy distribution and hydrogen line profiles. We found Teff/log g = 9190 ± 130 K/3.56 ± 0.08, 9600 ± 50 K/3.81 ± 0.04, 9600 ± 140 K/3.61 ± 0.12, and 10200 ± 220 K/3.88 ± 0.08 for γ Gem, o Peg, θ Vir, and ν Cap, respectively. Our detailed abundance analysis employs a hybrid technique for spectrum synthesis based on classical model atmospheres calculated in local thermodynamic equilibrium (LTE) assumption together with the non-LTE (NLTE) line formation for 18 of 26 investigated species. Comparison of the abundance patterns observed in A stars of different types (normal A, Am, and Ap) with similar fundamental parameters reveals significant abundance diversity that cannot be explained by the current mechanisms of abundance peculiarity formation in stellar atmospheres. We found a rise of the heavy element (Zn, Sr, Y, Zr, and Ba) abundance excess up to +1 dex with Teff increasing from 7200 to 10 000 K, with a further decrease down to solar value at Teff = 13 000 K, indicating that stars with solar element abundances can be found among late B-type stars.

Fast registration method for sequential star images.

Registration of sequential star images is an important component of space observation. Especially for onboard devices, the efficiency and robustness of registration algorithms are particularly important. The typical star image registration approach based on star matching has a low tolerance for incorrect matching, and the time cost will increase rapidly as the number of stars increases. Due to the high overlap and rigid transformation of adjacent star images, a proposed method based on star angular distance (SAD) is presented. Stars are easy to locate and extract as natural feature points, and there are a large number of identical stars in adjacent star images. The rotation and translation of the SAD, composed of identical stars in adjacent star images, are the same. Therefore, maximum intersection clustering (MIC) was proposed to cluster rotation and translation, and Gaussian weight iteration (GWI) was proposed to estimate rigid transformation parameters. The use of SAD as a star image feature reduces the complexity of star image features, which can improve the efficiency of the algorithm. MIC can tolerate errors within a certain range, and GWI can lessen their impact on the results, increasing the algorithm's robustness. Experimental results show that the proposed method can improve the trend of rapidly increasing computation as the number of stars increases and avoid the restriction that transformation parameters must be obtained with correctly matching stars. Compared to the typical triangle method and SAD similarity method, the proposed method has higher efficiency under different numbers of stars, and translation, rotation, and location errors.

A search for magnetic δ Scuti stars in Kepler hybrid candidates

ABSTRACT Numerous candidate hybrid stars of type δ Scuti–γ Doradus have been identified with the Kepler satellite. However, many of them lie outside the theoretically expected instability strip for hybrid pulsation, where δ Sct and γ Dor pulsations can be simultaneously excited. We postulate that some of these pulsating stars may not be genuine hybrid pulsators but rather magnetic δ Sct stars, for which the rotational modulation from spots on the surface associated with the magnetic field produces frequencies in the same domain as γ Dor pulsations. We search for the presence of a magnetic field in a small sample of selected hybrid δ Sct–γ Dor stars using spectropolarimetry. At the time of observations, the only δ Sct star known to have a magnetic field was HD 188774 with a field strength of a few hundred Gauss. Our observations were thus tailored to detect fields of this typical strength. We find no magnetic field in the hybrid candidate stars we observed. However, two of the three other magnetic δ Sct stars discovered since these observations have much weaker fields than HD 188774, and are of dynamo origin rather than fossil fields. It is likely that our observations are not sensitive enough to detect such dynamo magnetic fields in the cooler stars of our sample if they are present. This work nevertheless provides reliable upper limits on possible fossil fields in the hotter stars, pointing towards typically weaker fields in δ Sct stars than in OBA stars in general.

Waltzing Binaries: Probing the Line-of-sight Acceleration of Merging Compact Objects with Gravitational Waves

The line-of-sight acceleration of a compact binary coalescence (CBC) event would modulate the shape of the gravitational waves (GWs) it produces with respect to the corresponding nonaccelerated CBC. Such modulations could be indicative of its astrophysical environment. We investigate the prospects of detecting this acceleration in future observing runs of the LIGO-Virgo-KAGRA network, as well as in next-generation (XG) detectors and the proposed DECIGO. We place the first observational constraints on this acceleration for putative binary neutron star mergers GW170817 and GW190425. We find no evidence of line-of-sight acceleration in these events at 90% confidence. Prospective constraints for the fifth observing run of the LIGO at A+ sensitivity suggest that accelerations for typical binary neutron stars (BNSs) could be constrained with a precision of a/c ∼ 10−7 [s−1], assuming a signal-to-noise ratio of 10. These improve to a/c ∼ 10−9 [s−1] in XG detectors, and a/c ∼ 10−16 [s−1] in DECIGO. We also interpret these constraints in the context of mergers around supermassive black holes.

Chains of mini-boson stars

In this paper, we re-investigate the static, soliton-like solutions in the model of the Einstein gravity coupled to a free and complex scalar field, which have been known as mini-boson stars. With the numerical methods, we have discovered a new family of solutions in addition to the typical single mini-boson star solution. These solutions can be interpreted as chains of boson stars, consisting of multiple boson stars along the symmetry axis. We demonstrate the configuration of two types of chains, one with an even number of constituents and the other with an odd number of constituents. Furthermore, we also study the effect of the frequency of the complex scalar field on the ADM mass M and the U(1) scalar charge Q. It is noteworthy that the existence of chains of boson stars does not require the introduction of a complex scalar field with self-interacting potential.

A Catalog and Statistical Analysis for Magnetic Stars

Magnetic fields are significant in the structure and evolution of stars. We present a comprehensive catalog of 1784 known magnetic stars, detailing their identifications, HD numbers, precise locations, spectral types and averaged quadratic effective magnetic fields among other important information. The group comprises 177 O-type stars, 551 B-type stars, 520 A-type stars, 91 F-type stars, 53 G-type stars, 61 K-type stars, 31 M-type stars and an additional 300 stars whose spectral classification remains indeterminate. Our analysis examines the statistical properties of these magnetic stars. The relative integrated distribution function and number distribution function for all magnetic stars of the same spectral type can be effectively approximated using an exponential function of the averaged quadratic effective magnetic field. The analysis further reveals that A and B-type stars possess the strongest mean magnetic fields, indicating an easier detection of their magnetic fields.

Searching for magnetic fields in pulsating A-type stars: the discovery of a strong field in the probable δ Sct star HD 340577 and a null result for the γ Dor star HR 8799

ABSTRACT Numerous δ Sct and γ Dor pulsators are identified in the region of the Hertzsprung–Russell diagram that is occupied by chemically peculiar magnetic Ap stars. The connection between δ Sct and γ Dor pulsations and the magnetic field in Ap stars is however not clear: theory suggests for magnetic Ap stars some critical field strengths for pulsation mode suppression by computing the magnetic damping effect for selected p and g modes. To test these theoretical considerations, we obtained PEPSI spectropolarimetric snapshots of the typical Ap star HD 340577, for which δ Sct-like pulsations were recently detected in Transiting Exoplanet Survey Satellite data, and the γ Dor pulsator HR 8799, which is a remarkable system with multiple planets and two debris discs. Our measurements reveal the presence of a magnetic field with a strength of several hundred Gauss in HD 340577. The measured mean longitudinal field would be the strongest field measured so far in a δ Sct star if the pulsational character of HD 340577 is confirmed spectroscopically. No magnetic field is detected in HR 8799.

The space weather around the exoplanet GJ 436b

Context. The space environment in which planets are embedded mainly depends on the host star and impacts the evolution of the planetary atmosphere. The quiet M dwarf GJ 436 hosts a close-in hot Neptune which is known to feature a comet-like tail of hydrogen atoms that escaped from its atmosphere due to energetic stellar irradiation. Understanding such star-planet interactions is essential to shed more light on planet formation and evolution theories, in particular the scarcity of Neptune-sized planets below a 3 d orbital period, also known as the ‘Neptune desert’. Aims. We aimed to characterise the stellar environment around GJ 436, which requires accurate knowledge of the stellar magnetic field. The latter is studied efficiently with spectropolarimetry, since it is possible to recover the geometry of the large-scale magnetic field by applying tomographic inversion on time series of circularly polarised spectra. Methods. We used spectropolarimetric data collected in the optical domain with Narval in 2016 to compute the longitudinal magnetic field, examine its periodic content via Lomb-Scargle periodogram and Gaussian process regression analysis, and finally reconstruct the large-scale field configuration by means of Zeeman-Doppler imaging. Results. We found an average longitudinal field of −12 G and a stellar rotation period of 46.6 d using a Gaussian process model and 40.1 d using Zeeman-Doppler imaging, which are both consistent with the literature. The Lomb-Scargle analysis did not reveal any significant periodicity. The reconstructed large-scale magnetic field is predominantly poloidal, dipolar, and axisymmetric, with a mean strength of 16 G. This is in agreement with magnetic topologies seen for other stars of a similar spectral type and rotation rate.

Modeling the Mg I from the NUV to MIR

Context. Reliable atomic data are mandatory ingredients to obtain a realistic semiempirical model of any stellar atmosphere. Due to their importance, we further improved our recently published Mg I atomic model. Aims. We tested the new atomic model using atmospheric models of stars of different spectral types: the Sun (dG2), HD 22049 (dK2, Epsilon Eridani), GJ 832 (dM2), and GJ 581 (dM3). Methods. Significant improvements have been included in the atomic model, mainly to the electron impact excitation (ϒij) values. We used new Breit-Pauli distorted-wave (DW) multiconfiguration calculations, which proved to be relevant for many transitions in the mid-infrared (MIR) range. The new atomic model of Mg I includes the following: (i) recomputed (ϒij) data through the DW method, including the superlevels. (ii) For the nonlocal thermodynamic equilibrium (NLTE) population calculations, 5676 theoretical transitions were added (3001 term-to-term). (iii) All of these improvements were studied in the Sun and the stars listed above. Comparisons for the distribution of magnesium among the first ionization states and the formation of molecules, as well as for the population of the different energy levels and atmospheric heights, were carried out. Several lines, representative of the spectral ranges, were selected to analyze the changes that were produced. In particular, we exemplify these results with the problematic line 2853.0 Å, a transition between the third level and the ground state. Results. The magnesium distribution between ionization states for stars with different effective temperatures was compared. For the Sun and Epsilon Eridani, Mg II predominates with more than 95%, while for GJ 832 and GJ 581, Mg I represents more than 72% of the population. Moreover, in the latter stars, the amount of magnesium forming molecules in their atmosphere is at least two orders of magnitude higher. Regarding the NLTE population, a noticeable lower variability in the departure coefficients was found, indicating a better population coupling for the new model. Comparing the synthetic spectrum calculated with the older and new Mg I atomic model, these results show minimal differences in the visible range but they are stronger in the infrared (IR) for all of the stars. This aspect should be considered when using lines from this region as indicators. Nevertheless, some changes in the spectral type were found, also emphasizing the need to test the atomic models in different atmospheric conditions. The most noticeable changes occurred in the far-ultraviolet (FUV) and near-ultraviolet (NUV), obtaining a higher flux for the new atomic model regardless of the spectral type. The new model did not prevent the formation of the core emission in the synthetic NUV line 2853.0 Å. However, by including other observations, we could note that the emission indeed exists, although with a much lower intensity. Further tests have shown that to reduce the emission, the population of its upper level (3s3p 1P) should be reduced by a factor of about 100.

Stragglers of the thick disc

Young alpha-rich (YAR) stars have been detected in the past as outliers to the local age − [α/Fe] relation. These objects are enhanced in α-elements, but they are apparently younger than typical thick disc stars. Here, we study the global kinematics and chemical properties of YAR giant stars in the APOGEE DR17 survey and show that they have properties similar to those of the standard thick disc stellar population. This leads us to conclude that YAR are rejuvenated thick disc objects, and the most likely explanation is that they are evolved blue stragglers. This is confirmed by their position in the Hertzsprung–Russel diagram (HRD). Extending our selection to dwarfs allowed us to obtain the first general straggler distribution in an HRD of field stars. We also compared the elemental abundances of our sample with those of standard thick disc stars and found that our YAR stars are shifted in oxygen, magnesium, sodium, and the slow neutron-capture element cerium. Although we detected no sign of binarity for most objects, the enhancement in cerium may be a signature of a mass transfer from an asymptotic giant branch companion. The most massive YAR stars suggest that mass transfer from an evolved star may not be the only plausible formation pathway and that other scenarios, such as collision or coalescence, should be considered.

An H I story of galaxies in Abell 2626 and beyond

Context. To study the effects of environment on galaxies, we use H I observations of galaxies in and around the cluster Abell 2626 (A2626). The cluster can effectively be divided into three different environments: the cluster itself, a group environment in the periphery of the cluster (we call it the Swarm), and substructure in the cluster itself. We use these to study the dependence of the galaxy properties on environment. Aims. We have explored the relation between H I deficiency, H I morphology, and star formation deficiency for the galaxies in and around the A2626 galaxy cluster to investigate the environmental effects on these properties. Methods. To quantify the asymmetries of the outer H I disc of a galaxy, we used 1) three visual classes based on the outermost reliable H I contour (settled, disturbed, and unsettled H I discs), 2) the offset between the H I centre and the optical centre of a galaxy, and 3) the modified asymmetry parameter Amod as defined previously. Results. The H I deficiency of a galaxy is strongly correlated with the projected distance from the centre of A2626. Furthermore, substructure galaxies tend to be more asymmetric than the isolated galaxies in A2626, probably because tidal interactions are more efficient within the substructures than outside the substructures. Moreover, asymmetric, offset, and smaller H I discs are not necessarily the result of the cluster environment because they are also observed in substructures in A2626 and in the Swarm. This signifies that a pre-processing of the H I discs of galaxies in groups or substructures plays an important role, together with the processing in the cluster environment. Finally, the star formation rates for the galaxies in all three environments are slightly lower than the typical star formation rate for normal galaxies, as manifested by their offset from the star formation main sequence. This implies effective gas removal mechanisms in all three environments.

The nature of the X-ray sources in dwarf galaxies in nearby clusters from the KIWICS

ABSTRACT We present a deep search for and analysis of X-ray sources in a sample of dwarf galaxies (Mr < −15.5 mag) located within twelve galaxy clusters from the Kapteyn IAC WHT Enhanced Area Velocity Explores Isaac Newton Telescope Cluster Survey of photometric observations in the r and g using the Wide Field Camera at the 2.5-m Isaac Newton telescope. We first investigated the optical data, identified 2720 dwarf galaxies in all fields and determined their characteristics; namely, their colours, effective radii, and stellar masses. We then searched the Chandra data archive for X-ray counterparts of optically detected dwarf galaxies. We found a total of 20 X-ray emitting dwarf galaxies, with X-ray flux ranging from 1.7 × 10−15 to 4.1 × 10−14 erg cm−2 s−1 and X-ray luminosities varying from 2 × 1039 to 5.4 × 1041 erg s−1. Our results indicate that the X-ray luminosity of the sources in our sample is larger than the Eddington luminosity limit for a typical neutron star, even at the lowest observed levels. This leads us to conclude that the sources emitting X-rays in our sample are likely black holes. Additionally, we have employed a scaling relation between black hole and stellar mass to estimate the masses of the black holes in our sample, and have determined a range of black hole masses from 4.6 × 104 to 1.5 × 106 M⊙. Finally, we find a trend between X-ray to optical flux ratio and X-ray flux. We discuss the implications of our findings and highlight the importance of X-ray observations in studying the properties of dwarf galaxies.

Main Sequence Star Super-flare Frequency based on Entire Kepler Data

We wrote and used an automated flare detection Python script to search for super-flares on main sequence stars of types A, F, G, K and M in Kepler’s long-cadence data from Q0 to Q17. We studied the statistical properties of the occurrence rate of super-flares. For the G-type data set, we compared our results with the previous results of Okamoto et al. by splitting the data set into four rotational bands. We found similar power-law indices for the flare frequency distribution. Hence, we show that inclusion of a high-pass filter, sample biases, gyrochronology and completeness of flare detection is of no significance, as our results are similar to those of Okamoto et al. We estimated that a super-flare on G-type dwarfs with energy of 1035 erg occurs on a star once every 4360 yr. We found 4637 super-flares on 1896 G-type dwarfs. Moreover, we identified 321, 1125, 4538 and 5445 super-flares on 136, 522, 770 and 312 dwarfs of types A, F, K and M, respectively. We ascertained that the occurrence rate (dN/dE) of super-flares versus flare energy, E, shows a power-law distribution with , where α ≃ 2.0 to 2.1 for the spectral types from F-type to M-type stars. In contrast, the obtained α ≃ 1.3 for A-type stars suggests that the flare conditions differ from those of the other spectral-type stars. We note an increase in flare incidence rate in F-type to M-type stars and a decrease in A-type to F-type stars.

The Activity of a Solar-Type Star TOI-1422 and Mass Loss of the Atmosphere of the Planet TOI-1422b

The results of the analysis of the activity of a solar type star G2V TOI-1422 are presented and estimates of the loss of atmospheric matter of the planet TOI-1422b are made. The planet can be attributed to the type of hot Neptunes. Compared to other exoplanets of a similar mass range, it is expected that the planet has an extensive gas envelope. According to the long-term photometric survey of Kamogata Wide-field Survey (KWS) the TOI-1422 activity was analyzed and the existence of possible activity cycles of 1650–1680 days and 2450 days was suggested. The probable value of the rotation period P of the star lies in the range of 27 (+19, –8) days, observations of the KWS survey in the V filter indicate the most possible value for the period P = 32 days. Mass loss of the planet’s atmosphere is determined using an approximation formula corresponding to the model of atmospheric loss with an energy restriction. To estimate the flux of XUV photons analytical dependences were used linking the flux values and the parameter log R_{{{text{HK}}}}^{'}. Calculations have shown that the atmosphere matter loss of TOI-1422b is dot {M} = 9.4 times {{10}^{8}} g/s; considering the existing errors in determining the parameters of the atmosphere it lies in the range from 6.8 times {{10}^{8}} to 1.4 times {{10}^{9}} g/s, and considering the uncertainty in the value of the chromospheric activity index—from 8.3 times {{10}^{8}} to 1.1 times {{10}^{9}} g/s.

THE ACTIVITY OF A SOLAR-TYPE STAR TOI-1422 AND MASS LOSS OF THE ATMOSPHERE OF THE PLANET TOI-1422b

The results of the analysis of the activity of a solar type star G2V TOI-1422 are presented and estimates of the loss of atmospheric matter of the planet TOI-1422b are made. The planet can be attributed to the type of hot neptunes. Compared to other exoplanets of a similar mass range it is expected that the planet has an extensive gas envelope. According to the long-term photometric survey of Kamogata Wide-field Survey (KWS) the TOI-1422 activity was analyzed and the existence of possible activity cycles of 1650-1680 days and 2450 days was suggested. The probable value of the rotation period P of the star lies in the range of 27 (+19, –8) days, observations of the KWS survey in the V filter indicate the most possible value for P = 32 days. Mass loss of the planet’s atmosphere is determined using an approximation formula corresponding to the model of atmospheric loss with an energy restriction. To estimate the flux of XUV photons analytical dependences were used linking the flux values and the parameter \(\log R_{{{\text{HK}}}}^{'}\). Calculations have shown that the mass loss of TOI-1422b is \(\dot {M} = 9.4 \times \) 108 g/s and taking into account the existing errors in determining the parameters of the atmosphere it lies in the range from 6.8 × 108 g/s to 1.4 × 109 g/s.

Destructive breakdown studies of irradiated LGADs at beam tests for the ATLAS HGTD

In the past years, it has been observed at several beam test campaigns thatirradiated LGAD sensors break with a typical star shaped burn mark whenoperated at voltages much lower than those at which they were safely operatedduring laboratory tests. The study presented in this paper was designed todetermine the safe operating voltage that these sensors can withstand. Manyirradiated sensors from various producers were tested in two test beamfacilities, DESY (Hamburg) and CERN-SPS (Geneva), as part of ATLAS HighGranularity Timing Detector (HGTD) beam tests. The samples were placed in thebeam and kept under bias over a long period of time in order to reach a highnumber of particles crossing each sensor. Both beam tests lead to a similarconclusion, that these destructive events begin to occur when the averageelectric field in the sensor becomes larger than12 V/μm.

The MUSCLES Extension for Atmospheric Transmission Spectroscopy: UV and X-Ray Host-star Observations for JWST ERS & GTO Targets

X-ray through infrared spectral energy distributions (SEDs) are essential for understanding a star’s effect on exoplanet atmospheric composition and evolution. We present a catalog of panchromatic SEDs, hosted on the Barbara A. Mikulski Archive for Space Telescopes, for 11 exoplanet-hosting stars that have guaranteed JWST observation time as part of the ERS or GTO programs but have no previous UV characterization. The stars in this survey range from spectral type F4-M6 (0.14–1.57 M ☉), rotation periods of 4–132 days, and ages of approximately 0.5–11.4 Gyr. The SEDs are composite spectra using data from the Chandra X-ray Observatory and XMM-Newton, the Hubble Space Telescope, BT-Settl stellar atmosphere models, and scaled spectra of proxy stars of similar spectral type and activity. From our observations, we have measured a set of UV and X-ray fluxes as indicators of stellar activity level. We compare the chromospheric and coronal activity indicators of our exoplanet-hosting stars to the broader population of field stars and find that a majority of our targets have activity levels lower than the average population of cool stars in the solar neighborhood. This suggests that using SEDs of stars selected from exoplanet surveys to compute generic exoplanet atmosphere models may underestimate the typical host star’s UV flux by an order of magnitude or more, and consequently, that the observed population of exoplanetary atmospheres receive lower high-energy flux levels than the typical planet in the solar neighborhood.

The impact of dust evolution on the dead zone outer edge in magnetized protoplanetary disks

Context. The dead zone outer edge corresponds to the transition from the magnetically dead to the magnetorotational instability (MRI) active regions in the outer protoplanetary disk midplane. It has been previously hypothesized to be a prime location for dust particle trapping. A more consistent approach to access such an idea has yet to be developed, since the interplay between dust evolution and MRI-driven accretion over millions of years has been poorly understood. Aims. We provide an important step toward a better understanding of the MRI–dust coevolution in protoplanetary disks. In this pilot study, we present a proof of concept that dust evolution ultimately plays a crucial role in the MRI activity. Methods. First, we study how a fixed power-law dust size distribution with varying parameters impacts the MRI activity, especially the steady-state MRI-driven accretion, by employing and improving our previous 1+1D MRI-driven turbulence model. Second, we relax the steady-state accretion assumption in this disk accretion model, and partially couple it to a dust evolution model in order to investigate how the evolution of dust (dynamics and grain growth processes combined) and MRI-driven accretion are intertwined on million-year timescales, from a more sophisticated modeling of the gas ionization degree. Results. Dust coagulation and settling lead to a higher gas ionization degree in the protoplanetary disk, resulting in stronger MRI-driven turbulence as well as a more compact dead zone. On the other hand, fragmentation has an opposite effect because it replenishes the disk in small dust particles which are very efficient at sweeping up free electrons and ions from the gas phase. Since the dust content of the disk decreases over millions of years of evolution due to radial drift, the MRI-driven turbulence overall becomes stronger and the dead zone more compact until the disk dust-gas mixture eventually behaves as a grain-free plasma. Furthermore, our results show that dust evolution alone does not lead to a complete reactivation of the dead zone. For typical T-Tauri stars, we find that the dead zone outer edge is expected to be located roughly between 10 au and 50 au during the disk lifetime for our choice of the magnetic field strength and configuration. Finally, the MRI activity evolution is expected to be crucially sensitive to the choice made for the minimum grain size of the dust distribution. Conclusions. The MRI activity evolution (hence the temporal evolution of the MRI-induced α parameter) is controlled by dust evolution and occurs on a timescale of local dust growth, as long as there are enough dust particles in the disk to dominate the recombination process for the ionization chemistry. Once that is no longer the case, the MRI activity evolution is expected to be controlled by gas evolution and occurs on a viscous evolution timescale.

Can the MDCDW condensate withstand the heat of a cold neutron star?

The correct description of strongly interacting matter at low temperatures and moderately high densities—in particular the conditions realized inside neutron stars—is still unknown. We review some recent results on the magnetic dual chiral density wave (MDCDW) phase, a candidate phase of quark matter for this region of the QCD phase diagram. We highlight the effects of magnetic fields and temperature on the condensate, which can be explored using a high-order Ginzburg-Landau (GL) expansion. We also explain how the condensate’s nontrivial topology, which arises due to the asymmetry in the lowest Landau level modes, affects its physical properties. Finally, we comment on the possible relevance of these results to neutron star applications. Over a wide range of densities and magnetic field strengths, MDCDW is preferred over the chirally symmetric ground state at temperatures consistent with typical cold neutron stars, and in some cases, even hot ones.

GaiaData Release 3

Context.GaiaData Release 3 (DR3) provides a wealth of new data products for the astronomical community to exploit, including astrophysical parameters for half a billion stars. In this work, we demonstrate the high quality of these data products and illustrate their use in different astrophysical contexts.Aims.We produce homogeneous samples of stars with high-quality astrophysical parameters by exploitingGaiaDR3, while focusing on many regimes across the Hertzsprung-Russell (HR) diagram; spectral types OBA, FGKM, and ultracool dwarfs (UCDs). We also focus on specific subsamples of particular interest to the community: solar analogues, carbon stars, and theGaiaspectrophotometric standard stars (SPSS).Methods.We query the astrophysical parameter tables along with other tables inGaiaDR3 to derive the samples of the stars of interest. We validate our results using theGaiacatalogue itself and by comparison with external data.Results.We produced six homogeneous samples of stars with high-quality astrophysical parameters across the HR diagram for the community to exploit. We first focus on three samples that span a large parameter space: young massive disc stars (OBA; about 3 Million), FGKM spectral type stars (about 3 Million), and UCDs (about 20 000). We provide these sources along with additional information (either a flag or complementary parameters) as tables that are made available in theGaiaarchive. We also identify 15 740 bone fide carbon stars and 5863 solar analogues, and provide the first homogeneous set of stellar parameters of the SPSS sample. We demonstrate some applications of these samples in different astrophysical contexts. We use a subset of the OBA sample to illustrate its usefulness in analysing the Milky Way rotation curve. We then use the properties of the FGKM stars to analyse known exoplanet systems. We also analyse the ages of some unseen UCD-companions to the FGKM stars. We additionally predict the colours of the Sun in various passbands (Gaia, 2MASS, WISE) using the solar-analogue sample.Conclusions.GaiaDR3 contains a wealth of new high-quality astrophysical parameters for the community to exploit.