Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We present observations of NOAA AR 11159, obtained on 2011 February 14 in the 4.7 <jats:italic>μ</jats:italic>m band of carbon monoxide (CO) and coordinated with spectroscopic imaging of three atomic lines (Na <jats:sc>i</jats:sc> 5896 Å, Fe <jats:sc>i</jats:sc> 7090 Å, and Ca <jats:sc>ii</jats:sc> 8542 Å) which sample heights from the mid-photosphere to the chromosphere. Phase-difference spectra between the observed spectral lines instead indicate that the CO lines form at <jats:italic>z</jats:italic> ≈ 530−650 km in the quiet Sun. During the two hours of observations, seven long-lived cooling events (“cold bubbles”) were observed in CO in the region surrounding a large pore, but were not visible in the three atomic lines. These events show self-similar temporal evolution with time scales consistent with the chemical formation rate of CO at <jats:italic>z</jats:italic> ≈ 1000 km. Due to the lack of such features in the surrounding quiet Sun, we hypothesize that the magnetic canopy field surrounding the pore, which suppresses the upward propagation of acoustic waves into the chromosphere and the subsequent formation of shocks, depresses the rate of acoustic heating and allows CO to condense and cool the atmosphere at those heights. These “cold bubbles” may be a source of the chromospheric CO that produces the unexpectedly high (<jats:italic>z</jats:italic> ≈ 1000 km) limb extensions seen in the stronger CO lines, and may provide a unique opportunity to study this enigmatic component of the solar atmosphere in spatially resolved observations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We investigate the effects of the evolutionary processes in the internal magnetic structure of two interplanetary coronal mass ejections (ICMEs) detected in situ between 2020 November 29 and December 1 by the Parker Solar Probe (PSP). The sources of the ICMEs were observed remotely at the Sun in EUV and subsequently tracked to their coronal counterparts in white light. This period is of particular interest to the community as it has been identified as the first widespread solar energetic particle event of solar cycle 25. The distribution of various solar and heliospheric-dedicated spacecraft throughout the inner heliosphere during PSP observations of these large-scale magnetic structures enables a comprehensive analysis of the internal evolution and topology of such structures. By assembling different models and techniques, we identify the signatures of interaction between the two consecutive ICMEs and the implications for their internal structure. We use multispacecraft observations in combination with a remote-sensing forward modeling technique, numerical propagation models, and in situ reconstruction techniques. The outcome, from the full reconciliations, demonstrates that the two coronal mass ejections (CMEs) are interacting in the vicinity of the PSP. Thus, we identify the in situ observations based on the physical processes that are associated with the interaction and collision of both CMEs. We also expand the flux rope modeling and in situ reconstruction technique to incorporate the aging and expansion effects in a distorted internal magnetic structure and explore the implications of both effects in the magnetic configuration of the ICMEs.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Understanding the evolution of massive binary stars requires accurate estimates of their masses. This understanding is critically important because massive star evolution can potentially lead to gravitational-wave sources such as binary black holes or neutron stars. For Wolf–Rayet (WR) stars with optically thick stellar winds, their masses can only be determined with accurate inclination angle estimates from binary systems which have spectroscopic <jats:inline-formula> <jats:tex-math> <?CDATA $M\sin i$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>M</mml:mi> <mml:mi>sin</mml:mi> <mml:mi>i</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac589eieqn1.gif" xlink:type="simple" /> </jats:inline-formula> measurements. Orbitally phased polarization signals can encode the inclination angle of binary systems, where the WR winds act as scattering regions. We investigated four Wolf–Rayet + O star binary systems, WR 42, WR 79, WR 127, and WR 153, with publicly available phased polarization data to estimate their masses. To avoid the biases present in analytic models of polarization while retaining computational expediency, we used a Monte Carlo radiative-transfer model accurately emulated by a neural network. We used the emulated model to investigate the posterior distribution of the parameters of our four systems. Our mass estimates calculated from the estimated inclination angles put strong constraints on existing mass estimates for three of the systems, and disagree with the existing mass estimates for WR 153. We recommend a concerted effort to obtain polarization observations that can be used to estimate the masses of WR binary systems and increase our understanding of their evolutionary paths.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Axion-like particles (ALPs) are a well-motivated extension to the standard model of particle physics, and X-ray observations of cluster-hosted AGN currently place the most stringent constraints on the ALP coupling to electromagnetism, <jats:italic>g</jats:italic> <jats:sub> <jats:italic>a</jats:italic> <jats:italic>γ</jats:italic> </jats:sub>, for very light ALPs (<jats:italic>m</jats:italic> <jats:sub> <jats:italic>a</jats:italic> </jats:sub> ≲ 10<jats:sup>−11</jats:sup> eV). We revisit limits obtained by Reynolds et al. using Chandra X-ray grating spectroscopy of NGC 1275, the central AGN in the Perseus cluster, examining the impact of the X-ray spectral model and magnetic field model. We also present a new publicly available code, <jats:sc>ALPro</jats:sc>, which we use to solve the ALP propagation problem. We discuss evidence for turbulent magnetic fields in Perseus and show that it can be important to resolve the magnetic field structure on scales below the coherence length. We reanalyze the NGC 1275 X-ray spectra using an improved data reduction and baseline spectral model. We find the limits are insensitive to whether a partially covering absorber is used in the fits. At low <jats:italic>m</jats:italic> <jats:sub> <jats:italic>a</jats:italic> </jats:sub> (<jats:italic>m</jats:italic> <jats:sub> <jats:italic>a</jats:italic> </jats:sub> ≲ 10<jats:sup>−13</jats:sup> eV), we find marginally weaker limits on <jats:italic>g</jats:italic> <jats:sub> <jats:italic>a</jats:italic> <jats:italic>γ</jats:italic> </jats:sub> (by 0.1–0.3 dex) with different magnetic field models, compared to Model B from Reynolds et al. (2020). A Gaussian random field (GRF) model designed to mimic ∼50 kpc scale coherent structures also results in only slightly weaker limits. We conclude that the existing Model B limits are robust assuming that <jats:italic>β</jats:italic> <jats:sub>pl</jats:sub> ≈ 100, and are insensitive to whether cell-based or GRF methods are used. However, astrophysical uncertainties regarding the strength and structure of cluster magnetic fields persist, motivating high-sensitivity RM observations and tighter constraints on the radial profile of <jats:italic>β</jats:italic> <jats:sub>pl</jats:sub>.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present Very Large Array (VLA) and Atacama Large Millimeter/submillimeter Array (ALMA) observations of the close (0.″3 = 90 au separation) protobinary system SVS 13. We detect two small circumstellar disks (radii ∼12 and ∼9 au in dust, and ∼30 au in gas) with masses of ∼0.004–0.009 <jats:italic>M</jats:italic> <jats:sub>☉</jats:sub> for VLA 4A (the western component) and ∼0.009–0.030 <jats:italic>M</jats:italic> <jats:sub>☉</jats:sub> for VLA 4B (the eastern component). A circumbinary disk with prominent spiral arms extending ∼500 au and a mass of ∼0.052 <jats:italic>M</jats:italic> <jats:sub>☉</jats:sub> appears to be in the earliest stages of formation. The dust emission is more compact and with a very high optical depth toward VLA 4B, while toward VLA 4A the dust column density is lower, allowing the detection of stronger molecular transitions. We infer rotational temperatures of ∼140 K, on scales of ∼30 au, across the whole source, and a rich chemistry. Molecular transitions typical of hot corinos are detected toward both protostars, being stronger toward VLA 4A, with several ethylene glycol transitions detected only toward this source. There are clear velocity gradients, which we interpret in terms of infall plus rotation of the circumbinary disk, and pure rotation of the circumstellar disk of VLA 4A. We measured orbital proper motions and determined a total stellar mass of 1 <jats:italic>M</jats:italic> <jats:sub>☉</jats:sub>. From the molecular kinematics, we infer the geometry and orientation of the system, and stellar masses of ∼0.26 <jats:italic>M</jats:italic> <jats:sub>☉</jats:sub> for VLA 4A and ∼0.60 <jats:italic>M</jats:italic> <jats:sub>☉</jats:sub> for VLA 4B.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Type Ia supernovae (SNe) are believed to be caused by the thermonuclear explosion of a white dwarf (WD), but the nature of the progenitor system(s) is still unclear. Recent theoretical and observational developments have led to renewed interest in double-degenerate models, in particular the “helium-ignited violent merger” or “dynamically driven double-degenerate double-detonation” (D<jats:sup>6</jats:sup>). In this paper we take the output of an existing D<jats:sup>6</jats:sup> SN model and carry it into the supernova remnant (SNR) phase up to 4000 yr after the explosion, past the time when all the ejecta have been shocked. Assuming a uniform ambient medium, we reveal specific signatures of the explosion mechanism and spatial variations intrinsic to the ejecta. The first detonation produces an ejecta tail visible at early times, while the second detonation leaves a central density peak in the ejecta that is visible at late times. The SNR shell is off-center at all times, because of an initial velocity shift due to binary motion. The companion WD produces a large conical shadow in the ejecta, visible in projection as a dark patch surrounded by a bright ring. This is a clear and long-lasting feature that is localized, and its impact on the observed morphology is dependent on the viewing angle of the SNR. These results offer a new way to diagnose the explosion mechanism and progenitor system using observations of a Type Ia SNR.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present new functionality within <jats:monospace>PICASO</jats:monospace>, a state-of-the-art radiative transfer model for exoplanet and brown dwarf atmospheres, by developing a new pipeline that computes phase-resolved thermal emission (thermal phase curves) from three-dimensional (3D) models. Because <jats:monospace>PICASO</jats:monospace> is coupled to <jats:monospace>Virga</jats:monospace>, an open-source cloud code, we are able to produce cloudy phase curves with different sedimentation efficiencies (<jats:italic>f</jats:italic> <jats:sub>sed</jats:sub>) and cloud condensate species. We present the first application of this new algorithm to hot Jupiter WASP-43b. Previous studies of the thermal emission of WASP-43b from Kataria et al. found good agreement between cloud-free models and dayside thermal emission, but an overestimation of the nightside flux, for which clouds have been suggested as a possible explanation. We use the temperature and vertical wind structure from the cloud-free 3D general circulation models of Kataria et al. and post-process it using <jats:monospace>PICASO</jats:monospace>, assuming that clouds form and affect the spectra. We compare our models to results from Kataria et al., including Hubble Space Telescope Wide-Field Camera 3 (WFC3) observations of WASP-43b from Stevenson et al. In addition, we compute phase curves for Spitzer at 3.6 and 4.5 <jats:italic>μ</jats:italic>m and compare them to observations from Stevenson et al. We are able to closely recover the cloud-free results, even though <jats:monospace>PICASO</jats:monospace> utilizes a coarse spatial grid. We find that cloudy phase curves provide much better agreement with the WFC3 and Spitzer nightside data, while still closely matching the dayside emission. This work provides the community with a convenient, user-friendly tool to interpret phase-resolved observations of exoplanet atmospheres using 3D models.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The chemical evolution of the galaxy is largely guided by the yields from massive stars. Their evolution is heavily influenced by their internal mixing, allowing the stars to live longer and yield a more massive helium core at the end of their main-sequence evolution. Asteroseismology is a powerful tool for studying stellar interiors by providing direct probes of the interior physics of the oscillating stars. This work revisits the recently derived internal mixing profiles of 26 slowly pulsating B stars observed by the Kepler space telescope, in order to investigate how well the mixing profiles can in fact be distinguished from one another as well as provide predictions for the expected helium core masses obtained at the end of the main-sequence evolution. We find that for five of these stars the mixing profile is derived unambiguously, while the remaining stars have at least one other mixing profile which explains the oscillations equally well. Convective penetration is preferred over exponential diffusive overshoot for ≈55% of the stars, while stratified mixing is preferred in the envelope (≈39%). We estimate the expected helium core masses obtained at the end of the main-sequence evolution and find them to be highly influenced by the estimated amount of mixing occurring in the envelopes of the stars.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Wave–particle interactions can induce energy transfer at different timescales in collisionless plasmas, which leads to the reshaping of the particle velocity distribution function. Therefore, how to quantify wave–particle interactions is one of the fundamental problems in the heliosphere and in astrophysical plasmas. This study proposes a systematic method to quantify linear wave–particle interactions based on the Vlasov–Maxwellian model. We introduce energy transfer rates with various expressions by using perturbed electric fields and perturbed particle velocity distribution functions. Then, we use different expressions of the energy transfer rate to perform a comprehensive investigation of wave–particle interactions of the Alfvén-mode wave. We clarify the physical mechanisms responsible for the damping of the Alfvén-mode wave in wavevector space. Moreover, this study exhibits for the first time evident signatures of wave–particle interactions between Alfvén-mode waves and resonant/nonresonant particles in the velocity space. These resonant and nonresonant particles can induce energy transfer in opposite directions, which leads to self-regulation of the particle velocity distribution function. Furthermore, this study exhibits a comprehensive dependence of wave–particle interactions of the Alfvén-mode wave on the wavenumber and plasma beta (the ratio between the plasma thermal pressure and the magnetic pressure). These results illustrate that the proposed method would be very useful for quantifying different types of linear wave–particle interactions of an arbitrary wave mode.</jats:p>