Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We adopt the deep learning method <jats:sc>casi-3d</jats:sc> (Convolutional Approach to Structure Identification-3D) to systemically identify protostellar outflows in <jats:sup>12</jats:sup>CO and <jats:sup>13</jats:sup>CO observations of the nearby molecular clouds, Ophiuchus, Taurus, Perseus, and Orion. The total outflow masses are 267 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, 795 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, 1305 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, and 6332 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> for Ophiuchus, Taurus, Perseus, and Orion, respectively. We show the outflow mass in each cloud is linearly proportional to the total number of young stellar objects. The estimated total 3D deprojected outflow energies are 9 × 10<jats:sup>45</jats:sup> erg, 6 × 10<jats:sup>46</jats:sup> erg, 1.2 × 10<jats:sup>47</jats:sup> erg, and 6 × 10<jats:sup>47</jats:sup> erg for Ophiuchus, Taurus, Perseus, and Orion, respectively. The energy associated with outflows is sufficient to offset turbulent dissipation at the current epoch for all four clouds. All clouds also exhibit a break point in the spatial power spectrum of the outflow prediction map, which likely corresponds to the typical outflow mass and energy injection scale.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present multiwavelength observations of the Type II SN 2020pni. Classified at ∼1.3 days after explosion, the object showed narrow (FWHM intensity &lt;250 km s<jats:sup>−1</jats:sup>) recombination lines of ionized helium, nitrogen, and carbon, as typically seen in flash-spectroscopy events. Using the non-LTE radiative transfer code CMFGEN to model our first high-resolution spectrum, we infer a progenitor mass-loss rate of <jats:inline-formula> <jats:tex-math> <?CDATA $\dot{M}=(3.5\mbox{--}5.3)\times {10}^{-3}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>̇</mml:mo> </mml:mrow> </mml:mover> <mml:mo>=</mml:mo> <mml:mo stretchy="false">(</mml:mo> <mml:mn>3.5</mml:mn> <mml:mo>–</mml:mo> <mml:mn>5.3</mml:mn> <mml:mo stretchy="false">)</mml:mo> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac3820ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> yr<jats:sup>−1</jats:sup> (assuming a wind velocity of <jats:italic>v</jats:italic> <jats:sub> <jats:italic>w</jats:italic> </jats:sub> = 200 km s<jats:sup>−1</jats:sup>), estimated at a radius of <jats:italic>R</jats:italic> <jats:sub>in</jats:sub> = 2.5 × 10<jats:sup>14</jats:sup> cm. In addition, we find that the progenitor of SN 2020pni was enriched in helium and nitrogen (relative abundances in mass fractions of 0.30–0.40 and 8.2 × 10<jats:sup>−3</jats:sup>, respectively). Radio upper limits are also consistent with dense circumstellar material (CSM) and a mass-loss rate of <jats:inline-formula> <jats:tex-math> <?CDATA $\dot{M}\gt 5\times {10}^{-4}\,{M}_{\odot }\,{{\rm{yr}}}^{-1}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>̇</mml:mo> </mml:mrow> </mml:mover> <mml:mo>&gt;</mml:mo> <mml:mn>5</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>4</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.25em" /> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>☉</mml:mo> </mml:mrow> </mml:msub> <mml:mspace width="0.25em" /> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">yr</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac3820ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>. During the initial 4 days after first light, we also observe an increase in velocity of the hydrogen lines (from ∼250 to ∼1000 km s<jats:sup>−1</jats:sup>), suggesting complex CSM. The presence of dense and confined CSM, as well as its inhomogeneous structure, indicates a phase of enhanced mass loss of the progenitor of SN 2020pni during the last year before explosion. Finally, we compare SN 2020pni to a sample of other shock-photoionization events. We find no evidence of correlations among the physical parameters of the explosions and the characteristics of the CSM surrounding the progenitors of these events. This favors the idea that the mass loss experienced by massive stars during their final years could be governed by stochastic phenomena and that, at the same time, the physical mechanisms responsible for this mass loss must be common to a variety of different progenitors.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We use the anelastic spherical harmonic code to model the convective dynamo of solar-type stars. Based on a series of 15 3D MHD simulations spanning four bins in rotation and mass, we show what mechanisms are at work in these stellar dynamos with and without magnetic cycles and how global stellar parameters affect the outcome. We also derive scaling laws for the differential rotation and magnetic field based on these simulations. We find a weaker trend between differential rotation and stellar rotation rate, (<jats:inline-formula> <jats:tex-math> <?CDATA ${\rm{\Delta }}{\rm{\Omega }}\propto {(| {\rm{\Omega }}| /{{\rm{\Omega }}}_{\odot })}^{0.46}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="normal">Δ</mml:mi> <mml:mi mathvariant="normal">Ω</mml:mi> <mml:mo>∝</mml:mo> <mml:msup> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mo stretchy="false">∣</mml:mo> <mml:mi mathvariant="normal">Ω</mml:mi> <mml:mo stretchy="false">∣</mml:mo> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">Ω</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mrow> <mml:mn>0.46</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac469bieqn1.gif" xlink:type="simple" /> </jats:inline-formula>) in the MHD solutions than in their HD counterpart <jats:inline-formula> <jats:tex-math> <?CDATA ${\left(| {\rm{\Omega }}| /{{\rm{\Omega }}}_{\odot }\right)}^{0.66}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow> <mml:mfenced close=")" open="("> <mml:mrow> <mml:mo stretchy="false">∣</mml:mo> <mml:mi mathvariant="normal">Ω</mml:mi> <mml:mo stretchy="false">∣</mml:mo> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">Ω</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:mrow> </mml:mfenced> </mml:mrow> <mml:mrow> <mml:mn>0.66</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac469bieqn2.gif" xlink:type="simple" /> </jats:inline-formula>), yielding a better agreement with the observational trends based on power laws. We find that for a fluid Rossby number between 0.15 ≲ <jats:italic>Ro</jats:italic> <jats:sub>f</jats:sub> ≲ 0.65, the solutions possess long magnetic cycle, if <jats:italic>Ro</jats:italic> <jats:sub>f</jats:sub> ≲ 0.42 a short cycle and if <jats:italic>Ro</jats:italic> <jats:sub>f</jats:sub> ≳ 1 (antisolar-like differential rotation), a statistically steady state. We show that short-cycle dynamos follow the classical Parker–Yoshimura rule whereas the long-cycle period ones do not. We also find efficient energy transfer between reservoirs, leading to the conversion of several percent of the star's luminosity into magnetic energy that could provide enough free energy to sustain intense eruptive behavior at the star’s surface. We further demonstrate that the Rossby number dependency of the large-scale surface magnetic field in the simulation (<jats:inline-formula> <jats:tex-math> <?CDATA ${B}_{{\rm{L}},\mathrm{surf}}\sim {{Ro}}_{{\rm{f}}}^{-1.26}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>B</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">L</mml:mi> <mml:mo>,</mml:mo> <mml:mi>surf</mml:mi> </mml:mrow> </mml:msub> <mml:mo>∼</mml:mo> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="italic">Ro</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">f</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1.26</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac469bieqn3.gif" xlink:type="simple" /> </jats:inline-formula>) agrees better with observations (<jats:inline-formula> <jats:tex-math> <?CDATA ${B}_{V}\sim {{Ro}}_{{\rm{s}}}^{-1.4\pm 0.1}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>B</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>V</mml:mi> </mml:mrow> </mml:msub> <mml:mo>∼</mml:mo> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="italic">Ro</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">s</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1.4</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.1</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac469bieqn4.gif" xlink:type="simple" /> </jats:inline-formula>) and differs from dynamo scaling based on the global magnetic energy (<jats:inline-formula> <jats:tex-math> <?CDATA ${B}_{\mathrm{bulk}}\sim {{Ro}}_{{\rm{f}}}^{-0.5}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>B</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>bulk</mml:mi> </mml:mrow> </mml:msub> <mml:mo>∼</mml:mo> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="italic">Ro</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">f</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.5</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac469bieqn5.gif" xlink:type="simple" /> </jats:inline-formula>).</jats:p>

<jats:title>Abstract</jats:title> <jats:p>During magnetic reconnection in Earth’s magnetotail, a dipolarizing flux tube (DFT) is formed and carries large amounts of energy toward the Earth to produce the aurora. Electrons inside the entire DFT are generally hot and tenuous, because they originate from the low-density lobe region and subsequently are heated by reconnection. Here, we report a special DFT hosting both hot-tenuous and cold-dense electrons, and we observe unique electron thermalization and associated electrostatic turbulence inside such a DFT. Analyses of the ion dynamics indicate that formation of the special phenomenon might be due to the flow reversal on the DFT flank, which is found to be an isobaric process in the direction perpendicular to the magnetic field. Correlation analysis shows that electrostatic waves at frequencies of 2–70 Hz are well correlated with the temperature anisotropy of electrons in the range of 300–27,000 eV, and waves at a frequency above one electron gyrofrequency (<jats:italic>f</jats:italic> <jats:sub>ce</jats:sub>) have a strong negative correlation with the electron temperature anisotropy as well. This study can improve our understanding of electron dynamics in the magnetotail.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We explored simultaneous observations of chromospheric evaporation and condensation during the impulsive phase of a C6.7 flare on 2019 May 9. The solar flare was simultaneously observed by multiple instruments, i.e., the New Vacuum Solar Telescope (NVST), the Interface Region Imaging Spectrograph, the Atmospheric Imaging Assembly (AIA), Fermi, the Mingantu Spectral Radioheliograph, and the Nobeyama Radio Polarimeters. Using the single Gaussian fitting and the moment analysis technique, redshifted velocities at slow speeds of 15–19 km s<jats:sup>−1</jats:sup> are found in the cool lines of C <jats:sc>ii</jats:sc> and Si <jats:sc>iv</jats:sc> at one flare footpoint location. Redshifts are also seen in the H<jats:italic>α</jats:italic> line-of-sight velocity image measured by NVST at double footpoints. Those redshifts with slow speeds can be regarded as the low-velocity downflows driven by the chromospheric condensation. Meanwhile, the converging motions from double footpoints to the loop top are found in the high-temperature EUV images, such as AIA 131, 94, and 335 Å. Their apparent speeds are estimated to be roughly 126–210 km s<jats:sup>−1</jats:sup>, which could be regarded as the high-velocity upflows caused by the chromospheric evaporation. The nonthermal energy flux is estimated to be about 5.7 × 10<jats:sup>10</jats:sup> erg s<jats:sup>−1</jats:sup> cm<jats:sup>−2</jats:sup>. The characteristic timescale is roughly equal to 1 minute. All these observational results suggest an explosive chromospheric evaporation during the flare impulsive phase. While a hard X-ray/microwave pulse and a type III radio burst are found simultaneously, indicating that the explosive chromospheric evaporation is driven by the nonthermal electron.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The formation, development, and impact of slow shocks in the upstream regions of reconnecting current layers are explored. Slow shocks have been documented in the upstream regions of magnetohydrodynamic (MHD) simulations of magnetic reconnection as well as in similar simulations with the <jats:italic>kglobal</jats:italic> kinetic macroscale simulation model. They are therefore a candidate mechanism for preheating the plasma that is injected into the current layers that facilitate magnetic energy release in solar flares. Of particular interest is their potential role in producing the hot thermal component of electrons in flares. During multi-island reconnection, the formation and merging of flux ropes in the reconnecting current layer drives plasma flows and pressure disturbances in the upstream region. These pressure disturbances steepen into slow shocks that propagate along the reconnecting component of the magnetic field and satisfy the expected Rankine–Hugoniot jump conditions. Plasma heating arises from both compression across the shock and the parallel electric field that develops to maintain charge neutrality in a kinetic system. Shocks are weaker at lower plasma <jats:italic>β</jats:italic>, where shock steepening is slow. While these upstream slow shocks are intrinsic to the dynamics of multi-island reconnection, their contribution to electron heating remains relatively minor compared with that from Fermi reflection and the parallel electric fields that bound the reconnection outflow.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a multiwavelength study of the H <jats:sc>ii</jats:sc> region Sh 2-301 (S301) using deep optical data, near-infrared data, radio continuum data, and other archival data at longer wavelengths. A cluster of young stellar objects (YSOs) is identified in the northeast (NE) direction of S301. The H<jats:italic>α</jats:italic> and radio continuum images trace the distribution of the ionized gas surrounding a massive star, ALS 207, and the S301 H <jats:sc>ii</jats:sc> region is bounded by an arc-like structure of gas and dust emission in the southeastern direction. The northwestern part of S301 seems to be devoid of gas and dust emission, while the presence of molecular material between the NE cluster and the central massive star ALS 207 is found. The distribution of warm dust emission, ionized gas, and neutral hydrogen together suggests a blistered morphology of the S301 H <jats:sc>ii</jats:sc> region powered by ALS 207, which appears to be located near the edge of the cloud. The location of the NE cluster embedded in the cold molecular cloud is found opposite to the blistered morphology. There is a noticeable age difference investigated between the massive star and the NE cluster. This age difference, pressure calculation, photodissociation regions, and the distribution of YSOs favor the positive feedback of the massive star ALS 207 in S301. On a wider scale of S301, the H <jats:sc>ii</jats:sc> region and the young stellar cluster are depicted toward the central region of a hub-filamentary system, which is evident in the infrared images.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Orbital characteristics based on Gaia Early Data Release 3 astrometric parameters are analyzed for ∼4000 metal-poor stars ([Fe/H] ≤ −0.8) compiled from the Best and Brightest survey. Selected as metal-poor candidates based on broadband near- and far-IR photometry, 43% of these stars had medium-resolution (1200 ≲ <jats:italic>R</jats:italic> ≲ 2000) validation spectra obtained over a 7 yr campaign from 2014 to 2020 with a variety of telescopes. The remaining stars were chosen based on photometric metallicity determinations from the Huang et al. recalibration of the Sky Mapper Southern Survey. Dynamical clusters of these stars are obtained from the orbital energy and cylindrical actions using the <jats:monospace>HDBSCAN</jats:monospace> unsupervised learning algorithm. We identify 52 dynamically tagged groups (DTGs) with between five and 21 members; 18 DTGs have at least 10 member stars. Milky Way (MW) substructures such as Gaia-Sausage-Enceladus, the Metal-Weak Thick-Disk, Thamnos, the Splashed Disk, and the Helmi Stream are identified. Associations with MW globular clusters are determined for eight DTGs; no recognized MW dwarf galaxies were associated with any of our DTGs. Previously identified dynamical groups are also associated with our DTGs, with emphasis placed on their structural determination and possible new identifications. Chemically peculiar stars are identified as members of several DTGs, with six DTGs that are associated with <jats:italic>r</jats:italic>-process-enhanced stars. We demonstrate that the mean carbon and <jats:italic>α</jats:italic>-element abundances of our DTGs are correlated with their mean metallicity in an understandable manner. Similarly, we find that the mean metallicity, carbon, and <jats:italic>α</jats:italic>-element abundances are separable into different regions of the mean rotational-velocity space.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Absorption of the Ly<jats:italic>α</jats:italic> radiation on interstellar neutral hydrogen (ISN H) atoms in the heliosphere is a potentially important effect to account for in precise gas distribution simulations. In this paper, we develop a method to estimate the magnitude of absorption of solar Ly<jats:italic>α</jats:italic> radiation inside the solar wind termination shock and to include absorption effects in the Warsaw Test Particle Model (WTPM) by an appropriate modification of radiation pressure. We perform calculations of absorption effects on a 3D grid in the heliosphere and present a set of parameters to model absorption effects for the mean solar activity conditions. We show that absorption can change by up to 3%, depending on the solar activity level. Using a modified version of WTPM, we calculate the expected signal from IBEX-Lo and show that absorption may modify the simulated flux by up to 8%.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Chandra Deep Field-South and North surveys (CDFs) provide unique windows into the cosmic history of X-ray emission from normal (nonactive) galaxies. Scaling relations of normal-galaxy X-ray luminosity (<jats:italic>L</jats:italic> <jats:sub>X</jats:sub>) with star formation rate (SFR) and stellar mass (<jats:italic>M</jats:italic> <jats:sub>⋆</jats:sub>) have been used to show that the formation rates of low-mass and high-mass X-ray binaries (LMXBs and HMXBs, respectively) evolve with redshift across <jats:italic>z</jats:italic> ≈ 0–2 following <jats:italic>L</jats:italic> <jats:sub>HMXB</jats:sub>/SFR ∝ (1 + <jats:italic>z</jats:italic>) and <jats:italic>L</jats:italic> <jats:sub>LMXB</jats:sub>/<jats:italic>M</jats:italic> <jats:sub>⋆</jats:sub> ∝ (1 + <jats:italic>z</jats:italic>)<jats:sup>2−3</jats:sup>. However, these measurements alone do not directly reveal the physical mechanisms behind the redshift evolution of X-ray binaries (XRBs). We derive star formation histories for a sample of 344 normal galaxies in the CDFs, using spectral energy distribution (SED) fitting of FUV-to-FIR photometric data, and construct a self-consistent, age-dependent model of the X-ray emission from the galaxies. Our model quantifies how X-ray emission from hot gas and XRB populations vary as functions of host stellar-population age. We find that (1) the ratio <jats:italic>L</jats:italic> <jats:sub>X</jats:sub>/<jats:italic>M</jats:italic> <jats:sub>⋆</jats:sub> declines by a factor of ∼1000 from 0 to 10 Gyr and (2) the X-ray SED becomes harder with increasing age, consistent with a scenario in which the hot gas contribution to the X-ray SED declines quickly for ages above 10 Myr. When dividing our sample into subsets based on metallicity, we find some indication that <jats:italic>L</jats:italic> <jats:sub>X</jats:sub>/<jats:italic>M</jats:italic> <jats:sub>⋆</jats:sub> is elevated for low-metallicity galaxies, consistent with recent studies of X-ray scaling relations. However, additional statistical constraints are required to quantify both the age and metallicity dependence of X-ray emission from star-forming galaxies.</jats:p>