Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We carried out 3D dust + gas radiative hydrodynamic simulations of forming planets. We investigated a parameter grid of a Neptune-mass, a Saturn-mass, a Jupiter-mass, and a five-Jupiter-mass planet at 5.2, 30, and 50 au distance from their star. We found that the meridional circulation (Szulágyi et al. 2014; Fung &amp; Chiang 2016) drives a strong vertical flow for the dust as well, hence the dust is not settled in the midplane, even for millimeter-sized grains. The meridional circulation will deliver dust and gas vertically onto the circumplanetary region, efficiently bridging over the gap. The Hill-sphere accretion rates for the dust are ∼10<jats:sup>−8</jats:sup>–10<jats:sup>−10</jats:sup> <jats:italic>M</jats:italic> <jats:sub>Jup</jats:sub> yr<jats:sup>−1</jats:sup>, increasing with planet mass. For the gas component, the gain is 10<jats:sup>−6</jats:sup>–10<jats:sup>−8</jats:sup> <jats:italic>M</jats:italic> <jats:sub>Jup</jats:sub> yr<jats:sup>−1</jats:sup>. The difference between the dust and gas-accretion rates is smaller with decreasing planetary mass. In the vicinity of the planet, the millimeter-sized grains can get trapped easier than the gas, which means the circumplanetary disk might be enriched with solids in comparison to the circumstellar disk. We calculated the local dust-to-gas ratio (DTG) everywhere in the circumstellar disk and identified the altitude above the midplane where the DTG is 1, 0.1, 0.01, and 0.001. The larger the planetary mass, the more the millimeter-sized dust is delivered and a larger fraction of the dust disk is lifted by the planet. The stirring of millimeter-sized dust is negligible for Neptune-mass planets or below, but significant above Saturn-mass planets.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Because of the unquestionable presence of magnetic fields in stars, their role in the structure of stellar atmospheres has for a long time been a subject of speculation. In our contribution to this discussion we present spectropolarimetric evidence of the decrease of the radial component of the magnetic field with altitude in the atmosphere of HD 58260, a B-type magnetic star on the main sequence. We show that the Stokes <jats:italic>V</jats:italic> profiles of metal lines in emission of the outer atmosphere are evidence for a field three times weaker than absorption lines from inner layers. The extra flow of energetic particles due to the magnetic-gradient pumping mechanism could be at the origin of the magnetospheres surrounding this class of stars and at the basis of the high-energy phenomena observed. We also list a series of spectral lines useful for measuring the surface field of early-type stars.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The dominant uncertainty in the current measurement of the Hubble constant (<jats:italic>H</jats:italic> <jats:sub>0</jats:sub>) with strong gravitational lensing time delays is attributed to uncertainties in the mass profiles of the main deflector galaxies. Strongly lensed supernovae (glSNe) can provide, in addition to measurable time delays, lensing magnification constraints when knowledge about the unlensed apparent brightness of the explosion is imposed. We present a hierarchical Bayesian framework to combine a data set of SNe that are not strongly lensed and a data set of strongly lensed SNe with measured time delays. We jointly constrain (i) <jats:italic>H</jats:italic> <jats:sub>0</jats:sub> using the time delays as an absolute distance indicator, (ii) the lens model profiles using the magnification ratio of lensed and unlensed fluxes on the population level, and (iii) the unlensed apparent magnitude distribution of the SN population and the redshift–luminosity relation of the relative expansion history of the universe. We apply our joint inference framework on a future expected data set of glSNe and forecast that a sample of 144 glSNe of Type Ia with well-measured time series and imaging data will measure <jats:italic>H</jats:italic> <jats:sub>0</jats:sub> to 1.5%. We discuss strategies to mitigate systematics associated with using absolute flux measurements of glSNe to constrain the mass density profiles. Using the magnification of SN images is a promising and complementary alternative to using stellar kinematics. Future surveys, such as the Rubin and Roman observatories, will be able to discover the necessary number of glSNe, and with additional follow-up observations, this methodology will provide precise constraints on mass profiles and <jats:italic>H</jats:italic> <jats:sub>0</jats:sub>.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>A spectral survey of methyl acetylene (CH<jats:sub>3</jats:sub>CCH) was conducted toward the hot molecular core/outflow G331.512-0.103. Our APEX observations allowed the detection of 41 uncontaminated rotational lines of CH<jats:sub>3</jats:sub>CCH in the frequency range between 172 and 356 GHz. Through an analysis under the local thermodynamic equilibrium assumption, by means of rotational diagrams, we determined <jats:italic>T</jats:italic> <jats:sub>exc</jats:sub> = 50 ± 1 K, <jats:italic>N</jats:italic>(CH<jats:sub>3</jats:sub>CCH) = (7.5 ± 0.4) × 10<jats:sup>15</jats:sup> cm<jats:sup>2</jats:sup>, <jats:italic>X</jats:italic>[CH<jats:sub>3</jats:sub>CCH/H<jats:sub>2</jats:sub>] ≈ (0.8–2.8) × 10<jats:sup>−8</jats:sup>, and <jats:italic>X</jats:italic>[CH<jats:sub>3</jats:sub>CCH/CH<jats:sub>3</jats:sub>OH] ≈ 0.42 ± 0.05 for an extended emitting region (∼10″). The relative intensities of the <jats:italic>K</jats:italic> = 2 and <jats:italic>K</jats:italic> = 3 lines within a given <jats:italic>K</jats:italic>-ladder are strongly negatively correlated to the transitions’ upper <jats:italic>J</jats:italic> quantum number (<jats:italic>r</jats:italic> = −0.84). Pure rotational spectra of CH<jats:sub>3</jats:sub>CCH were simulated at different temperatures, in order to interpret this observation. The results indicate that the emission is characterized by a nonnegligible temperature gradient with upper and lower limits of ∼45 and ∼60 K, respectively. Moreover, the line widths and peak velocities show an overall strong correlation with their rest frequencies, suggesting that the warmer gas is also associated with stronger turbulence effects. The <jats:italic>K</jats:italic> = 0 transitions present a slightly different kinematic signature than the remaining lines, indicating that they might be tracing a different gas component. We speculate that this component is characterized by lower temperatures and therefore larger sizes. Moreover, we predict and discuss the temporal evolution of the CH<jats:sub>3</jats:sub>CCH abundance using a two-stage zero-dimensional model of the source constructed with the three-phase Nautilus gas-grain code.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Planetesimal formation is a crucial yet poorly understood process in planet formation. It is widely believed that planetesimal formation is the outcome of dust clumping by the streaming instability (SI). However, recent analytical and numerical studies have shown that the SI can be damped or suppressed by external turbulence, and at least the outer regions of protoplanetary disks are likely weakly turbulent due to magneto-rotational instability (MRI). We conduct high-resolution local shearing-box simulations of hybrid particle-gas magnetohydrodynamics (MHD), incorporating ambipolar diffusion as the dominant nonideal MHD effect, applicable to outer disk regions. We first show that dust backreaction enhances dust settling toward the midplane by reducing turbulence correlation time. Under modest level of MRI turbulence, we find that dust clumping is in fact easier than the conventional SI case, in the sense that the threshold of solid abundance for clumping is lower. The key to dust clumping includes dust backreaction and the presence of local pressure maxima, which in our work is formed by the MRI zonal flows overcoming background pressure gradient. Overall, our results support planetesimal formation in the MRI-turbulent outer protoplanetary disks, especially in ring-like substructures.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Ram pressure stripping has been proven to be effective in shaping galaxy properties in dense environments at low redshift. The availability of Multi Unit Spectroscopic Explorer (MUSE) observations of a sample of distant (<jats:italic>z</jats:italic> ∼ 0.3–0.5) clusters has allowed one to search for galaxies subject to this phenomenon at significant lookback times. In this paper we describe how we discovered and characterized 13 ram-pressure-stripped galaxies in the central regions of two intermediate redshift (<jats:italic>z</jats:italic> ∼ 0.3–0.4) clusters, A2744 and A370, using the MUSE spectrograph. Emission-line properties as well as stellar features have been analyzed to infer the presence of this gas-only stripping mechanism, that produces spectacular ionized gas tails (H<jats:italic>α</jats:italic> and even more astonishing [O <jats:sc>ii</jats:sc>](3727, 3729)) departing from the main galaxy body. The inner regions of these two clusters reveal the predominance of such galaxies among blue star-forming cluster members, suggesting that ram pressure stripping was even more effective at intermediate redshift than in today’s universe. Interestingly, the resolved [O <jats:sc>ii</jats:sc>]/H<jats:italic>α</jats:italic> line ratio in the stripped tails is exceptionally high compared to that in the disks of these galaxies, (which is comparable to that in normal low-<jats:italic>z</jats:italic> galaxies), suggesting lower gas densities and/or an interaction with the hot surrounding intracluster medium.</jats:p>