Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We analyze spectroscopic and photometric data to determine the projected inclinations of stars in three open clusters: the Pleiades, Praesepe, and M35. We determine the <jats:inline-formula> <jats:tex-math> <?CDATA $\sin i$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <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="apjac281dieqn1.gif" xlink:type="simple" /> </jats:inline-formula> values of 42, 35, and 67 stars in each cluster, respectively, and from their distributions we find that isotropic spins and moderate alignment are both consistent with the Pleiades and Praesepe data. While it is difficult to distinguish between these scenarios for a single cluster, an ensemble of such distributions may facilitate a distinction. The M35 inclination distribution is most consistent with a superposition of isotropic and anisotropic spins, the source of which could be systematic error or a physical grouping of aligned stars. We also study internal cluster kinematics using radial velocities and proper motions. Our kinematics analysis reveals significant plane-of-sky rotation in Praesepe, with a mean velocity of 0.132 ± 0.022 km s<jats:sup>−1</jats:sup> in a clockwise direction.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Molecular abundances are sensitive to the UV photon flux and cosmic-ray ionization rate. In starburst environments, the effects of high-energy photons and particles are expected to be stronger. We examine these astrochemical signatures through multiple transitions of HCO<jats:sup>+</jats:sup> and its metastable isomer HOC<jats:sup>+</jats:sup> in the center of the starburst galaxy NGC 253 using data from the Atacama Large Millimeter/submillimeter Array large program ALMA Comprehensive High-resolution Extragalactic Molecular inventory. The distribution of the HOC<jats:sup>+</jats:sup>(1−0) integrated intensity shows its association with “superbubbles,” cavities created either by supernovae or expanding H <jats:sc>ii</jats:sc> regions. The observed HCO<jats:sup>+</jats:sup>/HOC<jats:sup>+</jats:sup> abundance ratios are ∼10–150, and the fractional abundance of HOC<jats:sup>+</jats:sup> relative to H<jats:sub>2</jats:sub> is ∼1.5 × 10<jats:sup>−11</jats:sup>–6 × 10<jats:sup>−10</jats:sup>, which implies that the HOC<jats:sup>+</jats:sup> abundance in the center of NGC 253 is significantly higher than in quiescent spiral arm dark clouds in the Galaxy and the Galactic center clouds. Comparison with chemical models implies either an interstellar radiation field of <jats:italic>G</jats:italic> <jats:sub>0</jats:sub> ≳ 10<jats:sup>3</jats:sup> if the maximum visual extinction is ≳5, or a cosmic-ray ionization rate of <jats:italic>ζ</jats:italic> ≳ 10<jats:sup>−14</jats:sup> s<jats:sup>−1</jats:sup> (3–4 orders of magnitude higher than that within clouds in the Galactic spiral arms) to reproduce the observed results. From the difference in formation routes of HOC<jats:sup>+</jats:sup>, we propose that a low-excitation line of HOC<jats:sup>+</jats:sup> traces cosmic-ray dominated regions, while high-excitation lines trace photodissociation regions. Our results suggest that the interstellar medium in the center of NGC 253 is significantly affected by energy input from UV photons and cosmic rays, sources of energy feedback.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We use hydrodynamical simulations of star-forming gas with stellar feedback and sink particles—proxies for young stellar objects (YSOs)—to produce and analyze synthetic 1.1 mm continuum observations at different distances (150–1000 pc) and ages (0.49–1.27 Myr). We characterize how the inferred core properties, including mass, size, and clustering with respect to diffuse natal gas structure, change with distance, cloud evolution, and the presence of YSOs. We find that atmospheric filtering and core segmentation treatments have distance-dependent impacts on the resulting core properties for <jats:italic>d</jats:italic> &lt; 300 pc and 500 pc, respectively, which dominate over evolutionary differences. Concentrating on synthetic observations at further distances (650–1000 pc), we find a growing separation between the inferred sizes and masses of cores with and without YSOs in the simulations, which is not seen in recent observations of the Monoceros R2 (Mon R2) cloud at 860 pc. We find that the synthetic cores cluster in smaller groups, and that their mass densities are correlated with gas column density over a much narrower range, than those in the Mon R2 observations. Such differences limit the applicability of the evolutionary predictions we report here, but will motivate our future efforts to adapt our synthetic observation and analysis framework to next generation simulations, such as Star Formation in Gaseous Environments (STARFORGE). These predictions and systematic characterizations will help to guide the analysis of cores on the upcoming TolTEC Clouds to Cores Legacy Survey on the Large Millimeter Telescope Alfonso Serrano.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We develop and implement an inclination-dependent attenuation prescription for spectral energy distribution (SED) fitting and study its impact on derived star formation histories. We apply our prescription within the SED fitting code <jats:monospace>Lightning</jats:monospace> to a clean sample of 82, <jats:italic>z</jats:italic> = 0.21–1.35 disk-dominated galaxies in the Great Observatories Origins Deep Survey North and South fields. To compare our inclination-dependent attenuation prescription with more traditional fitting prescriptions, we also fit the SEDs with the inclination-independent Calzetti et al. (2000) attenuation curve. From this comparison, we find that fits to a subset of 58, <jats:italic>z</jats:italic> &lt; 0.7 galaxies in our sample, utilizing the Calzetti et al. (2000) prescription, recover similar trends with inclination as the inclination-dependent fits for the far-UV-band attenuation and recent star formation rates. However, we find a difference between prescriptions in the optical attenuation (<jats:italic>A</jats:italic> <jats:sub> <jats:italic>V</jats:italic> </jats:sub>) that is strongly correlated with inclination (<jats:italic>p</jats:italic>‐value &lt; 10<jats:sup>−11</jats:sup>). For more face-on galaxies, with <jats:italic>i</jats:italic> ≲ 50°, (edge-on, <jats:italic>i</jats:italic> ≈ 90°), the average derived <jats:italic>A</jats:italic> <jats:sub> <jats:italic>V</jats:italic> </jats:sub> is 0.31 ± 0.11 magnitudes lower (0.56 ± 0.16 magnitudes higher) for the inclination-dependent model compared to traditional methods. Further, the ratio of stellar masses between prescriptions also has a significant (<jats:italic>p</jats:italic>‐value &lt; 10<jats:sup>−2</jats:sup>) trend with inclination. For <jats:italic>i</jats:italic> = 0°–65°, stellar masses are systematically consistent between fits, with <jats:inline-formula> <jats:tex-math> <?CDATA ${\mathrm{log}}_{10}({M}_{\star }^{\mathrm{inc}}/{M}_{\star }^{\mathrm{Calzetti}})=-0.05\pm 0.03$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>log</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> </mml:msub> <mml:mo stretchy="false">(</mml:mo> <mml:msubsup> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⋆</mml:mo> </mml:mrow> <mml:mrow> <mml:mi>inc</mml:mi> </mml:mrow> </mml:msubsup> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msubsup> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⋆</mml:mo> </mml:mrow> <mml:mrow> <mml:mi>Calzetti</mml:mi> </mml:mrow> </mml:msubsup> <mml:mo stretchy="false">)</mml:mo> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:mn>0.05</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.03</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac25f3ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> dex and scatter of 0.11 dex. However, for <jats:italic>i</jats:italic> ≈ 80°–90°, the derived stellar masses are lower for the Calzetti et al. (2000) fits by an average factor of 0.17 ± 0.03 dex and scatter of 0.13 dex. Therefore, these results suggest that SED fitting assuming the Calzetti et al. (2000) attenuation law potentially underestimates stellar masses in highly inclined disk-dominated galaxies.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Recent high-spatial/spectral-resolution observations have enabled the formation mechanisms of giant planets to be constrained, especially at the final stages. The current interpretation of such observations is that these planets undergo magnetospheric accretion, suggesting the importance of planetary magnetic fields. We explore the properties of accreting, magnetized giant planets surrounded by their circumplanetary disks, using the physical parameters inferred for PDS 70 b/c. We compute the magnetic field strength and the resulting spin rate of giant planets and find that these planets may possess dipole magnetic fields of either a few 10 G or a few 100 G; the former is the natural outcome of planetary growth and radius evolution, while the resulting spin rate cannot reproduce the observations. For the latter, a consistent picture can be drawn, where strong magnetic fields induced by hot planetary interiors lead both to magnetospheric accretion and to spin-down due to disk locking. We also compute the properties of circumplanetary disks in the vicinity of these planets, taking into account planetary magnetic fields. The resulting surface density becomes very low, compared with the canonical models, implying the importance of radial movement of satellite-forming materials. Our model predicts a positive gradient of the surface density, which invokes traps for both satellite migration and radially drifting dust particles. This work thus concludes that the final formation stages of giant planets are similar to those of low-mass stars such as brown dwarfs, as suggested by recent studies.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Making use of both MUSE observations of 85 galaxies from the survey GASP (GAs Stripping Phenomena in galaxies with MUSE) and a large sample from MaNGA (Mapping Nearby Galaxies at Apache Point Observatory survey), we investigate the distribution of gas metallicity gradients as a function of stellar mass for local cluster and field galaxies. Overall, metallicity profiles steepen with increasing stellar mass up to 10<jats:sup>10.3</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> and flatten out at higher masses. Combining the results from the metallicity profiles and the stellar mass surface density gradients, we propose that the observed steepening is a consequence of local metal enrichment due to in situ star formation during the inside-out formation of disk galaxies. The metallicity gradient−stellar mass relation is characterized by a rather large scatter, especially for 10<jats:sup>9.8</jats:sup> &lt; <jats:italic>M</jats:italic> <jats:sub>⋆</jats:sub>/<jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> &lt; 10<jats:sup>10.5</jats:sup>, and we demonstrate that metallicity gradients anti-correlate with the galaxy gas fraction. Focusing on the galaxy environment, at any given stellar mass, cluster galaxies have systematically flatter metallicity profiles than their field counterparts. Many subpopulations coexist in clusters: galaxies with shallower metallicity profiles appear to have fallen into their present host halo sooner and have experienced the environmental effects for a longer time than cluster galaxies with steeper metallicity profiles. Recent galaxy infallers, like galaxies currently undergoing ram pressure stripping, show metallicity gradients more similar to those of field galaxies, suggesting they have not felt the effect of the cluster yet.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Martian ionosphere plays a crucial role in driving the interactions of the planet with solar photons and solar wind particles. The variations of the dayside Martian ionosphere with several controlling factors, including the solar extreme ultraviolet radiation, the background atmosphere, and the underlying thermal structure, have been the topic of extensive research in terms of electron distribution. In contrast, how the ionospheric composition varies has not been systematically investigated, a topic that is attempted in this study based on photochemical equilibrium computations performed at 100–200 km altitude, including a large number of reactions. Our calculations reveal the following compositional variations as natural outcomes of the ionospheric chemistry on Mars. (1) With increasing solar irradiance, the proportions of the majority of nonterminal ions are enhanced at the expense of reduced proportions of terminal ions, including <jats:inline-formula> <jats:tex-math> <?CDATA ${{\rm{O}}}_{2}^{+}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="normal">O</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac24feieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, HCO<jats:sup>+</jats:sup>, NO<jats:sup>+</jats:sup>, and H<jats:sub>3</jats:sub>O<jats:sup>+</jats:sup>. (2) At high electron temperatures, the proportion of NO<jats:sup>+</jats:sup> is modestly reduced, whereas the proportions of the other species are nearly unaffected. (3) The response of the ionospheric composition to the upper atmospheric composition is complicated, showing the strong negative response of many trace ions to ambient CO<jats:sub>2</jats:sub>, O, and CO, as well as the strong positive response of protonated ions to H<jats:sub>2</jats:sub>, nitrogen-bearing ions to N and N<jats:sub>2</jats:sub>, water-group ions to H<jats:sub>2</jats:sub>O, and <jats:inline-formula> <jats:tex-math> <?CDATA ${\mathrm{HO}}_{2}^{+}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>HO</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac24feieqn2.gif" xlink:type="simple" /> </jats:inline-formula> to O<jats:sub>2</jats:sub>. As an application of the model results, the recent ion measurements made on board the Mars Atmosphere and Volatile Evolution are used to provide hints about the realistic composition of the Martian upper atmosphere.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We have analyzed the parsec-scale jet kinematics of 447 bright radio-loud active active galactic nuclei (AGN), based on 15 GHz Very Long Baseline Array (VLBA) data obtained between 1994 August 31 and 2019 August 4. We present new total intensity and linear polarization maps obtained between 2017 January 1 and 2019 August 4 for 143 of these AGN. We tracked 1923 bright features for five or more epochs in 419 jets. The majority (60%) of the well-sampled jet features show either accelerated or nonradial motion. In 47 jets there is at least one nonaccelerating feature with an unusually slow apparent speed. Most of the jets show variations of 10°–50° in their inner jet position angle (PA) over time, although the overall distribution has a continuous tail out to 200°. AGN with spectral energy distributions peaked at lower frequencies tend to have more variable PAs, with BL Lac objects being less variable than quasars. The Fermi Large Area Telescope (LAT) gamma-ray-associated AGN also tend to have more variable PAs than the non-LAT AGN in our sample. We attribute these trends to smaller viewing angles for the lower spectral peaked and LAT-associated jets. We identified 13 AGN where multiple features emerge over decade-long periods at systematically increasing or decreasing PAs. Since the ejected features do not fill the entire jet cross section, this behavior is indicative of a precessing flow instability near the jet base. Although some jets show indications of oscillatory PA evolution, we claim no bona fide cases of periodicity since the fitted periods are comparable to the total VLBA time coverage.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Although it is well established that some extragalactic radio sources are time-variable, the properties of this radio variability, and its connection with host galaxy properties, remain to be explored—particularly for faint sources. Here we present an analysis of radio variable sources from the CHILES Variable and Explosive Radio Dynamic Evolution Survey (CHILES VERDES)—a partner project of the 1.4 GHz COSMOS H <jats:sc>i</jats:sc> Large Extragalactic Survey. CHILES VERDES provides an unprecedented combination of survey depth, duration, and cadence, with 960 hr of 1–2 GHz continuum VLA data obtained over 209 epochs between 2013 and 2019 in a 0.44 deg<jats:sup>2</jats:sup> section of the well-studied extragalactic deep field, COSMOS. We identified 18 moderate-variability sources (showing 10%–30% flux density variation) and 40 lower-variability sources (2%–10% flux density variation). They are mainly active galactic nuclei (AGNs) with radio luminosities in the range of 10<jats:sup>22</jats:sup>–10<jats:sup>27</jats:sup> W Hz<jats:sup>−1</jats:sup>, based on cross-matching with COSMOS multiwavelength catalogs. The moderate-variability sources span redshifts <jats:italic>z</jats:italic> = 0.22–1.56, have mostly flat radio spectra (<jats:italic>α</jats:italic> &gt; −0.5), and vary on timescales ranging from days to years. The lower-variability sources have similar properties, but generally have higher radio luminosities than the moderate-variability sources, extending to <jats:italic>z</jats:italic> = 2.8, and have steeper radio spectra (<jats:italic>α</jats:italic> &lt; −0.5). No star-forming galaxy showed statistically significant variability in our analysis. The observed variability likely originates from scintillation on short (∼week) timescales, and Doppler-boosted intrinsic AGN variability on long (month–year) timescales.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The study of stripped-envelope core-collapse supernovae (SNe), with evidence for strong interaction of SN ejecta with the circumstellar medium (CSM), provides insights into the pre-supernova progenitor, and a fast-forwarded view of the progenitor mass-loss history. In this context, we present late-time radio observations of SN 2004dk, a Type Ibc supernova located in the galaxy NGC 6118, at a distance of <jats:italic>d</jats:italic> <jats:sub> <jats:italic>L</jats:italic> </jats:sub> ≈ 23 Mpc. About 10 yr after explosion, SN 2004dk has shown evidence for H<jats:italic>α</jats:italic> emission, possibly linked to the SN ejecta interacting with a H-rich CSM. Using data from the VLA Low Band Ionosphere and Transient Experiment (VLITE), we confirm the presence of a late-time radio rebrightening accompanying the observed H<jats:italic>α</jats:italic> emission. We model the SN 2004dk radio light curves within the (spherically symmetric) synchrotron-self-absorption (SSA) model. Within this model, our VLITE observations combined with previously collected VLA data favor an interpretation of SN 2004dk as a strongly CSM-interacting radio SN going through a complex environment shaped by nonsteady mass loss from the SN progenitor.</jats:p>