Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Certain astronomy problems, such as the probabilistic cross-matching algorithms of Wilson &amp; Naylor, require descriptions of galaxy counts as a function of brightness in many different filter sets, for which we often lack dedicated observations. With this motivation in mind, I present a simple model for calculating differential galaxy counts for an arbitrary bandpass or wavelength. The model uses a double Schechter function to describe the number density of galaxies as a function of absolute magnitude, including redshift-driven galaxy evolution, for both “blue” and “red” galaxy types. Collating previously derived values for the parameterization of the evolving Schechter function—<jats:inline-formula> <jats:tex-math> <?CDATA ${M}_{0}^{* }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</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="rnaasac60a6ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, <jats:inline-formula> <jats:tex-math> <?CDATA ${\phi }_{0}^{* }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>ϕ</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</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="rnaasac60a6ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>, <jats:italic>P</jats:italic>, <jats:italic>Q</jats:italic>, and <jats:italic>α</jats:italic>—I fit the dependencies of these parameters as a function of wavelength, allowing for the tabulation of differential galaxy counts in a new filter for which observations are unavailable. Finally, I briefly compare the model with some differential galaxy counts obtained from the literature.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Using the Murchison Widefield Array we searched for, and did not detect, 145.980 MHz transmissions from the 4M spacecraft attached to the Chang’e 5-T1 rocket booster. This object was predicted to collide with the Moon on 2022 March 4. We observed for a ten minutes period on 2022 March 1, achieving noise levels of ∼4 Jy in a 10 kHz bandwidth. The expected signal level of a nominally operational transmitter would be ∼7500 Jy. Thus, we conclude that the transmitter was inactive (or operating at less than 5 mW) in the days before the predicted impact with the Moon, which is reasonable given that the nominal mission life of 4M was approximately 8 days in late 2014. A detection would have allowed 4M and its host booster to be tracked to near the point of collision, which was not possible using optical telescopes due to the event occurring in daytime.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present deep, full-sky maps built from Wide-field Infrared Survey Explorer and NEOWISE exposures spanning the 2010 January–2020 December time period. These coadds, which incorporate roughly 8 yr of W1 (3.4 <jats:italic>μ</jats:italic>m) and W2 (4.6 <jats:italic>μ</jats:italic>m) imaging, are the deepest ever full-sky maps at wavelengths of 3–5 <jats:italic>μ</jats:italic>m. Photometry based on these coadds will be a component of DESI Legacy Imaging Surveys DR10.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the results of deep ground-based <jats:italic>U</jats:italic>-band imaging of the Extended Groth Strip (EGS) field, and the creation of a best resolution mosaic and a best depth mosaic following the seeing-sorted stacking method of Ashcraft et al. The analysis uses 324 images taken from 2012 March to 2021 June using the Large Binocular Camera. The best resolution mosaic includes the 16.4% of images with FWHM ≤ 0.″9, while the best depth mosaic includes the 73.5% of images with FWHM ≤ 1.″6. Each image’s zero-point was matched to SDSS <jats:italic>u</jats:italic>, to account for transparency variations. Images with stellar ellipticity (1 − <jats:italic>b</jats:italic>/<jats:italic>a</jats:italic>) ≥ 0.08 were omitted. We find that the galaxy counts turn over at <jats:italic>U</jats:italic> <jats:sub>AB</jats:sub> ∼ 25.75 mag in the best resolution mosaic and at ∼26 mag in the best depth mosaic. The EGS field is the final UVCANDELS field analyzed using the seeing-sorted stacking method.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>This work is part of a multi-wavelength program to study the effects of X-ray/UV/optical stellar radiation on the chemistry of the circumbinary disk around the young high-eccentricity binary DQ Tau. ALMA observations for near/around 2021 December 5 periastron were postponed due to bad weather, but supporting Swift-XRT-UVOT TOO observations were successful. These Swift observations along with previous X-ray-optical-mm data show that DQ Tau keeps exhibiting powerful flares near periastron, offering a unique laboratory for studies of flare effects on the gas-phase ion chemistry in protoplanetary disks.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Most methods used to determine the white dwarf mass in non-magnetic cataclysmic variables are subject to large systematic errors. X-ray spectroscopy has the potential to enable mass estimation with a good accuracy, when calibrated against accurate and reliable values. This is now possible thanks to the work of Pala et al., who estimated the white dwarf masses for 43 cataclysmic variables relying in part on Gaia distances. In this research note we provide a brief update on the X-ray temperature versus white dwarf mass relationship using the X-ray spectroscopy results of Byckling et al. compared against the results of Pala et al., thereby putting the X-ray spectroscopy method on a securer footing.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>While Keplerian orbits account for the majority of the astrometric motion of directly-imaged planets, perturbations due to <jats:italic>N</jats:italic>-body interactions allow us to directly constrain exoplanet masses in multiplanet systems. This has the potential to improve our understanding of massive directly-imaged planets, which nearly all currently have only model-dependent masses. The VLTI-GRAVITY instrument has demonstrated that interferometry can achieve 100x better astrometric precision than existing methods, a level of precision that makes detection of planet–planet interactions possible. In this study, we show that in the HR-8799 system, planet–planet deviations from currently used Keplerian approximations are expected to be up to one-quarter of a milliarcsecond within five years, which will make them detectable with VLTI-GRAVITY. Modeling of this system to directly constrain exoplanet masses will be crucial in order to make precise predictions.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Common envelope evolution is widely accepted as the principal shaping agent in the formation of aspherical planetary nebulae. However, only some 20% of planetary nebulae are found to host post-common-envelope binary central stars. To probe the detectability of post-common-envelope binary central stars, and their potential to evade detection, we simulate the light curves of an array of these systems varying their stellar and orbital parameters. We find that while binaries with late-type companions and/or long orbital periods will likely go undetected, they are unlikely to represent a large fraction of the overall post-common-envelope central star population.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We announce the completion of two new Earth Trojan Asteroid (ETA) simulations. ETAs co-orbit the Sun with Earth and remain loosely bound to the fourth or fifth Lagrange points. To date, two ETAs have been detected (2010 TK<jats:sub>7</jats:sub> and 2020 XL<jats:sub>5</jats:sub>); however, based on their orbits, these are likely temporary captures rather than members of a primordial population. The motivation for our simulations is multi-faceted: (1) the lack of a detected population despite literature claims of stability over the age of the solar system, (2) ETAs are important for both solar system science and planetary defense, and (3) the proximity of ETAs makes them prime candidates for space exploration missions. These simulations are of extremely high fidelity, large in number and long in simulation time. We will be releasing a series of papers based upon these simulations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The analysis of high resolution SWP spectra obtained through the large aperture with the International Ultraviolet Explorer reveals that the far-ultraviolet flux of <jats:italic>ξ</jats:italic> Oct did not vary. In particular, the flux remained stable in a series of seven spectra taken consecutively over 3 hr and 24 minutes. This time interval is much shorter than the 1.78 days rotational period proposed for this star from its TESS lightcurve, which could explain for the absence of variability in the FUV. The comparison of the STIS spectrum of <jats:italic>ξ</jats:italic> Oct in the range 1300–1340 Å with synthetic spectra computed for the fundamental parameters of <jats:italic>ξ</jats:italic> Oct and a solar composition allows the identification of the strongest absorption features in the far-ultraviolet as due to resonance lines of O <jats:sc>i</jats:sc>, Si <jats:sc>ii</jats:sc> and C <jats:sc>ii</jats:sc>.</jats:p>