Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We use a combination of Hipparcos space mission data with the USNO dedicated ground-based astrometric program URAT-Bright designed to complement and verify Gaia results for the brightest stars in the south to estimate the small perturbations of observed proper motions caused by exoplanets. One of the 1423 bright stars in the program, <jats:italic>δ</jats:italic> Pav, stands out with a small proper motion difference between our long-term estimate and Gaia EDR3 value, which corresponds to a projected velocity of (−17, +13) m s<jats:sup>−1</jats:sup>. This difference is significant at a 0.994 confidence in the R.A. component, owing to the proximity of the star and the impressive precision of proper motions. The effect is confirmed by a comparison of long-term EDR3-Hipparcos and short-term Gaia EDR3 proper motions at a smaller velocity, but with formally absolute confidence. We surmise that the close Solar analog <jats:italic>δ</jats:italic> Pav harbors a long-period exoplanet similar to Jupiter.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report a new period mid-infrared variability of PMN J0948+0022 on 2020 April 26, observed by the Wide-field Infrared Survey Explore (WISE). This source faded consistently over a period of one day. The amplitude of variability is about 0.21 and 0.18 mag in the W1 (3.4 <jats:italic>μ</jats:italic>m) and W2 (4.6 <jats:italic>μ</jats:italic>m) bands, respectively. The intraday variability constrains the size of the mid-infrared emission region to about 5 × 10<jats:sup>−4</jats:sup> pc, which is rather smaller than that of the dust torus but consistent with the base of a jet. The mid-infrared color showed a significant bluer-when-brighter trend, similar to <jats:italic>γ</jats:italic>-ray emitting blazars. These characteristics suggest that the mid-infrared emission was dominated by the synchrotron emission of relativistic electrons in the jet.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report 14 radial velocities for three field stars located near the RR Lyrae variables NO Cas, NR Lyr, and V1176 Sgr. We identified the three field stars using Gaia Early Data Release 3. Two of these stars confirm the Gaia radial velocities. The third has no previously published radial velocity.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Most asteroids are somewhat elongated and have non-zero lightcurve amplitudes. Such asteroids can be detected in large-scale sky surveys even if their mean magnitudes are fainter than the stated sensitivity limits. We explore the detection of elongated asteroids under a set of idealized but useful approximations. We find that objects up to 1 mag fainter than a survey’s sensitivity limit are likely to be detected, and that the effect is most pronounced for asteroids with lightcurve amplitudes 0.1–0.4 mag. This imposes a bias on the derived size and shape distributions of the population that must be properly accounted for.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present photometric <jats:italic>B</jats:italic>, <jats:italic>V</jats:italic>, and <jats:italic>R</jats:italic> observations of the semiregular variable V698 Tau taken in 2020–2021. The star varies by ∼1 mag in each filter with a mean period of ∼185 days. At minimum light the star is noticeably redder in <jats:italic>V</jats:italic> − <jats:italic>R</jats:italic> than at maximum while slightly bluer in <jats:italic>B</jats:italic> − <jats:italic>V</jats:italic>. The magnitudes and colors are consistent with those of a reddened M8 giant.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>X-ray spectral fitting of astronomical sources requires convolving the intrinsic spectrum or model with the instrumental response. Standard forward modeling techniques have proven success in recovering the underlying physical parameters in moderate to high signal-to-noise regimes; however, they struggle to achieve the same level of accuracy in low signal-to-noise regimes. Additionally, the use of machine learning techniques on X-ray spectra requires access to the intrinsic spectrum. Therefore, the measured spectrum must be effectively deconvolved from the instrumental response. In this note, we explore numerical methods for inverting the matrix equation describing X-ray spectral convolution. We demonstrate that traditional methods are insufficient to recover the intrinsic X-ray spectrum and argue that a novel approach is required.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The ultra-wideband low (UWL) receiver is a new feed for the Parkes telescope, which covers the combined bandwidth of four previously installed receivers. In order to use the UWL for technosignature observations, several updates and upgrades were made on the Breakthrough Listen Parkes Data Recorder (BLPDR). This Research Note summarizes BLPDR hardware upgrades and new capacity for technosignature observations with the UWL receiver.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present new physical properties for an extreme (<jats:italic>L</jats:italic> <jats:sub>IR</jats:sub> &gt; 10<jats:sup>13</jats:sup> <jats:italic>L</jats:italic> <jats:sub>⊙</jats:sub>), unlensed dusty star-forming galaxy at <jats:italic>z</jats:italic> = 4.531, G09-81106. We compile fluxes from the literature, and include new Hubble Space Telescope data to generate SED models under various assumptions. G09-81106 has a number of physical characteristics that far surpass the average data for DSFGs, including high dust temperature (∼70 K) and star formation rate ( &gt; 2 × 10<jats:sup>3</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> yr<jats:sup>−1</jats:sup>). While barely within the average star-forming main sequence region, G09 is already an order of magnitude more massive and more star-forming than most star-forming galaxies at similar epochs. Visual inspection suggests these exceptional properties may be due to an ongoing merger, though future work with spatially resolved imaging and spectroscopic analysis will reveal its true nature.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In light of recently revised observational measurements of the radius and spectroscopic parameters of the extremely old and metal-poor Gaia benchmark star HD 140283—also known as the Methuselah star due to prior suggestions that its age is in tension with the age of the universe—we present new, best estimates for the star’s mass and age from stellar modeling. These are derived using 1D stellar evolutionary tracks computed with MESA and the most up-to-date measurements from CHARA interferometry. Excluding modeling variance from the uncertainties, we report a mass of 0.809 ± 0.001 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> and an age of 12.01 ± 0.05 Gyr (1<jats:italic>σ</jats:italic>). When dominant sources of modeling uncertainty are taken into account, we report 0.81 ± 0.05 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> and 12 ± 0.5 Gyr, respectively. These results are consistent with recent literature, and the best-fitting age is not in conflict with the currently accepted age of the universe (13.5 Gyr).</jats:p>