Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We present two new rapidly oscillating Ap (roAp) stars, TIC 198781841 and TIC 229960986, discovered in TESS photometric data. The periodogram of TIC 198781841 has a large peak at 166.506 day<jats:sup>−1</jats:sup> (1.93 mHz), with two nearby peaks at 163.412 day<jats:sup>−1</jats:sup> (1.89 mHz) and 169.600 day<jats:sup>−1</jats:sup> (1.96 mHz). These correspond to three independent high-overtone pressure modes, with alternating even and odd <jats:italic>ℓ</jats:italic> values. TIC 229960986 has a high-frequency triplet centered at 191.641 day<jats:sup>−1</jats:sup> (2.218 mHz), with sidebands at 191.164 day<jats:sup>−1</jats:sup> (2.213 mHz) and 192.119 day<jats:sup>−1</jats:sup> (2.224 mHz). This pulsation appears to be a rotationally split dipole mode, with sideband amplitudes significantly larger than that of the central peak; hence, both pulsation poles are seen over the rotation cycle. Our photometric identification of two new roAp stars underscores the remarkable ability of TESS to identify high-frequency pulsators without spectroscopic observations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report the recharacterization of TIC 471013547 as an eclipsing white dwarf binary using data obtained with the Transiting Exoplanet Survey Satellite (TESS). Eclipses from both components are detected, and we find a period of 3.541056 ± 0.000185 days with an ephemeris of TJD = 2458441.434 ± 0.000209 days. Its shared features with other double white dwarf eclipsing binaries and its lack of infrared excess indicate that the system likely consists of two white dwarfs.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Comparison of optical high resolution high signal-to-noise ELODIE spectra of 21 Com taken in 2004 April and separated by about half of the 2 days rotational period, reveals variations of the oxygen, calcium and strontium lines between rotational phases 0.94 and 0.48. Whereas the lines of oxygen and calcium are stronger at phase 0.94, those of strontium strengthen at phase 0.48. The synthesis of strong Sr <jats:sc>ii</jats:sc> lines yields disk-averaged estimates of the abundances of strontium: about 200 times solar at phase 0.94 and 450 solar at phase 0.48 for strontium. However the O <jats:sc>i</jats:sc> and Ca <jats:sc>ii</jats:sc> lines are too blended to derive unambiguous quantitative information on the abundance and distribution of oxygen and calcium over the surface of 21 Com. The likely underabundance of oxygen might be quantified using stronger far-ultraviolet transitions.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We describe a pipeline to measure scintillation in fast radio bursts (FRBs) detected by CHIME/FRB in the 400–800 MHz band by analyzing the frequency structure of the FRB's spectrum. We use the pipeline to measure the characteristic frequency bandwidths of scintillation between 4–100 kHz in 12 FRBs corresponding to timescales of ∼2–40 <jats:italic>μ</jats:italic>s for 10 FRBs detected by CHIME/FRB. For the other two FRBs, we did not detect scintillation in the region our analysis is sensitive. We compared the measured scintillation timescales to the NE2001 predictions for the scintillation timescales from the Milky Way. We find a strong correlation to be an indication that in most instances, the observed scintillation of FRBs can be explained by the Milky Way.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The nova V1674 Her (Nova Her 2021) has been reported to have the shortest interval between outburst and coronal line formation of any nova yet observed. We present optical and near-infrared spectroscopy from three epochs ranging from shortly before coronal line formation to shortly after. Taken together with the published results of Woodward et al., they indicate that not only did the coronal lines form very early in the nova’s development, but in going from undetectable to detectable in two days, and undetectable to significant, in six days, they developed very rapidly as well.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Infrared spectra of the dusty nova V1112 Persei (Nova Persei 2020) are presented from 29 and 48 days after the onset of dust formation, the later epoch corresponding to when obscuration by the nova dust was at a maximum. The dust emission was featureless and had temperatures of approximately 880 K and 690 K for the two epochs, respectively. Some dust formed along the line of sight and the total extinction for V1112 Per increased from E(B-V) = 0.8 prior to dust formation, to 1.2 on February 3, to 1.4 by February 22. Emission lines of both carbon and oxygen were present along with the dust emission indicating that the dust did not consume all of either of these element.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We compare some predictions of Wagoner &amp; Tandon (WT) with the results of the hydrodynamic and magnetohydrodynamic (MHD) simulations of Reynolds &amp; Miller (RM). It appears that the MHD simulations were not run for long enough and the numerical damping was not small enough to produce the observed high-frequency QPOs (and the g-mode seen in the hydro simulations).</jats:p>

<jats:title>Abstract</jats:title> <jats:p>I present a numerical fit to the peak harmonic gravitational wave frequency emitted by an eccentric binary system in the post-Newtonian approximation. This fit significantly improves upon a previous commonly-used fit in population synthesis studies, in particular for eccentricities ≲0.8.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>LUCI is an general-purpose spectral line-fitting pipeline which natively integrates machine learning algorithms to initialize fit functions. LUCI currently uses point-estimates obtained from a convolutional neural network (CNN) to inform optimization algorithms; this methodology has shown great promise by reducing computation time and reducing the chance of falling into a local minimum using convex optimization methods. In this update to LUCI, we expand upon the CNN developed in Rhea et al. so that it outputs Gaussian posterior distributions of the fit parameters of interest (the velocity and broadening) rather than simple point-estimates. Moreover, these posteriors are then used to inform the priors in a Bayesian inference scheme, either <jats:monospace>emcee</jats:monospace> or <jats:monospace>dynesty</jats:monospace>. The code is publicly available at crhea93:LUCI (<jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://github.com/crhea93/LUCI" xlink:type="simple">https://github.com/crhea93/LUCI</jats:ext-link>).</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We monitored the comet 67P/Churyumov-Gerasimenko close to its perihelion in November 2021 with the GROWTH-India Telescope. We observed two outbursts of this comet on 2021 October 29.940 and November 17.864 UTC, −3.12 days and +15.81 days respectively from the perihelion date. The brightening in the first outburst appears as a compact source, with a radial extent up to 8.″5. The comet brightened by 0.26 ± 0.03 mag in the outburst, with a 27% increase in the effective geometric cross-section and total outburst dust mass of ∼5.3 × 10<jats:sup>5</jats:sup> kg. The second outburst caused a brightening of 0.49 ± 0.08 mag with effective geometric cross-section and total outburst dust mass 2.5 times larger than the first event. These outbursts are up to an order of magnitude larger than the strongest outburst event observed in situ by the Rosetta spacecraft in 2015.</jats:p>