Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We present “Citizen ASAS-SN,” a citizen science project hosted on the Zooniverse platform which utilizes data from the All-Sky Automated Survey for SuperNovae (ASAS-SN). Volunteers are presented with ASAS-SN <jats:italic>g</jats:italic>-band light curves of variable star candidates. The classification workflow allows volunteers to classify these sources into major variable groups, while also allowing for the identification of unique variable stars for additional follow-up.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Convolution of spectra, maps, or even higher dimensional data is often part of data reduction or analysis. Often a Gaussian kernel is used. When the convolved data are measurements, they are associated with uncertainties. This research notice derives how uncertainties propagate through the convolution. While the math is straightforward algebra, the results are not readily available. Here, the uncertainty propagation applied to regularly gridded data is provided. The calculation is done for uncorrelated data and correlated data.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>There are 88 stars which lack colors, but have measured parallaxes in Gaia EDR3 that place them within 20 pc from the Sun. Among them we found two new common parallax and proper motion (CPPM) companions separated from their primaries by about 3″. The CPPM companion of a nearby (<jats:italic>d</jats:italic> = 14.98 pc) F1 star, <jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="object" xlink:href="HD 105452 B" xlink:type="simple">HD 105452 B</jats:named-content>, was already imaged with the Hubble Space Telescope and is now confirmed with Gaia data and photometrically classified by us as M4 dwarf. The other CPPM companion, <jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="object" xlink:href="SCR J1214-2345 B" xlink:type="simple">SCR J1214-2345 B</jats:named-content> orbiting an M4.5 dwarf at <jats:italic>d</jats:italic> = 10.77 pc, represents the faintest brown dwarf discovery made by Gaia so far. It was also imaged by the VISTA Hemisphere Survey and partly detected in the near-infrared. Our photometric classification led to an uncertain spectral type of T1 ± 3 and needs to be confirmed by spectroscopic follow-up.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a simulation showing that super-Nyquist frequencies may have periodic amplitude and frequency modulations, even if actually stable, in time series sampled like the Kepler data. These modulations are caused by the barycentric time correction, which destroys the evenly spaced time measurements, making the Nyquist frequency variable over the spacecraft orbit around the Sun. These modulations can easily be identified in pulsating stars from Kepler's photometric data.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We use data from the first two years of the public survey of the Zwicky Transient Facility to analyze colors of proposed Jupiter Trojan asteroid families. The well studied Eurybates cluster remains the only family with a significant number of color measurements, and we find that the average colors of this family are less red than typical Jupiter Trojans, in agreement with smaller studies. The limited number of objects detected in this and other surveys for the other families makes their colors continue to be uncertain.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present spectroscopic observations of superthin galaxies. Superthin galaxies have the thinnest stellar disks among disk galaxies. A sample of 138 superthins was observed in visible light with the 3.5 m telescope at Apache Point Observatory in New Mexico to obtain the rotation curves of the ionized gas in the galaxies. The sample represents the largest survey of superthin galaxies so far and provides a database to investigate the kinematic and dynamic properties of this special type of extragalactic objects. Here we present the rotation curves of our sample objects.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Previous critiques of the Drake Equation have highlighted its deterministic nature, implying that the number of civilizations is the same at all times. Here, I build upon earlier work and present a stochastic formulation. The birth of civilizations within the galaxy is modeled as following a uniform rate (Poisson) stochastic process, with a mean rate of <jats:italic>λ</jats:italic> <jats:sub> <jats:italic>C</jats:italic> </jats:sub>. Each then experiences a constant hazard rate of collapse, which defines an exponential distribution with rate parameter <jats:italic>λ</jats:italic> <jats:sub> <jats:italic>L</jats:italic> </jats:sub>. Thus, the galaxy is viewed as a frothing landscape of civilization birth and collapse. Under these assumptions, I show that <jats:italic>N</jats:italic> in the Drake Equation must follow another Poisson distribution, with a mean rate (<jats:italic>λ</jats:italic> <jats:sub> <jats:italic>C</jats:italic> </jats:sub>/<jats:italic>λ</jats:italic> <jats:sub> <jats:italic>L</jats:italic> </jats:sub>). This is used to demonstrate why the Copernican Principle does not allow one to infer <jats:italic>N</jats:italic>, as well evaluating the algebraic probability of being alone in the galaxy.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Expanding on the work of Snyder et al., we present merger pair analysis of mock surveys from the IllustrisTNG suite of 3D cosmological simulations. Our results, shown in the context of previous work with Illustris-1, are consistent with a flattening of the pair fraction curve at a redshift of <jats:italic>z</jats:italic> = 2.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The VLITE-Fast experiment combines the wide-field-of-view of single dish antennas operating at low frequency with the high angular resolution furnished by the 3–30 km baselines of the VLA, making it ideal for the detection and precise localization of radio transients. We describe the VLITE-Fast experiment, its capabilities, and operational status, and we briefly overview its main science case, the detection of fast radio bursts (FRBs) and determination of their host galaxies. We report on commissioning observations in an incoherent mode prohibiting precise localization. These include discovery of FRB 20200405A, detected during early science operations at dispersion measure (DM) = 212.3 pc cm<jats:sup>−3</jats:sup>, strongly in excess of the Galactic DM along the line of sight.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Recently, Vitral &amp; Mamon detected a central concentration of dark objects in the core-collapsed globular cluster NGC 6397, which could be interpreted as a subcluster of stellar-mass black holes. However, it is well established theoretically that any significant number of black holes in the cluster would provide strong dynamical heating and is fundamentally inconsistent with this cluster's core-collapsed profile. Claims of intermediate-mass black holes in core-collapsed clusters should similarly be treated with suspicion, for reasons that have been understood theoretically for many decades. Instead, the central dark population in NGC 6397 is exactly accounted for by a compact subsystem of white dwarfs (WDs), as we demonstrate here by inspection of a previously published model that provides a good fit to this cluster. These central WD subclusters are in fact a generic feature of core-collapsed clusters, while central black hole subclusters are present in all <jats:italic>non</jats:italic>-collapsed clusters.</jats:p>