Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Infrared color–magnitude diagrams are presented for variable M giants within the Two-Micron Sky Survey for which 10 <jats:italic>μ</jats:italic>m dust emission was detected in IRAS low-resolution spectra. Dust emission is mostly limited to a definable region in absolute <jats:italic>M</jats:italic> <jats:sub> <jats:italic>Ks</jats:italic> </jats:sub> magnitude and (<jats:italic>J</jats:italic> − <jats:italic>K</jats:italic> <jats:sub> <jats:italic>s</jats:italic> </jats:sub>) color, and to pulsation periods greater than 50 days.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Multiple investigations support describing galaxy growth as a stochastic process with correlations over a range of timescales governed by a parameter, <jats:italic>H</jats:italic>, empirically and theoretically constrained to be near unity. Here, we show that the distribution of UV-slopes, <jats:italic>β</jats:italic>, derived from an ensemble of theoretical <jats:italic>H</jats:italic> = 1 star formation histories is consistent with data at all redshifts <jats:italic>z</jats:italic> ≤ 16. At <jats:italic>z</jats:italic> = 0, the median value 〈<jats:italic>β</jats:italic> <jats:sub> <jats:italic>H</jats:italic>=1</jats:sub>〉 = − 2.27 agrees well with the canonical <jats:italic>β</jats:italic> <jats:sub>0</jats:sub> = −2.23 for local starbursts. At 4 ≲ <jats:italic>z</jats:italic> ≲ 16, JWST data span the model distribution’s 2nd to 98th percentiles. Values of −2.8 ≤ <jats:italic>β</jats:italic> ≤ −2.5 should be common in early galaxies without reference to exotic stellar populations—arising solely from a null hypothesis of <jats:italic>H</jats:italic> = 1 for the underlying diversity of galaxy growth histories. Future data should be interpreted with this fact in mind.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a catalog of X-ray Detected Be Stars (XDBS) with 161 Be stars from the Be Star Spectra (BeSS) database having X-ray counterparts in the Chandra Source Catalog v2.0, XMM-Newton 4XMM-DR11 Catalog, or Swift 2SXPS Catalog. The multi-wavelength catalog includes accurate optical positions, X-ray properties (fluxes, photon indices and hardness ratios), optical, near-infrared and infrared photometry, source classifications (when available), and other properties including proper motions, effective temperatures, X-ray to optical flux ratios as well. We also provide a convenient <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://home.gwu.edu/~kargaltsev/XDBS/" xlink:type="simple">https://home.gwu.edu/~kargaltsev/XDBS/</jats:ext-link>graphical user interface which allows for easy visualization of the catalog content.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>OGLE <jats:italic>I</jats:italic>-band observations for [M2002] SMC 20671, the optical counterpart of SXP 4.78, were searched for periodicities with <jats:italic>P</jats:italic> &gt; 0.5 days. Three sets of photometric signals were detected, which are attributed to non-radial pulsations of the Be star. All signals show considerable variability in power over the 16 seasons studied. The most likely periods of the NRPs are 0.5826, 0.6164, and 0.6424 days.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a convenient tool (ChaSES) which allows to search for extended structures in Chandra X-ray Observatory Advanced CCD Imaging Spectrometer images. The tool relies on DBSCAN clustering algorithm to detect regions with overdensity of photons compared to the background. Here we describe the design and functionality of the tool which we make publicly available on GitHub. We also provide online extensive examples of its applications to the real data.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Wind/Waves instrument has been collecting in situ electric field measurements in the solar wind as well as Earth's magnetosphere and geotail since 1994. The Thermal Noise Receiver (TNR) sub-instrument uses a wire dipole made of very long and thin whip antennas, highly convenient for Quasi-Thermal Noise (QTN) measurements. The instrument team has determined that twice during the mission, in 2000 and 2002, one of the antenna arms broke, changing the antenna response to plasma fluctuations. In this note, we use the QTN spectroscopy method developed specially for the TNR to determine the antenna length after each of these breaks. By parametrically varying the value of the antenna length used in the QTN calculation, we find that initial 50 m long antenna arm was initially shortened to ∼25.5 m in 2000, and then to ∼20 m in 2002.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The analysis of low and high resolution spectra of the chemically peculiar stars HR 7113 and HR 1800 recorded by the SWP camera on board the International Ultraviolet Explorer reveals no variations of the far-ultraviolet flux for spectra separated by 4 months and 3 days for HR 7113 and 1 day apart for HR 1800 respectively. The TESS lightcurve of HR 7113 suggests a period close to 6.46 days which is close to the orbital period previously determined. For HR 1800, a clear period is not seen, time intervals between successive maxima range from 5.53 to 5.82 days.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The asteroseismic scaling relation, Δ<jats:italic>ν</jats:italic> ≈ <jats:italic>ρ</jats:italic> <jats:sup>0.5</jats:sup>, linking a star’s large frequency separation, Δ<jats:italic>ν</jats:italic>, and its mean density, <jats:italic>ρ</jats:italic>, is not exact. Yet, it provides a very useful way to obtain fundamental stellar properties. Common ways to make the relation more accurate is to apply correction factors to it. Because the corrections depend on stellar properties, such as mass, <jats:italic>T</jats:italic> <jats:sub>eff</jats:sub>, and metallicity, it is customary to interpolate these properties over stellar model grids that include both Δ<jats:italic>ν</jats:italic>, measured from adiabatic frequencies of the models, and the models’ stellar density; hence linking both sides of the scaling relation. A grid and interpolation tool widely used for this purpose, known as Asfgrid, was published by Sharma &amp; Stello. Here, we present a significant extension of Asfgrid to cover higher- and lower-mass stars and to increase the density of grid points, especially in the low-metallicity regime.</jats:p>