Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>In this paper, we present the SDSS <jats:italic>g</jats:italic>′-, the Cousins <jats:italic>R</jats:italic> <jats:sub>c</jats:sub>-, and <jats:italic>I</jats:italic> <jats:sub>c</jats:sub>-band magnitudes and associated colors of Starlink's STARLINK-1113 (one of the standard Starlink satellites) and 1130 (Darksat) with a darkening treatment to its surface. Using the 105 cm Murikabushi telescope/MITSuME, simultaneous multicolor observations for the above satellites were conducted four times: on 2020 April 10 and May 18 (for Darksat), and 2020 June 11 (for Darksat and STARLINK-1113). We found that (1) the SDSS <jats:italic>g</jats:italic>′-band apparent magnitudes of Darksat (6.95 ± 0.11–7.65 ± 0.11 mag) are comparable to or brighter than that of STARLINK-1113 (7.69 ± 0.16 mag), (2) the shorter the observed wavelength is, the fainter the satellite magnitudes tend to become, (3) the reflected flux by STARLINK-1113 is extremely (&gt;1.0 mag) redder than that of Darksat, (4) there is no clear correlation between the solar phase angle and orbital altitude-scaled magnitude, and (5) by flux model fitting of the satellite trails with the blackbody radiation, it is found that the albedo of Darksat is about half that of STARLINK-1113. In particular, result (1) is inconsistent with previous studies. However, considering both solar and observer phase angles and atmospheric extinction, the brightness of STARLINK-1113 can be drastically reduced in the SDSS <jats:italic>g</jats:italic>′ and the Cousins <jats:italic>R</jats:italic> <jats:sub>c</jats:sub> band. Simultaneous multicolor–multispot observations of more than three colors would give us more detailed information regarding the impact of low-Earth-orbit satellite constellations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The recent discovery of a spiral feature in the <jats:italic>Z</jats:italic> − <jats:italic>V</jats:italic> <jats:sub> <jats:italic>Z</jats:italic> </jats:sub> phase plane in the solar neighborhood implies that the galactic disk has been remarkably affected by a dwarf galaxy passing through it some hundreds of millions of years ago. Using 429,500 Large Sky Area Multi-Object Fibre Spectroscopic Telescope K giants stars, we show that the spiral feature exists not only in the solar vicinity but it also extends to about 15 kpc from the Galactic center and then disappears beyond this radius. Moreover, we find that when the spiral features in a plot of <jats:italic>V</jats:italic> <jats:sub> <jats:italic>ϕ</jats:italic> </jats:sub> as a function of position in the <jats:italic>Z</jats:italic> − <jats:italic>V</jats:italic> <jats:sub> <jats:italic>Z</jats:italic> </jats:sub> plane at various galactocentric radii are remapped to the <jats:italic>R </jats:italic>− <jats:italic>Z</jats:italic> plane, the spiral can explain well the observed asymmetric velocity substructures. This is evidence that the phase spiral features are the same as the bulk motions found in previous work as well as this work. Test particle simulations and <jats:italic>N</jats:italic>-body simulations show that an encounter with a dwarf galaxy a few hundred million years ago will induce a perturbation in the galactic disk. In addition, we find that the last impact of Sgr dSph can also contribute to the flare. As a consequence of the encounter, the distribution function of disk stars at a large range of radii is imprinted by the gravitational perturbation.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We discuss properties of a Type IV burst, which was observed on 2017 September 6, as a result of the powerful flare X 9.3. At decameter wavelengths this burst was observed by the radio telescopes STEREO A, URAN-2, and the Nancay Decameter Array at frequencies 5–35 MHz. This moving Type IV burst was associated with a coronal mass ejection (CME) propagating in the southwest direction with a speed of 1570 km s<jats:sup>−1</jats:sup>. The maximum radio flux of this burst was about 300 s.f.u. and the polarization was more than 40%. In the frequency range of 8–33 MHz it continued for more than 2 hr. For STEREO A the associated CME was behind the limb, and its longitudinal angle was about 160°. This moving Type IV burst was observed by STEREO A at frequencies of 5–15 MHz in spite of the low sensitivity of STEREO A. This means that the radio emission directivity of a Type IV burst is rather wide. Assuming the plasma mechanism of Type IV radio emission we derived the plasma density distribution in the CME core at distances of 5.6 <jats:italic>R<jats:sub>s</jats:sub> </jats:italic> and 9.8 <jats:italic>R<jats:sub>s</jats:sub> </jats:italic> (<jats:italic>R<jats:sub>s</jats:sub> </jats:italic> is the solar radius), and its mass to be about 10<jats:sup>16</jats:sup> <jats:italic> </jats:italic>g. It is planned that the minimum perihelion of the Parker Solar Probe (PSP) spacecraft will be at about 9 <jats:italic>R<jats:sub>s</jats:sub> </jats:italic>. So we discuss in what conditions PSP will be in if it crosses a similar CME core.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Rotating star clusters near supermassive black holes are studied using Touma–Tremaine thermodynamics of gravitationally interacting orbital ellipses. A simple numerical procedure for calculating thermodynamic equilibrium states for an arbitrary distribution of stars over masses and semimajor axes is described. Spontaneous symmetry breaking and breakdown of thermodynamics at low positive temperatures are rigorously proven for nonrotating clusters. Rotation is introduced through a second temperature-like parameter. Both axially symmetric and lopsided rotational equilibria are found; the lopsided equilibria precess with the angular velocity that is given by the ratio of the two temperatures. The eccentric stellar disk in the nucleus of the Andromeda galaxy may be an example of a lopsided thermodynamic equilibrium of a rotating black hole star cluster. Stellar-mass black holes occupy highly eccentric orbits in broken-symmetry star clusters, and form flattened disklike configurations in rotating star clusters. They are attracted to orbits that are stationary in the frame of reference rotating with the angular velocity of the cluster. In spherical clusters, stellar-mass black holes’ orbits are significantly more eccentric than those of the lighter stars if the temperature is negative and more circular if the temperature is positive. Finally, we note that planets, comets, dark matter particles, and other light bodies tend to form a spherically symmetric nonrotating subcluster with maximum-entropy eccentricity distribution <jats:inline-formula> <jats:tex-math> <?CDATA ${s}_{\mathrm{cr}}P(e)=2e$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabbfaaieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, even if their host cluster is rotating and lopsided.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Mass segregation, a tendency for more massive galaxies to be distributed closer to the cluster center, is naturally expected from dynamical friction, but its presence is still controversial. Using deep optical observations of 14 Abell clusters (KYDISC) and a set of hydrodynamic simulations (YZiCS), we find in some cases a hint of mass segregation inside the virial radius. Segregation is visible more clearly when the massive galaxy fraction is used instead of mean stellar mass. The trend is more significant in the simulations than in the observations. To find out the mechanisms affecting mass segregation, we look into the evolution of individual simulated clusters. We find that the degree of mass segregation is different for different clusters: the trend is visible only for low-mass clusters. We compare the masses of galaxies and their dark halos at the time of infall and at the present epoch to quantify the amount of tidal stripping. We then conclude that satellites that get accreted at earlier epochs, or galaxies in more massive clusters, go through more tidal stripping. These combined effects result in a correlation between the host halo mass and the degree of stellar mass segregation.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Turbulence is a key process in many fields of astrophysics. Advances in numerical simulations of fluids over the last several decades have revolutionized our understanding of turbulence and related processes such as star formation and cosmic ray propagation. However, data from numerical simulations of astrophysical turbulence are often not made public. We introduce a new simulation-oriented database for the astronomical community: the Catalogue for Astrophysical Turbulence Simulations (CATS), located at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.mhdturbulence.com" xlink:type="simple">www.mhdturbulence.com</jats:ext-link>. CATS includes magnetohydrodynamic (MHD) turbulent box simulation data products generated by the public codes <jats:sc>athena++</jats:sc>, <jats:sc>arepo</jats:sc>, <jats:sc>enzo,</jats:sc> and <jats:sc>flash</jats:sc>. CATS also includes several synthetic observational data sets, such as turbulent HI data cubes. We also include measured power spectra and three-point correlation functions from some of these data. We discuss the importance of open-source statistical and visualization tools for the analysis of turbulence simulations such as those found in CATS.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We investigated the thermal properties of prominence formation using time series analysis of Solar Dynamics Observatory's Atmospheric Imaging Assembly (SDO/AIA) data. Here, we report the first time-lag measurements derived from SDO/AIA observations of a prominence and its cavity on the solar limb, made possible by AIA's different wave bands and high time resolution. With our time-lag analysis, which tracks the thermal evolution using emission formed at different temperatures, we find that the prominence cavity exhibited a mixture of heating and cooling signatures. This is in contrast to prior time-lag studies of multiple active regions that chiefly identified cooling signatures and very few heating signatures, which is consistent with nanoflare heating. We also computed time lags for the same pairs of SDO/AIA channels using output from a one-dimensional hydrodynamic model of prominence material forming through thermal nonequilibrium (TNE). We demonstrate that the SDO/AIA time lags for flux tubes undergoing TNE are predicted to be highly complex, changing with time and location along the flux tube, and are consistent with the observed time-lag signatures in the cavity surrounding the prominence. Therefore, the time-lag analysis is a sensitive indicator of the heating and cooling processes in different coronal regions. The time lags calculated for the simulated prominence flux tube are consistent with the behavior deduced from the AIA data, thus supporting the TNE model of prominence formation. Future investigations of time lags predicted by other models for the prominence mass could be a valuable method for discriminating among competing physical mechanisms.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present rest-frame optical spectroscopic observations of 24 Hot Dust-Obscured Galaxies (Hot DOGs) at redshifts 1.7–4.6 with KECK/NIRES. Our targets are selected, based on their extreme red colors, to be the highest-luminosity sources from the WISE infrared survey. In 20 sources with well-detected emission, we fit the key [O <jats:sc>iii</jats:sc>], H<jats:italic>β</jats:italic>, H<jats:italic>α</jats:italic>, [N <jats:sc>ii</jats:sc>], and [S <jats:sc>ii</jats:sc>] diagnostic lines to constrain physical conditions. Of the 17 targets with a clear detection of the [O <jats:sc>iii</jats:sc>]<jats:italic>λ</jats:italic>5007 Å emission line, 15 display broad blueshifted and asymmetric line profiles, with widths ranging from 1000 to 8000 km s<jats:sup>−1</jats:sup> and blueshifts up to 3000 km s<jats:sup>−1</jats:sup>. These kinematics provide strong evidence for the presence of massive ionized outflows of up to <jats:inline-formula> <jats:tex-math> <?CDATA $8000\ {M}_{\odot }\,{\mathrm{yr}}^{-1}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabc3bfieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, with a median of <jats:inline-formula> <jats:tex-math> <?CDATA $150\ {M}_{\odot }\,{\mathrm{yr}}^{-1}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabc3bfieqn2.gif" xlink:type="simple" /> </jats:inline-formula>. As many as eight sources show optical emission line ratios consistent with vigorous star formation. Balmer-line star formation rates, uncorrected for reddening, range from 30 to 1300 <jats:inline-formula> <jats:tex-math> <?CDATA ${M}_{\odot }\,{\mathrm{yr}}^{-1}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabc3bfieqn3.gif" xlink:type="simple" /> </jats:inline-formula>, with a median of <jats:inline-formula> <jats:tex-math> <?CDATA $50\ {M}_{\odot }\,{\mathrm{yr}}^{-1}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabc3bfieqn4.gif" xlink:type="simple" /> </jats:inline-formula>. Estimates of the SFR from Spectral Energy Distribution fitting of mid- and far-infrared photometry suggest significantly higher values. We estimate the central black hole masses to be of order <jats:inline-formula> <jats:tex-math> <?CDATA ${10}^{8-10}\,{M}_{\odot }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabc3bfieqn5.gif" xlink:type="simple" /> </jats:inline-formula>, assuming the present-day <jats:inline-formula> <jats:tex-math> <?CDATA ${M}_{\mathrm{BH}}\mbox{--}{\sigma }_{* }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabc3bfieqn6.gif" xlink:type="simple" /> </jats:inline-formula> relation. The bolometric luminosities and the estimated masses of the central black holes of these galaxies suggest that many of the active galactic nucleus-dominated Hot DOGs are accreting at or above their Eddington limit. The combination of ongoing star formation, massive outflows, and high Eddington ratios suggest Hot DOGs are a transitional phase in galaxy evolution.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We describe a new algorithm for reconstruction of differential emission measures (DEMs) in the solar corona. Although a number of such algorithms currently exist, they can have difficulty converging for some cases and can be complex, slow, or idiosyncratic in their output (i.e., their inversions can have features that are a result of the inversion code and instrument response, not of the solar source); we will document some of these issues in this paper. The new algorithm described here significantly reduces these drawbacks and is particularly notable for its simplicity; it is reproduced here, in full, on a single page. After we describe the algorithm, we compare its performance and fidelity with some prevalent methods. Although presented here for extreme-ultraviolet data, the algorithm is robust and extensible to any other wavelengths (e.g., X-rays) where the DEM treatment is valid.</jats:p>