Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>(ATel #15171) have recently reported the discovery of an X-ray source, NuSTAR J053449+2126.0, during a calibration observation which took place on 2020 April 25. We scan the Zwicky Transient Facility alerts and archival photometry to determine the nature of the source. Palomar Gattini-IR is searched as well. We identify no obvious counterpart candidate. Follow-up X-ray and optical studies are needed to determine the true counterpart.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a standalone implementation of a data-deconvolution method based on singular value decomposition. The tool is written in python and packaged in the open-source <jats:monospace>yonder</jats:monospace> package. <jats:monospace>yonder</jats:monospace> receives as input two matrices, one for the data and another for the errors, and outputs a denoised version of the original dataset. In this Research Note, we briefly describe the methodology and show a demonstration of the <jats:monospace>yonder</jats:monospace> on a simulated dataset.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report on optical and near-infrared light curves of the young eruptive star EX Lupi, which has shown significant brightening in the past month, indicating a new accretion burst.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Evidence is presented that the far-ultraviolet flux of <jats:italic>τ</jats:italic> Her recorded by the International Ultraviolet Explorer is variable in a series of six spectra taken consecutively over 4 hr and 45 minutes The centroids of the resonance lines of O <jats:sc>i</jats:sc>, C <jats:sc>ii</jats:sc> and Si <jats:sc>ii</jats:sc> are blueshifted in several spectra and resume their original positions over a timescale of 3 hr 5 minutes. The FUV flux also varies over the same timescale. The far-ultraviolet variability is discussed in light of the recent TESS lightcurve observed for <jats:italic>τ</jats:italic> Her.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Recently, the discovery and characterization of a new accreting-only symbiotic star THA 15–31 was presented. Motivated by the suggestion that the optical spectrum of the star might show the emission lines with higher ionization potential in comparison with previously studied epochs, we have obtained a low-resolution spectrum of this target. The spectrum does not reveal the presence of suggested He <jats:sc>ii</jats:sc> emission lines. Moreover, the near-UV excess seems to be even less prominent now in comparison with the previous observations, suggesting a decrease in mass transfer and accretion rate. The search for He <jats:sc>ii</jats:sc> emission lines should be repeated when the accretion rate is higher.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Doppler effect is commonly used to infer the velocity difference between stars based on the relative shifts in the rest-frame wavelengths of their spectral features. In wide binaries, the difference in gravitational redshift from the surfaces of the constituent stars with distinct compactness dominates at separations ≳10<jats:sup>−2</jats:sup> pc. I suggest that this effect became apparent for wide pairs in the Gaia eDR3 catalog but was incorrectly interpreted as a possible modification of Newtonian gravity in the internal kinematics of very wide binaries.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>From estimates of the near-surface heat capacity of planets it is shown that the thermal timescale is larger than the orbital period in the presence of a global ocean that is well-mixed to a depth of 100 m, or of an atmosphere with a pressure of several tens of bars. As a consequence, the temperature fluctuations of such planets on eccentric orbits are damped. The average temperature should be calculated by taking the temporal mean of the irradiation over an orbit, which increases with <jats:inline-formula> <jats:tex-math> <?CDATA $1/\sqrt{1-{e}^{2}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>1</mml:mn> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msqrt> <mml:mrow> <mml:mn>1</mml:mn> <mml:mo>−</mml:mo> <mml:msup> <mml:mrow> <mml:mi>e</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:msqrt> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="rnaasac5f0dieqn1.gif" xlink:type="simple" /> </jats:inline-formula>. This conclusion is independent of the orbital distance and valid for Sun-like stars; the damping is even stronger for low-mass main sequence hosts.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The open star cluster NGC 1605 has recently been reported to in fact consist of two clusters (one intermediate-aged and one old) that merged via a flyby capture. Here we show that Gaia data do not support this scenario. We also report the serendipitous discovery of a new open cluster, Can Batlló 1, with a similar age and distance.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Stellar metallicity is an important metric in analyzing stellar evolution. Measuring metallicity (e.g., [Fe/H]) usually requires spectroscopic data, but difficulties associated with gathering spectra for distant objects severely reduces the number of stars for which metallicity can be calculated. The Sloan Expedition for Galactic Understanding and Exploration (SEGUE) spectroscopic surveys are one of the most abundant public-sources of objects with spectra. Despite cataloging over 10<jats:sup>6</jats:sup> objects, the SEGUE data makes up only 0.4% of the data in SDSS photometric surveys. To overcome the limited spectra, this machine-learning method can approximate [Fe/H] from the 5 SDSS photometric filters with a root-mean-square-error (RMSE) of 0.277 dex. The RMSE from this method is similar to the scatter expected in [Fe/H] measurements from low-resolution spectra. Therefore, this method achieves similar accuracy to low-resolution spectra but can be applied to a few orders of magnitude more stars than what the current spectroscopic surveys allow.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report on three stellar occultation events by the Kuiper Belt object 2002 MS<jats:sub>4</jats:sub>, observed using a 300 mm telescope on Anarchist Mountain, BC, Canada. Using the three events we have determined chord diameters of (810 ± 70) km, (630 ± 140) km, and (780 ± 70) km. All of these diameters are consistent with those reported from previous occultation events. Based on these data we estimate that 2002 MS<jats:sub>4</jats:sub> is at least 810 ± 70 km in diameter These events also provide high-precision sky positions for 2002 MS<jats:sub>4</jats:sub> at the exact time of the occultation, which can be used to refine the orbital ephemeris of this target, improving predictions of future events. All data and processing outputs described in this Research Note can be retrieved from: <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://doi.org/10.11570/22.0001" xlink:type="simple">10.11570/22.0001</jats:ext-link> </jats:p>