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<jats:title>Abstract</jats:title> <jats:p>The absorbed soft X-ray (&lt;1 keV) emission from Compton thin type-II active galactic nuclei (AGNs) with neutral absorption columns in the range <jats:italic>N</jats:italic> <jats:sub>H</jats:sub> = 10<jats:sup>21−23</jats:sup> cm<jats:sup>−2</jats:sup> may contain emission from star formation or scattered photons from the primary X-ray emission in Compton-thin circumnuclear gas extending out to ∼1  kpc, or leaky-absorbers along the line of sight allowing a part of the primary AGN emission to manifest in the soft X-rays. In a recent sample study of 20 Compton thin type-II AGN, Laha et al. detected variability in the soft X-ray spectra in 5 sources with timescales &lt;20 years, indicating possibly that the primary AGN emission has leaked through the absorption column. I found that the sources with soft X-ray variability exhibit the lowest absorption column densities (<jats:italic>N</jats:italic> <jats:sub>H</jats:sub> ∼ 0.7–1.3 × 10<jats:sup>22</jats:sup> cm<jats:sup>−2</jats:sup>) in the sample.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Trojan asteroids of Mars and Jupiter are long-term stable, those of Earth are expected to be just transient companions. The first Trojan of our planet, 2010 TK<jats:sub>7</jats:sub>, was discovered in 2010 and its resonant state was found to be transient. Here, we provide a preliminary assessment of the current dynamical status and short-term orbital evolution of 2020 XL<jats:sub>5</jats:sub>, a recently discovered near-Earth asteroid that might be the second known representative of this elusive population. Our calculations show that the current orbit determination of 2010 TK<jats:sub>7</jats:sub> is consistent with that of a robust, present-day, yet transient, L<jats:sub>4</jats:sub> Earth Trojan. In sharp contrast, the current orbit determination of 2020 XL<jats:sub>5</jats:sub> is still too uncertain and its orbital evolution too chaotic to confirm a current Trojan engagement with Earth, although the nominal orbit shows such a behavior. More observations are required to provide a conclusive answer.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Constraints on the variation of the gravitational constant <jats:italic>G</jats:italic> have been obtained by many observers using different methods, the most reliable and stringent being those based on the orbital timing of bodies in the solar system and binary pulsars. We show that the constraints determined from orbital timing are on <jats:inline-formula> <jats:tex-math> <?CDATA $\dot{G}/G-3\dot{c}/c$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi>G</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>˙</mml:mo> </mml:mrow> </mml:mover> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi>G</mml:mi> <mml:mo>−</mml:mo> <mml:mn>3</mml:mn> <mml:mover accent="true"> <mml:mrow> <mml:mi>c</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>˙</mml:mo> </mml:mrow> </mml:mover> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi>c</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="rnaasabe6a3ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> rather than on <jats:inline-formula> <jats:tex-math> <?CDATA $\dot{G}/G$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi>G</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>˙</mml:mo> </mml:mrow> </mml:mover> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi>G</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="rnaasabe6a3ieqn4.gif" xlink:type="simple" /> </jats:inline-formula> when the speed of light <jats:italic>c</jats:italic> is also considered to be varying. Increasingly tighter constraint on <jats:inline-formula> <jats:tex-math> <?CDATA $\dot{G}/G$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi>G</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>˙</mml:mo> </mml:mrow> </mml:mover> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi>G</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="rnaasabe6a3ieqn5.gif" xlink:type="simple" /> </jats:inline-formula> from these observations are possibly due to <jats:inline-formula> <jats:tex-math> <?CDATA $\dot{G}/G-3\dot{c}/c=0$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi>G</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>˙</mml:mo> </mml:mrow> </mml:mover> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi>G</mml:mi> <mml:mo>−</mml:mo> <mml:mn>3</mml:mn> <mml:mover accent="true"> <mml:mrow> <mml:mi>c</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>˙</mml:mo> </mml:mrow> </mml:mover> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi>c</mml:mi> <mml:mo>=</mml:mo> <mml:mn>0</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="rnaasabe6a3ieqn6.gif" xlink:type="simple" /> </jats:inline-formula>. This relationship between <jats:italic>G</jats:italic> and <jats:italic>c</jats:italic> was determined in a previous work by fitting the supernovae 1a data using the relativistically covariant cosmological model with varying <jats:inline-formula> <jats:tex-math> <?CDATA $c,G$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>c</mml:mi> <mml:mo>,</mml:mo> <mml:mi>G</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="rnaasabe6a3ieqn7.gif" xlink:type="simple" /> </jats:inline-formula> and cosmological constant Λ.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The ELAIS-S1 field will be an Legacy Survey of Space and Time Deep Drilling field, and it also has extensive multiwavelength coverage. To improve the utility of the existing data, we use The Tractor to perform forced-photometry measurements in this field. We compile data in 16 bands from the DeepDrill, VIDEO, DES, ESIS, and VOICE surveys. Using a priori information from the high-resolution fiducial images in VIDEO, we model the images in other bands and generate a forced-photometry catalog. This technique enables consistency throughout different surveys, deblends sources from low-resolution images, extends photometric measurements to a fainter magnitude regime, and improves photometric-redshift estimates. Our catalog contains over 0.8 million sources covering a 3.4 deg<jats:sup>2</jats:sup> area in the VIDEO footprint and is available at <jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="dataset" xlink:href="https://doi.org/10.5281/zenodo.4540178" xlink:type="simple">10.5281/zenodo.4540178</jats:named-content>.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>E+A galaxies are post-starburst galaxies that have recently undergone quenching of their star formation, making them a valuable source for studying the evolution of galaxies. Using the SDSS Data Release 16, we found 13 “blue” E+A galaxy candidates and 117 “green” E+A galaxy candidates in and around the Coma cluster of galaxies. Blue E+A galaxies tend to be younger than green E+A galaxies, giving us a picture of how young galaxies transform into E+A galaxies. Based on their positions in R.A./decl./velocity space, we found that 8 of the blue E+A galaxy candidates seem to be located inside a large-scale galactic filament emanating from the center of the Coma Cluster. Their locations suggest there is an unusually high number of E+A galaxies throughout the filament. We have not yet determined whether these E+A galaxy candidates formed through merging or ram pressure stripping.</jats:p>

<jats:title>Abstract</jats:title> <jats:p> </jats:p>

<jats:title>Abstract</jats:title> <jats:p>The origin of the Soft X-ray excess in the spectra of several nearby active galactic nucleus is still highly debated. In this work we report the monotonic spectral hardening of a nearby bare Seyfert galaxy ESO 511-G030 over a time period of ∼110 ks. We found that both the soft (0.3–2  keV) and the hard X-ray (2–10  keV) bands have shown interesting variability during the 110 ks observation. The soft X-ray flux shows a sharp drop in the last ∼50 ks, by ∼30%, while the hard X-ray flux initially increased and then decreased. The overall effect of these variations is a monotonic increase in the hardness ratio. We conclude that: (A) The soft X-ray flux variations may be related to the changes in the primary hard X-ray. (B) The soft X-ray flux decreases by ∼36% in a timespan of ∼50 ks, indicating that its origin could be from a region as close as &lt;0.5 light-day from the supermassive black hole. A detailed hardness ratio resolved spectral analysis with state-of-the-art reflection models will be reported in a future paper.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The intensely varying Active Galactic nucleus (AGN) NGC 2992, on timescales of days to years, provides us with a unique testbed to study the response of the narrow FeK<jats:italic>α</jats:italic> emission line to the changes in the primary 2–10  keV AGN continuum. We find a strong correlation between the narrow FeK<jats:italic>α</jats:italic> line flux and the 2–10  keV flux with a Spearman correlation coefficient <jats:italic>s</jats:italic> = 0.70 and probability <jats:italic>p</jats:italic> &lt; 0.001, over a period of ∼20 yr. There is no evidence of such a correlation in &lt;1 yr, but the FeK<jats:italic>α</jats:italic> flux responds at ∼3 yr timescales, allowing us to put the reprocessor distance scale to 0.3 pc ≤ <jats:italic>d</jats:italic> ≤ 1 pc, consistent with that of torus reflection. The primary 2–10  keV continuum of NGC 2992 undergoes a high-low-high transition in ∼16 yr (2003–2019). Future long term monitoring will be crucial.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Hubble Space Telescope (HST) Ultraviolet Legacy Library of Young Stars as Essential Standards (ULLYSES) program is a HST Director's Discretionary program that is in the process of obtaining a large library of ultraviolet spectroscopic observations of young stars of both high and low masses. We present information on close companions to the T Tauri stars CVSO 109 and CVSO 165 in Orion that were observed with the HST as part of this program. CVSO 109 has a fainter companion at an angular separation <jats:italic>ρ</jats:italic> = 0.″64 near PA = 218° and Δ(F28X50LP) ≈ 0.6  mag, while the CVSO 165 companion is at <jats:italic>ρ</jats:italic> = 0.″30 near PA = 326° with Δ(F28X50LP) ≈ 1.7  mag. Both components of CVSO 165 appear to be active stars with strong emission features, while the CVSO 109 companion shows only modest indications of stellar activity. Extracted spectra for each of these components will be included in ULLYSES Data Release 2.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The far-UV spectral energy distribution of <jats:italic>α</jats:italic> Dor recorded by IUE is compared to that of the constant and normal star <jats:italic>ζ</jats:italic> Dra, which has similar fundamental parameters. <jats:italic>α</jats:italic> Dor has much less flux than <jats:italic>ζ</jats:italic> Dra shortwards of 1800 Å, due to the accumulation of very strong absorption lines of Si <jats:sc>ii</jats:sc>, in particular autoionization lines around 1400 Å. Two spectra of <jats:italic>α</jats:italic> Dor separated by 9 hr (i.e., much less than the rotational period) show evidence of modest variability shortwards of 1800 Å.</jats:p>