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Coronal height constraint in IRAS 13224-3809 and 1H 0707-495 by the random forest regressor
Chainakun, P.; Young, A. J.; Luangtip, W. +1 more
We develop a random forest regressor (RFR) machine learning model to trace the coronal evolution in two highly variable active galactic nuclei (AGNs) IRAS 13224-3809 and 1H 0707-495 observed with XMM-Newton, by probing the X-ray reverberation features imprinted on their power spectral density (PSD) profiles. Simulated PSDs in the form of a power l…
NGC 4388: a test case for relativistic disc reflection and Fe K fluorescence features
LaMassa, S.; Yaqoob, Tahir; Tzanavaris, P.
We present a new analysis of the Suzaku X-ray spectrum of the Compton-thin Seyfert 2 galaxy NGC 4388. The spectrum above ~2 keV can be described by a remarkably simple and rather mundane model, consisting of a uniform, neutral spherical distribution of matter, with a radial column density of $2.58\pm 0.02 \times 10^{23} \ \rm cm^{-2}$, and an Fe a…
An Extremely Massive White Dwarf Escaped from the Hyades Star Cluster
El-Badry, Kareem; Rodriguez, Antonio C.; van Roestel, Jan +5 more
We searched the Gaia DR3 database for ultramassive white dwarfs with kinematics consistent with having escaped the nearby Hyades open cluster, identifying three such candidates. Two of these candidates have masses estimated from Gaia photometry of approximately 1.1 solar masses; their status as products of single-stellar evolution that have escape…
New evidence about HW Vir's circumbinary planets from Hipparcos-Gaia astrometry and a reanalysis of the eclipse timing variations using nested sampling
Triaud, Amaury H. M. J.; Kervella, Pierre; Baycroft, Thomas A.
The post common-envelope eclipsing binary HW Virginis (HW Vir) has had many circumbinary companions proposed based on eclipse timing variations. Each proposed solution has lacked in predictability and orbital stability, leaving the origin of the eclipse timing variations an active area of research. Leveraging the catalogue of Hipparcos and Gaia pr…
Near-IR photometry of the small Uranian satellites with Keck at phase angles 0-2°
de Pater, Imke; Moeckel, Chris; Paradis, Samuel
We present photometric measurements of the seven brightest small inner moons of Uranus (Puck, Belinda, Rosalind, Portia, Juliet, Desdemona and Cressida) obtained with the Keck II telescope at 1.6 and 2 . 2 µm at phase angles of 0.026∘ and 0.36∘ in October-November 2019. We also applied our new calibration technique to the August 2015 data at…
The Differential Assembly History of the Centers and Outskirts of Main-sequence Galaxies at z 2.3
Giavalisco, Mauro; Ji, Zhiyuan; Cutler, Sam E. +1 more
We present a study of spatially resolved star formation histories (SFHs) for 60 z ~ 2.3 main-sequence, star-forming galaxies selected from the MOSDEF spectroscopic survey in the GOODS-N field, with median stellar mass $\mathrm{log}({M}_{\star }/{M}_{\odot })$ = 9.75 and spanning the range $8.6\lt \mathrm{log}({M}_{\star }/{M}_{\odot })\lt 11.5$ . …
Multiple stellar populations found outside the tidal radius of NGC 1851 via Gaia DR3 XP spectra
Milone, Antonino P.; Lagioia, Edoardo P.; Marino, Anna F. +6 more
Aims: Ancient galactic globular clusters (GCs) have long fascinated astronomers due to their intriguing multiple stellar populations (MPs), which are characterized by variations in light element abundances. Among these clusters, type II GCs stand out as they exhibit stars with large differences in heavy-element chemical abundances. These enig…
Speckle Interferometry at SOAR in 2022
Tokovinin, Andrei; Mason, Brian D.; Mendez, Rene A. +1 more
Results of the speckle-interferometry observations at the 4.1 m SOuthern Astrophysical Research Telescope obtained during 2022 are presented: 2508 measurements of 1925 resolved pairs or subsystems and 785 nonresolutions of 611 targets; 26 pairs are resolved here for the first time. This work continues our long-term effort to monitor orbital motion…
ZZ Ceti stars of the southern ecliptic hemisphere re-observed by TESS
Sódor, Ádám; Kawaler, Steven D.; Bognár, Zsófia +1 more
Context. In 2020, a publication presented the first-light results for 18 known ZZ Ceti stars observed by the TESS Space Telescope during the first survey observations of the southern ecliptic hemisphere. However, in the meantime, new measurements have become available from this field, in many cases with the new, 20 s ultrashort cadence mode.
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Wavelet spectral timing: X-ray reverberation from a dynamic black hole corona hidden beneath ultrafast outflows
Wilkins, D. R.
Spectral timing analyses based upon wavelet transforms provide a new means to study the variability of the X-ray emission from accreting systems, including AGN, stellar mass black holes, and neutron stars, and can be used to trace the time variability of X-ray reverberation from the inner accretion disc. The previously missing iron K reverberation…