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Two decades of optical timing of the shortest-period binary star system HM Cancri
Dhillon, V. S.; Hollands, Mark; Parsons, Steven G. +15 more
The shortest-period binary star system known to date, RX J0806.3+1527 (HM Cancri), has now been observed in the optical for more than two decades. Although it is thought to be a double degenerate binary undergoing mass transfer, an early surprise was that its orbital frequency, f0, is currently increasing as the result of gravitational …
Benchmarking MESA isochrones against the Hyades single star sequence
Brandner, Wolfgang; Calissendorff, Per; Kopytova, Taisiya
Based on GAIA Early Data Release 3 (EDR3), we revisit and update our sample of bonafide single stars in the Hyades open cluster. The small observational uncertainties in parallax and photometry of EDR3 result in a tightly defined stellar sequence, which is ideal for the testing and calibration of theoretical stellar evolutionary tracks and isochro…
Beyond Spectroscopy. II. Stellar Parameters for over 20 Million Stars in the Northern Sky from SAGES DR1 and Gaia DR3
Tan, Ke-Feng; Zhao, Gang; Fan, Zhou +18 more
We present precise photometric estimates of stellar parameters, including effective temperature, metallicity, luminosity classification, distance, and stellar age, for nearly 26 million stars using the methodology developed in the first paper of this series, based on the stellar colors from the Stellar Abundances and Galactic Evolution Survey (SAG…
The ALMA REBELS Survey: discovery of a massive, highly star-forming, and morphologically complex ULIRG at z = 7.31
Inami, H.; Bowler, R. A. A.; Rybak, M. +27 more
We present Atacama Large Millimeter/Submillimeter Array (ALMA) [C II] and ~158 $\rm \mu m$ continuum observations of REBELS-25, a massive, morphologically complex ultra-luminous infrared galaxy (ULIRG; LIR = $1.5^{+0.8}_{-0.5} \times 10^{12}$ L⊙) at z = 7.31, spectroscopically confirmed by the Reionization Era Bright Emission…
Estimating reddening of the continuum and broad-line region of active galactic nuclei: the mean reddening of NGC 5548 and the size of the accretion disc
Gaskell, C. Martin; Anderson, Frances C.; Birmingham, Sufia Á. +1 more
We use seven different methods to estimate broad-line and continuum reddenings of NGC 5548. We investigate two possible reddening curves considered for active galactic nuclei (AGNs): the mean AGN reddening curve of Gaskell & Benker (2007) which is relatively flat in the ultraviolet, and a curve that rises strongly into the ultraviolet like a S…
Analytic model for off-axis GRB afterglow images - geometry measurement and implications for measuring H0
Nakar, Ehud; Govreen-Segal, Taya
We present an analytic model for measuring the jet core angle (θc) and viewing angle (θobs) of off-axis gamma-ray bursts independently of the jet angular structure outside of the core. We model the images of off-axis jets, and using this model, we show that θobs and θc can be measured using any two of th…
Characterizing three-dimensional magnetic field, turbulence, and self-gravity in the star-forming region L1688
Lazarian, A.; Hu, Yue
Interaction of three-dimensional magnetic fields, turbulence, and self-gravity in the molecular cloud is crucial in understanding star formation but has not been addressed so far. In this work, we target the low-mass star-forming region L1688 and use the spectral emissions of 12CO, 13CO, C18O, and H I, as well as p…
The Power of the Rings: The GRB 221009A Soft X-Ray Emission from Its Dust-scattering Halo
Pintore, Fabio; Mereghetti, Sandro; Esposito, Paolo +11 more
GRB 221009A is the brightest gamma-ray burst (GRB) ever detected that has occurred at low Galactic latitude. Owing to this exceptional combination, its prompt X-ray emission could be detected for weeks in the form of expanding X-ray rings produced by scattering in Galactic dust clouds. We report on the analysis of 20 rings, generated by dust at di…
Carbon dredge-up required to explain the Gaia white dwarf colour-magnitude bifurcation
Blouin, Simon; Tremblay, Pier-Emmanuel; Bédard, Antoine
The Gaia colour-magnitude diagram reveals a striking separation between hydrogen-atmosphere white dwarfs and their helium-atmosphere counterparts throughout a significant portion of the white dwarf cooling track. However, pure-helium atmospheres have Gaia magnitudes that are too close to the pure-hydrogen case to explain this bifurcation. To repro…
Interrogating Solar Flare Loop Models with IRIS Observations 2: Plasma Properties, Energy Transport, and Future Directions
Kerr, Graham S.
During solar flares a tremendous amount of magnetic energy is released and transported through the Sun's atmosphere and out into the heliosphere. Despite over a century of study, many unresolved questions surrounding solar flares are still present. Among those are how does the solar plasma respond to flare energy deposition, and what are the impor…