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Microstructural Investigation and High Temperature Mechanical Behavior of AXE622 Cast Mg Alloy
Eftekhar, A. Habibi; Sadrossadat, S. Mohsen; Reihanian, M.
The microstructure and high temperature properties of the AXE622 Mg alloy were investigated after the conventional and semisolid casting processes. The tensile test was conducted at room temperature, and 473 K. Impression creep test was performed at a temperature range of 423-498 K under the stress range of 450-600 MPa. The microstructure of the c…
Expediting DECam Multimessenger Counterpart Searches with Convolutional Neural Networks
Bechtol, K.; García-Bellido, J.; Soares-Santos, M. +11 more
Searches for counterparts to multimessenger events with optical imagers use difference imaging to detect new transient sources. However, even with existing artifact-detection algorithms, this process simultaneously returns several classes of false positives: false detections from poor-quality image subtractions, false detections from low signal-to…
Exploring Gravitationally Lensed z ≳ 6 X-Ray Active Galactic Nuclei Behind the RELICS Clusters
Bradač, Maruša; Strait, Victoria; Coe, Dan +5 more
Although observations of high-redshift quasars demonstrate that many supermassive black holes (BHs) reached large masses within one billion years after the Big Bang, the origin of the first BHs is still a mystery. A promising way to constrain the origin of the first BHs is to explore the average properties of z ≳ 6 BHs. However, typical BHs remain…
The Accreting White Dwarfs in Cataclysmic Variables
Sion, Edward M.; Godon, Patrick
Accreting white dwarfs (WDs) in cataclysmic variables (CVs) provide crucial insights about the accretion of mass and angular momentum in all types of binaries, including accreting NSs and BHs. Accreting WDs are the critical component in the single degenerate pathway to SNe Ia, along with the double degenerate merger pathway, they are the standard …
Fragment Dynamics in Active Asteroid 331P/Gibbs
Jewitt, David; Hui, Man-To
We present a dynamical analysis of the fragmented active asteroid 331P/Gibbs. Using archival images taken by the Hubble Space Telescope from 2015 to 2018, we measured the astrometry of the primary and the three brightest (presumably the largest) components. Conventional orbit determination revealed a high degree of orbital similarity between the c…
Thermophysical and Compositional Properties of Paleobedforms on Mars
Chojnacki, Matthew; Fenton, Lori K.; Piqueux, Sylvain +4 more
Bedforms on Earth and Mars are often preserved in the rock record in the form of sedimentary rock with distinct cross-bedding. On rare occasions, the full-surface geometry of a bedform can be preserved through burial and lithification. These features, known as paleobedforms, are found in a variety of geographic locations on Mars. Evidence in the m…
The local universe in the era of large surveys - II. multi-wavelength characterization of activity in nearby S0 galaxies
del Olmo, A.; Jiménez-Palau, C.; Solanes, J. M. +2 more
This is the second paper in a series using data from tens of thousands S0 galaxies of the local Universe (z ≲ 0.1) retrieved from the NASA-Sloan Atlas. It builds on the outcomes of the previous work, which introduced a new classification scheme for these objects based on the principal component analysis (PCA) of their optical spectrum and its proj…
Faint Stars in a Faint Galaxy. II. The Low-mass Stellar Initial Mass Function of the Boötes I Ultrafaint Dwarf Spheroidal Galaxy
Wyse, Rosemary F. G.; Kozhurina-Platais, Vera; Platais, Imants +1 more
This paper presents improved constraints on the low-mass stellar initial mass function (IMF) of the Boötes I (Boo I) ultrafaint dwarf galaxy, based on our analysis of recent deep imaging from the Hubble Space Telescope. The identification of candidate stellar members of Boo I in the photometric catalog produced from these data was achieved using a…
The Interferometric Binary ϵ Cnc in Praesepe: Precise Masses and Age
Klement, Robert; Monnier, John D.; Schaefer, Gail H. +16 more
We observe the brightest member of the Praesepe cluster, ϵ Cnc, to precisely measure the characteristics of the stars in this binary system, en route to a new measurement of the cluster's age. We present spectroscopic radial velocity measurements and interferometric observations of the sky-projected orbit to derive the masses, which we find to be …
Theoretical mass-luminosity relations in Gaia G-band
Malkov, Oleg; Kovaleva, Dana; Zhukov, Aleksandr +1 more
We have analyzed the retrieval of the relation between mass and absolute Gaia G magnitude as obtained from theoretical models by Bressan et al. (Mon. Not. R. Astron. Soc. 427:127, 2012) for the stars of different luminosity classes. For subgiant and main-sequence stars, we provide approximate analytical direct and inverse relations based on the mo…