Search Publications
Dynamical Friction in Globular Cluster-rich Ultra-diffuse Galaxies: The Case of NGC5846-UDG1
Danieli, Shany; Bar, Nitsan; Blum, Kfir
Ultra-diffuse galaxies that contain a large sample of globular clusters (GCs) offer an opportunity to test the predictions of galactic dynamics theory. NGC5846-UDG1 is an excellent example, with a high-quality sample of dozens of GC candidates. We show that the observed distribution of GCs in NGC5846-UDG1 is suggestive of mass segregation induced …
Is [Y/Mg] a Reliable Age Diagnostic for FGK Stars?
van Saders, Jennifer L.; Huber, Daniel; Claytor, Zachary R. +3 more
Current spectroscopic surveys are producing large catalogs of chemical abundances for stars of all types. The yttrium-to-magnesium ratio, [Y/Mg], has emerged as a candidate age indicator for solar twins in the local stellar neighborhood. However, it is unclear whether it is a viable age diagnostic for more diverse stellar types, so we investigate …
Searching for a Hypervelocity White Dwarf SN Ia Companion: A Proper-motion Survey of SN 1006
Lu, Jessica R.; Rest, Armin; Zenteno, Alfredo +7 more
Type Ia supernovae (SNe Ia) are securely understood to come from the thermonuclear explosion of a white dwarf as a result of binary interaction, but the nature of that binary interaction and the secondary object is uncertain. Recently, a double white dwarf model known as the dynamically driven double-degenerate double-detonation (D6) model has bec…
Resolved Gaia Triples
Tokovinin, Andrei
A sample of 392 low-mass hierarchical triple stellar systems within 100 pc resolved by Gaia as distinct sources is defined. Owing to the uniform selection, the sample is ideally suited to study unbiased statistics of wide triples. The median projected separations in their inner and outer pairs are 151 and 2569 au, respectively, and the median sepa…
Looking at the Distant Universe with the MeerKAT Array: Discovery of a Luminous OH Megamaser at z > 0.5
Holwerda, Benne W.; Ravindranath, Swara; Somerville, Rachel S. +65 more
In the local universe, OH megamasers (OHMs) are detected almost exclusively in infrared-luminous galaxies, with a prevalence that increases with IR luminosity, suggesting that they trace gas-rich galaxy mergers. Given the proximity of the rest frequencies of OH and the hyperfine transition of neutral atomic hydrogen (H I), radio surveys to probe t…
Role of Longitudinal Waves in Alfvén-wave-driven Solar Wind
Shoda, Munehito; Shimizu, Kimihiko; Suzuki, Takeru K.
We revisit the role of longitudinal waves in driving the solar wind. We study how the p-mode-like vertical oscillation on the photosphere affects the properties of solar winds in the framework of Alfvén-wave-driven winds. We perform a series of one-dimensional magnetohydrodynamical numerical simulations from the photosphere to beyond several tens …
The Second AGILE MCAL Gamma-Ray Burst Catalog: 13 yr of Observations
Longo, F.; Morselli, A.; Chen, A. +20 more
We present the results of a systematic search and analysis of GRBs detected by the Astrorivelatore Gamma ad Immagini LEggero (AGILE) MiniCALorimeter (MCAL; 0.4-100 MeV) over a time frame of 13 yr, from 2007 to 2020 November. The MCAL GRB sample consists of 503 bursts triggered by MCAL, 394 of which were fully detected onboard with high time resolu…
Conditions for Proton Temperature Anisotropy to Drive Instabilities in the Solar Wind
Verscharen, Daniel; Chen, Christopher H. K.; Opie, Simon +2 more
Using high-resolution data from Solar Orbiter, we investigate the plasma conditions necessary for the proton temperature-anisotropy-driven mirror-mode and oblique firehose instabilities to occur in the solar wind. We find that the unstable plasma exhibits dependencies on the angle between the direction of the magnetic field and the bulk solar wind…
Dramatic Changes in the Observed Velocity of the Accretion Disk Wind in MCG-03-58-007 Are Revealed by XMM-Newton and NuSTAR
Ballo, L.; Reeves, J. N.; Braito, V. +6 more
Past X-ray observations of the nearby Seyfert 2 MCG-03-58-007 revealed the presence of a powerful and highly variable disk wind, where two possible phases outflowing with v out1/c ~ -0.07 and v out2/c ~ -0.2 were observed. Multi-epoch X-ray observations, covering the period from 2010 to 2018, showed that the lower-velocity co…
Hubble Space Telescope Imaging of Isolated Local Volume Dwarfs GALFA Dw3 and Dw4
Crnojević, D.; Mutlu-Pakdil, B.; Sand, D. J. +16 more
We present observations of the dwarf galaxies GALFA Dw3 and GALFA Dw4 with the Advanced Camera for Surveys on the Hubble Space Telescope. These galaxies were initially discovered as optical counterparts to compact H I clouds in the GALFA survey. Both objects resolve into stellar populations which display old red giant branch (RGB), younger helium-…