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Flare Rates, Rotation Periods, and Spectroscopic Activity Indicators of a Volume-complete Sample of Mid- to Late-M Dwarfs within 15 pc
Winters, Jennifer G.; Medina, Amber A.; Irwin, Jonathan M. +1 more
We present a study of flare rates, rotation periods, and spectroscopic activity indicators of 125 single stars within 15 parsecs and with masses between 0.1 and 0.3 M⊙ observed during the first year of the TESS mission, with the goal of elucidating the relationship between these various magnetically connected phenomena. We gathered mult…
All the PAHs: An AKARI-Spitzer Cross-archival Spectroscopic Survey of Aromatic Emission in Galaxies
Baba, Shunsuke; Imanishi, Masatoshi; Lai, Thomas S. -Y. +2 more
We present a large sample of 2.5-38 µm galaxy spectra drawn from a cross-archival comparison in the AKARI-Spitzer Extragalactic Spectral Survey, and investigate a subset of 113 star-forming galaxies with prominent polycyclic aromatic hydrocarbon (PAH) emission spanning a wide range of star formation properties. With AKARI's extended 2.5-5 &m…
Standing on the Shoulders of Giants: New Mass and Distance Estimates for Betelgeuse through Combined Evolutionary, Asteroseismic, and Hydrodynamic Simulations with MESA
Kobayashi, Chiaki; Nomoto, Ken'ichi; Ireland, Michael +3 more
We conduct a rigorous examination of the nearby red supergiant Betelgeuse by drawing on the synthesis of new observational data and three different modeling techniques. Our observational results include the release of new, processed photometric measurements collected with the space-based Solar Mass Ejection Imager instrument prior to Betelgeuse's …
Double White Dwarf Merger Products among High-mass White Dwarfs
Toonen, Silvia; Cheng, Sihao; Cummings, Jeffrey D. +1 more
Double white dwarf (double-WD) binaries may merge within a Hubble time and produce high-mass WDs. Compared to other high-mass WDs, the double-WD merger products have higher velocity dispersion because they are older. With the power of Gaia data, we show strong evidence for double-WD merger products among high-mass WDs by analyzing the transverse-v…
EvryFlare. III. Temperature Evolution and Habitability Impacts of Dozens of Superflares Observed Simultaneously by Evryscope and TESS
Law, Nicholas M.; Corbett, Hank; Gonzalez, Ramses +8 more
Superflares may provide the dominant source of biologically relevant UV radiation to rocky habitable-zone M-dwarf planets (M-Earths), altering planetary atmospheres and conditions for surface life. The combined line and continuum flare emission has usually been approximated by a 9000 K blackbody. If superflares are hotter, then the UV emission may…
A Dynamical Survey of Stellar-mass Black Holes in 50 Milky Way Globular Clusters
Chatterjee, Sourav; Kremer, Kyle; Weatherford, Newlin C. +1 more
Recent numerical simulations of globular clusters (GCs) have shown that stellar-mass black holes (BHs) play a fundamental role in driving cluster evolution and shaping their present-day structure. Rapidly mass-segregating to the center of GCs, BHs act as a dynamical energy source via repeated superelastic scattering, delaying the onset of core col…
Metallicity and α-Element Abundance Gradients along the Sagittarius Stream as Seen by APOGEE
Cohen, Roger E.; Bizyaev, Dmitry; Brownstein, Joel R. +27 more
Using 3D positions and kinematics of stars relative to the Sagittarius (Sgr) orbital plane and angular momentum, we identify 166 Sgr stream members observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) that also have Gaia DR2 astrometry. This sample of 63/103 stars in the Sgr trailing/leading arm is combined with an APOGE…
The ALMA Spectroscopic Survey in the HUDF: The Cosmic Dust and Gas Mass Densities in Galaxies up to z ∼ 3
Carilli, Chris; Inami, Hanae; Smail, Ian +24 more
Using the deepest 1.2 mm continuum map to date in the Hubble Ultra Deep Field, which was obtained as part of the ALMA Spectroscopic Survey (ASPECS) large program, we measure the cosmic density of dust and implied gas (H2+H I) mass in galaxies as a function of look-back time. We do so by stacking the contribution from all H-band selected…
Multi-gigayear White Dwarf Cooling Delays from Clustering-enhanced Gravitational Sedimentation
Cheng, Sihao; Bildsten, Lars; Schwab, Josiah +1 more
Cooling white dwarfs (WDs) can yield accurate ages when theoretical cooling models fully account for the physics of the dense plasma of WD interiors. We use MESA to investigate cooling models for a set of massive and ultramassive WDs (0.9-1.3 ${M}_{\odot }$ ) for which previous models have failed to match kinematic age indicators based on Gaia DR2…
Deflating Super-puffs: Impact of Photochemical Hazes on the Observed Mass-Radius Relationship of Low-mass Planets
Zhang, Xi; Gao, Peter
The observed mass-radius relationship of low-mass planets informs our understanding of their composition and evolution. Recent discoveries of low-mass, large-radius objects ("super-puffs") have challenged theories of planet formation and atmospheric loss, as their high inferred gas masses make them vulnerable to runaway accretion and hydrodynamic …