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Discovery of a Fast Iron Low-ionization Outflow in the Early Evolution of the Nearby Tidal Disruption Event AT 2019qiz
Cenko, S. B.; Veilleux, S.; Filippenko, Alexei V. +16 more
We report the results of ultraviolet (UV) and optical photometric and spectroscopic analysis of the tidal disruption event (TDE) AT 2019qiz. Our follow-up observations started <10 days after the source began to brighten in the optical and lasted for a period of six months. Our late-time host-dominated spectrum indicates that the host galaxy lik…
Highlights of Discoveries for δ Scuti Variable Stars From the Kepler Era
Guzik, Joyce Ann
The NASAKeplerand follow-on K2 mission (2009–2018) left a legacy of data and discoveries, finding thousands of exoplanets, and also obtaining high-precision long time-series data for hundreds of thousands of stars, including many types of pulsating variables. Here we highlight a few of the ongoing discoveries fromKeplerdata on δ Scuti pulsating va…
Action-based distribution function modelling for constraining the shape of the Galactic dark matter halo
Hattori, Kohei; Vasiliev, Eugene; Valluri, Monica
We estimate the 3D density profile of the Galactic dark matter (DM) halo within r ≲ 30 kpc from the Galactic centre by using the astrometric data for halo RR Lyrae stars from Gaia DR2. We model both the stellar halo distribution function and the Galactic potential, fully taking into account the survey selection function, the observational errors, …
Low-luminosity Galaxies in the Early Universe Have Observed Sizes Similar to Star Cluster Complexes
Oesch, P. A.; Bouwens, R. J.; Illingworth, G. D. +3 more
We compare the sizes and luminosities of faint z = 6-8 galaxies magnified by the Hubble Frontier Fields clusters with star-forming regions, as well as more evolved objects, in the nearby universe. Our high-redshift comparison sample includes 330 z = 6-8 galaxies, for which size measurements were made as part of a companion study where lensing magn…
TOI-431/HIP 26013: a super-Earth and a sub-Neptune transiting a bright, early K dwarf, with a third RV planet
Henning, Thomas; Barclay, Thomas; Gorjian, Varoujan +125 more
We present the bright (Vmag = 9.12), multiplanet system TOI-431, characterized with photometry and radial velocities (RVs). We estimate the stellar rotation period to be 30.5 ± 0.7 d using archival photometry and RVs. Transiting Exoplanet Survey Satellite (TESS) objects of Interest (TOI)-431 b is a super-Earth with a period of 0.49 d, a…
Magellanic Mayhem: Metallicities and Motions
Evans, N. W.; Belokurov, V.; Grady, J.
We assemble a catalog of Magellanic Cloud red giants from Data Release 2 of the Gaia mission and, utilizing machine-learning methods, obtain photometric metallicity estimates for them. In doing so, we are able to chemically map the entirety of the Magellanic System at once. Our maps reveal a plethora of substructure within our red giant sample, wi…
The origin of metal-poor stars on prograde disc orbits in FIRE simulations of Milky Way-mass galaxies
Faucher-Giguère, Claude-André; El-Badry, Kareem; Wetzel, Andrew +3 more
In hierarchical structure formation, metal-poor stars in and around the Milky Way (MW) originate primarily from mergers of lower mass galaxies. A common expectation is therefore that metal-poor stars should have isotropic, dispersion-dominated orbits that do not correlate strongly with the MW disc. However, recent observations of stars in the MW s…
X-ray spectral components of the blazar and binary black hole candidate OJ 287 (2005-2020)
Ciprini, S.; Nowak, M. A.; Komossa, S. +12 more
We present a comprehensive analysis of all XMM-Newton spectra of OJ 287 spanning 15 yr of X-ray spectroscopy of this bright blazar. We also report the latest results from our dedicated Swift UVOT and XRT monitoring of OJ 287, which started in 2015, along with all earlier public Swift data since 2005. During this time interval, OJ 287 was caught in…
Extreme-ultraviolet bursts and nanoflares in the quiet-Sun transition region and corona
Peter, H.; Chitta, L. P.; Young, P. R.
The quiet solar corona consists of myriads of loop-like features, with magnetic fields originating from network and internetwork regions on the solar surface. The continuous interaction between these different magnetic patches leads to transient brightenings or bursts that might contribute to the heating of the solar atmosphere. The literature on …
Hot Stars with Kepler Planets Have High Obliquities
Howard, Andrew W.; Petigura, Erik A.; Winn, Joshua N. +5 more
It has been known for a decade that hot stars with hot Jupiters tend to have high obliquities. Less is known about the degree of spin-orbit alignment for hot stars with other kinds of planets. Here, we reassess the obliquities of hot Kepler stars with transiting planets smaller than Neptune, based on spectroscopic measurements of their projected r…