Search Publications
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…
Magnetars and axion-like particles: probes with the hard X-ray spectrum
Sinha, Kuver; Guo, Huai-Ke; Fortin, Jean-François +2 more
Quiescent hard X-ray and soft gamma-ray emission from neutron stars constitute a promising frontier to explore axion-like-particles (ALPs). ALP production in the core peaks at energies of a few keV to a few hundreds of keV; subsequently, the ALPs escape and convert to photons in the magnetosphere. The emissivity goes as T6 while the con…
591 High-velocity Stars in the Galactic Halo Selected from LAMOST DR7 and Gaia DR2
Zhao, Gang; Xiang, Maosheng; Ting, Yuan-Sen +14 more
In this paper, we report 591 high-velocity star candidates (HiVelSCs) selected from over 10 million spectra of Data Release 7 (DR7) of the Large Sky Area Multi-object Fiber Spectroscopic Telescope and the second Gaia data release, with three-dimensional velocities in the Galactic rest frame larger than 445 km s-1. We show that at least …
From Pseudostreamer Jets to Coronal Mass Ejections: Observations of the Breakout Continuum
Antiochos, Spiro K.; Lynch, Benjamin J.; Kumar, Pankaj +3 more
The magnetic breakout model, in which reconnection in the corona leads to destabilization of a filament channel, explains numerous features of eruptive solar events, from small-scale jets to global-scale coronal mass ejections (CMEs). The underlying multipolar topology, pre-eruption activities, and sequence of magnetic-reconnection onsets (first b…
The effect of stellar multiplicity on protoplanetary discs: a near-infrared survey of the Lupus star-forming region
Ansdell, Megan; Pérez, Sebastián; Gonzalez-Ruilova, Camilo +9 more
We present results from a near-infrared (NIR) adaptive optics (AO) survey of pre-main-sequence stars in the Lupus molecular cloud with NACO at the Very Large Telescope (VLT) to identify (sub)stellar companions down to ~20-au separation and investigate the effects of multiplicity on circumstellar disc properties. We observe for the first time in th…