Search Publications
The Evolution of Rotation and Magnetic Activity in 94 Aqr Aa from Asteroseismology with TESS
Chaplin, William J.; Stassun, Keivan G.; Metcalfe, Travis S. +29 more
Most previous efforts to calibrate how rotation and magnetic activity depend on stellar age and mass have relied on observations of clusters, where isochrones from stellar evolution models are used to determine the properties of the ensemble. Asteroseismology employs similar models to measure the properties of an individual star by matching its no…
Speckle Interferometry at SOAR in 2019
Tokovinin, Andrei; Horch, Elliott P.; Mason, Brian D. +2 more
The results of speckle-interferometric observations at the 4.1 m Southern Astrophysical Research Telescope in 2019 are given, totaling 2555 measurements of 1972 resolved pairs with separations from 15 mas (median 0"21) and magnitude difference up to 6 mag, and non-resolutions of 684 targets. We resolved for the first time 90 new pairs or subsystem…
Discovery of a Giant Radio Fossil in the Ophiuchus Galaxy Cluster
Wik, D. R.; Giacintucci, S.; Markevitch, M. +3 more
The Ophiuchus galaxy cluster exhibits a curious concave gas density discontinuity at the edge of its cool core. It was discovered in the Chandra X-ray image by Werner and collaborators, who considered the possibility of it being a boundary of an active galactic nucleus (AGN)-inflated bubble located outside the core, but discounted this possibility…
The changing-type SN 2014C may come from an 11-M⊙ star stripped by binary interaction and violent eruption
Sun, Ning-Chen; Crowther, Paul A.; Maund, Justyn R.
SN 2014C was an unprecedented supernova (SN) that displayed a metamorphosis from Type Ib to Type IIn over ∼200 d. This transformation is consistent with a helium star having exploded in a cavity surrounded by a dense shell of the progenitor's stripped hydrogen envelope. For at least 5 yr post-explosion, the ejecta continued to interact with an out…
Modeling the Lyα transit absorption of the hot Jupiter HD 189733b
Holmström, M.; Lammer, H.; Fossati, L. +7 more
Context. Hydrogen-dominated atmospheres of hot exoplanets expand and escape hydrodynamically due to the intense heating by the X-ray and extreme ultraviolet (XUV) irradiation of their host stars. Excess absorption of neutral hydrogen has been observed in the Lyα line during transits of several close-in gaseous exoplanets, indicating such extended …
Zodiacal Exoplanets in Time (ZEIT). IX. A Flat Transmission Spectrum and a Highly Eccentric Orbit for the Young Neptune K2-25b as Revealed by Spitzer
Gaidos, Eric; Dalba, Paul A.; Rizzuto, Aaron C. +9 more
Transiting planets in nearby young clusters offer the opportunity to study the atmospheres and dynamics of planets during their formative years. To this end, we focused on K2-25b—a close-in (P = 3.48 days), Neptune-sized exoplanet orbiting a M4.5 dwarf in the 650 Myr Hyades cluster. We combined photometric observations of K2-25 covering a total of…
Ca II H&K stellar activity parameter: a proxy for extreme ultraviolet stellar fluxes
France, K.; Fossati, L.; Sreejith, A. G. +2 more
Atmospheric escape is an important factor shaping the exoplanet population and hence drives our understanding of planet formation. Atmospheric escape from giant planets is driven primarily by the stellar X-ray and extreme ultraviolet (EUV) radiation. Furthermore, EUV and longer wavelength UV radiation power disequilibrium chemistry in the middle a…
Distances to the supernova remnants in the inner disk
Liu, Jifeng; Gao, Jian; Wang, Shu +5 more
Context. Distance measurements of supernova remnants (SNRs) are essential as accurate estimates of physical size, dust masses, and some other properties of SNRs depend critically on accurate distance measurements. However, the determination of SNR distances is still a tough task.
Aims: Red clump stars (RCs) have a long history of being used a…
Mio—First Comprehensive Exploration of Mercury's Space Environment: Mission Overview
Barabash, Stas; Korablev, Oleg; Moncuquet, Michel +17 more
Mercury has a unique and complex space environment with its weak global magnetic field, intense solar wind, tenuous exosphere, and magnetospheric plasma particles. This complex system makes Mercury an excellent science target to understand effects of the solar wind to planetary environments. In addition, investigating Mercury's dynamic magnetosphe…
Three-dimensional Kinematic Reconstruction of the Optically Emitting, High-velocity, Oxygen-rich Ejecta of Supernova Remnant N132D
Law, Charles J.; Orlando, Salvatore; Gladders, Michael D. +9 more
We present a three-dimensional kinematic reconstruction of the optically emitting, oxygen-rich ejecta of supernova remnant N132D in the Large Magellanic Cloud (LMC). Data were obtained with the 6.5 m Magellan telescope in combination with the IMACS+GISMO instrument and survey [O III] λλ4959, 5007 line emission in a ∼3' × 3' region centered on N132…