Search Publications
Kinematics of the Palomar 5 Stellar Stream from RR Lyrae Stars
Price-Whelan, Adrian M.; Belokurov, Vasily; Bonaca, Ana +3 more
Thin stellar streams, formed from the tidal disruption of globular clusters, are important gravitational tools, sensitive to both global and small-scale properties of dark matter. The Palomar 5 stellar stream (Pal 5) is an exemplar stream within the Milky Way: its ∼20° tidal tails connect back to the progenitor cluster, and the stream has been use…
Current Sheets, Magnetic Islands, and Associated Particle Acceleration in the Solar Wind as Observed by Ulysses near the Ecliptic Plane
Zank, Gary P.; Bruno, Roberto; Li, Gang +16 more
Recent studies of particle acceleration in the heliosphere have revealed a new mechanism that can locally energize particles up to several MeV nucleon-1. Stream-stream interactions, as well as the heliospheric current sheet (CS)—stream interactions, lead to formation of large magnetic cavities, bordered by strong CSs, which in turn prod…
Evidence for short ∼ 1 Myr lifetimes from the He II proximity zones of z ∼ 4 quasars
Hennawi, Joseph F.; Worseck, Gábor; Khrykin, Ilya S.
The duration of quasar accretion episodes is a key quantity for distinguishing between models for the formation and growth of supermassive black holes, the evolution of quasars, and their potential feedback effects on their host galaxies. However, this critical time-scale, often referred to as the quasar lifetime, is still uncertain by orders of m…
The Role of Cluster Mass in the Multiple Populations of Galactic and Extragalactic Globular Clusters
Milone, Antonino P.; Tailo, Marco; Lagioia, Edoardo P. +2 more
Studies based on Hubble Space Telescope (HST) photometry in F275W, F336W, and F438W have shown that the incidence and complexity of multiple populations (MPs) in globular clusters (GCs) depend on cluster mass. This result, however, is based on nearby, low-reddening Galactic GCs, for which we can obtain accurate F275W photometry. In this work, we e…
Hot, rocky and warm, puffy super-Earths orbiting TOI-402 (HD 15337)
Latham, David W.; Ricker, George R.; Seager, Sara +30 more
Context. The Transiting Exoplanet Survey Satellite (TESS) is revolutionising the search for planets orbiting bright and nearby stars. In sectors 3 and 4, TESS observed TOI-402 (TIC-120896927), a bright V = 9.1 K1 dwarf also known as HD 15337, and found two transiting signals with periods of 4.76 and 17.18 days and radii of 1.90 and 2.21 R⊕
Size diversity of old Large Magellanic Cloud clusters as determined by internal dynamical evolution
Dalessandro, E.; Beccari, G.; Mucciarelli, A. +5 more
The distribution of size as a function of age observed for star clusters in the Large Magellanic Cloud (LMC) is very puzzling: young clusters are all compact, while the oldest systems show both small and large sizes. This phenomenon is commonly interpreted as being due to a population of binary black holes driving a progressive expansion of cluste…
The methane distribution and polar brightening on Uranus based on HST/STIS, Keck/NIRC2, and IRTF/SpeX observations through 2015
Sromovsky, L. A.; Fry, P. M.; Karkoschka, E. +2 more
Space Telescope Imaging Spectrograph (STIS) observations of Uranus in 2002 and 2012 revealed that both polar regions of Uranus were depleted in upper tropospheric methane relative to equatorial regions. Similar observations in 2015 confirm the relative stability of the north polar methane depletion, but show that the north polar region was becomin…
Hot Subdwarf Stars Observed in Gaia DR2 and LAMOST DR5
Han, Zhanwen; Deng, Licai; Luo, Yangping +1 more
Combing Gaia DR2 with LAMOST DR5, we spectroscopically identified 924 hot subdwarf stars, among which 32 stars exhibit strong double-lined composite spectra. We measured the effective temperature T eff, surface gravity {log} g, helium abundance y = nHe/nH, and radial velocities (RVs) of 892 non-composite spectra hot subdwarf stars by fi…
MOVES - II. Tuning in to the radio environment of HD189733b
Moutou, C.; Vidotto, A. A.; Bourrier, V. +7 more
We present stellar wind modelling of the hot Jupiter host HD189733, and predict radio emission from the stellar wind and the planet, the latter arising from the interaction of the stellar wind with the planetary magnetosphere. Our stellar wind models incorporate surface stellar magnetic field maps at the epochs 2013 June/July, 2014 September, and …
TESS first look at evolved compact pulsators. Asteroseismology of the pulsating helium-atmosphere white dwarf TIC 257459955
Córsico, Alejandro H.; Hermes, J. J.; Bell, Keaton J. +10 more
Context. Pulsation frequencies reveal the interior structures of white dwarf stars, shedding light on the properties of these compact objects that represent the final evolutionary stage of most stars. Two-minute cadence photometry from the Transiting Exoplanet Survey Satellite (TESS) records pulsation signatures from bright white dwarfs over the e…