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Lucy Mission to the Trojan Asteroids: Science Goals
Stern, S. Alan; Noll, Keith S.; Levison, Harold F. +22 more
The Lucy Mission is a NASA Discovery-class mission to send a highly capable and robust spacecraft to investigate seven primitive bodies near both the L4 and L5 Lagrange points with Jupiter: the Jupiter Trojan asteroids. These planetesimals from the outer planetary system have been preserved since early in solar system history…
Hubble WFC3 Spectroscopy of the Habitable-zone Super-Earth LHS 1140 b
Changeat, Quentin; Mori, Mayuko; Edwards, Billy +7 more
Atmospheric characterization of temperate, rocky planets is the holy grail of exoplanet studies. These worlds are at the limits of our capabilities with current instrumentation in transmission spectroscopy and challenge our state-of-the-art statistical techniques. Here we present the transmission spectrum of the temperate super-Earth LHS 1140b usi…
Fast rotating and low-turbulence discs at z ≃ 4.5: Dynamical evidence of their evolution into local early-type galaxies
Magnelli, B.; Gómez-Guijarro, C.; Jiménez-Andrade, E. F. +3 more
Massive starburst galaxies in the early Universe are estimated to have depletion times of ∼100 Myr and thus be able to convert their gas very quickly into stars, possibly leading to a rapid quenching of their star formation. For these reasons, they are considered progenitors of massive early-type galaxies (ETGs). In this paper, we study two high-z…
Estimate on Dust Scale Height from the ALMA Dust Continuum Image of the HD 163296 Protoplanetary Disk
Kataoka, Akimasa; Doi, Kiyoaki
We aim at estimating the dust scale height of protoplanetary disks from millimeter continuum observations. First, we present a general expression of intensity of a ring in a protoplanetary disk and show that we can constrain the dust scale height by the azimuthal intensity variation. Then, we apply the presented methodology to the two distinct rin…
An extended halo around an ancient dwarf galaxy
Erkal, Denis; Jerjen, Helmut; Frebel, Anna +7 more
The Milky Way is surrounded by dozens of ultrafaint (<105 L⊙) dwarf satellite galaxies1-3. They are the remnants of the earliest galaxies4, as confirmed by their ancient5 and chemically primitive6,7 stars. Simulations8-10 suggest that these systems formed within extend…
Interacting dark energy in a closed universe
Di Valentino, Eleonora; Melchiorri, Alessandro; Mena, Olga +2 more
Recent measurements of the Cosmic Microwave Anisotropies power spectra measured by the Planck satellite show a preference for a closed universe at more than $99 {{\ \rm per\ cent}}$ confidence level (CL). Such a scenario is however in disagreement with several low redshift observables, including luminosity distances of Type Ia supernovae. Here we …
The population of M dwarfs observed at low radio frequencies
Callingham, J. R.; Shimwell, T. W.; Vedantham, H. K. +12 more
Coherent low-frequency (≲200 MHz) radio emission from stars encodes the conditions of the outer corona, mass-ejection events and space weather1-5. Previous low-frequency searches for radio-emitting stellar systems have lacked the sensitivity to detect the general population, instead largely focusing on targeted studies of anomalously ac…
Fundamental relations for the velocity dispersion of stars in the Milky Way
Lewis, Geraint F.; Ting, Yuan-Sen; Huber, Daniel +35 more
We explore the fundamental relations governing the radial and vertical velocity dispersions of stars in the Milky Way, from combined studies of complementary surveys including GALAH, LAMOST, APOGEE, the NASA Kepler and K2 missions, and Gaia DR2. We find that different stellar samples, even though they target different tracer populations and employ…
Solar oxygen abundance
Carlsson, Mats; Reiners, Ansgar; Bergemann, Maria +10 more
Motivated by the controversy over the surface metallicity of the Sun, we present a re-analysis of the solar photospheric oxygen (O) abundance. New atomic models of O and Ni are used to perform non-local thermodynamic equilibrium (NLTE) calculations with 1D hydrostatic (MARCS) and 3D hydrodynamical (Stagger and Bifrost) models. The Bifrost 3D MHD s…
A stripped-companion origin for Be stars: clues from the putative black holes HR 6819 and LB-1
El-Badry, Kareem; Quataert, Eliot
HR 6819 is a bright (V = 5.36), blue star recently proposed to be a triple containing a detached black hole (BH). We show that the system is a binary and does not contain a BH. Using spectral decomposition, we disentangle the observed composite spectra into two components: a rapidly rotating Be star and a slowly rotating B star with low surface gr…