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A cold, massive, rotating disk galaxy 1.5 billion years after the Big Bang
Prochaska, J. Xavier; Rafelski, Marc; Neeleman, Marcel +1 more
Massive disk galaxies like the Milky Way are expected to form at late times in traditional models of galaxy formation1,2, but recent numerical simulations suggest that such galaxies could form as early as a billion years after the Big Bang through the accretion of cold material and mergers3,4. Observationally, it has been dif…
The dual origin of the Galactic thick disc and halo from the gas-rich Gaia-Enceladus Sausage merger
Grand, Robert J. J.; Gómez, Facundo A.; Fattahi, Azadeh +6 more
We analyse a set of cosmological magnetohydrodynamic simulations of the formation of Milky Way-mass galaxies identified to have a prominent radially anisotropic stellar halo component similar to the so-called 'Gaia Sausage' found in the Gaia data. We examine the effects of the progenitor of the Sausage (the Gaia-Enceladus Sausage, GES) on the form…
Evidence of ammonium salts in comet 67P as explanation for the nitrogen depletion in cometary comae
De Keyser, Johan; Gombosi, Tamas I.; Berthelier, Jean-Jacques +14 more
Cometary comae are generally depleted in nitrogen. The main carriers for volatile nitrogen in comets are NH3 and HCN. It is known that ammonia readily combines with many acids, such as HCN, HNCO and HCOOH, encountered in the interstellar medium as well as in cometary ice to form ammonium salts (NH4+X-) a…
Flare Statistics for Young Stars from a Convolutional Neural Network Analysis of TESS Data
Schlieder, Joshua E.; Günther, Maximilian N.; Montet, Benjamin T. +5 more
All-sky photometric time-series missions have allowed for the monitoring of thousands of young (tage < 800 Myr) stars in order to understand the evolution of stellar activity. Here, we developed a convolutional neural network (CNN), stella, specifically trained to find flares in Transiting Exoplanet Survey Satellite (TESS) short-cade…
Timing the Early Assembly of the Milky Way with the H3 Survey
van Dokkum, Pieter; Conroy, Charlie; Ting, Yuan-Sen +7 more
The archeological record of stars in the Milky Way opens a uniquely detailed window into the early formation and assembly of galaxies. Here we use 11,000 main-sequence turn-off stars with well-measured ages, $[\mathrm{Fe}/{\rm{H}}]$ , $[\alpha /\mathrm{Fe}]$ , and orbits from the H3 Survey and Gaia to time the major events in the early Galaxy. Loc…
The Multi-INstrument Burst ARchive (MINBAR)
Watts, Anna L.; Galloway, Duncan K.; Kuulkers, Erik +7 more
We present the largest sample of type I (thermonuclear) X-ray bursts yet assembled, comprising 7083 bursts from 85 bursting sources. The sample is drawn from observations with Xenon-filled proportional counters on the long-duration satellites RXTE, BeppoSAX, and International Gamma-Ray Astrophysics Laboratory between 1996 February 8 and 2012 May 3…
The First Habitable-zone Earth-sized Planet from TESS. I. Validation of the TOI-700 System
Kostov, Veselin B.; Barclay, Thomas; Vanderburg, Andrew +92 more
We present the discovery and validation of a three-planet system orbiting the nearby (31.1 pc) M2 dwarf star TOI-700 (TIC 150428135). TOI-700 lies in the TESS continuous viewing zone in the Southern Ecliptic Hemisphere; observations spanning 11 sectors reveal three planets with radii ranging from 1 R⊕ to 2.6 R⊕ and orbital pe…
Coherent radio emission from a quiescent red dwarf indicative of star-planet interaction
White, G. J.; Callingham, J. R.; Shimwell, T. W. +11 more
Low-frequency (ν ≲ 150 MHz) stellar radio emission is expected to originate in the outer corona at heights comparable to and larger than the stellar radius. Such emission from the Sun has been used to study coronal structure, mass ejections and space-weather conditions around the planets1. Searches for low-frequency emission from other …
Close Binary Companions to APOGEE DR16 Stars: 20,000 Binary-star Systems Across the Color-Magnitude Diagram
Green, Paul J.; Hogg, David W.; Majewski, Steven R. +21 more
Many problems in contemporary astrophysics—from understanding the formation of black holes to untangling the chemical evolution of galaxies—rely on knowledge about binary stars. This, in turn, depends on the discovery and characterization of binary companions for large numbers of different kinds of stars in different chemical and dynamical environ…
Magnetotail dipolarization fronts and particle acceleration: A review
Liu, Chengming; Grigorenko, Elena E.; Fu, Huishan +6 more