Search Publications
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…
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 …
A dynamic black hole corona in an active galaxy through X-ray reverberation mapping
Fabian, Andrew C.; Middleton, Matthew J.; Walton, Dominic J. +18 more
X-ray reverberation echoes are assumed to be produced in the strongly distorted spacetime around accreting supermassive black holes. This signal allows us to spatially map the geometry of the inner accretion flow1,2—a region that cannot yet be spatially resolved by any telescope—and provides a direct measure of the black hole mass and s…
A kilonova associated with GRB 070809
Li, Xiang; Jin, Zhi-Ping; Covino, Stefano +4 more
For on-axis typical short gamma-ray bursts (sGRBs), the forward shock emission is usually so bright1,2 that it renders the identification of kilonovae (also known as macronovae)3-6 in the early afterglow (t < 0.5 d) phase rather challenging. This is why previously no thermal-like kilonova component has been identified at s…
Direct evidence for shock-powered optical emission in a nova
Wade, Gregg A.; Moffat, Anthony F. J.; Izzo, Luca +39 more
Classical novae are thermonuclear explosions that occur on the surfaces of white dwarf stars in interacting binary systems1. It has long been thought that the luminosity of classical novae is powered by continued nuclear burning on the surface of the white dwarf after the initial runaway2. However, recent observations of giga…
A heatwave of accretion energy traced by masers in the G358-MM1 high-mass protostar
Eislöffel, J.; Stecklum, B.; Kim, Kee-Tae +20 more
High-mass stars are thought to accumulate much of their mass via short, infrequent bursts of disk-aided accretion1,2. Such accretion events are rare and difficult to observe directly but are known to drive enhanced maser emission3-6. In this Letter we report high-resolution, multi-epoch methanol maser observations toward G358…
Evidence for a vast prograde stellar stream in the solar vicinity
Hopkins, Philip F.; Sanderson, Robyn; Wetzel, Andrew +6 more
Massive dwarf galaxies that merge with the Milky Way on prograde orbits can be dragged into the disk plane before being completely disrupted. Such mergers can contribute to an accreted stellar disk and a dark matter disk. Here we present Nyx, a vast stellar stream in the vicinity of the Sun, which provides the first indication that such an event o…
The carbon monoxide-rich interstellar comet 2I/Borisov
Feldman, P. D.; Bodewits, D.; Noonan, J. W. +7 more
Interstellar comets offer direct samples of volatiles from distant protoplanetary disks. 2I/Borisov is the first notably active interstellar comet discovered in our Solar System1. Comets are condensed samples of the gas, ice and dust that were in a star's protoplanetary disk during the formation of its planets, and inform our understand…
Ubiquitous velocity fluctuations throughout the molecular interstellar medium
Henning, Thomas; Henshaw, Jonathan D.; Kruijssen, J. M. Diederik +23 more
The density structure of the interstellar medium determines where stars form and release energy, momentum and heavy elements, driving galaxy evolution1-4. Density variations are seeded and amplified by gas motion, but the exact nature of this motion is unknown across spatial scales and galactic environments5. Although dense s…
A measurement of water vapour amid a largely quiescent environment on Europa
Villanueva, G. L.; Roth, L.; Paganini, L. +4 more
Previous investigations proved the existence of local density enhancements in Europa's atmosphere, advancing the idea of a possible origination from water plumes. These measurement strategies, however, were sensitive either to total absorption or atomic emissions, which limited the ability to assess the water content. Here we present direct search…