Search Publications
The recurrent impact of the Sagittarius dwarf on the star formation history of the Milky Way
Ruiz-Lara, Tomás; Bernard, Edouard J.; Cassisi, Santi +1 more
Satellites orbiting disk galaxies can induce phase space features such as spirality, vertical heating and phase-mixing in their disks. Such features have also been observed in our own Galaxy, but the complexity of the Milky Way disk has only recently been fully mapped by Gaia Data Release 2 (DR2) data. This complex behaviour is mainly ascribed to …
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 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…
Evidence of a dynamically evolving Galactic warp
Bailer-Jones, C. A. L.; Fouesneau, M.; Andrae, R. +5 more
In a cosmological setting, the disk of a galaxy is expected to continuously experience gravitational torques and perturbations from a variety of sources, which can cause the disk to wobble, flare and warp1,2. Specifically, the study of galactic warps and their dynamic nature could reveal key information on the formation history of galax…
An ultrahot Neptune in the Neptune desert
Jackman, James A. G.; Bieryla, Allyson; Latham, David W. +81 more
About 1 out of 200 Sun-like stars has a planet with an orbital period shorter than one day: an ultrashort-period planet1,2. All of the previously known ultrashort-period planets are either hot Jupiters, with sizes above 10 Earth radii (R⊕), or apparently rocky planets smaller than 2 R⊕. Such lack of planets of inte…
Age dating of an early Milky Way merger via asteroseismology of the naked-eye star ν Indi
Smalley, Barry; Chaplin, William J.; Davies, Guy R. +82 more
Over the course of its history, the Milky Way has ingested multiple smaller satellite galaxies1. Although these accreted stellar populations can be forensically identified as kinematically distinct structures within the Galaxy, it is difficult in general to date precisely the age at which any one merger occurred. Recent results have rev…
Carbon star formation as seen through the non-monotonic initial-final mass relation
Ramirez-Ruiz, Enrico; Girardi, Léo; Cheng, Sihao +13 more
The initial-final mass relation (IFMR) links the birth mass of a star to the mass of the compact remnant left at its death. While the relevance of the IFMR across astrophysics is universally acknowledged, not all of its fine details have yet been resolved. A new analysis of a few carbon-oxygen white dwarfs in old open clusters of the Milky Way led…
An ultra-massive white dwarf with a mixed hydrogen-carbon atmosphere as a likely merger remnant
Gänsicke, B. T.; Dhillon, V. S.; Tremblay, P. -E. +11 more
White dwarfs are dense, cooling stellar embers consisting mostly of carbon and oxygen1, or oxygen and neon (with a few per cent carbon) at higher initial stellar masses2. These stellar cores are enveloped by a shell of helium, which in turn, is usually surrounded by a layer of hydrogen, generally prohibiting direct observatio…
Common dynamo scaling in slowly rotating young and evolved stars
Spada, Federico; Lehtinen, Jyri J.; Käpylä, Maarit J. +2 more
One interpretation of the activity and magnetism of late-type stars is that these both intensify with decreasing Rossby number up to a saturation level1-3, suggesting that stellar dynamos depend on both rotation and convective turbulence4. Some studies have claimed, however, that rotation alone suffices to parametrize this sc…