Search Publications
Radio emission as a stellar activity indicator
Callingham, J. R.; Vedantham, H. K.; Günther, M. N. +1 more
Radio observations of stars trace the plasma conditions and magnetic field properties of stellar magnetospheres and coronae. Depending on the plasma conditions at the emitter site, radio emission in the metre- and decimetre-wave bands is generated via different mechanisms, such as gyrosynchrotron, electron cyclotron maser instability, and plasma r…
The Extreme Low-mass End of the Mass–Metallicity Relation at z ∼ 7
Maseda, Michael V.; Labbé, Ivo; Nanayakkara, Themiya +17 more
The mass–metallicity relation provides crucial insights into the baryon cycle in galaxies and strong constraints on galaxy formation models. We use JWST NIRSpec observations from the UNCOVER program to measure the gas-phase metallicity in a sample of eight galaxies during the epoch of reionization at z = 6–8. Thanks to the strong lensing of the ga…
An abrupt change in the stellar spin-down law at the fully convective boundary
Angus, Ruth; Amard, Louis; See, Victor +2 more
Unlike partially convective stars such as the Sun, fully convective stars do not possess a radiative core. Whether a star needs this core to generate a solar-like magnetic dynamo is still unclear. Recent studies suggest fully and partially convective stars exhibit very similar period-activity relationships, hinting that dynamos generated by stars …
Dissecting the Gaia HR diagram - II. The vertical structure of the star formation history across the solar cylinder
Girardi, Léo; Fouesneau, Morgan; Luger, Rodrigo +11 more
Starting from the Gaia DR3 HR diagram, we derive the star formation history (SFH) as a function of distance from the Galactic plane within a cylinder centred on the Sun with a 200 pc radius and spanning 1.3 kpc above and below the Galaxy's midplane. We quantify both the concentration of the more recent star formation in the Galactic plane, and the…
JWST Reveals Powerful Feedback from Radio Jets in a Massive Galaxy at z = 4.1
Pentericci, Laura; Heckman, Timothy; Bosman, Sarah E. I. +11 more
We report observations of a powerful ionized gas outflow in the z = 4.1 luminous radio galaxy TNJ1338-1942 hosting an obscured quasar using the Near Infrared Spectrograph (NIRSpec) on board JWST. We spatially resolve a large-scale (∼15 kpc) outflow and measure outflow rates. The outflowing gas shows velocities exceeding 900 km s‑1 and b…
Hard X-rays and QPO in Swift J1727.8-1613: the rise and plateau of the 2023 outburst
Sunyaev, R.; Krivonos, R.; Sazonov, S. +5 more
We report on the detection of type-C quasi-periodic oscillations during the initial stages of the outburst of Swift J1727.8-1613 in 2023. Using data of the INTEGRAL observatory along with the data of the Mikhail PavlinskyART-XC telescope on board Spektr-RG and X-ray Telescope (XRT) of the Neil Gehrels Swift observatory the fast growth of the quasi…
A departure from the mass-metallicity relation in merging galaxies due to an infall of metal-poor gas
Pérez-Díaz, Borja; Pérez-Montero, Enrique; Fernández-Ontiveros, Juan A. +2 more
Heavy element accumulation and stellar mass assembly are fundamental processes in the formation and evolution of galaxies. However, the key elements that govern them, such as gas accretion and outflow, are not fully understood. This is especially true for luminous and massive galaxies, which usually suffer strong feedback as massive outflows and l…
Exploring the photometric variability of ultra-cool dwarfs with TESS
Gómez Maqueo Chew, Yilen; Segura, Antígona; Jofré, Emiliano +2 more
We present a photometric characterization of 208 ultra-cool dwarfs (UCDs) with spectral types between M4 and L4, from 20-s and 2-min cadence TESS light curves. We determine rotation periods for 87 objects ($\sim 42~{{\ \rm per\ cent}}$) and identify 778 flare events in 103 UCDs ($\sim 49.5~{{\ \rm per\ cent}}$). For 777 flaring events (correspondi…
Gaia uncovers difference in B and Be star binarity at small scales: evidence for mass transfer causing the Be phenomenon
Oudmaijer, René D.; Vioque, Miguel; Dodd, Jonathan M. +2 more
Be stars make up almost 20 per cent of the B star population, and are rapidly rotating stars surrounded by a disc; however the origin of this rotation remains unclear. Mass transfer within close binaries provides the leading hypothesis, with previous detections of stripped companions to Be stars supporting this. Here, we exploit the exquisite astr…
Composition and thermal properties of Ganymede's surface from JWST/NIRSpec and MIRI observations
Saur, J.; Fry, P. M.; Fletcher, L. N. +21 more
Context. We present the first spectroscopic observations of Ganymede by the James Webb Space Telescope undertaken in August 2022 as part of the proposal "ERS observations of the Jovian system as a demonstration of JWST's capabilities for Solar System science".
Aims: We aimed to investigate the composition and thermal properties of the surface…