Search Publications
The optical afterglow of the short gamma-ray burst associated with GW170817
Im, M.; Pian, E.; Palazzi, E. +33 more
The binary neutron star merger GW170817 was the first multi-messenger event observed in both gravitational and electromagnetic waves1,2. The electromagnetic signal began approximately two seconds post-merger with a weak, short burst of gamma rays3, which was followed over the next hours and days by the ultraviolet, optical an…
Atmospheric reconnaissance of the habitable-zone Earth-sized planets orbiting TRAPPIST-1
Owen, James E.; Triaud, Amaury H. M. J.; Wakeford, Hannah R. +14 more
Seven temperate Earth-sized exoplanets readily amenable for atmospheric studies transit the nearby ultracool dwarf star TRAPPIST-1 (refs 1,2). Their atmospheric regime is unknown and could range from extended primordial hydrogen-dominated to depleted atmospheres3-6. Hydrogen in particular is a powerful greenhouse gas that may…
Evidence of a plume on Europa from Galileo magnetic and plasma wave signatures
Khurana, Krishan K.; Kivelson, Margaret G.; Jia, Xianzhe +1 more
The icy surface of Jupiter's moon, Europa, is thought to lie on top of a global ocean1-4. Signatures in some Hubble Space Telescope images have been associated with putative water plumes rising above Europa's surface5,6, providing support for the ocean theory. However, all telescopic detections reported were made at the limit…
Extreme magnification of an individual star at redshift 1.5 by a galaxy-cluster lens
Pérez-González, Pablo G.; Weiner, Benjamin J.; Richard, Johan +42 more
Galaxy-cluster gravitational lenses can magnify background galaxies by a total factor of up to 50. Here we report an image of an individual star at redshift z = 1.49 (dubbed MACS J1149 Lensed Star 1) magnified by more than ×2,000. A separate image, detected briefly 0.26″ from Lensed Star 1, is probably a counterimage of the first star demagnified …
A luminous X-ray outburst from an intermediate-mass black hole in an off-centre star cluster
Romanowsky, Aaron J.; Brodie, Jean P.; Remillard, Ronald A. +13 more
A unique signature for the presence of massive black holes in very dense stellar regions is occasional giant-amplitude outbursts of multi-wavelength radiation from tidal disruption and subsequent accretion of stars that make a close approach to the black holes1. Previous strong tidal disruption event (TDE) candidates were all associated…
The nature of giant clumps in distant galaxies probed by the anatomy of the cosmic snake
Pérez-González, Pablo G.; Richard, Johan; Schaerer, Daniel +4 more
Giant stellar clumps are ubiquitous in high-redshift galaxies1,2. They are thought to play an important role in the build-up of galactic bulges3 and as diagnostics of star formation feedback in galactic discs4. Hubble Space Telescope (HST) blank field imaging surveys have estimated that these clumps have masses of …
The unexpectedly large dust and gas content of quiescent galaxies at z > 1.4
Finoguenov, A.; Daddi, E.; Béthermin, M. +13 more
Early-type galaxies (ETGs) contain most of the stars present in the local Universe and, above a stellar mass content of 5 × 1010 solar masses, vastly outnumber spiral galaxies such as the Milky Way. These massive spheroidal galaxies have, in the present day, very little gas or dust in proportion to their mass1, and their stel…
Detection of hydrogen sulfide above the clouds in Uranus's atmosphere
Fletcher, Leigh N.; Bézard, Bruno; Irwin, Patrick G. J. +4 more
Visible-to-near-infrared observations indicate that the cloud top of the main cloud deck on Uranus lies at a pressure level of between 1.2 bar and 3 bar. However, its composition has never been unambiguously identified, although it is widely assumed to be composed primarily of either ammonia or hydrogen sulfide (H2S) ice. Here, we prese…
Supervised machine learning for analysing spectra of exoplanetary atmospheres
Heng, Kevin; Fisher, Chloe; Márquez-Neila, Pablo +1 more
The use of machine learning is becoming ubiquitous in astronomy1-3, but remains rare in the study of the atmospheres of exoplanets. Given the spectrum of an exoplanetary atmosphere, a multi-parameter space is swept through in real time to find the best-fit model4-6. Known as atmospheric retrieval, this technique originates in…
Detection of a westward hotspot offset in the atmosphere of hot gas giant CoRoT-2b
Deming, Drake; Fortney, Jonathan J.; Knutson, Heather A. +9 more
Short-period planets exhibit day-night temperature contrasts of hundreds to thousands of kelvin. They also exhibit eastward hotspot offsets whereby the hottest region on the planet is east of the substellar point1; this has been widely interpreted as advection of heat due to eastward winds2. We present thermal phase observati…