Search Publications
Swings between rotation and accretion power in a binary millisecond pulsar
Wieringa, M. H.; Campana, S.; Stella, L. +20 more
It is thought that neutron stars in low-mass binary systems can accrete matter and angular momentum from the companion star and be spun-up to millisecond rotational periods. During the accretion stage, the system is called a low-mass X-ray binary, and bright X-ray emission is observed. When the rate of mass transfer decreases in the later evolutio…
Dusty starburst galaxies in the early Universe as revealed by gravitational lensing
Sharon, K.; Gladders, M. D.; Menten, K. M. +67 more
In the past decade, our understanding of galaxy evolution has been revolutionized by the discovery that luminous, dusty starburst galaxies were 1,000 times more abundant in the early Universe than at present. It has, however, been difficult to measure the complete redshift distribution of these objects, especially at the highest redshifts (z > …
An old disk still capable of forming a planetary system
Zhang, Ke; Gorti, Uma; Henning, Thomas +11 more
From the masses of the planets orbiting the Sun, and the abundance of elements relative to hydrogen, it is estimated that when the Solar System formed, the circumstellar disk must have had a minimum mass of around 0.01 solar masses within about 100 astronomical units of the star. (One astronomical unit is the Earth-Sun distance.) The main constitu…
Suppression of star formation in the galaxy NGC 253 by a starburst-driven molecular wind
Ott, Jürgen; Warren, Steven R.; Bolatto, Alberto D. +9 more
The under-abundance of very massive galaxies in the Universe is frequently attributed to the effect of galactic winds. Although ionized galactic winds are readily observable, most of the expelled mass (that is, the total mass flowing out from the nuclear region) is likely to be in atomic and molecular phases that are cooler than the ionized phases…
A rapidly spinning supermassive black hole at the centre of NGC 1365
Harrison, F. A.; Zhang, W. W.; Nardini, E. +9 more
Broad X-ray emission lines from neutral and partially ionized iron observed in active galaxies have been interpreted as fluorescence produced by the reflection of hard X-rays off the inner edge of an accretion disk. In this model, line broadening and distortion result from rapid rotation and relativistic effects near the black hole, the line shape…
A galaxy rapidly forming stars 700 million years after the Big Bang at redshift 7.51
Dickinson, M.; Ferguson, H. C.; Finkelstein, S. L. +18 more
Of several dozen galaxies observed spectroscopically that are candidates for having a redshift (z) in excess of seven, only five have had their redshifts confirmed via Lyman α emission, at z = 7.008, 7.045, 7.109, 7.213 and 7.215 (refs 1, 2, 3, 4). The small fraction of confirmed galaxies may indicate that the neutral fraction in the intergalactic…
A variable absorption feature in the X-ray spectrum of a magnetar
Mereghetti, Sandro; Esposito, Paolo; Turolla, Roberto +9 more
Soft-γ-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are slowly rotating, isolated neutron stars that sporadically undergo episodes of long-term flux enhancement (outbursts) generally accompanied by the emission of short bursts of hard X-rays. This behaviour can be understood in the magnetar model, according to which these sources are ma…
An observed correlation between plume activity and tidal stresses on Enceladus
Sotin, C.; Brown, R. H.; Baines, K. H. +6 more
Saturn's moon Enceladus emits a plume of water vapour and micrometre-sized ice particles from a series of warm fissures located near its south pole. This geological activity could be powered or controlled by variations in the tidal stresses experienced by Enceladus as it moves around its slightly eccentric orbit. The specific mechanisms by which t…
The rapid assembly of an elliptical galaxy of 400 billion solar masses at a redshift of 2.3
Altieri, B.; Aussel, H.; Pérez-Fournon, I. +41 more
Stellar archaeology shows that massive elliptical galaxies formed rapidly about ten billion years ago with star-formation rates of above several hundred solar masses per year. Their progenitors are probably the submillimetre bright galaxies at redshifts z greater than 2. Although the mean molecular gas mass (5 × 1010 solar masses) of th…
An age difference of two billion years between a metal-rich and a metal-poor globular cluster
Anderson, J.; Stetson, P. B.; Rich, R. M. +9 more
Globular clusters trace the formation history of the spheroidal components of our Galaxy and other galaxies, which represent the bulk of star formation over the history of the Universe. The clusters exhibit a range of metallicities (abundances of elements heavier than helium), with metal-poor clusters dominating the stellar halo of the Galaxy, and…