Search Publications
Measuring the ionisation fraction in a jet from a massive protostar
Sanna, A.; Purser, S. J. D.; Ray, T. P. +7 more
It is important to determine if massive stars form via disc accretion, like their low-mass counterparts. Theory and observation indicate that protostellar jets are a natural consequence of accretion discs and are likely to be crucial for removing angular momentum during the collapse. However, massive protostars are typically rarer, more distant an…
A peculiar low-luminosity short gamma-ray burst from a double neutron star merger progenitor
Li, Y.; Shao, L.; Zhang, S. +15 more
Double neutron star (DNS) merger events are promising candidates of short gamma-ray burst (sGRB) progenitors as well as high-frequency gravitational wave (GW) emitters. On August 17, 2017, such a coinciding event was detected by both the LIGO-Virgo gravitational wave detector network as GW170817 and Gamma-Ray Monitor on board NASA's Fermi Space Te…
Formation and dynamics of a solar eruptive flux tube
Kusano, Kanya; Inoue, Satoshi; Büchner, Jörg +1 more
Solar eruptions are well-known drivers of extreme space weather, which can greatly disturb the Earth's magnetosphere and ionosphere. The triggering process and initial dynamics of these eruptions are still an area of intense study. Here we perform a magnetohydrodynamic simulation taking into account the observed photospheric magnetic field to reve…
New Martian valley network volume estimate consistent with ancient ocean and warm and wet climate
Howard, Alan D.; Luo, Wei; Cang, Xuezhi
The volume of Martian valley network (VN) cavity and the amount of water needed to create the cavity by erosion are of significant importance for understanding the early Martian climate, the style and rate of hydrologic cycling, and the possibility of an ancient ocean. However, previous attempts at estimating these two quantities were based on sel…
A Solar cycle correlation of coronal element abundances in Sun-as-a-star observations
Warren, Harry P.; Brooks, David H.; Baker, Deborah +1 more
The elemental composition in the coronae of low-activity solar-like stars appears to be related to fundamental stellar properties such as rotation, surface gravity, and spectral type. Here we use full-Sun observations from the Solar Dynamics Observatory, to show that when the Sun is observed as a star, the variation of coronal composition is highl…
Dynamic molecular oxygen production in cometary comae
Yao, Yunxi; Giapis, Konstantinos P.
Abundant molecular oxygen was discovered in the coma of comet 67P/Churyumov-Gerasimenko. Its origin was ascribed to primordial gaseous O2 incorporated into the nucleus during the comet's formation. This thesis was put forward after discounting several O2 production mechanisms in comets, including photolysis and radiolysis of …
The Macronova in GRB 050709 and the GRB-macronova connection
Li, Xiang; Jin, Zhi-Ping; Covino, Stefano +6 more
GRB 050709 was the first short Gamma-ray Burst (sGRB) with an identified optical counterpart. Here we report a reanalysis of the publicly available data of this event and the discovery of a Li-Paczynski macronova/kilonova that dominates the optical/infrared signal at t>2.5 days. Such a signal would arise from 0.05 r-process material launched by…
Observing the release of twist by magnetic reconnection in a solar filament eruption
Zhang, Jun; Bi, Yi; Xue, Zhike +9 more
Magnetic reconnection is a fundamental process of topology change and energy release, taking place in plasmas on the Sun, in space, in astrophysical objects and in the laboratory. However, observational evidence has been relatively rare and typically only partial. Here we present evidence of fast reconnection in a solar filament eruption using hig…
Peak-ring structure and kinematics from a multi-disciplinary study of the Schrödinger impact basin
Kramer, Georgiana Y.; Collins, Gareth S.; Kring, David A. +2 more
The Schrödinger basin on the lunar farside is ~320 km in diameter and the best-preserved peak-ring basin of its size in the Earth-Moon system. Here we present spectral and photogeologic analyses of data from the Moon Mineralogy Mapper instrument on the Chandrayaan-1 spacecraft and the Lunar Reconnaissance Orbiter Camera (LROC) on the LRO spacecraf…
Earth's magnetosphere and outer radiation belt under sub-Alfvénic solar wind
Lugaz, Noé; Farrugia, Charles J.; Schwadron, Nathan A. +3 more
The interaction between Earth's magnetic field and the solar wind results in the formation of a collisionless bow shock 60,000-100,000 km upstream of our planet, as long as the solar wind fast magnetosonic Mach (hereafter Mach) number exceeds unity. Here, we present one of those extremely rare instances, when the solar wind Mach number reached ste…