Search Publications
Transient Water Vapor at Europa's South Pole
Nimmo, Francis; Saur, Joachim; Roth, Lorenz +4 more
In November and December 2012, the Hubble Space Telescope (HST) imaged Europa's ultraviolet emissions in the search for vapor plume activity. We report statistically significant coincident surpluses of hydrogen Lyman-α and oxygen OI 130.4-nanometer emissions above the southern hemisphere in December 2012. These emissions were persistently found in…
Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy
Madhusudhan, Nikku; Burrows, Adam; Fortney, Jonathan J. +13 more
Exoplanets that orbit close to their host stars are much more highly irradiated than their solar system counterparts. Understanding the thermal structures and appearances of these planets requires investigating how their atmospheres respond to such extreme stellar forcing. We present spectroscopic thermal emission measurements as a function of orb…
A fast and long-lived outflow from the supermassive black hole in NGC 5548
Kaastra, J. S.; Harrison, F. A.; Nandra, K. +31 more
Supermassive black holes in the nuclei of active galaxies expel large amounts of matter through powerful winds of ionized gas. The archetypal active galaxy NGC 5548 has been studied for decades, and high-resolution x-ray and ultraviolet (UV) observations have previously shown a persistent ionized outflow. An observing campaign in 2013 with six spa…
A local clue to the reionization of the universe
Heckman, Timothy M.; Leitherer, Claus; Borthakur, Sanchayeeta +1 more
Identifying the population of galaxies that was responsible for the reionization of the universe is a long-standing quest in astronomy. We present a possible local analog that has an escape fraction of ionizing flux of 21%. Our detection confirms the existence of gaps in the neutral gas enveloping the starburst region. The candidate contains a mas…
Magnetic moment and plasma environment of HD 209458b as determined from Lyα observations
Holmström, Mats; Lammer, Helmut; Kislyakova, Kristina G. +2 more
Transit observations of HD 209458b in the stellar Lyman-α(Lyα) line revealed strong absorption in both blue and red wings of the line interpreted as hydrogen atoms escaping from the planet’s exosphere at high velocities. The following sources for the absorption were suggested: acceleration by the stellar radiation pressure, natural spectral line b…
Super-Eddington Mechanical Power of an Accreting Black Hole in M83
Long, K. S.; Soria, R.; Kuntz, K. D. +5 more
Mass accretion onto black holes releases energy in the form of radiation and outflows. Although the radiative flux cannot substantially exceed the Eddington limit, at which the outgoing radiation pressure impedes the inflow of matter, it remains unclear whether the kinetic energy flux is bounded by this same limit. Here, we present the detection o…