Search Publications
Thin jets underlie the solar wind
Ugarte-Urra, Ignacio; Wang, Yi-Ming
The Solar Orbiter spacecraft was launched in 2020 by the European Space Agency to study how solar activity drives changes in the inner part of the heliosphere, the region that extends from the Sun to the surrounding interstellar medium. The Solar Orbiter is fitted with a suite of in situ and remote-sensing instruments that allow measurement of the…
Polarized x-rays constrain the disk-jet geometry in the black hole x-ray binary Cygnus X-1
Ingram, Adam; Wu, Kinwah; Enoto, Teruaki +111 more
A black hole x-ray binary (XRB) system forms when gas is stripped from a normal star and accretes onto a black hole, which heats the gas sufficiently to emit x-rays. We report a polarimetric observation of the XRB Cygnus X-1 using the Imaging X-ray Polarimetry Explorer. The electric field position angle aligns with the outflowing jet, indicating t…
Black hole spin–orbit misalignment in the x-ray binary MAXI J1820+070
Jonker, Peter G.; Piirola, Vilppu; Tsygankov, Sergey S. +10 more
The observational signatures of black holes in x-ray binary systems depend on their masses, spins, accretion rate, and the misalignment angle between the black hole spin and the orbital angular momentum. We present optical polarimetric observations of the black hole x-ray binary MAXI J1820+070, from which we constrain the position angle of the bin…
Cygnus X-1 contains a 21-solar mass black hole—Implications for massive star winds
Gou, Lijun; Byun, Do-Young; Bahramian, Arash +23 more
The evolution of massive stars is influenced by the mass lost to stellar winds over their lifetimes. These winds limit the masses of the stellar remnants (such as black holes) that the stars ultimately produce. We used radio astrometry to refine the distance to the black hole x-ray binary Cygnus X-1, which we found to be 2.22-0.17+…
A compositional link between rocky exoplanets and their host stars
Bitsch, Bertram; Sousa, Sérgio G.; Martioli, Eder +17 more
Stars and planets both form by accreting material from a surrounding disk. Because they grow from the same material, theory predicts that there should be a relationship between their compositions. In this study, we search for a compositional link between rocky exoplanets and their host stars. We estimate the iron-mass fraction of rocky exoplanets …
A massive stellar bulge in a regularly rotating galaxy 1.2 billion years after the Big Bang
Maiolino, Roberto; Zhang, Zhi-Yu; De Breuck, Carlos +5 more
Cosmological models predict that galaxies forming in the early Universe experience a chaotic phase of gas accretion and star formation, followed by gas ejection due to feedback processes. Galaxy bulges may assemble later via mergers or internal evolution. Here we present submillimeter observations (with spatial resolution of 700 parsecs) of ALESS …
GJ 367b: A dense, ultrashort-period sub-Earth planet transiting a nearby red dwarf star
Hellier, Coel; Latham, David W.; Quinn, Samuel N. +75 more
Ultrashort-period (USP) exoplanets have orbital periods shorter than 1 day. Precise masses and radii of USP exoplanets could provide constraints on their unknown formation and evolution processes. We report the detection and characterization of the USP planet GJ 367b using high-precision photometry and radial velocity observations. GJ 367b orbits …
Lithium pollution of a white dwarf records the accretion of an extrasolar planetesimal
Clemens, J. C.; Dufour, P.; Blouin, S. +4 more
Tidal disruption and subsequent accretion of planetesimals by white dwarfs can reveal the elemental abundances of rocky bodies in exoplanetary systems. Those abundances provide information on the composition of the nebula from which the systems formed, which is analogous to how meteorite abundances inform our understanding of the early Solar Syste…
A transient radio source consistent with a merger-triggered core collapse supernova
Kulkarni, S. R.; Hallinan, G.; Horesh, A. +10 more
A core collapse supernova occurs when exothermic fusion ceases in the core of a massive star, which is typically caused by exhaustion of nuclear fuel. Theory predicts that fusion could be interrupted earlier by merging of the star with a compact binary companion. We report a luminous radio transient, VT J121001+495647, found in the Very Large Arra…
‘Campfires’ may drive heating of solar atmosphere
Clery, Daniel
Researchers are getting closer to solving the mystery of why the Sun's wispy atmosphere is nearly 200 times hotter than its surface. Temperatures ought to decline as one moves out from the Sun's core, but the solar atmosphere, or corona, seethes at more than 1 million degrees Celsius, far hotter than the 5500°C temperature of the surface. Flares h…