Search Publications
Swope Supernova Survey 2017a (SSS17a), the optical counterpart to a gravitational wave source
Rest, A.; Foley, R. J.; Shappee, B. J. +14 more
On 17 August 2017, the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo interferometer detected gravitational waves (GWs) emanating from a binary neutron star merger, GW170817. Nearly simultaneously, the Fermi and INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory) telescopes detected a gamma-ray transient, GRB 17081…
Illuminating gravitational waves: A concordant picture of photons from a neutron star merger
Fox, O. D.; Cenko, S. B.; Sollerman, J. +78 more
Merging neutron stars offer an excellent laboratory for simultaneously studying strong-field gravity and matter in extreme environments. We establish the physical association of an electromagnetic counterpart (EM170817) with gravitational waves (GW170817) detected from merging neutron stars. By synthesizing a panchromatic data set, we demonstrate …
An accreting pulsar with extreme properties drives an ultraluminous x-ray source in NGC 5907
Wolter, Anna; Esposito, Paolo; Turolla, Roberto +20 more
Ultraluminous x-ray sources (ULXs) in nearby galaxies shine brighter than any x-ray source in our Galaxy. ULXs are usually modeled as stellar-mass black holes (BHs) accreting at very high rates or intermediate-mass BHs. We present observations showing that NGC 5907 ULX is instead an x-ray accreting neutron star (NS) with a spin period evolving fro…
Electromagnetic evidence that SSS17a is the result of a binary neutron star merger
Rest, A.; Foley, R. J.; Boutsia, K. +18 more
Eleven hours after the detection of gravitational wave source GW170817 by the Laser Interferometer Gravitational-Wave Observatory and Virgo Interferometers, an associated optical transient, SSS17a, was identified in the galaxy NGC 4993. Although the gravitational wave data indicate that GW170817 is consistent with the merger of two compact objects…
iPTF16geu: A multiply imaged, gravitationally lensed type Ia supernova
Sollerman, J.; Kulkarni, S. R.; Sullivan, M. +31 more
We report the discovery of a multiply imaged, gravitationally lensed type Ia supernova, iPTF16geu (SN 2016geu), at redshift z = 0.409. This phenomenon was identified because the light from the stellar explosion was magnified more than 50 times by the curvature of space around matter in an intervening galaxy. We used high-spatial-resolution observa…
Xenon isotopes in 67P/Churyumov-Gerasimenko show that comets contributed to Earth's atmosphere
Wurz, P.; Altwegg, K.; Balsiger, H. +27 more
The origin of cometary matter and the potential contribution of comets to inner-planet atmospheres are long-standing problems. During a series of dedicated low-altitude orbits, the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) on the Rosetta spacecraft analyzed the isotopes of xenon in the coma of comet 67P/Churyumov-Gerasimen…
On the generation of solar spicules and Alfvénic waves
De Pontieu, B.; Martínez-Sykora, J.; Hansteen, V. H. +3 more
In the lower solar atmosphere, the chromosphere is permeated by jets known as spicules, in which plasma is propelled at speeds of 50 to 150 kilometers per second into the corona. The origin of the spicules is poorly understood, although they are expected to play a role in heating the million-degree corona and are associated with Alfvénic waves tha…
Relativistic deflection of background starlight measures the mass of a nearby white dwarf star
Brown, Thomas M.; Casertano, Stefano; Anderson, Jay +12 more
Gravitational deflection of starlight around the Sun during the 1919 total solar eclipse provided measurements that confirmed Einstein’s general theory of relativity. We have used the Hubble Space Telescope to measure the analogous process of astrometric microlensing caused by a nearby star, the white dwarf Stein 2051 B. As Stein 2051 B passed clo…
Reconciling solar and stellar magnetic cycles with nonlinear dynamo simulations
Strugarek, A.; Beaudoin, P.; Charbonneau, P. +2 more
The Sun's activity, including sun-spot activity, varies on an 11-year cycle driven by changes in its magnetic field. Other nearby solar-type stars have their own cycles, but the Sun does not seem to match their behavior. Strugarek et al. used magnetohydrodynamic simulations to show that stellar activity periods should depend on the star's Rossby n…
Surface changes on comet 67P/Churyumov-Gerasimenko suggest a more active past
Jorda, L.; Lara, L. M.; Bertaux, J. -L. +53 more
The Rosetta spacecraft spent ~2 years orbiting comet 67P/Churyumov-Gerasimenko, most of it at distances that allowed surface characterization and monitoring at submeter scales. From December 2014 to June 2016, numerous localized changes were observed, which we attribute to cometary-specific weathering, erosion, and transient events driven by expos…