Exotic binary stars

Cataclysmic variable stars (CVs) are white dwarf stars that are accreting from an orbiting, low mass binary companion star. The accretion is facilitated by the proximity of the stars; typical orbital periods range from about ...

Rings and gaps in a developing planetary system

The discovery of an exoplanet has most often resulted from the monitoring of a star's flicker (the transiting method) or its wobble (the radial velocity method). Discovery by direct imaging is rare because it is so difficult ...

Ionized molecules trace galactic outflows

There is a process at work in most galaxies that affects both the central black hole mass as well as the galaxy's global velocity structure and luminosity. Astronomers suspect that feedback of some kind is involved, and one ...

Measuring white dwarf masses with gravitational lensing

Measuring the mass of a celestial body is one of the most challenging tasks in observational astronomy. The most successful method uses binary systems because the orbital parameters of the system depend on the two masses. ...

Imaging a galaxy's molecular outflow

A merger between galaxies can trigger can intense radiation from bursts star formation and from the accretion of gas onto the two supermassive black holes at their centers. Astronomers have observed a strong statistical correlation ...

A stellar system with three super-Earths

Over 3500 extra-solar planets have been confirmed to date. Most of them were discovered using the transit method, and astronomers can combine the transit light curves with velocity wobble observations to determine the planet's ...

The structure of an active galactic nucleus

The nuclei of most galaxies host supermassive black holes containing millions to billions of solar-masses of material. The immediate environments of these black holes typically include a tori of dust and gas and, as material ...

A new bound on axions

An axion is a hypothetical elementary particle whose existence was postulated in order to explain why certain subatomic reactions appear to violate basic symmetry constraints, in particular symmetry in time. The 1980 Nobel ...

Gravitational waves measure the universe

The direct detection of gravitational waves from at least five sources during the past two years offers spectacular confirmation of Einstein's model of gravity and space-time. Modeling of these events has also provided information ...

the geometry of nuclear black hole accretion disks

Supermassive black holes with millions or even billions of solar-masses of material are found at the nuclei of most galaxies, including our Milky Way. A torus of dust and gas orbits around the black hole (at least according ...

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