Gravitationally lensed quasars

The path of light is bent by mass, an effect predicted by Einstein's theory of gravity, and when a massive galaxy or cluster lies along our line-of-sight to a more distant galaxy its matter will act as a lens to image the ...

Dust production in evolved exoplanetary systems

Stellar variability has long offered insights into stars' physical properties. The star Mira (Omicron Ceti), for example, was so-named in 1596 by Dutch astronomers who were amazed by its miraculous brightening because of ...

Light echos in the Eta Carinae Nebula

The young star Eta Carinae shines prominently in the skies of the southern hemisphere. Although located relatively far away from Earth (about seven thousand light-years away, as compared with the average distance of naked-eye ...

'Oumuamua one year later

One year ago this week astronomers discovered an unusual object moving through space not too far from the Earth's orbit. In just a few days they realized it could not be a normal asteroid or comet – its path showed that ...

Active galactic nuclei and star formation

Most galaxies host a supermassive black hole (SMBH) at their nucleus. (A supermassive black hole is one whose mass exceeds a million solar-masses.) A key unresolved issue in galaxy formation and evolution is the role these ...

Remarkable flares from the galactic center

Sagittarius A* (Sgr A*), the supermassive black hole at the center of our Milky Way Galaxy, is 100 times closer to us than any other SMBH and therefore a prime candidate for studies of how matter radiates as it accretes onto ...

Four newly discovered Milky Way neighbors

Ultra-faint dwarf galaxies are the smallest, most dark matter dominated, and least chemically enriched stellar systems in the universe, and are important targets for understanding dark matter and galaxy formation. They comprise ...

A new classification scheme for exoplanet sizes

There are about 4433 exoplanets in the latest catalogs. Their radii have generally been measured by knowing the radius of their host star and then closely fitting the lightcurves as the planet transits across the face of ...

Chandra detection of diskless young stars

Stars frequently form in crowded environments. By combining the resources of multi-wavelength missions like Chandra in the X-ray and Spitzer in the infrared, astronomers are able to resolve ambiguities and assemble a much ...

The TESS Input Catalog

The Transiting Exoplanet Survey Satellite (TESS), launched on April 18, has as its core mission goal to discover small transiting exoplanets orbiting nearby bright stars, and to do so it will conduct a nearly all-sky photometric ...

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