GeminiFocus October 2018 - Page 9

John Blakeslee Science Highlights Fading reflections glimpsed by GMOS-South of Eta Carinae’s Great Eruption evoke supernova-like outflows; GMOS-North takes the measure of dwarfs found forming in the tidal tails of interacting galaxies; and Gemini plays a key role in setting a new record for the most distant known radio galaxy. Fast Outflows in the Echoes of Eta Carinae’s Great Eruption Students of the history of solar astronomy and telecommunications will be familiar with the Carrington Event, named for the English astronomer Richard Carrington who witnessed a brilliant solar flare erupt from a cluster of sunspots one September morning in 1859. The flare was associated with the largest coronal mass ejection on record, which traveled at a speed of about 2,000 kilometers per second (km/s) and reached the Earth less than 18 hours later. Although the explosion on the Sun’s surface lasted only about a minute and involved a negligible fraction of an Earth mass of material, the blast of charged particles impinging on the Earth’s magnetosphere wreaked havoc with telegraph lines across Eu- rope and North America and produced stunning auroral displays visible even in the tropics. Around the same time, stellar astronomers were witnessing the final stages of a far more energetic and sustained eruption by the southern star Eta Carinae (then known as Eta Ar- gus). Formerly a 4th-magnitude object, Eta Car brightened to 1st magnitude in the late 1820s and underwent a series of luminosity spikes during which it occasionally rivaled Canopus, a convenient comparison star located in the same constellation. The star then entered a plateau phase when it stayed above 0th magnitude from 1843 to 1858, before rapidly fading below naked-eye visibility in the 1860s. The extended period from the 1830s through the 1850s is called the Great Eruption. October 2018 GeminiFocus 7