Astronomers used a spectrometer to separate the light of the white dwarf into different wavelengths, which revealed the chemical signature of hydrogen on one side and helium on the other. The three observatories showed that Janus was rotating on its axis every 15 minutes - and showcased the star’s double-faced nature and composition. Caiazzo used the instrument, which scans the skies each night, for a recent survey of highly magnetized white dwarfs when an object appeared that rapidly changed in brightness.įollow-up observations were conducted by Caiazzo and her team using Palomar’s CHIMERA instrument, the HiPERCAM located on the Gran Telescopio Canarias in Spain’s Canary Islands and W.M. The unusual stellar remnant was first detected by the Zwicky Transient Facility, located at Caltech’s Palomar Observatory. As the stars cool over time, they tend to have helium atmospheres.īut typical white dwarfs don’t have one side of the star devoted to one element, and the other dominated by another. Given the blazing temperatures of white dwarfs, the hottest ones have hydrogen atmospheres. The strong gravitational influence at play during the death of a star means that the remaining heavy elements move toward the center while lighter elements like hydrogen or helium rise to the upper layer. White dwarfs are incredibly dense, compressing a mass comparable to our sun’s into something equivalent to an Earth-size planet. There is a ‘gravity hole’ in the Indian Ocean, and scientists now think they know why The blue shades represent low values and the reds/yellows represent high values. The colours in the image represent deviations in height (-100 m to +100 m) from an ideal geoid. At the time, it was the most accurate ever produced. In 2011, GOCE delivered a model of the 'geoid' pictured here.
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