helium tagged posts

In a first for white dwarfs, the burnt-out cores of dead stars, astronomers have discovered that at least one member of this cosmic family is two faced. One side of the white dwarf is composed of hydrogen, while the other is made up of helium.

“The surface of the white dwarf completely changes from one side to the other,” says Ilaria Caiazzo, a postdoctoral scholar at Caltech who leads a new study on the findings in the journal Nature. “When I show the observations to people, they are blown away.”

White dwarfs are the scalding remains of stars that were once like our sun. As the stars age, they puff up into red giants; eventually, their outer fluffy material is blown away and their cores contract into dense, fiery-hot white dwarfs...

Helium is the second most abundant element in the universe after hydrogen. But scientists aren’t sure just how much there actually is in the Sun’s atmosphere, where it is hard to measure. Knowing the amount of helium in the solar atmosphere is important to understanding the origin and acceleration of the solar wind—the constant stream of charged particles from the Sun.

In 2009, NASA launched a sounding rocket investigation to measure helium in the extended solar atmosphere—the first time we’ve gathered a full global map...

Data offer new clues about why stars explode. A team of astronomers at The Ohio State University showed that the satellite survey TESS, could be used to monitor a particular type of supernova, giving scientists more clues about what causes white dwarf stars to explode – and about the elements those explosions leave behind.

“We have known for years that these stars explode, but we have terrible ideas of why they explode,” said Patrick Vallely, lead author of the study and an Ohio State astronomy graduate student...

Artist’s impression of the exoplanet HAT-P-11b with its extended helium atmosphere blown away by the star, an orange dwarf star smaller, but more active, than the Sun.
Credit: © Denis Bajram

Although helium is a rare element on Earth, it is ubiquitous in the Universe. It is, after hydrogen, the main component of stars and gaseous giant planets. Despite its abundance, helium was only detected recently in the atmosphere of a gaseous giant by an international team including astronomers from the University of Geneva (UNIGE), Switzerland. The team, this time led by Genevan researchers, has observed in detail and for the first time how this gas escapes from the overheated atmosphere of an exoplanet, literally inflated with helium. The results are published in Science.

Helium is the second...