Astronomers have realized an nearly unfathomable quantity about stars in latest a long time, however the heavens nonetheless handle to shock us every so often. A crew of scientists utilizing the European Southern Observatory’s Very Giant Telescope have found a very new kind of stellar explosion, which has been labeled a “micronova.” Because the identify implies, a micronova just isn’t as violent as a nova, however we’re nonetheless speaking a couple of nuclear explosion that lasts for hours.
The novas scientists had been beforehand aware of can final weeks or months. They had been first recognized as an astronomical occasion a whole bunch of years in the past, once they appeared within the sky as “new” stars. In actuality, these occasions consequence from white dwarfs interacting with different kinds of stars. A white dwarf is the collapsed core of a star that has expended its nuclear gas however doesn’t have sufficient mass to grow to be a neutron star or a black gap. These objects are nonetheless extraordinarily dense, composed of so-called “electron-degenerate matter.”
Novas happen when a white dwarf in a binary system pulls matter like hydrogen away from its companion star. The floor of a white dwarf continues to be extraordinarily sizzling, inflicting the hydrogen to fuse into helium, producing a thermonuclear explosion so shiny that we are able to see it from many mild years away.
The worldwide crew grew to become conscious of a brand new stellar occasion when analyzing knowledge from NASA’s Transiting Exoplanet Survey Satellite tv for pc (TESS), which tracks the luminance of stars with a view to spot potential exoplanets. It seems to be for small, repeated dips brought on by a transiting exoplanet, however the crew famous a number of shiny flashes that didn’t match recognized astronomical phenomena. The flashes gave the impression to be coming from white dwarfs, however they had been too short-lived and localized to be novas. Thus, micronovas.
A brand new paper lays out a mechanism that explains the micronovas. As a substitute of matter igniting in a fusion fireball everywhere in the star, it’s funneled towards the polar areas by the white dwarf’s magnetic subject. A very robust magnetic subject may additionally confine the hydrogen to these areas, triggering localized thermonuclear explosions. See above for an animation of this mannequin.
To substantiate this speculation, astronomers are going to want to establish extra micronovas. The crew suspect these occasions may very well be plentiful all through the universe, however their shorter length and decrease brightness will make them more durable to detect than a standard nova.