Hubble clocks explode into oblivion

When a star releases as much energy in a matter of days as our Sun does in several billion years, you know it won’t stay visible for long.

Like intergalactic paparazzi, POTis hubble space telescope captured the fast-fading celebrity status of a supernova, the self-detonation of a star. The Hubble snapshots have been assembled into a tell-tale film of the titanic stellar explosion that disappears into oblivion in the spiral galaxy NGC 2525, located 70 million light-years away.

This video zooms in on the barred spiral galaxy NGC 2525, located 70 million light-years away in the southern constellation Puppis. About half the diameter of our Milky Way, was discovered by the British astronomer William Herschel in 1791 as a “spiral nebula”. The sharpness of the image increases as we get closer to the Hubble view. As we zoom in on an outer spiral arm, a Hubble time-lapse video is inserted showing the dim light from supernova 2018gv. Hubble did not record the initial explosion in January 2018, but for almost a year it took consecutive photos, from 2018 to 2019, that have been assembled in a time-lapse sequence. At its peak, the exploding star was as bright as 5 billion suns. Credit: NASA, ESA, J. DePasquale (STScI), M. Kornmesser and M. Zamani (ESA / Hubble), A. Riess (STScI / JHU) and the SH0ES team, and Digital Sky Survey

Hubble began observing SN 2018gv in February 2018, after the supernova was first detected by amateur astronomer Koichi Itagaki a few weeks earlier, in mid-January. Hubble astronomers were using the supernova as part of a program to accurately measure the expansion rate of the universe, a key value in understanding the physical foundations of the cosmos. The supernova serves as a landmark to measure the distances of galaxies, a fundamental value necessary to measure the expansion of space.

In the time-lapse sequence, which spans nearly a year, the supernova first appears as a blazing star located at the outer edge of the galaxy. It initially outshines the brightest stars in the galaxy before disappearing from view.

“No fireworks display on the ground can rival this supernova, captured in its fading glory by the Hubble space telescope,” said Nobel laureate Adam Riess of the Space Telescope Science Institute (STScI) and Johns Hopkins University in Baltimore, leader of the Supernova and Supernovae H search team z₀ for the Equation of State Team (SH0ES) to measure the expansion rate of the universe.

The type of supernova seen in this sequence originated from a burned-out star, a white dwarf located in a nearby binary system, which is accumulating material from its companion star. When the white dwarf reaches a critical mass, its core heats up enough to ignite nuclear fusion, turning it into a giant atomic bomb. This process of thermonuclear escape tears the dwarf apart. The opulence is short-lived as the fireball fades.

Because all supernovae of this type reach the same brightness, they are known as “standard candles”, which act like cosmic tape measures. By knowing the actual brightness of the supernova and observing its brightness in the sky, astronomers can calculate the distances of their host galaxies. This allows astronomers to measure the expansion rate of the universe. Over the past 30 years, Hubble has helped dramatically improve the accuracy of the expansion rate of the universe.