This Record-Fast Nova Could Be Seen With The Naked Eye For a Day And Then Vanished

Some stars are brilliant yet short-lived. These transient novae dot the sky, with one bursting into visible light every few years... However, it was the recent fleeting apparition of a 'new star' that allowed astronomers to study the mysteries of the Universe.

Seidji Ueda, a Japanese amateur astronomer, was the first to raise the alarm throughout the world.

Amateurs are constantly on the lookout for galactic novae since it is one of the primary sectors in which they may contribute to actual research. Since 1911, the American Association of Variable Star Observers (AAVSO) has served as the primary clearinghouse for nova sightings and light curves.

The finding was made during the night of June 21, 2021. The'star' was a galactic nova in the northern constellation of Hercules the Hero, close near its boundary with Sagitta and Aquila, just off the galactic plane. The nova was given a name soon after: V1674 Herculis (V1674 Her or Nova Herculis 2021).

Novae often achieve a peak brightness for several days or weeks before fading from vision. Recent notable novae include Nova Delphini 2013 and Nova Centauri 2013. Such 'new stars' can give known constellations an unusual appearance.

However, Nova Herculis 2021 has a surprise in store for them. The nova reached maximum brightness, flirting with naked-eye brilliance at magnitude +6, before disappearing from view in just one day. The nova had faded a hundredfold in the twenty-four hours following its outburst. This breaks the three-day record set in 1991 by Nova V838 Herculis (also in Hercules).

Novae are formed when a compact white dwarf star absorbs material from a main sequence companion. The material becomes crushed on the surface of the white dwarf, which can then ignite in a violent flash under the pressure of nuclear fusion.

In what is known as a recurring nova, a nova can explode many times. Novae may also grow and mature into supernovae, which can be viewed across the Universe.

"The white dwarf that exploded is massive and growing in mass toward a Supernova 1A explosion," according to astronomer Sumner Starrfield of the University of Minnesota. "It ejected far less mass than necessary to be accrete by the white dwarf and initiate an explosion."

Novae are important because they return heavier elements to the universe, and Type IA supernovae serve as standard candles for measuring extra-galactic distances.

Even stranger, Nova Herculis 2021 has a 501-second 'wobble.' This oscillation may be seen across the visible and x-ray spectrums and is stable from brilliant to dim magnitudes. This, coupled with changes in the energetic wind released by the nova into the surrounding interstellar medium, appears to be dictated by the white dwarf star's orbital period relative to its partner.

Nova Herculis 2021 is thought to be 4,750 parsecs (15,500 light-years) away.

"We are continuing to observe this system since it has not returned to quiescence," Starrfield explains. "We know that it has a ~500-second oscillation—presumably the white dwarf rotation period—and an about 3.6 hour rotation period that is probably the rotation period of the binary. We need more spectroscopy and photometry to better understand those periods and the implications of those periods."

The Large Binocular Telescope on Mount Graham in Arizona, coupled with its multi-object double and PEPSI spectrograph, was used to observe Nova Herculis 2021.

The study of novae may also help to solve the 'cosmological lithium conundrum,' or the source of lithium abundance in metal-rich stars like our Sun.

"Both theory and observations now imply that classical novae are the lithium producers in the galaxy," Starrfield adds. "A long-standing problem has been why there is more lithium in stars like the Sun than produced by the Big Bang." 

Nova Herculis is a fascinating find to follow in our Universe's bizarre star zoo.

Read the report on Nova Herculis out of the University of Minnesota and Ohio State University in the Research Notes of the American Astronomical Society.

This article was originally published by Universe Today. Read the original article.