(ORDO NEWS) — Some stars burn brightly, but not for long. These fleeting novae dot the sky, and every few years one of them flares up, visible to the naked eye… but it was the recent brief appearance of just such a “nova” that gave astronomers the opportunity to explore the mysteries of the universe.
Japanese amateur astronomer Seiji Ueda was the first to sound the alarm around the world.
Hobbyists are always on the hunt for new galactic stars as this is one of the key areas where they can contribute to real science. The American Association of Variable Star Observers (AAVSO) has been a key information center for nova and light curve observations since 1911.
The discovery was made on the night of June 21, 2021. The “star” was a galactic nova in the northern constellation of Hercules Heracles, right on its border with Sagittarius and Aquila, not far from the galactic plane. Soon the new one had a name: V1674 Herculis (V1674 Her or Nova Herculis 2021).
As a rule, new ones reach their maximum brightness for several days or weeks before disappearing from view. Recent memorable novae include Nova Delphina 2013 and Nova Centauri 2013. Such “novae” can give familiar constellations a decidedly odd look.
But the New Hercules of 2021 has a surprise in store. The nova topped out, flirting with naked-eye brightness at magnitude +6 before disappearing from view in just one day. Twenty-four hours after the eruption, the new star dimmed a hundredfold. This exceeds the 3-day record set by Nova V838 Hercules (also in Hercules) in 1991.
Novae are formed when a dense white dwarf sucks material from a main-sequence companion. Material is compressed on the surface of the white dwarf, which can then ignite under the pressure of nuclear fusion in a powerful flare.
New stars can flare multiple times, which is known as a repeating nova. New stars can also form and, over time, turn into supernovae that can be observed throughout the universe.
“The exploding white dwarf is massive and growing in mass in the direction of the Supernova 1A explosion,” astronomer Sumner Starrfield of the University of Minnesota told Universe Today. “It ejected far less mass than needed to accrete as a white dwarf and initiate an explosion.”
New stars are vital as they blast heavier elements back into space, and Type IA supernovae are used as standard candles. for measuring extragalactic distances.
Even stranger, Nova Hercules 2021 is exhibiting a 501-second “wobble”. This oscillation is visible in the visible and X-ray spectrum and persists from bright to faint magnitudes.
This, along with variations in the energetic wind expelled by the nova into the surrounding interstellar medium, appears to be due to the orbital period of the white dwarf compared to its companion.
New Hercules 2021 is estimated at 4750 parsecs. (15,500 light years).
“We continue to monitor this system as it has not returned to rest,” says Starrfield. “We know that it has a wobble of about 500 seconds presumably the rotation period of a white dwarf and a rotation period of about 3.6 hours, which is likely the rotation period of a binary system.
We need more spectroscopy and photometry to better understand these periods and the consequences of those periods.”
Observations of Nova Hercules 2021 were made with the Large Binocular Telescope on Mount Graham in Arizona and its multi-object double and PEPSI spectrograph.
The study of new stars may also contribute to solving the “lithium cosmological problem” and the source of the abundance of lithium in metal-rich stars such as our Sun.
“Both theory and observations now imply that classical novae are producers in the galaxy,” says Starrfield. “The long-standing problem has been why stars like the Sun contain more lithium than was formed in the Big Bang.”
The new Hercules is an exciting discovery in our universe’s strange stellar menagerie. .
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