A ‘new star’ from a nova outburst is expected soon

New star: Animation of an exploding smaller star orbiting a big orange star in the middle of a glowing disk.
Artist’s conception of red giant star and white dwarf. A stream of material flows from the red giant to the white dwarf, eventually causing a runaway thermonuclear reaction on the white dwarf that will appear as a new star, or nova, in earthly skies. Image via NASA/ Goddard Space Flight Center.
  • A famous, distant variable star called T Coronae Borealis is predicted to become visible to the unaided eye in 2024.
  • It could be a once-in-a-lifetime viewing opportunity to view the star, since it waxes in brightness – becoming visible in our skies as a nova or “new” star – only about every 80 years.
  • This star last erupted in 1946. And astronomers believe it will do so again between February and September 2024. Find its constellation now. Then prepare to be amazed when the “new” star, or nova, pops into view.
  • NASA published this original article on February 27, 2024. Edits by EarthSky.

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    A nova could trigger a new star soon

    T Coronae Borealis, or T CrB, is located 3,000 light-years away from Earth. It is a recurring nova with outbursts about every 80 years. Its last outburst was in 1946, and astronomers believe another will occur between February and September 2024.

    The star system, normally magnitude +10, is far too dim to see with the unaided eye. After the nova occurs, it will jump to around magnitude +2. That is roughly the same brightness to the North Star, Polaris.

    Once its brightness peaks, it should be visible to the unaided eye for several days and just over a week with binoculars before it dims again, possibly for another 80 years.

    Corona Borealis is easy to see, in a dark sky

    As we wait for the nova, become familiar with the constellation Corona Borealis, or the Northern Crown, a small, semicircular arc between Boötes the Herdsman and Hercules the Strongman. This is where the outburst will appear as a new star.

    Corona Borealis is visible in the Northern Hemisphere spring and summer (autumn and winter in the Southern Hemisphere). It’s best viewed in the month of July. You’ll find it between two bright stars and two larger constellations. You’ll need a dark sky to see it.

    Star chart with 3 constellations outlined, Hercules, Corona Borealis and Bootes, and labeled stars.
    Late at night in the spring, and high overhead during summer months, find the bright stars Vega and Arcturus. Then locate the constellations Hercules and Boötes. The semicircle of stars between them is the constellation Corona Borealis. Image via NASA.
    Star chart of Corona Borealis, stars in black on white, with red circle indicating location of star TCrB.
    Star chart of Corona Borealis with red circle indicating location of star T CrB. Image via IAU/ Wikipedia (CC BY-SA 4.0).

    Recurring novae are rare

    As a matter of fact, this recurring nova is only one of five in our galaxy. This happens because T CrB is a binary system with a white dwarf and red giant. The stars are close enough that as the red giant becomes unstable from its increasing temperature and pressure and begins ejecting its outer layers, the white dwarf collects that matter onto its surface. The shallow, dense atmosphere of the white dwarf eventually heats enough to cause a runaway thermonuclear reaction – which produces the nova we see from Earth.

    Bottom line: A recurring nova in Corona Borealis – T CrB – will probably appear as a “new star” and brighten enough to see with the unaided eye sometime in 2024.

    Via NASA

    March 12, 2024

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