The Naked-Eye Sky Will (Briefly) Host a New Star

RockDoctor (Slashdot reader #15,477) wants to tell you about a 'new' star that will be visible to the naked eye — without a telescope — sometime before September:
By 'star', I do not mean 'comet', 'meteorite' or 'firefly', but genuine [star] photons arriving here after about 3000 years in flight, causing your eyes to see a bright point on the nighttime sky. When it happens, the star will go from needing-a- telescope-or-good-binoculars-to-see, to being the 50th (or even 30th) brightest star in the sky.
For a week or so. Of course, it could just go full-on supernova, and be visible in daylight for a few weeks, and dominate the night sky for months. But that's unlikely.

Named 'T Corona Borealis' (because it's the 20th variable star studied in the constellation 'Corona Borealis') it's now visible all night, all year, for about 60% of the world's population (although normally you need binoculars to see it).

But RockDoctor writes that in 2016, 'T CrB' (as it is known) has started showing 'a similar pattern of changes' to what happened in the late 1930s when it became one of only 10 'recurring nova' known to science:

In 2023, the pattern continued and the match of details got better. The star is expected to undergo another 'eruption' — becoming one of the brightest few stars in the sky, within the next couple of months. Maybe the next couple of weeks. Maybe the next couple of hours....
Last week, astrophysicist Dr Becky Smethurst posted on the expected event in her monthly 'Night Sky News' video blog. If you prefer your information in text not video, the AAVSO (variable star observers) posted a news alert for it's observers a while ago. They also hosted a seminar on the star, and why it's eruption is expected Real Soon Now, which is also on YouTube. A small selection of recent papers on the subject are posted here, which also includes information on how to get the most up-to-date brightness readings (unless you're a HST / JWST / Palomar / Hawai`i / Chile telescope operator). Yes, the 'big guns' of astronomy have prepared their 'TOO — Target Of Opportunity' plans, and will be dropping normal observations really quickly when the news breaks and slewing TOO the target.

You won't need your eclipse glasses for this. (Dr Becky's video covers where you can send them for re-use.) But you might want to photograph the appropriate part of the sky so you'll notice when the bomb goes off. Bomb? Did I say that the best model for what is happening is a thermonuclear explosion like a H-bomb the size of the Earth detonating? Well, that's the best analogue.

This CNN article includes a nice animation from NASA illustrating the multi-star interaction that's causing the event:

The stars in the orbiting pair are close enough to each other that they interact violently. The red giant becomes increasingly unstable over time as it heats up, casting off its outer layers that land as matter on the white dwarf star. The exchange of matter causes the atmosphere of the white dwarf to gradually heat until it experiences a 'runaway thermonuclear reaction,' resulting in a nova [according to NASA]...

The NASAUniverse account on X, formerly known as Twitter, will provide updates about the outburst and its appearance.


The BBC reiterates the key data points — that 'The rare cosmic event is expected to take place sometime before September 2024. When it occurs it will likely be visible to the naked eye. No expensive telescope will be needed to witness this cosmic performance, says NASA.'

Read more of this story at Slashdot.