A relatively dim star is expected to become one of the brightest in the sky later this year

As it has done twice before at intervals of 80 years, a relatively dim star is expected to go nova later this year, becoming for a short time one of the brightest stars in the sky.

Located in the Northern Crown constellation, T Coronae Borealis (T CrB) is a pretty average looking star, most of the time. With a brightness of about magnitude +10, it’s right on the limits of what you could see with a pair of binoculars, and even if you do go looking there’s not much to see.

At least, that’s the case for about 79 out of 80 years. But on that 80th year, the star suddenly brightens drastically up to around magnitude +2, which puts it on par with the north star Polaris. That makes it one of the brightest stars in the night sky, easily visible with the naked eye even when washed out by city lights. This once-in-a-lifetime outburst last occurred in 1946, and before that 1866.

And lucky for stargazers, T CrB seems to be about two years ahead of schedule, with astronomers predicting it will flare up again between March and September 2024. It’ll appear as a bright ‘new’ star for a few days with the naked eye, and a little over a week with binoculars, before it settles down again for another few decades. Astronomers noticed last year that T CrB had started to dim, which data from 1945 showed preceded the last brightening event.

The star is actually a binary, made up of a white dwarf and a red giant. The white dwarf is pulling material from the red giant, and as that new material piles up, it eventually gathers enough mass to go critical and produce a thermonuclear explosion. The result is a nova, a smaller version of a supernova that unlike supernovae occurs repeatedly.

Update on rocket startup Stoke Space’s effort to make completely reusable rocket

Link here. This Nasaspaceflight.com article provides an excellent update on the status of the development of Stoke’s Nova rocket, which will have a radical new engine design in its upper stage, using a ring of small nozzles rather than one single central one. That design will allow the upper stage to return to Earth for reuse, something that no other rocket now in use at present can do.

Stoke Space recently carried out the first test of the full-size 30-thruster version of the innovative engine that the company is producing for its in-development second stage. This will be an integral part of its future Nova rocket, which aims to be a fully reusable medium lifter.

The engine test took place on Feb. 26 and follows the engine’s first test flight on its prototype vehicle, Hopper 2, in September 2023. Although fitted with only 15 chambers for that flight, Hopper 2 flew for 15 seconds, achieved a maximum altitude of 30 feet, traversed to a landing site, and touched down softly.

The article includes a lot of interesting technical details about this upper stage and what engineers are learning about this radical engine design. Worth reading. At present Stoke is the only company other than SpaceX attempting to make its upper stage fully reusable. If successful it will jump ahead of everyone else.

No launch schedule however for its new rocket was revealed in this report, so it might be awhile, if ever, before any of this bears fruit.

Stoke Space raises $100 million in private investment capital

The rocket startup Stoke Space, which is developing a radically new engine concept for its rockets, has now successfully raised $100 million in private investment capital.

This investment more than doubles the company’s total funding, which now sits at $175 million. The company also announced the official name of its first rocket: Nova.

The funding round was led by Industrious Ventures with participation from the University of Michigan, Sparta Group, Long Journey, and others. Existing investors Breakthrough Energy, YCombinator, Point72 Ventures, NFX, MaC Ventures, Toyota Ventures, and In-Q-Tel also participated. This latest funding round is evidence of strong demand for Stoke’s services, its growing success, and the confidence of investors in its future. As part of this round of fundraising Steve Angel, Chairman of the Board, Linde plc, will join Stoke’s Board of Directors. Angel is also the former CEO of Linde and a member of the Board of Directors of GE.

The company says it will use this money to develop the rocket’s first stage engines, which will follow the same ring nozzle design of its upper stage, a prototype of which it successfully test flew on a short hop last month. Under that design, the engine doesn’t have one central nozzle, but instead the thrust is funnelled out of a ring of tiny nozzles that circle the stage’s outer perimeter. The company believes this design will allow it to return its upper stage safely from orbit for re-use.

New data makes past nova too bright, but not bright enough to be supernova

The uncertainty of science: Astronomers, using new data from the Gemini North ground-based telescope, have found that a star that brightened in 1670 and was labeled a nova is much farther away than previously thought, which means that 1670 eruption was far too powerful for a nova, but not powerful enough to make it a supernova.

By measuring both the speed of the nebula’s expansion and how much the outermost wisps had moved during the last ten years, and accounting for the tilt of the nebula on the night sky, which had been estimated earlier by others, the team determined that CK Vulpeculae lies approximately 10,000 light-years distant from the Sun — about five times as far away as previously thought. That implies that the 1670 explosion was far brighter, releasing roughly 25 times more energy than previously estimated [4]. This much larger estimate of the amount of energy released means that whatever event caused the sudden appearance of CK Vulpeculae in 1670 was far more violent than a simple nova.

“In terms of energy released, our finding places CK Vulpeculae roughly midway between a nova and a supernova,” commented Evans. “[T]he cause — or causes — of the outbursts of this intermediate class of objects remain unknown. I think we all know what CK Vulpeculae isn’t, but no one knows what it is.”

Recent research has also suggested that the cause of the eruption was not from the interaction of a binary system with one normal star and a white dwarf, as believed for decades, but possibly a binary system with a brown dwarf, or a red giant star, or two normal stars. All are remain possible, none however have been confirmed.

Astronomers predict binary stellar merger in 2022

Astronomers are predicting that a two binary stars that orbit so close together that they share an atmosphere will merge and explode as a bright red nova in approximately five years.

According to the actual paper [pdf], they also predict that this will be a naked eye event, visible in the northern hemisphere.

Note that a red nova is not a supernova. These are different types of explosions, with the supernova many times more powerful and rare. Nonetheless, the event itself will spectacular, should the prediction be correct.

A star that went nova last week is now visible to the naked eye.

A star that went nova last week is now visible to the naked eye.

“Nova Delphini 2013 is among the 30 brightest novae ever recorded,” says S&T editor in chief Robert Naeye. “It’s a wonderful target for backyard observers, given that it’s visible to the naked eye and relatively easy to find. But it’s also attracting the intense interest of scientists, who are using a wide assortment of telescopes and astronomical satellites to better understand these enigmatic explosions.”

Though related scientifically to certain kinds of supernovae, this is not a supernova. Nonetheless, it is rare for these events to be bright enough to be visible to the naked eye. Go outside tonight and take a look!