Neutrinos Yield First Experimental Evidence of Catalyzed Fusion Dominant in Many Stars
An international team of about 100 scientists of the Borexino Collaboration, including particle physicist Andrea Pocar at the University of Massachusetts Amherst, report in Nature this week detection of neutrinos from the sun, directly revealing for the first time that the carbon-nitrogen-oxygen (CNO) fusion-cycle is at work in our sun.
The CNO cycle is the dominant energy source powering stars heavier than the sun, but it had so far never been directly detected in any star, Pocar explains.
For much of their life, stars get energy by fusing hydrogen into helium, he adds. In stars like our sun or lighter, this mostly happens through the ‘proton-proton’ chains. However, many stars are heavier and hotter than our sun, and include elements heavier than helium in their composition, a quality known as metallicity. The prediction since the 1930’s is that the CNO-cycle will be dominant in heavy stars.
Neutrinos emitted as part of these processes provide a spectral signature allowing scientists to distinguish those from the ‘proton-proton chain’ from those from the ‘CNO-cycle.’ Pocar points out, “Confirmation of CNO burning in our sun, where it operates at only one percent, reinforces our confidence that we understand how stars work.”
Beyond this, CNO neutrinos can help resolve an important open question in stellar physics, he adds. That is, how the sun’s central metallicity, as can only be determined by the CNO neutrino rate from the core, is related to metallicity elsewhere in a star. Traditional models have run into a difficulty – surface metallicity measures by spectroscopy do not agree with the sub-surface metallicity measurements inferred from a different method, helioseismology observations.
Pocar says neutrinos are really the only direct probe science has for the core of stars, including the sun, but they are exceedingly difficult to measure. As many as 420 billion of them hit every square inch of the earth’s surface per second, yet virtually all pass through without interacting. Scientists can only detect them using very large detectors with exceptionally low background radiation levels.
The Borexino detector lies deep under the Apennine Mountains in central Italy at the INFN’s Laboratori Nazionali del Gran Sasso. It detects neutrinos as flashes of light produced when neutrinos collide with electrons in 300-tons of ultra-pure organic scintillator. Its great depth, size, and purity make Borexino a unique detector for this type of science, alone in its class for low-background radiation, Pocar says. The project was initiated in the early 1990s by a group of physicists led by Gianpaolo Bellini at the University of Milan, Frank Calaprice at Princeton and the late Raju Raghavan at Bell Labs.
Until its latest detections, the Borexino collaboration had successfully measured components of the ‘proton-proton’ solar neutrino fluxes, helped refine neutrino flavor-oscillation parameters, and most impressively, even measured the first step in the cycle: the very low-energy ‘pp’ neutrinos, Pocar recalls.
Its researchers dreamed of expanding the science scope to also look for the CNO neutrinos – in a narrow spectral region with particularly low background – but that prize seemed out of reach. However, research groups at Princeton, Virginia Tech and UMass Amherst believed CNO neutrinos might yet be revealed using the additional purification steps and methods they had developed to realize the exquisite detector stability required.
Over the years and thanks to a sequence of moves to identify and stabilize the backgrounds, the U.S. scientists and the entire collaboration were successful. “Beyond revealing the CNO neutrinos which is the subject of this week’s Nature article, there is now even a potential to help resolve the metallicity problem as well,” Pocar says.
Before the CNO neutrino discovery, the lab had scheduled Borexino to end operations at the close of 2020. But because the data used in the analysis for the Nature paper was frozen, scientists have continued collecting data, as the central purity has continued to improve, making a new result focused on the metallicity a real possibility, Pocar says. Data collection could extend into 2021 since the logistics and permitting required, while underway, are non-trivial and time-consuming. “Every extra day helps,” he remarks.
Pocar has been with the project since his graduate school days at Princeton in the group led by Frank Calaprice, where he worked on the design, construction of the nylon vessel and the commissioning of the fluid handling system. He later worked with his students at UMass Amherst on data analysis and, most recently, on techniques to characterize the backgrounds for the CNO neutrino measurement.
Reference: “Experimental evidence of neutrinos produced in the CNO fusion cycle in the Sun” by The Borexino Collaboration, 25 November 2020, Nature.
This work was supported in the U.S. by the National Science Foundation. Borexino is an international collaboration also funded by the Italian National Institute for Nuclear Physics (INFN), and funding agencies in Germany, Russia and Poland.
Spacewalking astronauts encounter cable trouble while hooking up European lab – Firstpost
The Associated PressJan 28, 2021 11:46:15 IST
Spacewalking astronauts encountered cable trouble Wednesday while attempting to make improvements to the International Space Station’s European lab. Only one of the two lab upgrades was completely successful. NASA’s Mike Hopkins and Victor Glover installed a new antenna on Columbus, one of three high-tech labs at the orbiting outpost. It took a few tries by scientists in Europe to get it turned on properly. No longer needed, the boxy antenna cover was thrown overboard.
“Here we go. Countdown: 3-2-1,” Glover radioed as he heaved it safely away from the space station.
Elsewhere on the lab, Glover could not hook up all the power and data cables on a science research platform that’s been awaiting activation for almost a year. He managed to hook up four of six cables. They checked out well with power flowing, enabling partial use of the platform.
But connectors on two cables would not close all the way, and those had to be capped. Engineers will try to come up with a work-around for a future spacewalk, so the entire platform can house experiments.
SpaceX delivered the platform named Bartolomeo to the space station last spring. The shelf was installed with the station’s robot arm but had to wait until Wednesday’s spacewalk to get hooked up.
Airbus, which built and runs Bartolomeo, is looking to sell space on the platform for private research projects. It’s Europe’s first commercial venture outside the station.
.@Astro_Illini and @AstroVicGlover completed today’s spacewalk at 1:24pm ET after installing a new science antenna then readying the station for future power system upgrades. More… https://t.co/31plsfOck2 pic.twitter.com/g1I3mlwJHE
— International Space Station (@Space_Station) January 27, 2021
Danish astronaut Andreas Morgensen guided the spacewalkers from Mission Control in Houston, where controllers wore masks and were seated apart because of the pandemic. The spacewalk lasted seven hours.
Hopkins and Glover will perform a second spacewalk on Monday to complete battery upgrades to the station’s solar power grid. The latest spacewalk was the third for Hopkins and first for Glover.
They are part of SpaceX’s second astronaut flight that launched in November. Their docked Dragon capsule was visible on NASA TV during the spacewalk.
First Private Crew Will Visit Space Station. The Price Tag: $55 Million Each – KCCU
A crew of private astronauts will pay around $55 million each to spend about eight days at the International Space Station next January in what would be a new step for joint private-public space missions. Axiom Space, a Houston company, says the trip will be led by former NASA astronaut and space station commander Michael López-Alegría.
The proposed Ax-1 mission will use a SpaceX rocket to put three paying customers — American Larry Connor, Canadian Mark Pathy and Israeli Eytan Stibbe – into low-Earth orbit on the space station. All of the trio are wealthy entrepreneurs and investors. The group will be under the command of López-Alegría, who is now an executive at Axiom.
It would be the first time an entirely private mission sends astronauts to the International Space Station. Russia sold the first ride to the station to a private citizen, American businessman Dennis Tito, in 2001.
All of the private astronauts for the upcoming mission are far older than the average NASA astronaut’s age of 34. The space agency does not have age restrictions for astronaut candidates, who generally range from 26 to 46 years old. At 70, Connor is surpassed in age only by John Glenn, who flew on the space shuttle when he was 77.
Under NASA’s rules for private astronaut missions, Axiom must ensure its astronauts meet the space agency’s medical standards. They must also undergo training and certification procedures required for crew members of the International Space Station.
While the paying customers represent a new era of space tourism, they will also perform research as the space station whizzes over the Earth.
Connor will work with the Mayo Clinic and Cleveland Clinic on research projects, Axiom says, while Pathy will collaborate with the Canadian Space Agency and the Montreal Children’s Hospital. Stibbe plans to do experiments for Israeli researchers, working with the Ramon Foundation and Israel’s space agency.
“We sought to put together a crew for this historic mission that had demonstrated a lifelong commitment to improving the lives of the people on Earth, and I’m glad to say we’ve done that with this group,” Axiom Space President and CEO Michael Suffredini said as the company announced the crew.
Similar missions are planned for the future, Suffredini said. Axiom hopes to arrange up to two trips per year — and the company also wants to build its own privately funded space station. Under that plan, its modules would be attached to the space station as soon as 2024. And when the space station is retired, the Axiom modules would break off to continue in orbit on their own.
NASA announced its plans to open the International Space Station to commercial activities in June 2019, saying it wants businesses to use innovation and ingenuity to speed up development of “a thriving commercial economy in low-Earth orbit.”
The space agency has a plan to recoup the steep costs of a private citizen visiting the space station. Its pricing policy lists expenses such as a daily fee of $11,250 per person for “regenerative life support and toilet” and $22,500 per person for crew supplies such as food and air. The price sheet also includes a data plan, priced at $50 per gigabyte.
New app makes figuring out CBRM solid waste collection schedule easier – CBC.ca
Residents of Cape Breton Regional Municipality will now have an easy way to find out what day their solid waste collection falls on.
A new app has been developed that allows residents to enter their address and find the specific day and time their garbage or recycling should be sitting at the end of their driveway.
The CBRM solid waste department had been working for months with an app developer who has made similar apps throughout North America.
Francis Campbell, the solid waste manager for CBRM, said one of the best parts of the app is the database that allows residents to search for what to do with specific waste materials.
“The search tool will educate residents in how to recycle or properly dispose of materials, and it’ll provide the curbside drop-off locations,” said Campbell.
The app sets up reminders through the calendar on a person’s phone so they will be reminded the night before to put out their garbage, recycling or green bin.
It also will be able to quickly let residents know if there is a cancellation or delay on a collection day, as well as post holiday cancellations.
Earlene MacMullin, the deputy mayor of CBRM, said she downloaded the app while getting the presentation on it and already found it useful.
“This is already fantastic and it seems very simplistic. I know deep down it isn’t, but in my first three minutes of using it, I encourage residents to check this out,” said MacMullin.
There will also be a web-based version along with online information regarding waste collection on the CBRM website. This will be coming when the app is fully launched in a few weeks time.
Coun. Cyril MacDonald said he is glad that people who do not have access to a smartphone can still have access to the information.
“We’re not removing a service. You’re still able to get your calendar printed off, so I think this is great,” said MacDonald.
People who may not have access to a computer or a smartphone will still have the option to call the CBRM solid waste hotline to find out the information they need.
Mayor Amanda McDougall said she is happy she has an easy way to never forget what waste is being collected each week.
The app is now available for download through smartphone app stores.
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