Starting in late 2019, Betelgeuse began drawing a lot of attention after it mysteriously started dimming, only to brighten again a few months later. For a variable star like Betelgeuse, periodic dimming and brightening are normal, but the extent of its fluctuation led to all sorts of theories as to what might be causing it. Similar to Tabby’s Star in 2015, astronomers offered up the usual suspects (minus the alien megastructure theory!)
Whereas some thought that the dimming was a prelude to the star becoming a Type II supernova, others suggested that dust clouds, enormous sunspots, or ejected clouds of gas were the culprit. In any case, the “Great Dimming of Betelgeuse” has motivated an international team of astronomers to propose that a “Betelgeuse Scope” be created that cant monitor the star constantly.
The paper that outlines their proposal was recently presented at the International Society for Optics and Photonics (SPIE) Optical Engineering + Applications 2020, a virtual conference that took place from Aug. 24th to Sept. 4th. The paper, “Betelgeuse scope: single-mode-fibers-assisted optical interferometer design for dedicated stellar activity monitoring,” is also available online as part of the Proceedings of SPIE, Vol. 11490.
To recap, Betelgeuse is a red giant star that is about 12 times as massive as our Sun and about 900 times as large. It is located about 700 light-years from Earth in the Orion constellation and is easily spotted by looking for “the Hunter’s” left shoulder. Ordinarily, Betelgeuse is the second-brightest star in Orion (after Rigel) and the tenth-brightest star in the night sky.
Starting in November of 2019, the star began to dim rather suddenly, reaching a historical minimum of just 37% of its average brightness by Feb. 10th, 2020. At this point, Betelgeuse began to brighten until the end of May, at which point the dimming started all over again. For the sake of their article, the team explored different theories as to what caused the dimming.
This included the “Dark Spots hypothesis,” which was based on submillimeter observations taken by the James Clerk Maxwell Telescope and Atacama Pathfinder Experiment. Then there’s the “Dust formation and blocking hypothesis,” which is based on observations conducted with the VLT/SPHERE and the Hubble Space Telescope that suggest that there was a mass ejection from a large convective cell in the photosphere.
According to the authors, all of these possibilities can be investigated by observing the change of Betelgeuse’s angular diameter accurately. In order to do this, telescopes that are capable of conducting high-angular resolution observations (such as optical interferometry) would be needed. In this process, visible light is gathered by two or more telescopes and then combined to obtain higher-resolution images.
As they state in their study, today’s optical telescope facilities are not optimized for the kind of time-evolution monitoring that would be needed. In short, conducting this type of campaign would mean committing observation time from multiple facilities, which is a very expensive prospect. For this reason, the team recommends that a telescope be commissioned for the task.
As Dr. Narsireddy Anugu, a Prize Fellow in Astronomical Instrumentation and Technology at the University of Arizona’s Steward Observatory and the lead author on the study, explained to Universe Today via email:
“High-angular observations are required to image any existing dark spots on the Betelgeuse’s surface and ‘rogue’ convection cells. Collaborators [are also needed], and we have been taken some data with the Very Large Telescope Interferometer at Paranal, Chile (led by M. Montarges) and the CHARA array at the Mount Wilson Observatory. We are currently working on image reconstruction of interferometry data to reveal any dark spots and convection cells on the Betelgeuse surface.”
As they describe it, this “Betelgeuse Scope” will leverage advancements made in the field of optical interferometry and the telecommunication industry. It will consist of an array of 12 x 4 inch Cassegrain-reflector optical telescopes, which will be mounted to the surface of a large radio dish, which will allow for snapshot imaging of convection cells and time-evolution monitoring. As Dr. Anugu described it:
“We have proposed a unique six telescope interferometer concept installing on a radio antenna. This concept aims at a low budget by cutting the costs of pointing and tracking of each individual telescope using the already existing pointing and tracking of the radio antenna. Another benefit of installing the telescope array on a common mount is that we don’t need longer delay lines as in the classical non-common mount based long-baseline interferometers. Where an active compensation of changing the geometrical delay is required between the wavefronts reaching any two telescopes.”
Polarization-maintaining single-mode optical fibers will then carry the coherent beams from the individual optical telescopes to a central beam-combining facility. To compensate for atmospheric turbulence, vibrations, and pointing errors caused by windy conditions, the team recommends a fast steering mirror, a standard tip-tilt correction system, a fast frame rate detector, and a metrology laser system to measure vibrations.
In addition to being able to monitor Betelgeuse and resolve the mystery of its dimming, the Betelgeuse Scope will also allow for significant advancements in the field of astronomy. Said Dr. Anugu:
“Our proposed telescope monitors the Betelgeuse every-night with high-angular resolutions, makes a movie of motion of dynamic convection activity on the surface. This way, we will probe future mysterious dimming events such as 2019-2020 and origins of the dust formation around the Betelgeuse.”
At present, Anugu and his team are building a prototype of their proposed telescope, which will be mounted on the University of Arizona’s 6-meter (~20 foot) radio dish. So far, they have procured one set of light-collecting and fiber injection optics (12 are needed overall) and are integrating them into their lab at the Steward Observatory. They anticipate that the prototype will be finished and ready to be installed by the end of the year.
“Our proposed concept is straight forward, but we are building a pathfinder to test them,” said Dr. Anugu. “Once successful, we reuse the same optics and actuators for the actual 12-m radio antenna, and 12 telescope interferometer array as this concept is scalable and modular.”
Further Reading: arXiv
'The blob': Scientists confirm discovery of a completely new undersea species – National Post
Deep in the dark, murky waters of our oceans, a gelatinous blob, shaped like a dislodged human molar, floats along the seabed.
Thanks to its love for extreme depths and remote oceanic corners, no one had ever seen the blob, or even knew it existed, until a team of scientists accidentally discovered it during a deep-sea dive off the coast of Puerto Rico in 2015, with help from an underwater, remotely-operated vehicle called ‘Deep Discover.’
Five years on, in a paper published this month, scientists with the National Oceanic and Atmospheric Administration (NOAA) have confirmed that the blob is an entirely new species of undersea creature, Duobrachium sparksae – a never-before-seen species of jelly-like ctenophore. It’s also the first time that researchers have discovered a species using high-definition video footage only.
“It’s unique because we were able to describe a new species based entirely on high-definition video,” explained NOAA marine biologist Allen Collins in a release.
“We don’t have the same microscopes as we would in a lab, but the video can give us enough information to understand the morphology in detail, such as the location of their reproductive parts and other aspects.”
Ctenophores, also known as comb jellies, have bulbous, balloon-like bodies, from which protrude two tentacle-like strings, known as cilia. There are between 100 and 150 species of comb jellies, according to the NOAA, and despite their name, they are not at all related to jellyfish. Ctenophores, the group explains, are carnivorous, and many are highly efficient predators that eat small arthropods and many kinds of larvae.
Massive Puerto Rico radio telescope collapses – CBC.ca
A huge, already damaged radio telescope in Puerto Rico that has played a key role in astronomical discoveries for more than half a century completely collapsed on Tuesday.
The telescope’s 816-tonne receiver platform fell onto the reflector dish more than 122 metres below.
The U.S. National Science Foundation had earlier announced that the Arecibo Observatory would be closed. An auxiliary cable snapped in August, causing a 30-metre gash on the 305-metre-wide dish and damaging the receiver platform that hung above it. Then a main cable broke in early November.
The collapse stunned many scientists who had relied on what was until recently the largest radio telescope in the world.
“It sounded like a rumble. I knew exactly what it was,” said Jonathan Friedman, who worked for 26 years as a senior research associate at the observatory and still lives near it. “I was screaming. Personally, I was out of control…. I don’t have words to express it. It’s a very deep, terrible feeling.”
Yeah here is <a href=”https://twitter.com/SciBry?ref_src=twsrc%5Etfw”>@SciBry</a>’s before and after. <a href=”https://t.co/kBXxwh3kJC”>pic.twitter.com/kBXxwh3kJC</a>
Friedman ran up a small hill near his home and confirmed his suspicions: A cloud of dust hung in the air where the structure once stood, demolishing hopes held by some scientists that the telescope could somehow be repaired.
“It’s a huge loss,” said Carmen Pantoja, an astronomer and professor at the University of Puerto Rico who used the telescope for her doctorate. “It was a chapter of my life.”
Scientists worldwide had been petitioning U.S. officials and others to reverse the NSF’s decision to close the observatory. The NSF said at the time that it intended to eventually reopen the visitor centre and restore operations at the observatory’s remaining assets, including its two LIDAR facilities used for upper atmospheric and ionospheric research, including analyzing cloud cover and precipitation data.
Thousands of people have worked hard and passionately to keep <a href=”https://twitter.com/hashtag/Arecibo?src=hash&ref_src=twsrc%5Etfw”>#Arecibo</a> observatory at the forefront of planetary science and planetary defense. What a terrible, heart-breaking day for them all. <a href=”https://t.co/OstDIEvjrF”>https://t.co/OstDIEvjrF</a>
The telescope was built in the 1960s with money from the Defence Department amid a push to develop anti-ballistic missile defences. It had endured hurricanes, tropical humidity and a recent string of earthquakes in its 57 years of operation.
The telescope has been used to track asteroids on a path to Earth, conduct research that led to a Nobel Prize and determine if a planet is potentially habitable. It also served as a training ground for graduate students and drew about 90,000 visitors a year.
“I am one of those students who visited it when young and got inspired,” said Abel Mendez, a physics and astrobiology professor at the University of Puerto Rico at Arecibo who has used the telescope for research. “The world without the observatory loses, but Puerto Rico loses even more.”
He last used the telescope on Aug. 6, just days before a socket holding the auxiliary cable that snapped failed in what experts believe could be a manufacturing error. The National Science Foundation, which owns the observatory that is managed by the University of Central Florida, said crews who evaluated the structure after the first incident determined that the remaining cables could handle the additional weight.
But on Nov. 6, another cable broke.
A spokesperson for the observatory said there would be no immediate comment, and a spokesperson for the University of Central Florida did not return requests for comment.
Scientists had used the telescope to study pulsars to detect gravitational waves as well as search for neutral hydrogen, which can reveal how certain cosmic structures are formed. About 250 scientists worldwide had been using the observatory when it closed in August, including Mendez, who was studying stars to detect habitable planets.
“I’m trying to recover,” he said. “I am still very much affected.”
Chinese robot probe sent to retrieve lunar rocks lands on the moon, officials say – Global News
A Chinese robot probe sent to return lunar rocks to Earth for the first time since the 1970s landed on the moon Tuesday, the government announced, adding to a string of increasingly bold space missions by Beijing.
The Chang’e 5 probe “successfully landed” at its planned site, state TV and news agencies reported, citing the China National Space Administration. They didn’t immediately announce any more details.
The probe, launched Nov. 24 from the tropical southern island of Hainan, is the latest venture by a Chinese space program that fired a human into orbit in 2003, has a probe en route to Mars and aims eventually to land a human on the moon.
Plans call for the robot lander to drill into the lunar surface and load 2 kilograms (4.4 pounds) of rocks and debris into an ascent stage that will blast off to return them to Earth.
If it succeeds, it will be the first time scientists have obtained fresh samples of lunar rocks since a Soviet probe in the 1970s.
The Chang’e 5 flight is China’s third successful lunar landing. Its predecessor, Chang’e 4, became the first probe to land on the moon’s little-explored far side.
The latest flight includes collaboration with the European Space Agency, which is helping to monitor the mission.
China making renewed commitment to lunar missions
China’s space program has proceeded more cautiously than the U.S.-Soviet space race of the 1960s, which was marked by fatalities and launch failures.
In 2003, China became the third country to fire an astronaut into orbit on its own after the Soviet Union and the United States. It also launched a crewed space station.
Space officials say they hope eventually to land a human on the moon but no time line or other details have been announced.
China, along with neighbours Japan and India, also has joined the growing race to explore Mars.
The Tianwen 1 probe launched in July is en route to the red planet carrying a lander and a robot rover to search for water.
© 2020 The Canadian Press
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