The researchers have found unprecedented levels of complexity and rapid changes in jets and gas bubbles blasting off of the stars at the centers of both nebulas. Hubble is allowing the researchers to converge on an understanding of the mechanisms underlying the chaos.

“When I looked in the Hubble archive and realized no one had observed these nebulas with Hubble’s Wide Field Camera 3 across its full wavelength range, I was floored,” said Joel Kastner of Rochester Institute of Technology, Rochester, New York, leader of the new study. “These new multi-wavelength Hubble observations provide the most comprehensive view to date of both of these spectacular nebulas. As I was downloading the resulting images, I felt like a kid in a candy store.”

By examining this pair of nebulas with Hubble’s full, panchromatic capabilities — making observations in near-ultraviolet to near-infrared light — the team has had several “aha” moments. In particular, the new Hubble images reveal in vivid detail how both nebulas are splitting themselves apart on extremely short timescales — allowing astronomers to see changes over the past couple decades. Some of this rapid change may be indirect evidence of one star merging with its companion star.

“The nebula NGC 7027 shows emission at an incredibly large number of different wavelengths, each of which highlights not only a specific chemical element in the nebula, but also the significant, ongoing changes in its structure,” said Kastner. The research team also observed the Butterfly Nebula, which is a counterpart to the “jewel bug” nebula: Both are among the dustiest planetary nebulas known and both also contain unusually large masses of gas because they are so newly formed. This makes them a very interesting pair to study in parallel, say researchers.

Hubble’s broad multi-wavelength views of each nebula are helping the researchers to trace the nebulas’ histories of shock waves. Such shocks typically are generated when fresh, fast stellar winds slam into and sweep up more slowly expanding gas and dust ejected by the star in its recent past, generating bubble-like cavities with well-defined walls.

Researchers suspect that at the hearts of both nebulas are — or were — two stars circling around each other, like a pair of figure skaters. Evidence for such a central “dynamic duo” comes from the bizarre shapes of these nebulas. Each has a pinched, dusty waist and polar lobes or outflows, as well as other, more complex symmetrical patterns.

A leading theory for the generation of such structures in planetary nebulas is that the mass-losing star is one of two stars in a binary system. The two stars orbit one another closely enough that they eventually interact, producing a gas disk around one or both stars. The disk is the source of outflowing material directed in opposite directions from the central star.

Similarly, the smaller star of the pair may merge with its bloated, more rapidly evolving stellar companion. This also can create outflowing jets of material that may wobble over time. This creates a symmetric pattern, perhaps like the one that gives NGC 6302 its “butterfly” nickname. Such outflows are commonly seen in planetary nebulas.

“The suspected companion stars in NGC 6302 and NGC 7027 haven’t been directly detected because they are next to, or perhaps have already been swallowed by, larger red giant stars, a type of star that is hundreds to thousands of times brighter than the Sun,” said team member Bruce Balick of the University of Washington in Seattle. “The hypothesis of merging stars seems the best and simplest explanation for the features seen in the most active and symmetric planetary nebulas. It’s a powerful unifying concept, so far without rival.”

The Butterfly Nebula

Imagine a lawn sprinkler spinning wildly, tossing out two S-shaped streams. At first it appears chaotic, but if you stare for a while, you can trace its patterns. The same S-shape is present in the Butterfly Nebula, except in this case it is not water in the air, but gas blown out at high speed by a star. And the “S” only appears when captured by the Hubble camera filter that records near-infrared emission from singly ionized iron atoms.

“The S-shape in the iron emission from the Butterfly Nebula is a real eye-opener,” Kastner said. The S-shape directly traces the most recent ejections from the central region, since the collisions within the nebula are particularly violent in these specific regions of NGC 6302. “This iron emission is a sensitive tracer of energetic collisions between slower winds and fast winds from the stars,” Balick explained. “It’s commonly observed in supernova remnants and active galactic nuclei, and outflowing jets from newborn stars, but is very rarely seen in planetary nebulas.”

“The fact that the iron emission is only showing up along these opposing, off-center directions implies that the source of the fast flows is wobbling over time, like a spinning top that’s about to fall,” added Kastner. “That’s another tell-tale sign of the presence of a disk, which directs the flow, and also a binary companion.”

The ‘Jewel Bug’ Nebula

The planetary nebula NGC 7027 had been slowly puffing away its mass in quiet, spherically symmetric or perhaps spiral patterns for centuries — until relatively recently. “In some respects, the changes within this nebula are even more dramatic than those within the Butterfly,” Kastner said. “Something recently went haywire at the very center, producing a new cloverleaf pattern, with bullets of material shooting out in specific directions.”

The research team’s new images of NGC 7027 show emission from singly ionized iron that closely resembles observations made by NASA’s Chandra X-ray Observatory in 2000 and 2014 as part of earlier research by Kastner, team member Rodolfo Montez Jr. of the Center for Astrophysics | Harvard & Smithsonian, and collaborators. The iron emission traces the southeast-to-northwest-oriented outflows that also produce the X-ray-emitting shocks imaged by Chandra. “We have a sneaking suspicion that this nebula is a great example of what happens when a red giant star abruptly swallows a companion,” Montez Jr. said.

“This is the first study that definitively shows a strong association between not moving and cancer death,” said Susan Gilchrist, M.D., associate professor of Clinical Cancer Prevention and lead author of the study, published today in JAMA Oncology. “Our findings show that the amount of time a person spends sitting prior to a cancer diagnosis is predictive of time to cancer death.”

Researchers also found that replacing 30 minutes of sedentary time with physical activity was associated with a 31% lower risk of cancer death for moderate-intensity activity, such as cycling, and an 8% lower risk of cancer death for light-intensity activity, such as walking.

“Conversations with my patients always begin with why they don’t have time to exercise,” said Gilchrist, who leads MD Anderson’s Healthy Heart Program. “I tell them to consider standing up for 5 minutes every hour at work or taking the stairs instead of the elevator. It might not sound like a lot, but this study tells us even light activity has cancer survival benefits.”

Study design

This study involved a cohort of participants from the nationally representative REGARDS study, which recruited more than 30,000 U.S. adults over the age of 45 between 2003 and 2007 to study long-term health outcomes.

To measure sedentary behavior, 8,002 REGARDS participants who did not have a cancer diagnosis at study enrollment wore an accelerometer on their hip during waking hours for seven consecutive days. The accelerometer data was gathered between 2009 and 2013. After a mean follow-up of 5 years, 268 participants died of cancer. Longer duration of sedentary behavior was independently associated with a greater risk of cancer death.

The study also found that engaging in either light or moderate to vigorous physical activity made a difference. Investigators assessed sedentary time, light-intensity physical activity (LIPA) and moderate to vigorous physical activity (MVPA) in the same model and found that LIPA and MVPA, not sedentary behavior, remained significantly associated with cancer mortality.

“From a practical perspective, this means that individuals who replaced either 10 to 30 minutes of sedentary time with either LIPA or MVPA had a lower risk of cancer mortality in the REGARDS cohort,” Gilchrist said.

The study had several limitations, including a potentially healthier participant sample compared to the full REGARDS cohort and a lack of site-specific cancer data, including type of tumor and treatment.

“Our findings reinforce that it’s important to ‘sit less and move more’ and that incorporating 30 minutes of movement into your daily life can help reduce your risk of death from cancer,” Gilchrist said. “Our next step is to investigate how objectively measured sedentary behavior impacts site-specific cancer incidence and if gender and race play a role.”

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Analyzing Centers for Disease Control and Prevention data from 1962 to 2016, WVU economists found that flu deaths increased by between 5 and 24 percent during the NFL, NBA, NHL and MLB seasons, with the largest increase for NHL games.

Given that COVID-19 is believed to be more contagious and deadlier, Economics Professor Brad Humphreys has a message for sports leagues until a vaccine is available or herd immunity exists: “Don’t let the fans back into the games.”

“Opening pro sports games to fans is probably a terrible idea, in terms of public health,” said Humphreys, one of the authors of the paper “Professional Sporting Events Increase Seasonal Influenza Mortality in U.S. Cities.” “You’re right on top of people and everybody’s yelling, screaming, high-fiving and hugging. And you’ve got people eating and drinking. You could be putting the virus right into your mouth. The bottom line is we need to be very careful if we’re considering opening up games to the fans.”

Humphreys’ WVU co-authors include Jane Ruseski, associate professor of economics, and Alexander Cardazzi, a Ph.D. student.

Researchers examined cities that introduced a new sport franchise from the big four leagues over the 54-year timeframe. Welcoming new teams in all leagues led to an increase in flu mortality, according to the report.

“We found data that reported flu mortality by city by week dating back to the 1960s,” Humphreys said. “We decided the best experiment was to try to look at what happened when a city got a new pro sports team compared to cities that didn’t. As it turned out, after a new professional sports team came into a city, that flu season and every flu season afterward had more people dying of the flu.

“It isn’t one or two people dying. This is closer to 30 or 40 additional flu deaths over the course of flu season. When you blow it up to a virus that’s more fatal like COVID-19, we could be talking about hundreds of additional deaths because of these games.”

The study also showed a decline in flu deaths in U.S. cities during season stoppages. That means cities reported fewer flu deaths during the 2011 NBA lockout and the 1982 NFL strike.

Research began in March when organizations, such as the NBA, suspended play due to the COVID-19 outbreak in the U.S. Humphreys was further intrigued after reading about a soccer game in Italy that was believed to have been a catalyst in spiking that country’s positive cases.

On Feb. 19, the day of a soccer match between Atalanta and Valencia, there were only three confirmed cases in the country of Italy. Two weeks later, that number jumped to 997 — just in Bergamo, northeast of Milan and home to the Atalanta team.

“At the time, they had the highest death rate anywhere in the world,” Humphreys said. “That game served as a super-spreader event.”

The NBA and NHL both plan to resume their seasons this summer, but without fans in attendance. In fact, NBA players will have the option of wearing an Oura smart ring that detects early signs of the novel coronavirus — which is part of research from the WVU Rockefeller Neuroscience Institute.

Details of the upcoming MLB and NFL seasons remain uncertain.

The economists hope this timely research will not only help inform sports league reopening policy decisions, but mass gatherings in general such as concerts, conferences and conventions.

“You’ll have some people say, ‘Oh, but everybody can wear a mask,'” Humphreys said. “But you’ve seen how people are complying with that, right? And if these arenas are at full capacity, social distancing isn’t happening.”

A COVID-19 model formerly used by the White House projects that more than 200,000 American could die from the virus by October. As of late Wednesday, 119,000 people have died of the novel coronavirus in the U.S., with a total of 2.2 million positive cases.

“Our results reveal that bringing fans back to games would be a huge mistake,” Humphreys said. “Imagine someone going to a game and sitting in the stands and then they go see grandma at the nursing home. Let’s wait til we have a vaccine or reach herd immunity.”