Jan 18, 2021 (Nanowerk News) The core mass of the giant exoplanet WASP-107b is much lower than what was thought necessary to build up the immense gas envelope surrounding giant planets like Jupiter and Saturn, according to a Canadian-led team of astronomers, including McGill University Professor Eve Lee. This intriguing discovery by Caroline Piaulet of the Université de Montréal under the supervision of Björn Benneke suggests that gas-giant planets form a lot more easily than previously believed. Published in Astronomical Journal (“WASP-107b’s Density Is Even Lower: A Case Study for the Physics of Planetary Gas Envelope Accretion and Orbital Migration”) by a team of astronomers from Canada, the U.S., Germany and Japan, the new analysis of WASP-107b’s internal structure has big implications. “This study pushes the boundaries of our theoretical understanding of how giant-sized planets form. WASP-107b is one of the puffiest planets out there, and we need a creative solution to explain how these tiny cores can build such massive gas envelopes,” says co-author Eve Lee, Assistant Professor in the Department of Physics at McGill University and McGill Space Institute.

As big as Jupiter but 10 times lighter

WASP-107b was first detected in 2017 around WASP-107, a star about 212 light years from Earth in the Virgo constellation. The planet is very close to its star — over 16 times closer than the Earth is to the Sun. About as big as Jupiter but 10 times lighter, WASP-107b is one of the least dense exoplanets known: a type astrophysicists have dubbed “super-puffs” or “cotton-candy” planets. The astronomers first used observations of WASP-107 obtained at the Keck Observatory in Hawaii to assess the planet’s mass more accurately. They used the radial velocity method, which allows scientists to determine a planet’s mass by observing the wobbling motion of its host star due to the planet’s gravitational pull. They concluded that the mass of WASP-107b is about one tenth that of Jupiter, or about 30 times that of Earth. In analyzing the planet’s most likely internal structure, they came to a surprising conclusion: with such a low density, the planet must have a solid core of no more than four times the mass of the Earth. This means that more than 85 percent of its mass is included in the thick layer of gas that surrounds this core. In comparison, Neptune, which has a similar mass to WASP-107b, only has 5 to 15 percent of its total mass in its gas layer.

A gas giant in the making

Planets form in the disc of dust and gas that surrounds a young star called a protoplanetary disc. Classical models of gas-giant planet formation are based on Jupiter and Saturn. In these, a solid core at least 10 times more massive than the Earth is needed to accumulate a large amount of gas before the disc dissipates. Without a massive core, gas-giant planets were not thought able to cross the critical threshold necessary to build up and retain their large gas envelopes. How then do we explain the existence of WASP-107b, which has a much less massive core? Professor Lee, who is a world-renowned expert on super-puff planets like WASP-107b, has several hypotheses. “For WASP-107b, the most plausible scenario is that the planet formed far away from the star, where the gas in the disc is cold enough that gas accretion can occur very quickly,” she said. “The planet was later able to migrate to its current position, either through interactions with the disc or with other planets in the system,” she says.

Discovery of a second planet

The Keck observations of the WASP-107 system cover a much longer period of time than previous studies have, allowing the research team to make an additional discovery: the existence of a second planet, WASP-107c, with a mass of about one-third that of Jupiter, considerably more than WASP-107b’s. WASP-107c is also much farther from the central star; it takes three years to complete one orbit around it, compared to only 5.7 days for WASP-107b. Also interesting: the eccentricity of this second planet is high, meaning its trajectory around its star is more oval than circular. “WASP-107c has in some respects kept the memory of what happened in its system,” said Piaulet. “Its great eccentricity hints at a rather chaotic past, with interactions between the planets which could have led to significant displacements, like the one suspected for WASP-107b.” The researchers plan to continue studying WASP-107b, hopefully with the James Webb Space Telescope set to launch in 2021, which will provide a much more precise idea of the composition of the planet’s atmosphere.

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Mary Jane Clinkard suffers from a neuromuscular disability that requires her to exercise to maintain her strength, but with municipal pools under lockdown since Boxing Day, she hasn’t been able to do that.

Now her muscles feel weak, stiff and painful, and her independence is in jeopardy. The 50-year-old fears she’ll need a personal support worker to get in and out of her wheelchair if she can’t get back into the water soon.

Clinkard, who has hypotonia, told CBC’s Ottawa Morning it’s especially disheartening when she hears others talking about the activities they’re able to do during the lockdown.

“I get really, really frustrated when I hear, ‘We all go skating or go skiing,’ and I’m like, ‘Well, I can’t do either of those,'” Clinkard said.

Once the pools reopened in July, it took Clinkard months of swimming three times a week to get back into shape. Then Ontario entered another lockdown.

The Sandy Hill woman would like to see swimming pools deemed essential, and said she’s not the only one who depends on them for her health.

“There are other people who cannot walk, who cannot ski, cannot skate,” she said.

No exemptions

According to Dan Chenier, the city’s general manager of recreation, cultural and facility services, the provincial restrictions currently in place don’t allow exemptions for people wishing to use indoor municipal facilities for physical therapy or rehabilitation.

“Provincial authorities have been made aware of the request for an exemption for […] these services and the City will be monitoring the revised regulations for any changes,” Chenier said in an emailed statement. 

When am I going to be back in the water? When am I going to be able to swim again?– Mary Jane Clinkard

According to the office of Sylvia Jones, Ontario’s solicitor general, the second wave of COVID-19 poses a serious threat to the province’s most vulnerable. 

“The single most important thing Ontarians can do right now to protect our most vulnerable is to stay at home,” wrote Stephen Warner, Jones’s press secretary and issues manager. “As we continue our vaccine rollout, this is our best defense against this virus.”

According to Warner, municipalities don’t have the power to ease restrictions put in place under the province’s lockdown. 

Restrictions ‘frustrating and difficult’

Under the stay-at-home order, only “exercising, including walking or moving around outdoors using an assistive mobility device, or using an outdoor recreational amenity” are allowed. 

Coun. Matt Luloff, who represents Orléans and sits on the city’s community and protective services committee, called that lack of flexibility “frustrating and difficult.”

On Monday, Luloff told Ottawa Morning if exemptions can be made for NHL players, then people who rely on certain facilities for their health and well-being should be granted similar leeway.

“We can say to one group of people that it’s fine to … bubble and to provide entertainment for us,” he told Ottawa Morning on Monday. “But when there’s a real need, a real physical [or] mental health need, that’s just not as important as getting to see the Sens play.”

“Maybe if the city doesn’t feel comfortable opening people pools for everybody, they can open one pool for people who really need it,” Clinkard suggested. “When am I going to be back in the water? When am I going to be able to swim again?”

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