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Written by: NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

Published: 30 July 2023

A young planet whirling around a petulant red dwarf star is changing in unpredictable ways orbit-by-orbit. It is so close to its parent star that it experiences a consistent, torrential blast of energy, which evaporates its hydrogen atmosphere – causing it to puff off the planet.

But during one orbit observed with NASA's Hubble Space Telescope, the planet looked like it wasn't losing any material at all, while an orbit observed with Hubble a year and a half later showed clear signs of atmospheric loss.

This extreme variability between orbits shocked astronomers. "We've never seen atmospheric escape go from completely not detectable to very detectable over such a short period when a planet passes in front of its star," said Keighley Rockcliffe of Dartmouth College in Hanover, New Hampshire. "We were really expecting something very predictable, repeatable. But it turned out to be weird. When I first saw this, I thought 'That can't be right.'"

Rockcliffe was equally puzzled to see, when it was detectable, the planet's atmosphere puffing out in front of the planet, like a headlight on a fast-bound train. "This frankly strange observation is kind of a stress-test case for the modeling and the physics about planetary evolution. This observation is so cool because we're getting to probe this interplay between the star and the planet that is really at the most extreme," she said.

Located 32 light-years from Earth, the parent star AU Microscopii (AU Mic) hosts one of the youngest planetary systems ever observed. The star is less than 100 million years old (a tiny fraction of the age of our Sun, which is 4.6 billion years old).

The innermost planet, AU Mic b, has an orbital period of 8.46 days and is just 6 million miles from the star (about 1/10th the planet Mercury's distance from our Sun). The bloated, gaseous world is about four times Earth's diameter.

AU Mic b was discovered by NASA’s Spitzer and the Transiting Exoplanet Survey Satellite, or TESS, space telescopes in 2020. It was spotted with the transit method, meaning telescopes can observe a slight dip in the star's brightness when the planet crosses in front of it.

Red dwarfs like AU Microscopii are the most abundant stars in our Milky Way galaxy. They therefore should host the majority of planets in our galaxy. But can planets orbiting red dwarf stars like AU Mic b be hospitable to life?

A key challenge is that young red dwarfs have ferocious stellar flares blasting out withering radiation. This period of high activity lasts a lot longer than that of stars like our Sun.

The flares are powered by intense magnetic fields that get tangled by the roiling motions of the stellar atmosphere. When the tangling gets too intense, the fields break and reconnect, unleashing tremendous amounts of energy that are 100 to 1,000 times more energetic than our Sun unleashes in its outbursts.

It's a blistering fireworks show of torrential winds, flares, and X-rays blasting any planets orbiting close to the star. "This creates a really unconstrained and frankly, scary, stellar wind environment that's impacting the planet's atmosphere," said Rockcliffe.

Under these torrid conditions, planets forming within the first 100 million years of the star's birth should experience the most amount of atmospheric escape. This might end up completely stripping a planet of its atmosphere.

"We want to find out what kinds of planets can survive these environments. What will they finally look like when the star settles down? And would there be any chance of habitability eventually, or will they wind up just being scorched planets?" said Rockcliffe. "Do they eventually lose most of their atmospheres and their surviving cores become super-Earths? We don't really know what those final compositions look like because we don't have anything like that in our solar system."

While the star's glare prevents Hubble from directly seeing the planet, the telescope can measure changes in the star's apparent brightness caused by hydrogen bleeding off the planet and dimming the starlight when the planet transits the star. That atmospheric hydrogen has been heated to the point where it escapes the planet's gravity.

The never-before-seen changes in atmospheric outflow from AU Mic b may indicate swift and extreme variability in the host red dwarf's outbursts. There is so much variability because the star has a lot of roiling magnetic field lines.

One possible explanation for the missing hydrogen during one of the planet's transits is that a powerful stellar flare, seen seven hours prior, may have photoionized the escaping hydrogen to the point where it became transparent to light, and so was not detectable.

Another explanation is that the stellar wind itself is shaping the planetary outflow, making it observable at some times and not observable at other times, even causing some of the outflow to "hiccup" ahead of the planet itself. This is predicted in some models, like those of John McCann and Ruth Murray-Clay from the University of California at Santa Cruz, but this is the first kind of observational evidence of it happening and to such an extreme degree, say researchers.

Hubble follow-up observations of more AU Mic b transits should offer additional clues to the star and planet's odd variability, further testing scientific models of exoplanetary atmospheric escape and evolution.

Rockcliffe is lead author on the science paper accepted for publication in The Astronomical Journal.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.

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Written by: LAKE COUNTY NEWS REPORTS

Published: 29 July 2023

NORTHERN CALIFORNIA — Lake County’s representative in the California Assembly has been promoted to a key role in the Legislature.

On Friday, Assemblymember Cecilia Aguiar-Curry (D-Winters) was appointed speaker pro tempore of the California Assembly by Speaker Robert Rivas (D-Salinas), who administered the oath of office to her in a ceremony at the State Capitol.

“I am extraordinarily grateful to Speaker Rivas for his faith and confidence in me,” Aguiar-Curry said. “I am excited to work hand in hand with Majority Leader Bryan and the rest of our leadership team to serve the speaker, the Assembly Democratic Caucus, our legislative institutions, and the working people of this state.”

The Assembly speaker pro-tempore reports directly to Speaker Rivas and runs the Assembly floor together with the Majority Leader Isaac Bryan (D-Los Angeles).

“I won’t lie to you, I never thought I would be here — ever, in my wildest dreams — because I, like many others, started from nothing and here I am a grandmother, and I’m standing in front of all of you, telling you that we are going to change the world,” Aguiar-Curry said.

She said she couldn’t ask for a better job and told Rivas she wouldn’t let him down.

Aguiar-Curry, first elected to the Legislature in November 2016, represents the Fourth Assembly District, which includes all of Yolo, Napa, Colusa and Lake counties, and parts of Sonoma County.

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Written by: LAKE COUNTY NEWS REPORTS

Published: 29 July 2023

LAKE COUNTY, Calif. — The county of Lake announced that it has received a $75,000 grant from the California Cultural and Historical Endowment for the transformation of the Lake Pomo Gallery at the Historic Courthouse Museum in Lakeport.

This initiative, which began in March 2022, represents a collaborative effort between Lake County Museum staff and the volunteer Tribal Advisory Committee to the Museums of Lake County.

The funding is part of the $19.7 million awarded by the California Cultural and Historical Endowment to support 63 museum projects spanning from San Diego to Shasta counties.

These projects aim to provide resources for small capital projects and programs in museums that have been severely affected by COVID-19 and serve historically underserved communities or students subject to Title 1.

Wade Crowfoot, California Natural Resources Secretary, expressed his enthusiasm for the initiative, stating, “California's museums teach us about our state's dynamic, diverse history and culture. This funding will support projects across the state that lift up history and culture that has been underrepresented in the past and enable more people to learn these remarkable stories.”

The ambitious endeavor will lead to the establishment of a permanent exhibit in the Historic Courthouse Museum, showcasing the rich and vibrant history of the seven federally recognized Pomo Nations of the Clear Lake basin.

The exhibit will feature an extensive basketry collection and other cultural objects displayed in modern cases, incorporating dynamic mounts and interactive screens with oral histories and other cultural content in collaboration with the tribes in Lake County: Big Valley Band of Pomo Indians, Elem Indian Colony of Pomo Indians, Habematolel Pomo of Upper Lake, the Koi Nation of Northern California, Middletown Rancheria of Pomo Indians of California, the Robinson Rancheria of Pomo Indians of California and the Scotts Valley Band of Pomo Indians.

Additionally, contemporary art from Pomo artists will be included to connect the present and future with the generations of Lake County's indigenous heritage.

Planning for this transformative project began in the summer 2023, with a grand opening scheduled for 2024.

The gallery will welcome museum visitors and students on tours, fostering knowledge and appreciation for the culture and identity of the Lake Pomo tribes.

In another partnership, the county of Lake also was successful in its application to the Upstate California Creative Corps Grant program, which will enable the completion of the Lake Pomo Family statue on the grounds of the Historic Courthouse Museum in Lakeport.

This grant is part of a broader media, outreach and engagement campaign designed to increase awareness for issues such as public health, water and energy conservation, climate mitigation, and emergency preparedness, relief, and recovery.

The California Arts Council views the California Creative Corps program as an opportunity for job creation and human infrastructure development, fostering artist engagement in public work and intersectional public interest goals.

The life-size bronze sculpture featuring a Lake Pomo family will be erected on the grounds of the museum.

The project represents the culmination of nearly a decade of fundraising efforts and will be a major attraction for the community, drawing visitors to the county and museums alike. The statue holds profound symbolism, representing the cultural beauty and heritage of the Lake Pomo people for generations to come.

This statue project aims to address historical trauma and foster healing within Indigenous communities that have endured centuries of marginalization and assimilation. The power of public art, such as this statue, promotes well-being by providing individuals with a sense of purpose and inviting public spaces that encourage physical activity, socialization, and a deeper understanding of the world.

Throughout the process, the Tribal Advisory Committee to the Museums of Lake County has worked closely with Kelseyville artist Rolf Kriken to ensure cultural authenticity of the individual figures in the statue and reflect the family bonds, resiliency, and intergenerational connection of the Pomo people.

The committee, consisting of elders and tribal members representing all seven Pomo tribes, has creatively guided the project and contributed significantly to its realization.

Their vision and input have been central to the creation of the Lake Pomo Family bronze statue, county officials said.