From National Aeronautics and Space Administration (US) Chandra X-ray Telescope (US): “The Give and Take of Mega-Flares From Stars” 

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From National Aeronautics and Space Administration (US) Chandra X-ray Telescope (US)

June 16, 2021

Media contacts:
Megan Watzke
Chandra X-ray Center, Cambridge, Mass.
617-496-7998
mwatzke@cfa.harvard.edu

Molly Porter
Marshall Space Flight Center, Huntsville, Alabama
256-544-0034
molly.a.porter@nasa.gov

How do flares, or outbursts, from young stars affect planets that orbit around them?

The largest study of star-forming regions in X-rays using NASA’s Chandra X-ray Observatory seeks to answer that question.

Researchers identified flares from over 1,000 young stars, many of which are much more powerful than those seen from our Sun today.

This study will help scientists learn more about both the beneficial and destructive impacts these flares can have.

The Lagoon Nebula (M8)
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Quick Look: Super Flares.

The long relationships between stars and the planets around them — including the Sun and the Earth — may be even more complex than previously thought. This is one conclusion of a new study involving thousands of stars using NASA’s Chandra X-ray Observatory.

By conducting the largest survey ever of star-forming regions in X-rays, a team of researchers has helped outline the link between very powerful flares, or outbursts, from youthful stars, and the impact they could have on planets in orbit.

“Our work tells us how the Sun may have behaved and affected the young Earth billions of years ago,” said Kostantin Getman of Pennsylvania State University in University Park, Pennsylvania who led the study. “In some ways, this is our ultimate origin story: how the Earth and Solar System came to be.”

The scientists examined Chandra’s X-ray data of more than 24,000 stars in 40 different regions where stars are forming. They captured over a thousand stars that gave off flares that are vastly more energetic than the most powerful flare ever observed by modern astronomers on the Sun, the “Solar Carrington Event” in 1859. “Super” flares are at least one hundred thousand times more energetic than the Carrington Event and “mega” flares up to 10 million times more energetic.

These powerful flares observed by Chandra in this work occur in all of the star-forming regions and among young stars of all different masses, including those similar to the Sun. They are also seen at all different stages in the evolution of young stars, ranging from early stages when the star is heavily embedded in dust and gas and surrounded by a large planet-forming disk, to later stages when planets would have formed and the disks are gone. The stars in the study have ages estimated to be less than 5 million years, compared to the Sun’s age of 4.5 billion years.

The team found several super-flares occur per week for each young star, averaged over the whole sample, and about two mega-flares every year.

“We want to know what kinds of impact — good and bad — these flares have on the early lives of planets,” said co-author Eric Feigelson, also of Penn State. “Flares this powerful can have major implications.”

Over the past two decades, scientists have argued that these giant flares can help “give” planets to still-forming stars by driving gas away from disks of material that surround them. This can trigger the formation of pebbles and other small rocky material that is a crucial step for planets to form.

On the other hand, these flares may “take away” from planets that have already formed by blasting any atmospheres with powerful radiation, possibly resulting in their complete evaporation and destruction in less than 5 million years.

The researchers also performed detailed modeling of 55 bright super- and mega-flares and found that most of them resemble long-lasting flares seen on the Sun that produce “coronal mass ejections,” powerful ejections of charged particles that can damage planetary atmospheres. The Solar Carrington Event involved such an ejection.

This work is also important for understanding the flares themselves. The team found that the properties of the flares, such as their brightness and frequency, are the same for young stars with and without planet-forming disks. This implies that the flares are likely similar to those seen on the Sun, with loops of magnetic field having both footprints on the surface of the star, rather than one anchored to the disk and one to the star.

“We’ve found that these giant flares are like ones on the Sun but are just greatly magnified in energy and frequency, and the size of their magnetic loops,” said co-author Gordon Garmire from the Huntingdon Institute for X-ray Astronomy (US) in Huntingdon, Pennsylvania”. Understanding these stellar outbursts may help us understand the most powerful flares and coronal mass ejections from the Sun.”

This work was presented at the recent meeting of the American Astronomical Society (US) and is described in a paper led by Getman that was accepted for publication in The Astrophysical Journal.

See the full article here .


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NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

In 1976 the Chandra X-ray Observatory (called AXAF at the time) was proposed to National Aeronautics and Space Administration (US) by Riccardo Giacconi and Harvey Tananbaum. Preliminary work began the following year at NASA’s Marshall Space Flight Center(US) and the Harvard Smithsonian Center for Astrophysics(US) . In the meantime, in 1978, NASA launched the first imaging X-ray telescope, Einstein (HEAO-2), into orbit. Work continued on the AXAF project throughout the 1980s and 1990s. In 1992, to reduce costs, the spacecraft was redesigned. Four of the twelve planned mirrors were eliminated, as were two of the six scientific instruments. AXAF’s planned orbit was changed to an elliptical one, reaching one third of the way to the Moon’s at its farthest point. This eliminated the possibility of improvement or repair by the space shuttle but put the observatory above the Earth’s radiation belts for most of its orbit. AXAF was assembled and tested by TRW (now Northrop Grumman Aerospace Systems) in Redondo Beach, California.

AXAF was renamed Chandra as part of a contest held by NASA in 1998, which drew more than 6,000 submissions worldwide. The contest winners, Jatila van der Veen and Tyrel Johnson (then a high school teacher and high school student, respectively), suggested the name in honor of Nobel Prize–winning Indian-American astrophysicist Subrahmanyan Chandrasekhar. He is known for his work in determining the maximum mass of white dwarf stars, leading to greater understanding of high energy astronomical phenomena such as neutron stars and black holes. Fittingly, the name Chandra means “moon” in Sanskrit.

Originally scheduled to be launched in December 1998, the spacecraft was delayed several months, eventually being launched on July 23, 1999, at 04:31 UTC by Space Shuttle Columbia during STS-93. Chandra was deployed from Columbia at 11:47 UTC. The Inertial Upper Stage’s first stage motor ignited at 12:48 UTC, and after burning for 125 seconds and separating, the second stage ignited at 12:51 UTC and burned for 117 seconds. At 22,753 kilograms (50,162 lb), it was the heaviest payload ever launched by the shuttle, a consequence of the two-stage Inertial Upper Stage booster rocket system needed to transport the spacecraft to its high orbit.

Chandra has been returning data since the month after it launched. It is operated by the SAO at the Chandra X-ray Center in Cambridge, Massachusetts, with assistance from Massachusetts Institute of Technology(US) and Northrop Grumman Space Technology. The ACIS CCDs suffered particle damage during early radiation belt passages. To prevent further damage, the instrument is now removed from the telescope’s focal plane during passages.

Although Chandra was initially given an expected lifetime of 5 years, on September 4, 2001, NASA extended its lifetime to 10 years “based on the observatory’s outstanding results.” Physically Chandra could last much longer. A 2004 study performed at the Chandra X-ray Center indicated that the observatory could last at least 15 years.

In July 2008, the International X-ray Observatory, a joint project between European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU), NASA and Japan Aerospace Exploration Agency (JAXA) (国立研究開発法人宇宙航空研究開発機構], was proposed as the next major X-ray observatory but was later cancelled. ESA later resurrected a downsized version of the project as the Advanced Telescope for High Energy Astrophysics (ATHENA), with a proposed launch in 2028.

European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU) Athena spacecraft depiction

On October 10, 2018, Chandra entered safe mode operations, due to a gyroscope glitch. NASA reported that all science instruments were safe. Within days, the 3-second error in data from one gyro was understood, and plans were made to return Chandra to full service. The gyroscope that experienced the glitch was placed in reserve and is otherwise healthy.