NASA’s IXPE Measures White Dwarf Star for First Time

By Michael Allen 
 
For the first time, scientists have used NASA’s IXPE (Imaging X-ray Polarization Explorer) to study a white dwarf star. Using IXPE’s unique X-ray polarization capability, astronomers examined a star called the intermediate polar EX Hydrae, unlocking the geometry of energetic binary systems. 
 
In 2024, IXPE spent nearly one week focused on EX Hydrae, a white dwarf star system located in the constellation Hydra, approximately 200 light-years from Earth. A paper about the results published in the Astrophysical Journal. Astrophysics research scientists based at the Massachusetts Institute of Technology in Cambridge led the study, along with co-authors at the University of Iowa, East Tennessee State University, University of Liége, and Embry Riddle Aeronautical University. 
 
A white dwarf star occurs after a star runs out of hydrogen fuel to fuse in its core but is not massive enough to explode as core-collapse supernovae. What remains is very dense, roughly the same diameter as Earth with as much mass as our Sun.  
 
EX Hydrae is in a binary system with a main sequence companion star, from which gas is continuously falling onto the white dwarf. How exactly the white dwarf is accumulating, or accreting, this matter and where it arrives on the white dwarf depends on the strength of the white dwarf star’s magnetic field. 
 
In the case of EX Hydrae, its magnetic field is not strong enough to focus matter completely at the star’s poles. But, it is still rapidly adding mass to the accretion disk, earning the classification “intermediate polars. 

By Michael Allen

For the first time, scientists have used NASA’s IXPE (Imaging X-ray Polarization Explorer) to study a white dwarf star. Using IXPE’s unique X-ray polarization capability, astronomers examined a star called the intermediate polar EX Hydrae, unlocking the geometry of energetic binary systems.

In 2024, IXPE spent nearly one week focused on EX Hydrae, a white dwarf star system located in the constellation Hydra, approximately 200 light-years from Earth. A paper about the results published in the Astrophysical Journal. Astrophysics research scientists based at the Massachusetts Institute of Technology in Cambridge led the study, along with co-authors at the University of Iowa, East Tennessee State University, University of Liége, and Embry Riddle Aeronautical University.

A white dwarf star occurs after a star runs out of hydrogen fuel to fuse in its core but is not massive enough to explode as core-collapse supernovae. What remains is very dense, roughly the same diameter as Earth with as much mass as our Sun.

EX Hydrae is in a binary system with a main sequence companion star, from which gas is continuously falling onto the white dwarf. How exactly the white dwarf is accumulating, or accreting, this matter and where it arrives on the white dwarf depends on the strength of the white dwarf star’s magnetic field.

In the case of EX Hydrae, its magnetic field is not strong enough to focus matter completely at the star’s poles. But, it is still rapidly adding mass to the accretion disk, earning the classification “intermediate polars.

In an intermediate polar system, material forms an accretion disk while also being pulled towards its magnetic poles. During this phenomenon, matter reaches tens of millions of degrees Fahrenheit, bouncing off other material bound to the white dwarf star, creating large columns of gas that emit high-energy X-rays – a cosmic situation perfect for IXPE to study.

“NASA IXPE’s one-of-a-kind polarimetry capability allowed us to measure the height of the accreting column from the white dwarf star to be almost 2,000 miles high – without as many assumptions required as past calculations,” said Sean Gunderson, MIT scientist and lead author on the paper. “The X-rays we observed likely scattered off the white dwarf’s surface itself. These features are far smaller than we could hope to image directly and clearly show the power of polarimetry to ‘see’ these sources in detail never before possible.”

Information from IXPE’s polarization data of EX Hydrae will help scientists understand other highly energetic binary systems.

More about IXPE 

 The IXPE mission, which continues to provide unprecedented data enabling groundbreaking discoveries about celestial objects across the universe, is a joint NASA and Italian Space Agency mission with partners and science collaborators in 12 countries. It is led by NASA’s Marshall Space Flight Center in Huntsville, Alabama. BAE Systems, Inc., headquartered in Falls Church, Virginia, manages spacecraft operations together with the University of Colorado’s Laboratory for Atmospheric and Space Physics in Boulder. Learn more about IXPE’s ongoing mission here: 

https://www.nasa.gov/ixpe

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Lee Mohon

NASA Selects Tech Proposals to Advance Search-for-Life Mission

NASA announced Monday the selection of industry proposals to advance technologies for the agency’s Habitable Worlds Observatory concept – the first mission that would directly image Earth-like planets around stars like our Sun and study the chemical composition of their atmospheres for signs of life. This flagship space telescope also would enable wide-ranging studies of our universe and support future human exploration of Mars, our solar system, and beyond.

“The Habitable Worlds Observatory is exactly the kind of bold, forward-leaning science that only NASA can undertake,” said NASA Administrator Jared Isaacman. “Humanity is waiting for the breakthroughs this mission is capable of achieving and the questions it could help us answer about life in the universe. We intend to move with urgency, and expedite timelines to the greatest extent possible to bring these discoveries to the world.”

To achieve its science goals, the Habitable Worlds Observatory would need a stable optical system that moves no more than the width of an atom while it conducts observations. The mission also would require a coronagraph – an instrument that blocks the light of a star to better see its orbiting planets – thousands of times more capable than any space coronagraph ever built. The Habitable Worlds Observatory would be designed to allow servicing in space, to extend its lifetime and bolster its science over time.

To further the readiness of these technologies, NASA has selected proposals for three-year, fixed-price contracts from the following companies:

• Astroscale U.S. Inc., Denver
• BAE Systems Space and Mission Systems, Inc., Boulder, Colorado
• Busek Co. Inc, Natick, Massachusetts
• L3 Harris Technologies Inc., Rochester, New York
• Lockheed Martin Inc., Palo Alto, California
• Northrop Grumman Inc., Redondo Beach, California
• Zecoat Co. Inc., Granite City, Illinois

“Are we alone in the universe? is an audacious question to answer, but one that our nation is poised to pursue, leveraging the groundwork we’ve laid from previous NASA flagship missions. With the Habitable Worlds Observatory, NASA will chart new frontiers for humanity’s exploration of the cosmos,” said Shawn Domagal-Goldman, director of the Astrophysics Division at NASA Headquarters in Washington. “Awards like these are a critical component of our incubator program for future missions, which combines government leadership with commercial innovation to make what is impossible today rapidly implementable in the future.”

The newly selected proposals build on previous industry involvement, which began in 2017 under NASA’s “System-Level Segmented Telescope Design” solicitations and continued with awards for large space telescope technologies in 2024. The newly selected proposals will help inform NASA’s approach to planning for the Habitable Worlds Observatory concept, as the agency builds on technologies and lessons learned from its Hubble Space Telescope, James Webb Space Telescope, and upcoming Nancy Grace Roman Space Telescope.

To learn more about NASA’s Habitable Worlds Observatory, visit:

https://nasa.gov/hwo

-end-

Alise Fisher
Headquarters, Washington
202-358-2546
alise.m.fisher@nasa.gov

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Tiernan P. Doyle

What’s Up: January 2026 Skywatching Tips from NASA

Jupiter beams bright, Saturn and the Moon cozy up, and the Beehive Cluster appears

Jupiter is at its biggest and brightest all year, the Moon and Saturn pair up, and the Beehive Cluster buzzes into view.

Skywatching Highlights

• Jan. 10: Jupiter at opposition
• Jan. 23: Saturn and Moon conjunction
• Jan. (throughout): Beehive Cluster

Transcript

Jupiter is at its biggest and brightest

The Moon and Saturn share the sky 

And the beehive cluster makes an appearance 

That’s what’s up, this January

January 10, Jupiter will be at its most brilliant of the entire year! 

This night, Jupiter will be at what’s called “opposition,” meaning that Earth will be directly between Jupiter and the Sun. 

In this alignment, Jupiter will appear bigger and brighter in the night sky than it will all year – talk about starting off the new year bright! 

To see Jupiter at its best this year, look to the east and all evening long, you’ll be able to see the planet in the constellation Gemini. It will be one of the brightest objects in the night sky (only the moon and Venus will be brighter)  

Saturn and the Moon will share the sky on January 23rd as part of a conjunction!  

A conjunction is when objects in the sky look close together even though they’re actually far apart. 

To spot the pair, look to the west and you’ll see Saturn just below the moon, sparkling in the night sky. 

The beehive cluster will be visible in the night sky throughout January!

The beehive cluster, more formally known as Messier 44, or M44, is made of at least 1,000 stars

It’s an open star cluster, meaning it’s a loosely-bound group of stars. There are thousands of open star clusters like the beehive in the Milky Way Galaxy! 

To see the beehive cluster, look to the eastern night sky after sunset and before midnight throughout the month – especially great nights to spot the cluster are around the middle of January when the cluster isn’t too high or low in the sky to see.   

With dark skies you might be able to spot the beehive with just your eyes, but binoculars or a small telescope will help. 

Here are the phases of the Moon for January.

You can stay up to date on all of NASA’s missions exploring the solar system and beyond at science.nasa.gov.

I’m Chelsea Gohd from NASA’s Jet Propulsion Laboratory, and that’s What’s Up for this month.

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NASA Hubble Helps Detect ‘Wake’ of Betelgeuse’s Elusive Companion Star

4 Min Read

NASA Hubble Helps Detect ‘Wake’ of Betelgeuse’s Elusive Companion Star

Using new observations from NASA’s Hubble Space Telescope and ground-based observatories, astronomers tracked the influence of a recently discovered companion star, Siwarha, on the gas around Betelgeuse. The research, from scientists at the Center for Astrophysics | Harvard & Smithsonian (CfA), reveals a trail of dense gas swirling through Betelgeuse’s vast, extended atmosphere, shedding light on why the giant star’s brightness and atmosphere have changed in strange and unusual ways.

The results of the new study were presented Monday at a news conference at the 247th meeting of the American Astronomical Society in Phoenix and are accepted for publication in The Astrophysical Journal.

The team detected Siwarha’s wake by carefully tracking changes in the star’s light over nearly eight years. These changes show the effects of the previously unconfirmed companion as it plows through the outer atmosphere of Betelgeuse. This discovery resolves one of the biggest mysteries about the giant star, helping scientists to explain how it behaves and evolves while opening new doors to understanding other massive stars nearing the end of their lives.

Located roughly 650 light-years away from Earth in the constellation Orion, Betelgeuse is a red supergiant star so large that more than 400 million Suns could fit inside. Because of its enormous size and proximity, Betelgeuse is one of the few stars whose surface and surrounding atmosphere can be directly observed by astronomers, making it an important and accessible laboratory for studying how giant stars age, lose mass, and eventually explode as supernovae.

Using NASA’s Hubble and ground-based telescopes at the Fred Lawrence Whipple Observatory and Roque de Los Muchachos Observatory, the team was able to see a pattern of changes in Betelgeuse, which provided clear evidence of a long-suspected companion star and its impact on the red supergiant’s outer atmosphere. Those include changes in the star’s spectrum, or the specific colors of light given off by different elements, and the speed and direction of gases in the outer atmosphere due to a trail of denser material, or wake. This trail appears just after the companion crosses in front of Betelgeuse every six years, or about 2,100 days, confirming theoretical models.

“It’s a bit like a boat moving through water. The companion star creates a ripple effect in Betelgeuse’s atmosphere that we can actually see in the data,” said Andrea Dupree, an astronomer at the CfA, and the lead study author. “For the first time, we’re seeing direct signs of this wake, or trail of gas, confirming that Betelgeuse really does have a hidden companion shaping its appearance and behavior.”

For decades, astronomers have tracked changes in Betelgeuse’s brightness and surface features in hopes of figuring out why the star behaves the way it does. Curiosity intensified after the giant star appeared to “sneeze” and became unexpectedly faint in 2020. Two distinct periods of variation in the star were especially puzzling for scientists: a short 400-day cycle, recently attributed to pulsations within the star itself, and the long, 2,100-day secondary period.

Until now, scientists have considered everything from large convection cells and clouds of dust to magnetic activity, and the possibility of a hidden companion star. Recent studies concluded that the long secondary period was best explained by the presence of a low-mass companion orbiting deep within Betelgeuse’s atmosphere, and another team of scientists reported a possible detection, but until now, astronomers lacked the evidence to prove what they believed was happening. Now, for the first time, they have firm evidence that a companion is disrupting the atmosphere of this supergiant star.

“The idea that Betelgeuse had an undetected companion has been gaining in popularity for the past several years, but without direct evidence, it was an unproven theory,” said Dupree. “With this new direct evidence, Betelgeuse gives us a front-row seat to watch how a giant star changes over time. Finding the wake from its companion means we can now understand how stars like this evolve, shed material, and eventually explode as supernovae.”

With Betelgeuse now eclipsing its companion from our point of view, astronomers are planning new observations for its next emergence in 2027. This breakthrough may also help explain similar mysteries in other giant and supergiant stars.

The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.

Related Images & Videos

Betelgeuse and Wake of its Companion Star (Artist’s Concept)

This artist’s concept shows the red supergiant star Betelgeuse and an orbiting companion star. The companion, which is orbiting clockwise from this point of view, generates a dusty wake that expands outward.

Betelgeuse: Effect of Companion Star Wake

Scientists used NASA’s Hubble Space Telescope to look for evidence of a wake being generated by a companion star orbiting Betelgeuse. The team found a noticeable difference in light shown in the lefthand peak when the companion star was at different points in its orbit.

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