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By NASA
6 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Knowing whether or not a planet elsewhere in the galaxy could potentially be habitable requires knowing a lot about that planet’s sun. Sarah Peacock relies on computer models to assess stars’ radiation, which can have a major influence on whether or not one of these exoplanets has breathable atmosphere.
Name: Sarah Peacock
Title: Assistant Research Scientist
Formal Job Classification: Astrophysicist
Organization: Exoplanets and Stellar Astrophysics Laboratory, Astrophysics Division, Science Directorate (Code 667)
Sarah Peacock is a research scientist with the Exoplanets and Stellar Astrophysics Laboratory at NASA’s Goddard Space Flight Center in Greenbelt, Md.Courtesy of Sarah Peacock What do you do and what is most interesting about your role here at Goddard?
My overarching research goal is to find habitable planets in other solar systems. To do this, I study the high-energy radiation that specific stars produce to help determine if life can exist on any earthlike planets that orbit them.
What is your educational background?
In 2013, I received a Bachelor of Arts in astrophysics from the University of Virginia. I received both my master’s and doctorate degrees from the Lunar and Planetary Laboratory at the University of Arizona in 2016 and 2019, respectively.
What drew you to study the stars?
In high school, I took an astronomy class. We had a planetarium in our school and I had a wonderful teacher who inspired me to fall in love with the stars. She also showed us how many of the Harry Potter characters are drawn from the constellations and that spoke to my heart because I am a Harry Potter fan!
How did you come to Goddard?
I started at Goddard as a NASA post-doctoral fellow in July 2020, but I first saw the center the day before Goddard shut down due to COVID.
How does high-energy radiation show you what planets outside our solar system might be habitable?
High-energy radiation can cause a planet to lose its atmosphere. If a planet is exposed to too much high-energy radiation, the atmosphere can be blown off, and if there is no atmosphere, then there is nothing for life as we know it to breathe.
We cannot directly measure the specific radiation that I study, so we have to model it. The universe has so many stars, and almost all stars host a planet. There are approximately 5,500 confirmed exoplanets so far, with an additional 7,500 unconfirmed exoplanets.
I help identify systems that either have too much radiation, so planets in the habitable zone (the region around a star where liquid water could exist on a planet’s surface) are probably lifeless, or systems that have radiation levels that are safer. Ultimately, my research helps narrow down the most likely systems to host planets that should have stable atmospheres.
Sarah Peacock research goal is to find habitable planets in other solar systems.Courtesy of Sarah Peacock Where does your data come from?
I predominately use data from the Hubble Space Telescope and from the now-retired spacecraft GALEX. My work itself is more theory-focused though: I create a modeled stellar spectrum across all wavelengths and use observations to validate my modeling.
What other areas of research are you involved in?
I am working with a team analyzing data from the James Webb Space Telescope to see if earthlike planets around M-type stars (a star that is cooler and smaller than the Sun) have atmospheres and, if so, what the composition of those atmospheres is. An exciting result from this work is that we may have detected water in the atmosphere of a rocky planet for the first time ever. However, we cannot yet distinguish with our current observations if that water comes from the planet or from spots on the star (starspots on this host star are cold enough for water to exist in gas form).
I am also helping manage a NASA Innovative Advance Concept (NIAC) study led by my mentor, Ken Carpenter, to work on the Artemis Enabled Stellar Imager (AeSI). If selected for further development, this imager would be an ultraviolet/optical interferometer located on the South Pole of the Moon. With this telescope, we would be able to map the surface of stars, image accretion disks, and image the centers of Active Galactic Nuclei.
As a relatively new employee to Goddard, what have been your first impressions?
Everyone who I have met, especially those in my lab, are incredibly friendly and welcoming. Starting during the pandemic, I was worried about feeling isolated, but instead, I was blown away by how many folks in my lab reached out to set up calls to introduce themselves and suggest opportunities for collaboration. It made me feel welcome.
Who is your mentor and what did your mentor advise you?
Ken Carpenter is my mentor. He encourages me to pursue my aspirations. He supports letting me chart my own path and being exposed to many different areas of research. I thank Ken for his support and encouragement and for including me on his projects.
“Everyone who I have met, especially those in my lab, are incredibly friendly and welcoming.”Courtesy of Sarah Peacock What do you do for fun?
I am a new mom, so my usual hobbies are on pause! Right now, fun is taking care of my baby and introducing life experiences to him.
As a recently selected member of the Executive Committee for NASA’s Exoplanet Exploration Program Analysis Group (ExoPAG), what are your responsibilities?
The NASA ExoPAG is responsible for soliciting and coordinating scientific community input into the development and execution of NASA’s exoplanet exploration program. We solicit opinions and advice from any scientist who studies exoplanets. We are a bridge between NASA’s exoplanet scientists and NASA Headquarters in Washington.
What is a fun fact about yourself?
I got married the same day I defended my Ph.D. I had my defense in the morning and got married in the afternoon at the courthouse.
Who is your favorite author?
I love to read; I always have three books going. My favorite author is Louise Penny, who writes mysteries, but I read all genres. Right now, I am reading a biography about Marjorie Merriweather Post.
What is your favorite quote?
“The most that can be expected from any model is that it can supply a useful approximation to reality: All models are wrong; some models are useful.” —Box and Draper 1987
By Elizabeth M. Jarrell
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Conversations With Goddard is a collection of Q&A profiles highlighting the breadth and depth of NASA’s Goddard Space Flight Center’s talented and diverse workforce. The Conversations have been published twice a month on average since May 2011. Read past editions on Goddard’s “Our People” webpage.
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Last Updated Dec 10, 2024 Related Terms
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By NASA
NASA/CXC/SAO/D. Bogensberger et al; Image Processing: NASA/CXC/SAO/N. Wolk; Even matter ejected by black holes can run into objects in the dark. Using NASA’s Chandra X-ray Observatory, astronomers have found an unusual mark from a giant black hole’s powerful jet striking an unidentified object in its path.
The discovery was made in a galaxy called Centaurus A (Cen A), located about 12 million light-years from Earth. Astronomers have long studied Cen A because it has a supermassive black hole in its center sending out spectacular jets that stretch out across the entire galaxy. The black hole launches this jet of high-energy particles not from inside the black hole, but from intense gravitational and magnetic fields around it.
The image shows low-energy X-rays seen by Chandra represented in pink, medium-energy X-rays in purple, and the highest-energy X-rays in blue.
In this latest study, researchers determined that the jet is — at least in certain spots — moving at close to the speed of light. Using the deepest X-ray image ever made of Cen A, they also found a patch of V-shaped emission connected to a bright source of X-rays, something that had not been seen before in this galaxy.
Called C4, this source is located close to the path of the jet from the supermassive black hole and is highlighted in the inset. The arms of the “V” are at least about 700 light-years long. For context, the nearest star to Earth is about 4 light-years away.
Source C4 in the Centaurus A galaxy.NASA/CXC/SAO/D. Bogensberger et al; Image Processing: NASA/CXC/SAO/N. Wolk; While the researchers have ideas about what is happening, the identity of the object being blasted is a mystery because it is too distant for its details to be seen, even in images from the current most powerful telescopes.
The incognito object being rammed may be a massive star, either by itself or with a companion star. The X-rays from C4 could be caused by the collision between the particles in the jet and the gas in a wind blowing away from the star. This collision can generate turbulence, causing a rise in the density of the gas in the jet. This, in turn, ignites the X-ray emission seen with Chandra.
The shape of the “V,” however, is not completely understood. The stream of X-rays trailing behind the source in the bottom arm of the “V” is roughly parallel to the jet, matching the picture of turbulence causing enhanced X-ray emission behind an obstacle in the path of the jet. The other arm of the “V” is harder to explain because it has a large angle to the jet, and astronomers are unsure what could explain that.
This is not the first time astronomers have seen a black hole jet running into other objects in Cen A. There are several other examples where a jet appears to be striking objects — possibly massive stars or gas clouds. However, C4 stands out from these by having the V-shape in X-rays, while other obstacles in the jet’s path produce elliptical blobs in the X-ray image. Chandra is the only X-ray observatory capable of seeing this feature. Astronomers are trying to determine why C4 has this different post-contact appearance, but it could be related to the type of object that the jet is striking or how directly the jet is striking it.
A paper describing these results appears in a recent issue of The Astrophysical Journal. The authors of the study are David Bogensberger (University of Michigan), Jon M. Miller (University of Michigan), Richard Mushotsky (University of Maryland), Niel Brandt (Penn State University), Elias Kammoun (University of Toulouse, France), Abderahmen Zogbhi (University of Maryland), and Ehud Behar (Israel Institute of Technology).
NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.
Read more from NASA’s Chandra X-ray Observatory.
Learn more about the Chandra X-ray Observatory and its mission here:
https://www.nasa.gov/chandra
https://chandra.si.edu
Visual Description
This release features a series of images focusing on a collision between a jet of matter blasting out of a distant black hole, and a mysterious, incognito object.
At the center of the primary image is a bright white dot, encircled by a hazy purple blue ring tinged with neon blue. This is the black hole at the heart of the galaxy called Centaurus A. Shooting out of the black hole is a stream of ejected matter. This stream, or jet, shoots in two opposite directions. It shoots toward us, widening as it reaches our upper left, and away from us, growing thinner and more faint as it recedes toward the lower right. In the primary image, the jet resembles a trail of hot pink smoke. Other pockets of granular, hot pink gas can be found throughout the image. Here, pink represents low energy X-rays observed by Chandra, purple represents medium energy X-rays, and blue represents high energy X-rays.
Near our lower right, where the jet is at its thinnest, is a distinct pink “V”, its arms opening toward our lower right. This mark is understood to be the result of the jet striking an unidentified object that lay in its path. A labeled version of the image highlights this region, and names the point of the V-shape, the incognito object, C4. A wide view version of the image is composited with optical data.
At the distance of Cen A, the arms of the V-shape appear rather small. In fact, each arm is at least 700 light-years long. The jet itself is 30,000 light-years long. For context, the nearest star to the Sun is about 4 light-years away.
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Lane Figueroa
Marshall Space Flight Center, Huntsville, Alabama
256-544-0034
lane.e.figueroa@nasa.gov
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
NASA’s IXPE (Imaging X-ray Polarimetry Explorer) has helped astronomers better understand the shapes of structures essential to a black hole – specifically, the disk of material swirling around it, and the shifting plasma region called the corona.
The stellar-mass black hole, part of the binary system Swift J1727.8-1613, was discovered in the summer of 2023 during an unusual brightening event that briefly caused it to outshine nearly all other X-ray sources. It is the first of its kind to be observed by IXPE as it goes through the start, peak, and conclusion of an X-ray outburst like this.
This illustration shows NASA’s Imaging X-ray Polarimetry Explorer (IXPE) spacecraft, at lower left, observing the newly discovered binary system Swift J1727.8-1613 from a distance. At the center is a black hole surrounded by an accretion disk, shown in yellow and orange, and a hot, shifting corona, shown in blue. The black hole is siphoning off gas from its companion star, seen behind the black hole as an orange disk. Jets of fast-moving, superheated particles stream from both poles of the black hole. Author: Marie Novotná Swift J1727 is the subject of a series of new studies published in The Astrophysical Journal and Astronomy & Astrophysics. Scientists say the findings provide new insight into the behavior and evolution of black hole X-ray binary systems.
“This outburst evolved incredibly quickly,” said astrophysicist Alexandra Veledina, a permanent researcher at the University of Turku, Finland. “From our first detection of the outburst, it took Swift J1727 just days to peak. By then, IXPE and numerous other telescopes and instruments were already collecting data. It was exhilarating to observe the outburst all the way through its return to inactivity.”
Until late 2023, Swift J1727 briefly remained brighter than the Crab Nebula, the standard X-ray “candle” used to provide a baseline for units of X-ray brightness. Such outbursts are not unusual among binary star systems, but rarely do they occur so brightly and so close to home – just 8,800 light years from Earth. The binary system was named in honor of the Swift Gamma-ray Burst Mission which initially detected the outburst with its Burst Alert Telescope on Aug. 24, 2023, resulting in the discovery of the black hole.
X-ray binary systems typically include two close-proximity stars at different stages of their lifecycle. When the elder star runs out of fuel, it explodes in a supernova, leaving behind a neutron star, white dwarf, or black hole. In the case of Swift J1727, the powerful gravity of the resulting black hole stripped material from its companion star, heating the material to more than 1.8 million degrees Fahrenheit and producing a vast outpouring of X-rays. This matter formed an accretion disk and can include a superheated corona. At the poles of the black hole, matter also can escape from the binary system in the form of relativistic jets.
IXPE, which has helped NASA and researchers study all these phenomena, specializes in X-ray polarization, the characteristic of light that helps map the shape and structure of such ultra-powerful energy sources, illuminating their inner workings even when they’re too distant for us to see directly.
Because light itself can’t escape their gravity, we can’t see black holes. We can only observe what is happening around them and draw conclusions about the mechanisms and processes that occur there. IXPE is crucial to that work.
/wp-content/plugins/nasa-blocks/assets/images/article-templates/anne-mcclain.jpg Alexandra Veledina
NASA Astrophysicist
“Because light itself can’t escape their gravity, we can’t see black holes,” Veledina said. “We can only observe what is happening around them and draw conclusions about the mechanisms and processes that occur there. IXPE is crucial to that work.”
Two of the IXPE-based studies of Swift J1727, led by Veledina and Adam Ingram, a researcher at Newcastle University in Newcastle-upon-Tyne, England, focused on the first phases of the outburst. During the brief period of months when the source became exceptionally bright, the corona was the main source of observed X-ray radiation.
“IXPE documented polarization of X-ray radiation traveling along the estimated direction of the black hole jet, hence the hot plasma is extended in the accretion disk plane,” Veledina said. “Similar findings were reported in the persistent black hole binary Cygnus X-1, so this finding helps verify that the geometry is the same among short-lived eruptive systems.”
The team further monitored how polarization values changed during Swift J1727’s peak outburst. Those conclusions matched findings simultaneously obtained during studies of other energy bands of electromagnetic radiation.
A third and a fourth study, led by researchers Jiří Svoboda and Jakub Podgorný, both of the Czech Academy of Sciences in Prague, focused on X-ray polarization at the second part of the Swift J1727’s outburst and its return to a highly energetic state several months later. For Podgorný’s previous efforts using IXPE data and black hole simulations, he recently was awarded the Czech Republic’s top national prize for a Ph.D. thesis in the natural sciences.
The polarization data indicated that the geometry of the corona did not change significantly between the beginning and the end of the outburst, even though the system evolved in the meantime and the X-ray brightness dropped dramatically in the later energetic state.
The results represent a significant step forward in our understanding of the changing shapes and structures of accretion disk, corona, and related structures at black holes in general. The study also demonstrates IXPE’s value as a tool for determining how all these elements of the system are connected, as well as its potential to collaborate with other observatories to monitor sudden, dramatic changes in the cosmos.
“Further observations of matter near black holes in binary systems are needed, but the successful first observing campaign of Swift J1727.8–1613 in different states is the best start of a new chapter we could imagine,” said Michal Dovčiak, co-author of the series of papers and leader of the IXPE working group on stellar-mass black holes, who also conducts research at the Czech Academy of Sciences.
More about IXPE
IXPE, 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. IXPE is led by NASA’s Marshall Space Flight Center in Huntsville, Alabama. Ball Aerospace, headquartered in Broomfield, Colorado, 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
Elizabeth Landau
NASA Headquarters
elizabeth.r.landau@nasa.gov
202-358-0845
Lane Figueroa
NASA’s Marshall Space Flight Center
256-544-0034
lane.e.figueroa@nasa.gov
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Last Updated Dec 06, 2024 Related Terms
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By USH
A security camera recently captured an eerie scene that has left people intrigued and spooked. In the footage, recorded at dawn, a mysterious figure dressed in white appears near a large vehicle. What makes the video even stranger is the reaction of two nearby dogs, who seem unusually distressed and unsettled by the presence.
While the exact location in Mexico where this happened hasn’t been confirmed, many are already speculating about the figure’s identity. Some believe it could be La Llorona, the legendary weeping woman from Mexican folklore. La Llorona is said to wander in sorrow, mourning her lost children, and has been the focus of countless ghost stories over the years.
Others have suggested a different explanation, claiming the figure resembles a "nightcrawler," a strange cryptid reportedly known for its bizarre appearance.
Skeptics, however, argue that it might just be a person caught in an unusual moment, and the dogs’ reactions could be explained by their heightened senses picking up on something out of the ordinary. Still, the dogs' unsettling behavior has sparked debate about whether the encounter might have been something paranormal.
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By NASA
4 min read
NASA, JAXA XRISM Mission Looks Deeply Into ‘Hidden’ Stellar System
The Japan-led XRISM (X-ray Imaging and Spectroscopy Mission) observatory has captured the most detailed portrait yet of gases flowing within Cygnus X-3, one of the most studied sources in the X-ray sky.
Cygnus X-3 is a binary that pairs a rare type of high-mass star with a compact companion — likely a black hole.
Cygnus X-3 is a high-mass binary consisting of a compact object (likely a black hole) and a hot Wolf-Rayet star. This artist’s concept shows one interpretation of the system. High-resolution X-ray spectroscopy indicates two gas components: a heavy background outflow, or wind, emanating from the massive star and a turbulent structure — perhaps a wake carved into the wind — located close to the orbiting companion. As shown here, a black hole’s gravity captures some of the wind into an accretion disk around it, and the disk’s orbital motion sculpts a path (yellow arc) through the streaming gas. During strong outbursts, the companion emits jets of particles moving near the speed of light, seen here extending above and below the black hole. NASA’s Goddard Space Flight Center “The nature of the massive star is one factor that makes Cygnus X-3 so intriguing,” said Ralf Ballhausen, a postdoctoral associate at the University of Maryland, College Park, and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It’s a Wolf-Rayet star, a type that has evolved to the point where strong outflows called stellar winds strip gas from the star’s surface and drive it outward. The compact object sweeps up and heats some of this gas, causing it to emit X-rays.”
A paper describing the findings, led by Ballhausen, will appear in a future edition of The Astrophysical Journal.
“For XRISM, Cygnus X-3 is a Goldilocks target — its brightness is ‘just right’ in the energy range where XRISM is especially sensitive,” said co-author Timothy Kallman, an astrophysicist at NASA Goddard. “This unusual source has been studied by every X-ray satellite ever flown, so observing it is a kind of rite of passage for new X-ray missions.”
XRISM (pronounced “crism”) is led by JAXA (Japan Aerospace Exploration Agency) in collaboration with NASA, along with contributions from ESA (European Space Agency). NASA and JAXA developed the mission’s microcalorimeter spectrometer instrument, named Resolve.
Observing Cygnus X-3 for 18 hours in late March, Resolve acquired a high-resolution spectrum that allows astronomers to better understand the complex gas dynamics operating there. These include outflowing gas produced by a hot, massive star, its interaction with the compact companion, and a turbulent region that may represent a wake produced by the companion as it orbits through the outrushing gas.
XRISM’s Resolve instrument has captured the most detailed X-ray spectrum yet acquired of Cygnus X-3. Peaks indicate X-rays emitted by ionized gases, and valleys form where the gases absorb X-rays; many lines are also shifted to both higher and lower energies by gas motions. Top: The full Resolve spectrum, from 2 to 8 keV (kiloelectron volts), tracks X-rays with thousands of times the energy of visible light. Some lines are labeled with the names of the elements that produced them, such as sulfur, argon, and calcium, along with Roman numerals that refer to the number of electrons these atoms have lost. Bottom: A zoom into a region of the spectrum often dominated by features produced by transitions in the innermost electron shell (K shell) of iron atoms. These features form when the atoms interact with high-energy X-rays or electrons and respond by emitting a photon at energies between 6.4 and 7 keV. These details, clearly visible for the first time with XRISM’s Resolve instrument, will help astronomers refine their understanding of this unusual system. JAXA/NASA/XRISM Collaboration In Cygnus X-3, the star and compact object are so close they complete an orbit in just 4.8 hours. The binary is thought to lie about 32,000 light-years away in the direction of the northern constellation Cygnus.
While thick dust clouds in our galaxy’s central plane obscure any visible light from Cygnus X-3, the binary has been studied in radio, infrared, and gamma-ray light, as well as in X-rays.
The system is immersed in the star’s streaming gas, which is illuminated and ionized by X-rays from the compact companion. The gas both emits and absorbs X-rays, and many of the spectrum’s prominent peaks and valleys incorporate both aspects. Yet a simple attempt at understanding the spectrum comes up short because some of the features appear to be in the wrong place.
That’s because the rapid motion of the gas displaces these features from their normal laboratory energies due to the Doppler effect. Absorption valleys typically shift up to higher energies, indicating gas moving toward us at speeds of up to 930,000 mph (1.5 million kph). Emission peaks shift down to lower energies, indicating gas moving away from us at slower speeds.
Some spectral features displayed much stronger absorption valleys than emission peaks. The reason for this imbalance, the team concludes, is that the dynamics of the stellar wind allow the moving gas to absorb a broader range of X-ray energies emitted by the companion. The detail of the XRISM spectrum, particularly at higher energies rich in features produced by ionized iron atoms, allowed the scientists to disentangle these effects.
“A key to acquiring this detail was XRISM’s ability to monitor the system over the course of several orbits,” said Brian Williams, NASA’s project scientist for the mission at Goddard. “There’s much more to explore in this spectrum, and ultimately we hope it will help us determine if Cygnus X-3’s compact object is indeed a black hole.”
XRISM is a collaborative mission between JAXA and NASA, with participation by ESA. NASA’s contribution includes science participation from CSA (Canadian Space Agency).
Download additional images from NASA’s Scientific Visualization Studio
By Francis Reddy
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Media Contact:
Claire Andreoli
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claire.andreoli@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Nov 25, 2024 Related Terms
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