NASA's IXPE Sends First Science Image

Cassiopeia A
Cassiopeia A

NASA’s Imaging X-Ray Polarimetry Explorer, which launched into space Dec. 9, 2021, delivered its first imaging data since completing its month-long commissioning phase.

All instruments are functioning well aboard the observatory, which is on a quest to study some of the most mysterious and extreme objects in the universe.

IXPE first focused its X-ray eyes on Cassiopeia A (Cas A), an object consisting of the remains of a star that exploded in the 17th century. The shock waves from the explosion have swept up surrounding gas, heating it to high temperatures and accelerating cosmic ray particles to make a cloud that glows in X-ray light. Other telescopes, including Chandra, have studied Cas A before, but IXPE will allow researchers to examine it in a new way.

The newly-release image combines IXPE and Chandra data of Cas A. The saturation of the magenta color corresponds to the intensity of X-ray light observed by IXPE, which has been overlaid on high-energy X-rays, shown in blue, from Chandra. With different kinds of detectors, Chandra and IXPE have different levels of angular resolution, or sharpness. The IXPE data in this new image contain collected from Jan. 11 to 18, while the Chandra data come from observations over the 22-year mission thus far.

An Expanse of Light

Collage of six images
An Expanse of Light
Credit: X-ray: NASA/CXC/SAO; Optical: NASA/STScI, Palomar Observatory, DSS;

The recent launches of the James Webb Space Telescope (Webb) and the Imaging X-ray Polarimetry Explorer (IXPE) by NASA and its international partners are excellent reminders that the universe emits light or energy in many different forms. To fully investigate cosmic objects and phenomena, scientists need telescopes that can detect light across what is known as the electromagnetic spectrum.

This gallery provides examples of the ways that different types of light from telescopes on the ground and in space can be combined. The common thread in each of these selections is data from NASA's Chandra X-ray Observatory, illustrating how X-rays — which are emitted by very hot and energetic processes — are found throughout the Universe.

Why Make Sonifications of Astronomical Data?

3 images of the objects sonified in this edition
Jingle, Pluck, and Hum: Sounds from Space
Credit: NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)

When you travel to a foreign country where they speak a language you do not understand, it is usually imperative that you find a way to translate what is being communicated to you. In some respects, the same can be said about data collected from objects in space.

A telescope like NASA's Chandra X-ray Observatory captures X-rays, which are invisible to the human eye, from sources across the cosmos. This high-energy light gets sent back down to Earth in the form of ones and zeroes. From there, the data are transformed into a variety of different things — from plots to spectra to images.

This last category — images — is arguably what most telescopes are best known for. For most of astronomy's long history, however, most who are blind or visually impaired (BVI) can often not fully experience the wonders that telescopes have captured.

In recent decades, that has begun to change. There are various ways that astronomers, data scientists, astronomy communication professionals, and others can work with communities of different abilities, from creating 3D prints and visual descriptions to sound-based products. As part of the Chandra X-ray Center and NASA's Universe of Learning, a team of experts led by Dr. Kimberly Arcand has been working to "sonify" (turn into sound) data from some of NASA's greatest telescopes.

Upgrading Our Views of the Universe

Screen shot of NOIRLab/IPAC/ESA/STScI/CfA FITS Liberator version 4
NOIRLab/IPAC/ESA/STScI/CfA FITS Liberator, Version 4

How do we image our Universe? There are many different ways of translating information from the cosmos. But in working with scientific data and image processing software, you can create your own astronomy images from FITS files. "FITS," which stands for Flexible Image Transport System, is a digital file format used mainly by astronomers to work with data of cosmic objects. Today, we are happy to help announce an update to the open source FITS Liberator software that can be used to process your own astronomical data. —Kimberly Kowal Arcand (CfA)

Astronomy is predominantly a visual science. However, an important tool is needed to produce breathtaking color images from the observations made with telescopes such as the NASA/ESA Hubble Space Telescope, NASA's Chandra X-ray Observatory, or the telescopes of NSF's NOIRLab at the international Gemini Observatory, Kitt Peak National Observatory, and Cerro Tololo Inter-American Observatory. The key to unlocking those magnificent vistas is specialized image-processing software.

Data Sonification: A New Cosmic Triad of Sound

View Wavelengths
Sonification Credit: NASA/CXC/SAO/K. Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)

A new trio of examples of 'data sonification' from NASA missions provides a new method to enjoy an arrangement of cosmic objects. Data sonification translates information collected by various NASA missions — such as the Chandra X-ray Observatory, Hubble Space Telescope, and Spitzer Space Telescope — into sounds.

This image of the Bullet Cluster (officially known as 1E 0657-56) provided the first direct proof of dark matter, the mysterious unseen substance that makes up the vast majority of matter in the Universe. X-rays from Chandra (pink) show where the hot gas in two merging galaxy clusters has been wrenched away from dark matter, seen through a process known as "gravitational lensing" in data from Hubble (blue) and ground-based telescopes. In converting this into sound, the data pan left to right, and each layer of data was limited to a specific frequency range. Data showing dark matter are represented by the lowest frequencies, while X-rays are assigned to the highest frequencies. The galaxies in the image revealed by Hubble data, many of which are in the cluster, are in mid-range frequencies. Then, within each layer, the pitch is set to increase from the bottom of the image to the top so that objects towards the top produce higher tones.

Data Sonification: Sounds from Around the Milky Way

Explore Solos
Sonification Credit: NASA/CXC/SAO/K. Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)

The center of our Milky Way galaxy is too distant for us to visit in person, but we can still explore it. Telescopes give us a chance to see what the Galactic Center looks like in different types of light. By translating the inherently digital data (in the form of ones and zeroes) captured by telescopes in space into images, astronomers create visual representations that would otherwise be invisible to us.

But what about experiencing these data with other senses like hearing? Sonification is the process that translates data into sound, and a new project brings the center of the Milky Way to listeners for the first time. The translation begins on the left side of the image and moves to the right, with the sounds representing the position and brightness of the sources. The light of objects located towards the top of the image are heard as higher pitches while the intensity of the light controls the volume. Stars and compact sources are converted to individual notes while extended clouds of gas and dust produce an evolving drone. The crescendo happens when we reach the bright region to the lower right of the image. This is where the 4-million-solar-mass supermassive black hole at the center of the Galaxy, known as Sagittarius A* (A-star), resides, and where the clouds of gas and dust are the brightest.

Users can listen to data from this region, roughly 400 light years across, either as "solos" from NASA's Chandra X-ray Observatory, Hubble Space Telescope, and Spitzer Space Telescope, or together as an ensemble in which each telescope plays a different instrument. Each image reveals different phenomena happening in this region about 26,000 light years from Earth. The Hubble image outlines energetic regions where stars are being born, while Spitzer's infrared image shows glowing clouds of dust containing complex structures. X-rays from Chandra reveal gas heated to millions of degrees from stellar explosions and outflows from Sagittarius A*.

In addition to the Galactic Center, this project has also produced sonified versions of the remains of a supernova called Cassiopeia A, or Cas A, and the "Pillars of Creation" located in Messier 16.

Welcome to Emily Zhang, Chandra Summer Intern

Emily Zhang
Emily Zhang on the Athabasca Glacier in Banff National Park in Canada. Emily traveled there in the summer of 2018, coincidentally just after finishing her first research project at the CfA! Credit: Emily Zhang

We are delighted to introduce Emily Zhang, who is working as a summer intern in the Chandra X-ray Center at the Center for Astrophysics. Emily is spending half of her time working on astronomy research with Dr Pat Slane and half working on science communication with us in the Chandra Communications and Public Engagement group. She is an undergraduate at Columbia University majoring in astrophysics and (hopefully) concentrating in political science. We asked Emily some questions about her background and interests in astronomy and science communication.

How did your interest in astronomy develop?

I remember watching the TV show Nova with my parents when I was little, and thinking that outer space looked so beautiful and so different from the rest of the world I knew. I also remember going on trips to my local planetarium (the Hayden Planetarium at the Museum of Science in Boston) growing up, and coming out of their shows crying at how big the universe was. I have a vivid memory of checking out a book on black holes for kids from the library, and reading that if you went through a black hole, you could end up in a new universe with up to 11 dimensions. This was not something I understood at all as a 4th grader, but I was impressed.

Behind the Scenes with the Image Makers

2019 Chandra Archive Image Collection
2019 Chandra Archive Collection
Credit: Enhanced Image by Judy Schmidt (CC BY-NC-SA) based on
images provided courtesy of NASA/CXC/SAO & NASA/STScI.

It is both an art and a science to make images of objects from space. Most astronomical images are composed of light that humans cannot detect with their eyes. Instead, the data from telescopes like NASA’s Chandra X-ray Observatory are “translated,” so to speak, into a form that we can understand. This process is done following strict guidelines to ensure scientific accuracy while trying to achieve the highest levels of aesthetics possible.

Over the two decades of the Chandra mission, we have had many talented people who have been involved with making our publicly-released images. We interviewed our current team and share some of their answers to questions posed to all of them below. Kim Arcand is Chandra’s visualization lead and has been with the mission since before launch; Nancy Wolk has been involved with Chandra’s data analysis, software, and spacecraft science operations before joining the image processing team; Lisa Frattare spent years making images from the Hubble Space Telescope before switching career gears but continues to lend her expertise part-time to Chandra’s efforts; Judy Schmidt is a citizen scientist who spends some of her free time using public data to make gorgeous images of space, including those featured in our latest release.

Exploring New Paths of Study with Chandra

Chandra spacecraft image
Illustration: Chandra X-ray Observatory

We make progress in astrophysics in a variety of ways. There is the sort that starts along a defined path, driven by meticulous proposals for telescope time or detailed science justifications for new missions. The plan is to advance knowledge by traveling further than others, or clearing a broader path. And then there are others.

A big mission like NASA's Chandra X-ray Observatory begins with plans for investigation along a slew of different directions and lines of study. At the time of Chandra's launch on July 23rd, 1999, scientists thought these paths would mainly follow studies of galaxy clusters, dark matter, black holes, supernovas, and young stars. Indeed, in the last 20 years we've learned about black holes ripping stars apart (reported eg in 2004, 2011 and 2017), about a black hole generating the deepest known note in the universe, about dark matter being wrenched apart from normal matter in the famous Bullet Cluster and similar objects, about the discovery of the youngest supernova remnant in our galaxy, and much more.

Gearing Up for Chandra’s 20th


Beginning in less than a month, we will be celebrating the 20th anniversary of the launch of NASA’s Chandra X-ray Observatory into space. To get Chandra-philes (Chandra-ites?) ready and bring new ones into the fold, we have been busy here at the Chandra X-ray Center preparing a slew of activities, products, and more to usher in our favorite X-ray telescope’s third decade of operation. Here are just a few of the things to look forward to this year:

  • Launching with yet more content soon, a special section of the website devoted to the Chandra’s 20thanniversary. (Keep an eye on the calendar of events list for potential opportunities in your area to speak with Chandra scientists.)
  • A collection of new Chandra images will be released twenty years to the day – July 23rd– that the Space Shuttle Columbia launched Chandra into orbit.


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