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.

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.

Cluster Merger
Credit: X-ray: NASA/CXC/RIKEN/L. Gu et al; Radio: NCRA/TIFR/GMRT; Optical: SDSS

For the first time, astronomers have found two giant clusters of galaxies that are just about to collide, as reported in a new press release by RIKEN. This observation is important in understanding the formation of structure in the Universe, sincelarge-scale structures—such as galaxies and clusters of galaxies—are thought to grow by collisions and mergers.

The composite image shows the separate galaxy clusters 1E2215 and 1E2216, located about 1.2 billion light years from Earth, captured as they enter a critical phase of merging. Chandra’s X-ray data (blue) have been combined with a radio image from the Giant Metrewave Radio Telescope in India (red). These images were then overlaid on an optical image from the Sloan Digital Sky Survey that shows galaxies and stars in the field of view.

Coma Cluster
Credit: X-ray: NASA/CXC/Univ. of Chicago, I. Zhuravleva et al, Optical: SDSS

This image represents a deep dataset of the Coma galaxy cluster obtained by NASA's Chandra X-ray Observatory. Researchers have used these data to study how the hot gas in the cluster behaves, as reported in our press release. One intriguing and important aspect to study is how much viscosity, or "stickiness," the hot gas demonstrates in these cosmic giants.

Galaxy clusters are comprised of individual galaxies, hot gas, and dark matter. The hot gas in Coma glows in X-ray light observed by Chandra. Seen as the purple and pink colors in this new composite image, the hot gas contains about six times more mass than all of the combined galaxies in the cluster. The galaxies appear as white in the optical part of the composite image from the Sloan Digital Sky Survey. (The unusual shape of the X-ray emission in the lower right is caused by the edges of the Chandra detectors being visible.)

Chandra's New Operations Control Center

A new state-of-the-art facility that will operate NASA's Chandra X-ray Observatory has opened. This new Operations Control Center, or OCC, will help Chandra continue its highly efficient performance as NASA's premier X-ray observatory.

As the name suggests, the OCC controls the operation of the Chandra spacecraft while it is in orbit, as scientists and engineers design plans for efficiently and safely observing its targets.

Two years before Chandra's launch into space in 1999, NASA awarded the Smithsonian Astrophysical Observatory a contract to establish the first OCC as part of the Chandra X-ray Center, under the direction of NASA's Marshall Space Flight Center. Northrup Grumman was and continues to be a prime contractor for Chandra, employing many staff members at the OCC.

Professor David Buote

We welcome Professor David Buote as our guest blogger. Buote was one of the first Chandra Postdoctoral Fellows and is now a Professor at the University of California at Irvine. He has studied X-rays from massive elliptical galaxies and galaxy clusters since the time he was a graduate student. His new work with Aaron Barth on the dark matter in a relic elliptical galaxy is the subject of our latest press release.

This year marks the 20th anniversary of the Chandra X-ray Observatory and a chance to celebrate its many and diverse accomplishments. A critical aspect of Chandra's impact on astrophysics is its synergies with observations of phenomena throughout the electromagnetic (EM) spectrum and through other channels like gravity waves and neutrinos. Our study highlights how studies of the X-ray emission of a rare type of galaxy complement and augment what has been learned from observations of the stellar light at longer wavelengths.

Galaxies are broadly divided into two types — disks and spheroids — with substantial overlap in their properties. The spheroids — or elliptical galaxies — are approximately round but range in shape as observed on the sky from nearly circular to elongated somewhat like an American football viewed from the side. Most of what we know about the stars in galaxies comes from observations of visible light photons with lots of help from observations in the nearby ultraviolet and infrared (IR) parts of the EM spectrum.

Costanza Argiroffi

We are pleased to welcome Costanza Argiroffi as a guest author. Costanza led the study reporting the first secure detection of a coronal mass ejection from a star other than the Sun. She is an astrophysicist from the University of Palermo, Italy, where she is from. Her main research field is the study of low-mass stars. She obtained her PhD from the University of Palermo in 2006, and during her studies spent a few months at the Smithsonian Astrophysical Observatory in Cambridge, MA. Then she worked as a postdoc and, since 2008, as a researcher at the University of Palermo.

Coronal Mass Ejections (CMEs) are large-scale expulsions of material previously confined in the atmosphere of a star. CMEs are among the most powerful magnetic phenomena occurring in the atmosphere of the Sun, reaching velocities of about 2 million miles per hour, masses of about 200,000 billion pounds, and kinetic energies equivalent to about 125 million Krakatoa eruptions.

Using data from NASA’s Chandra X-ray Observatory, we have made the first unambiguous detection of a CME by a star other than the Sun.

Markarian 1216
Credit: X-ray: NASA/CXC/Univ. of CA Irvine/D. Buote; Optical: NASA/STScI

Data from NASA's Chandra X-ray Observatory (left) have helped astronomers reveal that a galaxy has more dark matter packed into its core than expected after being isolated for billions of years, as reported in our press release. The image on the right shows the galaxy called Markarian 1216 (abbreviated as Mrk 1216) in visible light from NASA's Hubble Space Telescope over the same field of view.

Mrk 1216 belongs to a family of elliptically shaped galaxies that are more densely packed with stars in their centers than most other galaxies. Astronomers think they have descended from red, compact galaxies called "red nuggets" that formed about a billion years after the Big Bang, but then stalled in their growth about 10 billion years ago.

Fornax Cluster
Credit: X-ray: NASA/CXC/Nanjing University/X. Jin et al.

This image from NASA's Chandra X-ray Observatory shows the region around NGC 1399 and NGC 1404, two of the largest galaxies in the Fornax galaxy cluster. Located at a distance of about 60 million light years, Fornax is one of the closest galaxy clusters to Earth. This relative proximity allows astronomers to study the Fornax cluster in greater detail than most other galaxy clusters.