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.

Visit: Journey Through an Exploded Star

A new way to interact and explore Cassiopeia A, the remains of an exploded star, has launched. The press release below outlines this novel initiative between the Smithsonian Center for Learning and Digital Access and the Chandra X-ray Center. Led by Chandra’s Kimberly Arcand, this project allows you to watch, interact, or learn about this supernova remnant while delving into astrophysics, computer science, and more.

This online interactive version of Cas A (as it’s referred to) is one latest milestone with Chandra. Cas A was the “First Light” image that Chandra observed just weeks after being launched into space in 1999. In the nearly twenty years since, Chandra has repeatedly observed Cas A, revealing new secrets about this object from the neutron star at its center to the elements of life it has expelled.

A decade ago, a team of scientists and image processors came together and created the first-ever three-dimensional model of Cas A. Now, this 3D model enters a new phase with the launching of "Journey Through an Exploded Star"” We hope you will explore with us.

Yongquan Xue

We are pleased to welcome Yongquan Xue, a professor at the Department of Astronomy, University of Science and Technology of China (USTC), as a guest blogger. He is an astrophysicist whose main research field is X-ray high-energy astrophysics, and has been significantly involved in the Chandra Deep Fields. Yongquan led the Nature paper that is the subject of our latest press release on the discovery of a magnetar-powered X-ray transient. Before joining USTC in 2012, he worked at Penn State University as a postdoc, after obtaining his astrophysics B.S. and M.S. degrees at Peking University, and Ph.D. degree at Purdue University, respectively.

A neutron star is the compact object formed after a supernova explosion occurring in the late evolutionary stage of a massive star, and it is one of the most mysterious objects in the universe. It is composed of almost all neutrons, and has some extreme physical properties such as ultra-high density and a super-strong magnetic field. It is an excellent natural laboratory for testing basic physical laws. However, up to now, our understanding about the basic properties of neutron stars (e.g., the equation of state, which describes the relation among pressure, density, etc.) is still relatively vague.

CDF-S XT2
Credit: X-ray: NASA/CXC/Uni. of Science and Technology of China/Y. Xue et al; Optical: NASA/STScI

These images show the location of an event, discovered by NASA's Chandra X-ray Observatory, that likely signals the merger of two neutron stars. A bright burst of X-rays in this source, dubbed XT2, could give astronomers fresh insight into how neutron stars — dense stellar objects packed mainly with neutrons — are built.

Chandra X-ray Close-up of the Core of M87, EHT Image of Black Hole
Credit, X-ray: NASA/CXC/Villanova University/J. Neilsen, Radio: Event Horizon Telescope Collaboration

There are a lot of clichés that get thrown around when talking about big scientific discoveries. Words like “breakthrough” or “game changing” are often used. They grab people’s attention, but it’s fairly rare that they apply.

Today’s announcement of the first image ever taken of a black hole (more precisely, of its shadow) truly rises up to that standard. By definition, nothing not even light, can escape the gravitational grasp of a black hole. This, however, is only true if you get too close, and the boundary between what can and cannot get away is called the event horizon.

This dark portrait of the event horizon was obtained of the supermassive black hole in the center of the galaxy Messier 87 (M87 for short) by the Event Horizon Telescope (EHT), an international collaboration whose support includes the National Science Foundation. This achievement is certainly a breakthrough, and we at NASA’s Chandra X-ray Observatory congratulate and applaud the hundreds of scientists, engineers, and others who worked on the Event Horizon Telescope to obtain this extraordinary result.

Astronomers frequently talk about selection effects, where results can be biased because of the way that the objects in a sample are selected. For example, if distant galaxies above a certain X-ray flux – the amount of observed X-rays – are selected for a survey, the most distant objects will tend to be the most luminous, in other words producing the most X-rays.

For doing Chandra publicity we also have a bias, as we are always on the lookout for results where NASA’s Chandra X-ray Observatory data play a starring role. However, there are many papers where Chandra has an important supporting role instead, and other observatories are the stars. Our colleagues at the European Space Agency (ESA) and the University of California, Los Angeles (UCLA), have put out press releases on just such a result.