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.

The Teacup, SDSS J1430+1339
Credit: X-ray: NASA/CXC/Univ. of Cambridge/G. Lansbury et al; Optical: NASA/STScI/W. Keel et al.

Fancy a cup of cosmic tea? This one isn't as calming as the ones on Earth. In a galaxy hosting a structure nicknamed the "Teacup," a galactic storm is raging.

The source of the cosmic squall is a supermassive black hole buried at the center of the galaxy, officially known as SDSS 1430+1339. As matter in the central regions of the galaxy is pulled toward the black hole, it is energized by the strong gravity and magnetic fields near the black hole. The infalling material produces more radiation than all the stars in the host galaxy. This kind of actively growing black hole is known as a quasar.

NGC 3079
Credit: X-ray: NASA/CXC/University of Michigan/J-T Li et al.; Optical: NASA/STScI

We all know bubbles from soapy baths or sodas. These bubbles of everyday experience on Earth are only a few inches across, and consist of a thin film of liquid enclosing a small volume of air or other gas. In space, however, there are very different bubbles — composed of a lighter gas inside a heavier one — and they can be huge.

The galaxy NGC 3079, located about 67 million light years from Earth, contains two "superbubbles" unlike anything here on our planet. A pair of balloon-like regions stretch out on opposite sides of the center of the galaxy: one is 4,900 light years across and the other is only slightly smaller, with a diameter of about 3,600 light years. For context, one light year is about 6 trillion miles, or 9 trillion kilometers.

Orsolya Kovács

We welcome Orsolya Kovács, a third-year PhD student at the Eötvös Loránd University, Hungary where she obtained her MSc degree in astronomy, as our guest blogger. Currently, she is a pre-doctoral fellow at the Smithsonian Astrophysical Observatory, and is the first author on a recent paper on the WHIM featured in our latest press release.

I was working on a totally different subject before I started the missing baryon project with a small group of scientists at the Smithsonian Astrophysical Observatory (SAO) about two years ago. Before I came to the United States as a Ph.D. student, I was involved in analyzing optical data of variable stars observed at the beautiful Piszkéstető Station in the Mátra Mountains, Hungary. In my master’s thesis, I focused on the variable stars of an extremely old open cluster in the Milky Way, and at that time, I also got the chance to gain some observing skills from my Hungarian supervisor.

So the very beginning of my astronomy career was all about optical astronomy. But before getting really into optical astronomy and mountain life, I decided to interrupt this idyllic period, and find some new challenges: I wanted to spend part of my Ph.D. years learning X-ray astrophysics. With this in my mind, I applied to the SAO’s pre-doctoral program, and a few months later I arrived in Massachusetts.

Shortly after introducing me to the basics of X-ray astronomy, Ákos Bogdán at SAO proposed a crazy idea about how to observe the ‘invisible’, i.e. the missing part of the ordinary (baryonic) matter that could possibly solve the long-standing missing baryon problem. The missing baryon problem is related to the mismatch between the observed and theoretically predicted amount of matter.

WHIM Simulation
Credit: Illustration: Springel et al. (2005); Spectrum: NASA/CXC/CfA/Kovács et al.

New results from NASA's Chandra X-ray Observatory may have helped solve the Universe's "missing mass" problem, as reported in our latest press release. Astronomers cannot account for about a third of the normal matter — that is, hydrogen, helium, and other elements — that were created in the first billion years or so after the Big Bang.

Scientists have proposed that the missing mass could be hidden in gigantic strands or filaments of warm (temperature less than 100,000 Kelvin) and hot (temperature greater than 100,000 K) gas in intergalactic space. These filaments are known by astronomers as the "warm-hot intergalactic medium" or WHIM. They are invisible to optical light telescopes, but some of the warm gas in filaments has been detected in ultraviolet light. The main part of this graphic is from the Millenium simulation, which uses supercomputers to formulate how the key components of the Universe, including the WHIM, would have evolved over cosmic time.