Chandra Finds Evidence for Violent Stellar Merger

Jul
13

GRB 140903A
Gamma-ray bursts, or GRBs, are some of the most violent and energetic events in the Universe. Although these events are the most luminous explosions in the universe, a new study using NASA's Chandra X-ray Observatory, NASA's Swift satellite and other telescopes suggests that scientists may be missing a majority of these powerful cosmic detonations.

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"We Got This"

Jul
11
Women Summit
Illustration: NASA/CXC/K.Divona


Last month, I was honored to attend an extraordinary event: the United State of Women Summit convened by the White House. Since the word "summit" means a pinnacle, this couldn’t have been more appropriate for how I viewed this day and the amazing attendees I was able to share it with.

The United State of Women Summit brought together leaders in all different professional fields – from politics to entertainment, from science to finance. The common thread among all of the participants, however, was easy to find: everyone there wanted to continue to foster and enhance the opportunities for girls and women in whatever endeavors they may choose to pursue.

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Tracking Down a Stealthy Black Hole

Jun
27

We are pleased to welcome Bailey Tetarenko as our guest blogger. She is the lead author on a paper featured in our latest press release about a possible new population of black holes in the Galaxy. Bailey received her undergraduate degree in Astrophysics at the University of Calgary and then a master’s in Physics at the University of Alberta in 2014. She is now two years into her Ph.D. in Physics at the University of Alberta, where she is studying the black hole population of the Milky Way.

Bailey Tetarenko
From right to left Bailey Tetarenko, Dr. Arash Bahramian and Dr. Craig Heinke and Dr. Greg Sivakoff. Credit: John Ulan


For fans of black holes, we live in exciting times. Nearly all of our empirical knowledge about stellar mass black holes – that is, black holes weighing about 5 to 35 times the mass of the sun – comes from black hole X-ray binary systems. In these systems a black hole pulls in material from a nearby companion star, causing the system to become very bright in X-rays. But, recently gravitational waves have been detected from pairs of distant black holes that emit no electromagnetic radiation (a.k.a. all forms of light). And now, my team's work suggests that there are many black hole X-ray binaries in our own Milky Way that emit relatively little X-rays.

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How to Hold a Dead Star in Your Hand

Jun
21

star in your hand
Illustration: NASA/CXC/K.DiVona

Objects in space are rather far away. The Moon is our closest celestial neighbor at nearly a quarter million miles from Earth, and the nearest star, our Sun, is 93 million miles away.

These extreme distances mean that it’s usually impossible to touch real objects in space (meteorites that fall to the ground not withstanding). Advances in both astronomy and technology, however, now allow you to do the next best thing: hold a 3-D model of one based on real data.

Cassiopeia A is located about 10,000 light years from Earth. How does that compare with our local cosmic objects of the Sun and Moon? One light year equals the distance that light travels in a year, or just under 6 trillion miles (~10 trillion km). This means that Cassiopeia A is an impressive 60,000,000,000,000,000 miles (100,000,000,000,000,000 km) from Earth. But since it’s in our Milky Way, it’s in our cosmic back yard, so to speak.

The story behind such a remarkable feat starts with how astronomers study space. Unlike previous generations of sky gazers, today’s astronomers look at the Universe in many kinds of light, across the full electromagnetic spectrum. Through advanced telescopes and detectors, scientists can “see” from radio waves to gamma rays. Why is this important? We need to look at the Universe in all the types of lights to even begin to understand it.

Take X-rays, for example. Back in 1999, NASA’s Chandra X-ray Observatory was launched in order to observe the high-energy Universe including such things as colliding galaxies, black holes, and supernova remnants.

One such supernova remnant that Chandra studies is Cassiopeia A. About 400 years ago, in our own Milky Way galaxy, a star that was about 15 to 20 times the mass of our Sun, detonated in a supernova explosion.

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Smaller Stars Pack Big X-ray Punch For Would-be Planets

Jun
13

TW Hya
Young stars much less massive than the Sun can unleash a torrent of X-ray radiation that can significantly shorten the lifetime of planet-forming disks surrounding these stars. This result comes from a new study of a group of nearby stars using data from NASA's Chandra X-ray Observatory and other telescopes.

Researchers found evidence that intense X-ray radiation produced by some of the young stars in the TW Hya association (TWA), which on average is about 160 light years from Earth, has destroyed disks of dust and gas surrounding them. These disks are where planets form. The stars are only about 8 million years old, compared to the 4.5-billion-year age of the Sun. Astronomers want to learn more about systems this young because they are at a crucial age for the birth and early development of planets.

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Coding (and Coloring) the Universe

Jun
13

Micro to macro
Micro to macro
Illustration: NASA/CXC/K.Divona

When people ask me what I do for work, I often say that I’m a storyteller. It’s not that I stand on a stage with a microphone and narrate long tales to a rapt audience.

My stories are told differently, not through voice or music, but through lines of code and technical applications. They are stories, of science.

As an undergraduate, I began my career in molecular biology, looking at the tiny organisms that can transmit Lyme disease to humans aboard the Ixodes Scapularis (a.k.a., the Deer tick). But by the time I graduated, I was moving on to learn about another type of science: that of computers.

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Cosmic Genealogy: the Ancestors of Supermassive Black Holes

May
24
Fabio Pacucci
Fabio Pacucci

It is a pleasure to welcome Fabio Pacucci as a guest blogger. Fabio led the study that is the subject of our latest press release. He is going to defend his Ph.D. Thesis at the Scuola Normale Superiore in Pisa (Italy), under the supervision of Andrea Ferrara. During his Ph.D. he spent several months at the Institute d’Astrophysique de Paris (IAP) in France, Yale University and Harvard University in the USA. In September he is starting his first postdoctoral position at Yale University. Fabio has mainly been working on understanding the properties of the first black hole seeds, formed when the Universe was less than one billion years old.

It was a sunny and hot afternoon in Pisa when Andrea Ferrara, my Ph.D. supervisor, suggested that I study the first black holes formed in the Universe. This topic is among the most interesting in cosmology. We know that almost every galaxy hosts a supermassive black hole (SMBH) at its center. In the Milky Way there is a black hole about 4 million times more massive than the Sun, but objects up to 10 billion times the mass of the Sun have also been observed.

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Help Wanted: A Universe of Images

May
16

Survey

Images of our shared Universe provide snapshots of various phases of life and death, and different physical phenomena, found in locations across the cosmos. Modern telescopes allow us to “see” what the human eye cannot. This new generation of ground- and space-based telescopes has created an explosion of images for people everywhere to explore.

The Aesthetics & Astronomy project studies the perception of multi-wavelength astronomical imagery and the effects of the scientific and artistic choices in processing this astronomical data. The images come from a variety of space and ground-based observatories, including NASA’s Chandra X-ray Observatory and Hubble Space Telescope. Studies such as these can benefit astronomy across the electromagnetic spectrum of astronomical images, and may help visualization of data in other scientific disciplines.

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Chandra Movie Captures Expanding Debris From a Stellar Explosion

May
12

Tycho's Supernova Remnant
When the star that created this supernova remnant exploded in 1572, it was so bright that it was visible during the day. And though he wasn't the first or only person to observe this stellar spectacle, the Danish astronomer Tycho Brahe wrote a book about his extensive observations of the event, gaining the honor of it being named after him.

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"Russian Doll" Galaxy Clusters Reveal Information About Dark Energy

Apr
28

We are happy to welcome Dr. Andrea Morandi as our guest blogger, who is giving us insight into his recent work on using galaxy clusters to investigate the nature of dark energy. Originally from Italy, Dr. Morandi received his Ph.D. in astronomy from the University of Bologna. Prior to his current position as a research assistant at the University of Alabama in Huntsville, Dr. Morandi was a post-doctoral fellow at the DARK Cosmology Center in Copenhagen and Tel Aviv University, followed by time as a research associate at Purdue University.

Andrea Morandi

In 1998 and 1999 astronomers discovered the accelerating expansion of the Universe, providing evidence for the existence of the mysterious dark energy driving this acceleration. The same year I started to study astronomy at the Bologna University, fascinated by this major breakthrough in cosmology. I guess my interest for cosmology started from here.

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