[Brian's blog] A Look into the Building Blocks of Life

Maggie’s note: Please welcome a new guest blogger, astronomer Brian Williams!

Most of the stars in the universe will, like our Sun, live steadily for billions of years before ending in relative serenity. However, a select few will go out in a blaze of glory called a supernova, the explosion of an entire star. These cosmic blasts are among the most powerful events in the universe, and can be seen at distances of billions of light years; releasing, in a matter of seconds, an amount of energy equal to the Sun’s output over billions of years. In the past few decades, observations of distant supernovas helped astronomers pin down the expansion rate of the universe, allowing the determination that the universe is not, as was previously expected, slowing down in its expansion, but speeding up, due to the presence of a mysterious force known as “dark energy.”

Nearly all of the matter in the universe that we understand is made of hydrogen and helium, the simplest elements, created in the Big Bang. The rest, including the oxygen that we breath, the carbon, calcium, and iron in our bodies, sodium and choride on our dinner tables, and the silicon in our computer chips were forged in the cores of stars: hot and powerful element factories that convert lighter elements into heavier ones. The gravity that holds stars together generally keeps these elements locked deep inside their interiors, never to be spread throughout the universe. Luckily, supernova explosions provide a mechanism to do just this, liberating these fundamental building blocks of planetary systems and, indeed, life itself, throughout the universe. It is no exaggeration to say that we owe our entire existence to the life, and death, of stars that existed before our Sun and solar system were even created.

In my research at NASA’s Goddard Space Flight Center, the fading of a supernova from view marks only the beginning of my interests. I study the fiery aftermath of the explosion, which remains visible for thousands of years. An exploding star doesn’t simply dissipate into nothingness; rather, it forms a nebula known as a supernova remnant, a cloud of gas expanding at speeds of several million miles per hour. The gas cloud is made up of both material that has been ejected from the now exploded star and particles of gas and dust tenuously floating in the interstellar medium, the scientific name for the space between the stars. An example of a supernova remnant is shown below. This remnant, the remains of a star that exploded in 1604 A.D, is known as Kepler’s SNR, named for the famous German astronomer who kept detailed records of “De Stella Nova” (the New Star).

Kepler’s Supernova remnant, as seen by NASA’s Spitzer Space Telescope (red), Hubble Space Telescope (yellow), and Chandra X-ray Observatory (green and blue). Credit: NASA, R. Sankrit (NASA Ames) and W.P. Blair (Johns Hopkins Univ.)

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[Maggie's blog] Shiny: a Look at Astro-H Flight Hardware

Here’s some brand new photos from one of the missions we are working on here at the Astrophysics Science Division – Astro-H! Astro-H is an orbiting X-ray astronomy observatory being developed by the Japanese Aerospace Exploration Agency (JAXA). NASA and JAXA have teamed up to develop a high resolution “Soft X-Ray Spectrometer” (SXS) for the mission.

The SXS uses a state-of-the-art X-ray calorimeter spectrometer at the focus of an X-ray telescope. The calorimeter is a low-temperature sensor that measures the energy of each X-ray photon as heat and is extraordinarily precise. NASA Goddard has the lead responsibility for the SXS detector system.

We at Goddard are also providing two telescopes, one for the SXS and one for another instrument, the Soft X-ray Imager (SXI).

Pictured here is one completed X-ray telescope for ASTRO-H plus one quadrant of a telescope. The black part on top of the X-ray telescope is the precollimator. The precollimator helps eliminate the glare from bright X-ray sources from outside the nominal viewing direction. It will be made in Japan but these visiting colleagues actually brought a test version to make sure it fits properly with the Goddard-made parts.

Credit: Kenji Hamaguchi

Takashi Okajima (left) and Pete Serlemitsos(right) with visiting Japanese colleagues in the middle. They are pictured with the finished flight hardware.

Credit: Kenji Hamaguchi

(Astro-H will also have hard X-ray telescopes, similar to the ones on NuSTAR – those are entirely made in Japan.)

If you’d like to learn more about how X-ray telescopes work, check out our website for NASA/Japanese X-ray astronomy collaborations, particular the technology section. Also, Suzaku (the previous generation collaborative observatory) carried a similar instrument to the SXS and similar detectors.

[podcast] NuStar: NASA’s Newest X-Ray Eyes

Click to listen! (7.5MB MP3, right-click to save)
Transcript (Text, PDF)

It’s an exciting experience for any space geek to watch a new satellite launch into orbit. Even through an online video feed, it’s thrilling to see something that Earthlings worked for years to create headed for its new home, to be our newest eyes on the Universe. These launches don’t happen so often, especially for astrophysics missions, where we see the launch of a new observatory every few years at most. Earlier in 2012, we were excited about the launch of NuSTAR, a small explorer X-ray mission collaboratively created by teams at Caltech, NASA, and over a dozen other institutions around the world.

NuSTAR advances the international astronomical community’s ability to observe some of the hottest, densest, and most energetic objects in the Universe. Its detectors are sensitive at significantly higher energies than other X-ray observatories such as Chandra and XMM-Newton, giving astronomers a chance to extend the range of data they collect. During its mission lifetime, NuSTAR will conduct a survey for massive black holes, study the particles accelerated in active galaxies, and observe the remnants of exploded stars and the chemical elements they’ve left behind.

We were interested to find out more about NASA Goddard’s involvement in the mission, so we interviewed post-doc Dr. Dan Wik about his work with the satellite’s optics and his interest in observing galaxy clusters with NuSTAR.

Credit: Dan Wik

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[Blog] Awesomeness Round-Up – 6/11/2012

On Tuesday, June 5, Venus passed in front of the Sun – an event that was visible on seven continents for those that were fortunate enough to have clear weather. These “transits” of Venus are very rare, coming in pairs separated by more than a hundred years. This June’s transit, the second of a 2004-2012 pair, won’t be repeated until the year 2117.

Credit: NASA/SDO, AIA

Credit: JAXA/NASA/Lockheed Martin

The first image is a composite of images taken by the Solar Dynamics Observatory that shows the path that Venus took across the disk of the Sun. The second is a close-up image taken by Hinode – a joint JAXA/NASA mission to study the connections of the sun’s surface magnetism, primarily in and around sunspots.
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[Koji's blog] An “X-ray Astronomer” Among Radio Telescopes

To me, an observational astronomer, there is no such thing as X-ray astronomy. What I do is astronomical research on objects that happen to emit X-rays, as well as ultraviolet, visible, and infrared, etc. light. My research interest is not X-rays, but astronomical objects called cataclysmic variables and symbiotic stars – both involve dense “ash” of sun-like stars called white dwarfs in binary systems.

Having said that, to instrument builders, X-ray astronomy *is* a distinct discipline. Also, it takes time to become adept at using any complex tools and X-ray data analysis is no exception. In that sense, in terms of technical proficiency, I am an X-ray astronomer. I have also worked with infrared, visible light, and ultraviolet observations before – but not radio observations, not even by collaborating with the experts, until recently.

This is changing, partly because a phenomenon I’m very interested in called “nova outburst” can produce radio waves and X-ray photons. Basically, novae are nuclear explosions on the surface of the white dwarfs in cataclysmic variables and symbiotic stars. The material ejected (called ejecta) from these explosions emit radio waves when they are just expanding. However, collisions within the ejecta or collisions of the ejecta with some other materials can heat them up to many millions of degrees, making them bright in X-rays. So it makes a lot of sense to observe novae with X-rays and radio at the same time. Another reason for my evolving collaboration is that the premier instrument of radio astronomy has undergone a significant upgrade in the last several years, making them capable of doing observations that were never possible before.

Recently, I had the chance to visit the Science Operations Center of National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico. About one hour west, on the high plains of San Augustin, is what used to be called the Very Large Array (VLA). The VLA uses a set of 27 antennas, each having a diameter of 25 meters (or 82 feet). By combining the signals from these antennas, the VLA acts like a much bigger telescope – the separations of the antennas, not the size of each individual antenna, determine how detailed an image we get (“the angular resolution”). The antennas of the VLA can be moved along special railroad tracks to several pre-constructed stations to suit the need of the observers. It’s a stunning sight to see the VLA, particularly when the entire array is moving from one target on the sky to the next. I even got to climb up on the 28th antenna undergoing routine maintenance (you don’t want to do that with ones in use – for one thing, if the antenna is tilted to observe an object low in the sky, it would be very dangerous).

Credit: Koji Mukai

Credit: Koji Mukai

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[Maggie's blog] Meet NuSTAR!

Meet the Nuclear Spectroscopic Telescope Array or NuSTAR – a new X-ray telescope that’s being launched in March of 2012. Below is the actual telescope in its pre-launch configuration:

Credit: NASA/JPL-Caltech/Orbital

And here is what it will look like post-launch!

Credit: NASA

NuSTAR has an interesting design that includes a deployable mast, which is used to extend the observatory to its full 10 meter focal length. Because this mast will flex slightly as the spacecraft orbits, NuSTAR employs a laser measurement system to monitor the degree of motion of the mirrors relative to the detectors.

NuSTAR will survey high-energy X-ray emission from black holes, help determine how chemical elements are cooked up in supernova explosions, and find new, previously unknown high energy sources. Gorgeous Chandra X-ray Observatory imagery has been done at relatively low X-ray energies – NuSTAR will extend the energy range of X-ray images by nearly a factor of 10, via breakthroughs in detector technology and X-ray optics.

You can read more at the HEASARC Picture of the Week and on the NuStar website. For education and outreach about NuSTAR, try the Caltech site.

[Blog] Awesomeness Round-Up – 12/22/2011

Credit: NASA/ESA/HubbleSite

Looking for a space-themed way to say “Happy Holidays!” to your family and friends? How about some printable holiday cards with Hubble images? Every card features fabulous astronomical objects… and when you go to download a card, you’ll find links to articles about related Hubble discoveries! The ornaments above feature Mars, the Whirlpool Galaxy, the star LL Ori, and several nebulae – the Cone Nebula, the Orion Nebula, the Retina Nebula, the Eskimo Nebula, the Bubble Nebula, and the Crab Nebula. Can you tell which is which?
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[Maggie's blog] A Fond Farewell to ROSAT

It’s time for me to be nostalgic about another satellite. Last time it was the Rossi X-ray Timing Explorer which I really started my career in websites/education/outreach on. This time, it’s the Röntgensatellit, or ROSAT, a German-led X-ray telescope. When I was an intern here, my first job was to add captions to our archive of ROSAT images!

ROSAT exceeded its 5-year mission by four years and was finally turned off in 1999. Now, 12 years later, ROSAT is expected to re-enter the Earth’s atmosphere sometime in October 2011 and break up.

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[Blog] Awesomeness Round-Up – 10/3/2011

There are gorgeous new shots of a full-scale test version of one layer of the James Webb Space Telescope’s tennis court-sized sunshield:

Credit: NGAS

Credit: NGAS

There are two more on their Flickr.

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[Try It At Home] X-ray Data: Light curves, Spectra & Images Activity

Here at the Astrophysics Science Division, we have a large group that studies X-ray astronomy. X-ray astronomy doesn’t get as much press as observations from telescopes like the Hubble, but nevertheless is a very valuable tool for understanding how the universe works.

In this blog entry we’ll talk about how X-ray observations differ from those made at optical wavelengths, what kind of data you get from X-ray telescopes, and we’ll give you a fun activity you can try at home or in the classroom to demonstrate the different types of X-ray astronomy data (which will include light curves, spectra, and images).

The Chandra spacecraft

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