Tagged: NASA Blueshift Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 2:52 pm on July 22, 2015 Permalink | Reply
    Tags: , , NASA Blueshift   

    From NASA Blueshift: “How Many Stars in the Milky Way?” 

    NASA Blueshift
    NASA Blueshift

    July 22, 2015
    Maggie Masetti

    Recently I was asked to help someone answer the question of how many stars are in the Milky Way – that there were differing answers out there, and which was the right one?

    This question turns out to have a really interesting (and possibly frustrating?) answer. And the answer is that we really don’t know. We can make estimates, but there isn’t a firm, solid, 100% answer.

    A gorgeous panorama of the Milky Way. Read more. Credit: ESO/S. Brunier

    Why is this? Well, first off, there isn’t a way to simply count the number of stars in the Milky Way individually – that’s where the estimates come in. To make an estimate, we have to calculate the mass of our galaxy, and then the percentage of that mass that is made up of stars.

    Then we have to decide what the mass of an average star is so we can calculate the number of stars in the galaxy. This is not trivial either – you could say our Sun is an average sized star, which would give you one estimate for the number of stars in the galaxy. But our Sun may not really be typical – there are a lot of much lower-mass stars out there. Using a low-mass red dwarf as an average-mass star will give you a totally different answer for the total number of stars in our galaxy.

    This diagram shows a brown dwarf in relation to Earth, Jupiter, a low-mass star, and the sun. Credit: NASA

    It’s kind of like if you had a 10 pound bag. You can see in the top of the bag and can tell that there are coins there, mixed in with candy, dried beans, screws, rice, and other things you can’t see, but that must be heavy enough to make the bag weigh 10 pounds. Now try to calculate how many coins are in that bag – it’s hard to do because you can only really count the coins you can see – so you have to figure out if the contents of the bag that you can see is representative of the whole of the bag. Are coins evenly distributed throughout? Let’s say you can say with relative confidence that coins make up 10% of mass of the bag, or one pound. How many coins are there total? Well, you can see pennies and quarters and nickels, and each type of coin has a different mass and size. If you picked the quarter as being the average mass of a single coin, you might get one answer for the total number of coins. But if you picked the penny, which is lighter, you’d have a higher total number of coins because there are more pennies to the pound than quarters.

    Image credit: theilr

    There are different models for estimating the number of stars in the Milky Way and the answers they give differ depending on what is used as the average mass of a star. The most common answer seems to be that there are 100 billion stars in the Milky Way on the low-end and 400 billion on the high end. But I’ve seen even higher numbers thrown around.

    Credit: NASA, ESA, W. Clarkson (Indiana University and UCLA), and K. Sahu (STScl)

    See the full article here.

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition

    Blueshift is produced by a team of contributors in the Astrophysics Science Division at Goddard. Started in 2007, Blueshift came from our desire to make the fascinating stuff going on here every day accessible to the outside world.

    NASANASA Goddard Banner

  • richardmitnick 10:50 am on July 4, 2015 Permalink | Reply
    Tags: , , NASA Blueshift   

    From NASA Blueshift: 

    NASA Blueshift
    NASA Blueshift

    July 4, 2015
    Sara Mitchell

    Happy Fourth of July to those of you that celebrate it! We couldn’t let the date slip by without presenting a little display of cosmic fireworks. We think you’ll find they’re much quieter than the earthly kind.

    We start with this 3D visualization of the nebula Gum 29 with the star cluster Westerlund 2 at its core. Young stars light up the gas around them as we sail through:

    Credit: NASA, ESA, G. Bacon, L. Frattare, Z. Levay, and F. Summers (Viz3D Team, STScI), and J. Anderson (STScI)

    In 1901, GK Persei captivated skygazers as it briefly appeared as the brightest object in the night sky. Now, astronomers understand that this light show was caused by a thermonuclear explosion on the surface of a white dwarf star. This recent image of GK Persei contains X-rays from Chandra (blue), optical data from NASA’s Hubble Space Telescope (yellow), and radio data from the National Science Foundation’s Very Large Array (pink).

    Image credit:
    X-ray: NASA/CXC/RIKEN/D.Takei et al; Optical: NASA/STScI; Radio: NRAO/VLA

    Supernova 1987A has put on a light show that has kept astronomers studying it for nearly 30 years. The vivid ring of material around the supernova, captured here by Hubble’s Advanced Camera for Surveys, was likely shed by the original star about 20,000 years before it exploded.

    Image credit: NASA, ESA, P. Challis and R. Kirshner (Harvard-Smithsonian Center for Astrophysics)

    Astronomers have nicknamed this planetary nebula “Eskimo Nebula” because they see a head wearing a parka hood. The gas clouds around this object composed the outer layers of a Sun-like star thousands of years ago. Now, a strong wind of particles from the central star is ejecting the unusually long filaments seen around it.

    Image credit: NASA/Andrew Fruchter (STScI)

    The Helix Nebula, another beautiful planetary nebula, has an eerie resemblance to a giant, all-seeing eye in this infrared image from the Spitzer Space Telescope. This object is what remains after the death of a small- to medium-sized star. The tiny white dot in the center is a white dwarf, the glowing red gas was blown out when the star died, and the outer gaseous layers are seen in brilliant blue and green.

    Image credit: NASA/JPL-Caltech/Univ.of Ariz.

    A stellar nursery is a surprisingly violent and energetic place. Astronomers have a chance to peer inside NGC 3603, a starburst cluster in the constellation Carina, because ultraviolet radiation and stellar winds have blown a cavity in the gas and dust surrounding these huge young stars.

    mage credit: NASA, ESA, R. O’Connell (University of Virginia), F. Paresce (National Institute for Astrophysics, Bologna, Italy), E. Young (Universities Space Research Association/Ames Research Center), the WFC3 Science Oversight Committee, and the Hubble Heritage Team (STScI/AURA)

    Enjoy and learn.

    See the full article here.

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition

    Blueshift is produced by a team of contributors in the Astrophysics Science Division at Goddard. Started in 2007, Blueshift came from our desire to make the fascinating stuff going on here every day accessible to the outside world.

    NASANASA Goddard Banner

  • richardmitnick 5:45 pm on December 9, 2014 Permalink | Reply
    Tags: , , , , NASA Blueshift,   

    From blueshift: “Happy Birthday, Swift!” 

    NASA Blueshift
    NASA Blueshift

    December 9, 2014
    Maggie Masetti

    This is our third Happy Birthday post for a satellite in the last year or so – which is pretty cool actually, to have satellites that are hitting significant milestones and have had the longevity to still be doing great science. We had Fermi’s 5th birthday in August 2013, followed by Spitzer’s 10th in September 2013.

    NASA Fermi Telescope

    NASA Spitzer Telescope

    And then we just recently hit Swift’s 10th birthday. What is Swift? Swift is an observatory that has been dedicated to studying gamma-ray bursts (GRBs) – and it can study GRBs and their afterglows at gamma ray, X-ray, ultraviolet, and optical wavelengths.

    NASA SWIFT Telescope

    GRBs are short-lived bursts of gamma-ray light, which can last from few milliseconds to several minutes, and shine hundreds of times brighter than a typical supernova and about a million trillion times as bright as our Sun. Furthermore, when a GRB erupts, it is briefly the brightest source of cosmic gamma ray photons in the observable Universe. (Thanks to Imagine the Universe!, more info there.) What exactly was causing these incredibly energetic bursts was a big mystery. Enter Swift. Data from Swift (and also the gamma-ray Fermi observatory) have given us valuable clues that are helping us solve this mystery. (We got the scoop on the latest in the interview you’ll see below.

    We actually built Swift here at NASA Goddard. I was fortunate enough to get the chance to see the satellite before it launched. They displayed it in its cleanroom. Here is me 10 years ago with Brendan, Steve, and Meredith. (Meredith and Steve have been a huge help to Blueshift behind the scenes on the server side of things.)

    With Swift

    Sara and I talked to the Principal Investigator for the Swift mission, Neil Gehrels, to ask him 10 questions about Swift for its 10th Anniversary.

    Blueshift: What is your role with Swift? How long have you been involved with the project?

    Neil Gehrels: I am the lead scientist of Swift. In NASA jargon, my role is Principal Investigator. My involvement started at the very beginning in 1996 when Nick White and I conceived of the mission.

    Blueshift: How did Swift come to be?

    Neil Gehrels: NASA has competitions every other year for small to medium sized missions. Typically 40 teams put in proposals and one is chosen to fly through a rigorous and grueling peer review process. We proposed Swift in 1998 and were fortunate enough to have it selected. The observatory was constructed from 1999 to 2004 and then launched.

    Blueshift: Were you at the launch? What was it like to watch Swift head into space?

    Neil Gehrels: Yes, I was in the control center at the launch. It was one of the most exciting days of my life. Exhilaration mixed with fear of failure! Luckily everything went perfectly.

    Blueshift: Why gamma rays? What are they, and what do they tell us about the Universe?

    Neil Gehrels: Gamma rays are like really powerful X-rays. Just like the X-rays at the dentist office, they are very penetrating rays of light. The are produced in the hottest, most explosive events in the universe. We use them to study the death of stars and birth of black holes.

    Blueshift: What’s Swift’s role within the international fleet of astrophysics satellites?

    Neil Gehrels: Swift is the NASA’s premier satellite for observing the most explosive and dynamic sources in the universe. Objects such as gamma-ray bursts and supernovae. The observatory detects the transient sources and then repoints itself, without human intervention, at the source for detailed observations with the on-board telescopes

    Blueshift: What research have you personally done with Swift?

    Neil Gehrels: My personal research is studying gamma-ray bursts. Whenever one is detected by Swift, which occurs about twice per week, I receive a text message on my phone and run to the nearest computer to look at the new data.

    Blueshift: Did you expect to still be doing amazing science with Swift ten years later?

    Neil Gehrels: Swift was built to operate for 2 years, but hoped it would go much longer. It is such a joy to have it still working perfectly after ten years.

    Blueshift: Has Swift helped provide answers to major astronomical mysteries such as the cause of gamma-ray bursts?

    Neil Gehrels: Yes, Swift has made major discoveries every year. We found out that long and short gamma-ray bursts have very different origins. Long bursts are from exploding stars and short bursts are from the collision of compact neutron stars. Another big finding was the detection of 2 gamma-ray bursts from the very distant edges of the universe. They were produced in the explosions of very early stars.

    Blueshift: What do you think are the top discoveries made by Swift over the last decade?

    Neil Gehrels: In addition to the major discoveries about gamma-ray bursts, another biggie was detecting a the shredding of a star by a massive black hole. The star drifted too close to the black hole and was torn apart by the strong gravity of the black hole. Another fun discovery was a flash of X-rays from a new supernova explosion. We were lucky to be looking in the direction of a new supernova at the time the star first collapsed and discovered a brilliant pulse of X-rays. It was the long-predict “shock break-out” where a wave of heat zooms through the star at the moment of collapse and bursts out of the surface.

    Blueshift: What’s next for Swift?

    Neil Gehrels: Hopefully Swift will last another 10 years. We are using it in a new way lately, as a resource for astronomers. Our colleagues send an alert to us when they find something interesting going on in the universe and we point Swift at it.


    And happy birthday to Swift, we hope you have many more!

    The cake from Swift’s birthday party. Credit: Maggie Masetti

    See the full article, with animation, here.

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition

    Blueshift is produced by a team of contributors in the Astrophysics Science Division at Goddard. Started in 2007, Blueshift came from our desire to make the fascinating stuff going on here every day accessible to the outside world.

    NASANASA Goddard Banner

  • richardmitnick 6:45 pm on November 25, 2014 Permalink | Reply
    Tags: , , , , NASA Blueshift   

    From NASA/Blue Shift: “Novae in Different Lights” 

    NASA Blueshift
    NASA Blueshift

    First Article:

    A “Noval” Mystery

    November 10, 2014
    Maggie Masetti

    The mystery around Nova V959 Mon was recently deciphered with the use of multiwavelength light – including radio, X-ray, and gamma-ray.

    First off, what is a nova? It’s basically a huge thermonuclear explosion that’s caused when a dense white dwarf star pulls material from an orbiting companion star onto itself. The resulting blast spews gaseous debris outward.

    And what’s the mystery around V959 Mon? Well, in 2012, astronomers using the Fermi Gamma-ray Space Telescope noticed that V959 Mon gave off gamma-rays, which was a new and surprising development in the study of novae. Also now astronomers had to figure out the mechanism by which this occurred.

    Credit: NASA/Sonoma State

    Fortunately, there were radio observations made at the same time with the Karl G. Jansky Very Large Array (VLA), as well as later ones by the Very Long Baseline Array (VLBA) and the European VLBI network. The VLA data indicated that there were subatomic particles moving nearly at the speed of light, that were interacting with the magnetic field in the shock front. Both radio and gamma-ray emission requires such fast-moving particles – so by locating the site of one, we can locate the other. The later VLBI observations show two “distinct knots of radio emission,” which were moving away from each other.

    Adding all these together with more VLA observations in 2014 and UK observations made with e-MERLIN, finally provided scientists with the needed information for piecing this together.

    Credit: Dave Finley, courtesy National Radio Astronomy Observatory and Associated Universities, Inc.


    European VLBI
    European VLBI

    eMerlin Radio Telecope Array

    What is happening is this. The white dwarf star, which is the nuclear ash of a star like the sun, pulls matter – fresh fuel – from its companion star to itself. When enough fuel accumulates after thousands of years, the surface layer detonates in a thermonuclear explosion. This seems to throw off the envelope preferentially in the orbital plane of the binary. Later, the white dwarf blows off a wind of particles, and this wind moves even faster than the material the star initially threw off. When this faster flow of particles hits the slower moving material, it creates a shock, which accelerates the particles to the speeds necessary to produce gamma-rays and the knots of radio emission.

    Says Laura Chomiuk, Michigan State University researcher, “We not only found where the gamma-rays came from, but also got a look at a previously-unseen scenario that may be common in other nova explosions.”

    And indeed, since the 2012 outburst of V959 Mon, the Fermi telescope has detected gamma-rays from three additional nova explosions.

    These images show Fermi data centered on each of the four gamma-ray novae observed by the LAT. Colors indicate the number of detected gamma rays with energies greater than 100 million electron volts (blue indicates lowest, yellow highest).
    Image Credit: NASA/DOE/Fermi LAT Collaboration

    We got the chance to interview Laura Chomiuk to ask her more about her research on this nova and about the scientific questions that surrounded it.

    NASA Blueshift: Tell us a little bit about yourself! How did you get into working on novae?

    Laura Chomiuk: I’ve just started my second year as a professor at Michigan State. I’m loving my job so far – working with a lot of excited and exciting students and postdocs, having the freedom to think about interesting scientific questions, and be able to take advantage of our lovely national observatories. I actually got into studying novae because of one of these lovely public observatories – the Very Large Array. After graduate school, I spent some time hanging out at the telescope, helping polish up some of its new capabilities, and a team of scientists came knocking because they wanted help observing novae with the VLA. I got so lucky that day! It had never occurred to me to study novae before, but they turned out to be so much richer and more interesting and well, weirder, than I could have dreamed!

    NASA Blueshift: Could you explain your research in a nutshell?

    Laura Chomiuk: Novae are supposed to be these relatively low-energy, garden variety explosions that we understand really well, but they keep throwing surprises at us. The most recent surprise was that they appear to emit really high energy light with gamma-ray wavelengths, as detected by NASA’s Fermi Gamma-Ray Telescope. Gamma-ray sources are rare in our galaxy, and nobody expected gamma-rays from novae, because gamma-rays are typically produced in really fast, violent shocks, and novae weren’t supposed to have such energetic blasts. Our team was able to zoom in one of these gamma-ray producing novae and take really detailed images using a bunch of radio telescopes. These pictures showed the expansion of the nova explosion and also showed how the nova could produce gamma-rays. We found that the nova explosion isn’t at all spherical like a ball, but instead it is elongated like an hourglass. The fast moving material in the hourglass plows into really dense, slow-moving stuff that hangs out at the waist of the hourglass, and this interaction gives you the violent shocks needed for gamma-ray production.


    A nova does not explode like an expanding ball, but instead throws out gas in different directions at different times and different speeds. When this gas inevitably crashes together, it produces shocks and high-energy gamma-ray photons. The complex explosion and gas collisions in nova V959 Mon is illustrated above. In the first days of the nova explosion, dense relatively slow-moving material is expelled along the binary star system’s equator (yellow material in bottom left panel). Over the next several weeks, fast winds pick up and are blown off the binary, but they are funneled along the binary star system’s poles (blue material in bottom central panel). The equatorial and polar material crashes together at their intersection, producing shocks and gamma-ray emission (red regions in central panel). Finally, at later times, the nova stops blowing a wind, and the material drifts off into space, the fireworks finished (in bottom right panel). Our [artist conception] images, in the top row, illustrate these phases. In the top left panel, the color image shows the bulk of the nova ejecta, as imaged by e-MERLIN. Around that time, the shocks were imaged with the EVN array, and showed the locations of shocks and gamma-ray production (shown here as black contours, tracing synchrotron emission). The center panel shows similar components one month later, when the shocked knots have expanded and a third component has become visible. At late times (color image in the top right panel), the brightest, densest material is now oriented differently, corresponding to the slower moving equatorial material.
    Credit: L. Chomiuk, B. Saxton, NRAO/AUI/NSF

    NASA Blueshift: What are novae? What do scientists hope to learn about them?

    Laura Chomiuk: Novae are the most common nuclear explosions in the Universe. They happen when a white dwarf star (which is a compact core left over when a star like our Sun dies) has a nearby companion star, and the white dwarf manages to pull gas off its companion star. The gas on the white dwarf collects and grows in pressure over time, until nuclear fusion explosively turns on. Then all that collected gas gets blown off into space at speeds of thousands of miles per second—that is the nova! After the nova, the whole process can actually repeat. The white dwarf will start to pull gas from its companion star again, and will likely host another nova sometime in the future—it could be 10 years, or a million years.

    I’m really interested in novae because there is still so much we don’t understand about them. They are supposed to be relatively simple, common explosions, but they show all this surprising behavior—the strange hourglass geometry and strong shocks in our recent paper are just one example. For example, a nova is supposed to be a single nuclear explosion, but novae often look like they have multiple outbursts in rapid succession, and continue to expel material for sometimes months after the initial explosion. Ultimately, I would like to understand how much mass and energy are released by nova explosions, and the physics that determines this release. But first we have to wade through a lot of strange and complicated behaviors!

    NASA Blueshift: What is V959 Mon? What does its name mean? What made it the right candidate for these observations, compared to other systems?

    Laura Chomiuk: V959 Mon was the subject of our paper. It was one of the first novae detected in gamma-rays, and turns out to be a really nice, nearby novae to study. The fact that it is unusually nearby [6500 light years away] was convenient, because it meant the nova was brighter than usual, and allowed for higher-quality images. I wish every nova would be as well-behaved as V959 Mon.

    The name V959 Mon is typical of how we name variable stars. The ‘V’ stands for variable, meaning that its brightness changes with time. It was the 959th variable star discovered in the constellation Monoceros (a Monoceros is apparently a unicorn, not a rhinoceros as I had been believing until I just googled it).

    NASA Blueshift: How do different wavelengths of light help you understand nova explosions? In particular, how do radio observations help you understand gamma-ray emissions when they’re at opposite ends of the electromagnetic spectrum?

    Laura Chomiuk: Each wavelength regime gives unique insights into the complex explosions of novae, and in the case of radio and gamma-ray wavelengths, these insights are very complimentary. Violent shocks in astronomical explosions can accelerate particles to near the speed of light, creating so called ‘cosmic rays’. It is the interaction of these cosmic rays with their surroundings that produces gamma-rays and radio emission. So in the case of V959 Mon, radio waves acted as a tracer of gamma-ray production.

    NASA Blueshift: How does your collaboration work? How do you coordinate with researchers working in multiple wavelengths, especially with systems that are event-based and rapidly changing?

    Laura Chomiuk: Our collaboration involves people from all over the world, and I really am proud of the number of scientists and telescopes that worked together to collect observations for V959 Mon. When it became clear that V959 Mon was an unusually interesting, nearby event, we sent out a telegram to all astronomers letting them know that we planned to observe it with one particular radio telescope, the VLA. This inspired astronomers from other parts of the U.S. and Europe to try and obtain additional data on their telescopes, and we were in regular contact about how best to cover this interesting event. To make sure that we get good coverage on a time-variable event, it’s very important to stay focused and keep the channels of communication open. We have regular telecons and email discussions, and try to meet face-to-face whenever we can!

    NASA Blueshift: What makes this discovery new/interesting/useful for scientists in better understanding novae, gamma-rays, etc.? What question(s) did this help answer?

    Laura Chomiuk: Astronomical sources that produce gamma-rays really are unusual and exceptionally energetic. In our Galaxy, there are only a few classes of stellar objects that produce gamma-rays: neutron star pulsars, accreting compact objects—and now novae. Novae show that a much wider range of physical conditions can result in these most energetic of photons than previously thought.

    Also, our study sheds some light on how nova explosions are actually powered. Our imaging of V959 Mon is consistent with a scenario wherein the binary star system whips around inside the gaseous nova envelope, and actually transfers some of the binary orbit’s energy to the nova ejecta. This “binary eggbeater” process gives an extra kick to the explosion and shapes the nova ejecta, potentially explaining some of the complexities we see in novae.

    NASA Blueshift: And, of course, what new questions did it create? What’s next?

    Laura Chomiuk: Since V959 Mon, Fermi has gone on to detect gamma-rays from several more novae, implying that perhaps all novae produce these most energetic photons. However, it remains unclear if the process for producing gamma-rays we identified in V959 Mon applies to these other novae. We are continuing to observe novae at radio, optical, X-ray, and gamma-ray wavelengths to understand their complex explosions, strong shocks, and ejecta geometries.

    Second Article:

    In part one of this series, we talked to researcher Laura Chomiuk about the scientific mysteries of novae V959 Mon. She has collaborated with two Blueshifters, Koji Mukai, and Tommy Nelson, who also study novae, but primarily at X-ray energies. We chatted with Tommy to learn more about his research in general and in specific regard to V959 Mon.

    These images show Fermi data centered on each of the four gamma-ray novae observed by the LAT. Colors indicate the number of detected gamma rays with energies greater than 100 million electron volts (blue indicates lowest, yellow highest).
    Image Credit:NASA/DOE/Fermi LAT Collaboration

    NASA Blueshift: Can you tell our readers a little about yourself?

    Tommy Nelson: My name is Tommy Nelson, and I’m a research associate and lecturer at the University of Minnesota in Minneapolis. My background is in X-ray astronomy, primarily studies of novae in outburst and other accreting white dwarf binary systems. I was a postdoctoral researcher at Goddard for almost 3 years after graduate school, where I worked with Koji Mukai on science, and the wonderful Blueshift team on a few outreach projects. I left NASA primarily for family reasons – my spouse got a job here in Minnesota. However, I continued to work with Koji, Laura Chomiuk, and our colleague Jeno Sokoloski at Columbia University after I moved – mainly because they are all wonderful collaborators and I have so much fun working with them. Analyzing radio observations of novae was definitely a new, challenging experience for me, but it has given me a new, refreshing view of nova outbursts that I would not have obtained from X-ray studies alone.

    The white dwarf star in V407 Cygni, shown here in an artist’s concept, went nova in 2010. Scientists think the outburst primarily emitted gamma rays (magenta) as the blast wave plowed through the gas-rich environment near the system’s red giant star. Image Credit: NASA’s Goddard Space Flight Center/S. Wiessinger

    NASA Blueshift: Laura told us quite a bit about novae and her observations of them. How do x-ray observations add to the understanding of novae?

    Tommy Nelson: X-ray observations of novae are wonderful because they can reveal the presence of any shocks in the ejected material. This is important if you want to understand why novae make gamma-rays, because our current theories of particle acceleration identify shocks as the location where particles are sped up to very high velocities. The detection of X-rays at energies above 1 keV indicates hot gas with temperatures greater than 1 million degrees – an undeniable signature of shocks. By measuring the temperature of the X-ray emitting gas, we can also figure out the difference in velocities between the fast and slow material, another important factor in determining how well shocks can accelerate particles.

    X-ray observations are the ideal compliment to radio studies. While the VLA can reveal the shape of the ejecta and the amount of matter being thrown off during the outburst, X-rays add new information by telling us about the dynamics and energetics of the nova explosion.

    Credit: Tommy Nelson

    NASA Blueshift: You also worked on the multiwavelength studies of the nova V959 Mon, which we interviewed Laura Chomiuk about. Your team’s first paper, led by Laura, focused on radio and gamma-ray observations. What other wavelengths did you use, and what additional information have those observations given you about this source?

    Tommy Nelson: In addition to the radio observations that Laura’s paper focuses on, we also obtained X-ray observations of V959 Mon during the outburst with Swift, Chandra, and Suzaku. The X-rays have allowed us to constrain the difference in velocity between the two phases of mass ejection: something that wasn’t possible with the radio data alone. We also confirmed the internal shock picture by watching the X-rays become less absorbed by gas over a period of 3 months. This drop in absorption is due to the expansion of the slower ejected material ahead of the shock front. In other words, everything we see in the X-rays and radio ties together nicely! I’m currently writing these results up and we hope the paper will be out in the near future.

    NASA SWIFT Telescope

    NASA Chandra TelescopeNASA Chandra schematic

    Suzaku ISAS telescope

    NASA Blueshift: What’s next for your research regarding novae?

    Tommy Nelson: For now, my research will continue to focus on getting well-sampled, multiwavelength data sets for novae in outburst. We have really only started obtaining coordinated radio, optical and X-ray observations for novae in the last few years, and so the number of well studied systems is still small. We know that the behavior of novae varies widely from object to object, so in order to pin down some of the fundamental physical processes taking place—particularly those related to mass ejection—we need to increase our sample size.

    NASA Blueshift: Thanks, Tommy!

    We also chatted briefly with Koji to learn a little more about his involvement with the research. We love how it illustrates what a small community astronomy can be.

    Koji Mukai: My involvement with this group initially started in February, 2006, with a phone call from Dr. Jennifer (Jeno) Sokoloski (who is now at Columbia University), because a star called RS Oph went nova, and Jeno wanted to organize an campaign of X-ray observations very quickly. We had met at conferences before, and Jeno knew I knew people who worked on RXTE and Swift at Goddard. I suggested using RXTE, and we ended up getting some really nice early X-ray data on RS Oph. Jeno and I have been collaborating ever since.

    NASA/RXTE The Rossi X-ray Timing Explorer

    This 2006 explosion of RS Oph was observed by so many people using so many different instruments that a conference on this one nova was organized. There I met Tommy Nelson, who was working on a different set of X-ray data on RS Oph as a graduate student at Wisconsin. I ended up hiring Tommy as my post-doc to work here at Goddard. One day, Tommy was chatting with some friends (probably over coffee), who happened to mention that there is this new gamma-ray source which appears to be a nova. That’s how we first found out about gamma-rays from novae. Later, Tommy and I started working with Jeno and others on radio observation of novae, and it turns out Laura Chomiuk and Tommy are close friends from their Wisconsin days. Small world.

    See the first article here, the second article here.

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition

    Blueshift is produced by a team of contributors in the Astrophysics Science Division at Goddard. Started in 2007, Blueshift came from our desire to make the fascinating stuff going on here every day accessible to the outside world.

    NASANASA Goddard Banner

  • richardmitnick 2:46 pm on September 6, 2014 Permalink | Reply
    Tags: , , , , NASA Blueshift,   

    From NASA Blueshift: “A Ride on SOFIA” 

    NASA Blueshift
    NASA Blueshift

    September 5, 2014
    Maggie Masetti

    This is a guest blog by astronomer Brian Williams


    A joint project between NASA and the German space agency (DLR), the Stratospheric Observatory for Infrared Astronomy, or SOFIA, is a bit of a departure from NASA’s traditional telescope fleet. Rather than flying in space, SOFIA features a 2.5-meter telescope implanted into the side of a modified Boeing 747SP. The telescope observes the cosmos in infrared wavelengths beyond what our eyes can see, and doing so requires getting above the water vapor in the atmosphere close to the Earth’s surface that absorbs infrared radiation. SOFIA accomplishes this by flying at around 40,000 feet, revealing a part of the spectrum that is inaccessible from the ground.

    In May, I had observations being done on SOFIA to observe a bright supernova that exploded a few years ago. The supernova, given the catalog number 2010jl, had been observed with Spitzer last year, where it was noted to be bright in the infrared, several years post-explosion. This is quite rare, and we were granted follow-up observations with SOFIA to observe at even longer wavelengths. By observing at various places in the spectrum, we can put better constraints on the source of the bright emission and determine what is special about this supernova that makes its surroundings glow brightly several years after exploding. As part of this, I got the chance to go on the observing flight on the night of May 5-6th. Here’s the story of the experience.

    NASA Spitzer Telescope


    This composite image of UGC 5189A shows X-ray data from Chandra in purple and optical data from Hubble Space Telescope in red, green and blue. SN 2010jl is the very bright X-ray source near the top of the galaxy (X-ray image: NASA / CXC / Royal Military College of Canada / P. Chandra et al; Optical image: NASA / STScI)

    NASA Chandra Telescope

    NASA Hubble Telescope
    NASA/ESA Hubble

    SOFIA flies out of NASA’s Armstrong Flight Research Center in Palmdale, CA, about an hour north of Los Angeles. I arrived at Armstrong’s Hangar 703 early in the afternoon of the 5th. I had electronically requested temporary security access through my NASA badge to save myself paperwork at the gate. Crossing my fingers that everything had been filled out correctly, I held my badge up to the security scanner. The light changed from red to green, and I heard an electronic locking mechanism open. I was good to go. I met up with my contact person inside and met some of the other people who would be onboard the night’s flight: a group of half a dozen middle and high school teachers from across the country, chosen as part of SOFIA’s Airborne Astronomy Ambassadors Program.

    Driving up to the hangar that houses SOFIA, on the left. Credit: Brian Williams

    Up first at 3:00 was an airplane safety briefing required for anyone who had not flown on SOFIA before. I couldn’t help but wonder if this was really necessary. I fly roughly 50,000 miles a year… I think I know how to find the exits on a plane. That said, this hour long briefing was surprisingly useful and interesting. I learned that there’s a correct and incorrect way to use the sliderafts (hint: jump onto the slide, don’t sit) and don the life preservers. I held some of the equipment that you hear about in the pre-flight videos that we all ignore on commercial flights. I put on a portable oxygen mask (SOFIA is not laid out like a normal plane, having most of the seats removed for equipment, so the typical oxygen masks that fall from the overhead compartment are not on the aircraft). I even learned how to use the emergency escape ropes from a hatch on top of the cockpit, which apparently are real things. They took us on a walk-through of the aircraft, pointing out where various important things are. Flashlights, fire extinguishers, life preservers, the like. They took us into the cockpit. They let me sit in the pilot’s seat. This wasn’t part of the safety briefing. I believe the safety officer said that no one had ever asked him that before, but he said it was fine, and it just goes to show what you can get if you ask for it.

    Boarding the plane for the safety walkthrough. Credit: Brian Williams

    Me in the cockpit. I didn’t touch anything. Credit: Brian Williams

    I didn’t get to wear this jacket during the flight, but I borrowed it for this pic. A few minutes before takeoff. Credit Brian Wiliams

    After a break for food, we met for the pre-flight mission briefing. This involved everyone who would be on the flight that night, as well as a few support staff on the ground. The flight personnel that night consisted of two pilots and a flight engineer upstairs in the cockpit, a lead and assistant mission director, two instrument scientists, two telescope operators, three German scientists from DLR who were monitoring the telescope operation for an upcoming servicing, a safety officer, the six teachers, and me. I’ve almost certainly forgotten someone, but that’s approximately correct. We went over the flight plan for the evening and got the latest updates on the weather and atmospheric conditions and the status of the instruments onboard. Everything looked great. As the only “guest scientist” on the flight, they asked me to say a few words about what we’d be observing that night. When it was over we headed out to the plane for the flight to begin. Wheels up at 7:05 pm PDT.

    SOFIA on the tarmac, being prepped for flight. Credit: Brian Williams

    The flight lasted about ten hours, landing at 4:58 on the morning of May 6th. While SOFIA’s telescope has some flexibility in where it can point, it is still largely tied to a direction that is approximately perpendicular to the direction the plane is flying. Thus, what looks like a nonsensical route for a plane to fly is actually a carefully choreographed dance designed to place all the night’s targets within view. We started off flying northeast until we were over Colorado, then turned northwest to fly all the way up to British Columbia. We then backtracked to Montana, flew over North Dakota, then headed back northwest again to Alberta. Finally, we had a long, straight shot back to southern California for a landing. The flight itself drags on a bit over the course of the night after the initial excitement wears off. There are no in-flight movies or meals. There’s only so much you can chat with people after that many hours. They did allow us go up to the cockpit and hang out with the pilots, so that was neat. A few people napped. We weren’t awarded frequent flier miles, but it was still a great experience. Upon landing, the crew went home and the teachers went to their hotel. I took advantage of the crash-pad at Armstrong and slept for a few hours before driving back to LA to get on another plane and head home.

    Brian, getting ready for takeoff. Credit: Brian Williams

    Interior of the plane in flight, facing forward, showing some of the flight crew. Credit: Brian Williams

    Shortly after takeoff, looking back at NASA’s Armstrong Research Center and the runway. Credit: Brian Williams

    Facing the rear of the plane and the telescope. Credit: Brian Williams

    The data didn’t show a direct detection of supernova 2010jl, but all hope is not lost. We prepared for that possibility, and my colleagues and I are analyzing the data to see if useful upper limits can be extracted from the data. Much like the curious case of the dog that didn’t bark, sometimes not seeing a thing can tell you as much about it as if you had seen it, if you can figure out why it isn’t there. A negative signal may imply that the type of dust that is present around this supernova doesn’t emit much light at the longer wavelengths that SOFIA observes at. It may also mean that the overall brightness has faded over the course of a few months. Follow-up observations with other instruments and theoretical modeling of the emission that we see and don’t see will allow us to answer these questions.

    See the full article here.

    Blueshift is produced by a team of contributors in the Astrophysics Science Division at Goddard. Started in 2007, Blueshift came from our desire to make the fascinating stuff going on here every day accessible to the outside world.

    NASANASA Goddard Banner

    ScienceSprings relies on technology from

    MAINGEAR computers



  • richardmitnick 7:52 pm on May 1, 2014 Permalink | Reply
    Tags: , , , , NASA Blueshift   

    From Maggie’s Blog at NASA Blueshift: “[Maggie’s blog] X-ray Detectors on the Move” 

    NASA Blueshift

    NASA Blueshift

    Here at NASA Goddard, in Astrophysics, we have quite a large group that studies high-energy light – that is X-rays and gamma-rays. Not only do our astrophysicists study the objects that emit light at these energies, some of them build the instruments to collect this astronomical data.

    One such astrophysicist is Dr. Rich Kelley. [Fun fact – he plays lead guitar in the Blueshift podcast theme song, which is primarily his composition.] His latest project is a Soft X-ray Spectrometer (SXS) on the joint US/Japanese satellite Astro-H, which is due to launch in 2015. Astro-H will explore the extreme universe that is abundant with high energy phenomena around black holes and supernova explosions, and observe clusters of galaxies filled with high-temperature plasma.

    astro h

    Illustration: Akihiro Ikeshita / JAXA

    The SXS is a system of X-ray calorimeters that sit behind an X-ray telescope. A calorimeter works by detecting tiny temperature changes. When an incoming X-ray is absorbed in the detector, the detector heats up a tiny, tiny amount. In order to detect such a small temperature difference, the detector must be very cold – it will run at 50 milli-Kelvins, or 50 thousandths of a degree above absolute zero. You can read more about how X-ray calorimeters work on the Collaboration website for Astro-H.

    The SXS just recently passed a big milestone when its detectors were shipped to Japan for integration and testing.

    I got the chance to see them, literally right before they put the shipping cover on. Rich gave me a little tour and I was able to snap this picture through the clean tent:

    maggie 1
    Credit: Maggie Masetti

    Rich gave us a few close-up images of the hardware, which Kevin Boyce, systems engineer and sometime Blueshift blogger, captioned for us. [Second fun fact: Kevin plays bass on the Blueshift podcast theme song. Ok, full disclosure – Rich, Kevin and I play in a band together.]

    Credit: NASA

    Above you see the Detector Assembly (DA) and 3rd stage of the Adiabatic Demagnetization Refrigerator (ADR) that keeps the detectors at 50 milli-Kelvins. The detectors are just behind the center of the circular plate labeled Detector Assembly. The ADR has three stages, of which this is the warmest, running between 1.5 and 4.5 Kelvins. The other two stages are on the other side of the mounting plate, and can be seen in the photo below. An ADR consists of a superconducting magnet, a slug of ferromagnetic salt (the “salt pill”), and one or more heat switches. The magnet and salt pill are inside the area marked as “ADR”.

    Credit: NASA

    Above is the bottom of their subsystem. Here you can see the magnets for Stage 1 and Stage 2 of the ADR. Actually what you see is magnetic shielding. It is important to keep the very high magnetic fields contained within our instrument, so as not to confuse the geomagnetic sensor (essentially a compass) on the spacecraft. Therefore we have this shielding. The suspension systems are also marked. Each of these is a set of Kevlar strings that support the salt pill within the magnet. This is used to thermally isolate the salt pill from the much hotter surroundings. For instance, in Stage 1 the salt pill runs at 50 mK, while the surroundings are about 1.2 K (24 times hotter; that’s a bigger ratio than between our body temperature and the surface of the sun).

    nasa 2
    Credit: NASA

    Above is other view of the DA and ADR 3rd stage. The detector output wires are marked. All other wires you see are either current supply to the superconducting magnets or thermometer wires. There are 44 thermometers in the system, so we can measure temperature in many different places. Also visible in this photo is a temporary protective cap, made of a small aluminum parts tray and tape, to protect the X-ray filter from damage. The filters allow X-rays through, but not visible light, ultraviolet, infrared, or radio waves. They are very delicate; you can break them by breathing on them.

    We’ll keep you updated on this cool (literally!) mission – we wish them the best!

    See the full article here.

    Blueshift is produced by a team of contributors in the Astrophysics Science Division at Goddard. Started in 2007, Blueshift came from our desire to make the fascinating stuff going on here every day accessible to the outside world.

    NASANASA Goddard Banner

    ScienceSprings is powered by MAINGEAR computers

  • richardmitnick 8:12 pm on April 18, 2014 Permalink | Reply
    Tags: , , , , NASA Blueshift,   

    From NASA/Blueshift: “[Maggie’s Blog] A Secondary Space Mirror” 

    NASA Blueshift

    April 18, 2014
    Maggie Masetti

    One of the cool things about the James Webb Space Telescope’s design is the giant boom that sticks out in front of the telescope. This structure is what holds the telescope’s secondary mirror. It’s the “small” round gold thing, visible in this artist’s conception.

    Credit: NASA

    Here’s what it looks like for real. This is the flight mirror, the one that is going into space! It’s coated in gold like JWST’s other mirrors to optimize it for reflecting infrared light.

    Credit: NASA/Chris Gunn

    It’s actually pretty big – in fact it’s not much smaller than the Spitzer Space Telescope’s primary mirror! (Spitzer’s primary mirror is 0.85 meters in diameter, JWST’s secondary mirror is 0.74 meters.) It just looks small next to JWST’s 21 foot diameter primary mirror!

    Credit: NASA

    Northrop Grumman has the pathfinder, or test version of this boom structure that will hold the secondary mirror.

    Credit: Paul Geithner

    I found out a little more about it from Deputy Project Manager for JWST, Paul Geithner, and Optical Telescope Element Manager, Lee Feinberg. Here’s their caption for the above photo.

    This is the secondary mirror structure (SMSS) for the Pathfinder telescope structure. The flight one will be virtually identical. This image is from a ‘walkout’ of the structure from its stowed to its deployed condition. The scale is evident in the photo, comparing the people and the structure. This walkout involved careful offloading of weight in the 1g environment on Earth; this deployment will take place in space where there is the inertia of the mass but not the weight, and ground deployments require offloading. The flight SMSS is in strength testing, and it will be integrated with the backplane before it is sent to NASA Goddard for telescope assembly.

    Before this, the Pathfinder telescope backplane and SMSS will come to Goddard for ‘pathfinding’ operations as practice for the integration we will do on the flight in 2015. Once at Goddard, two spare primary mirror segments and a spare secondary will be installed to make up the Pathfinder telescope.

    This is the first time a deployable secondary mirror structure for a space telescope has ever been tested. The SMSS is over 8 meters (26.2 feet) tall.

    Here is the Northrop Grumman Integration and Test team after successfully transferring the pathfinder SMSS from the floor assembly jig (that tall, black, latticed structure you see in the other photo) to the backplane pathfinder.

    Credit: Northrop Grumman

    We’ll be sure to give a report when this huge structure shows up at NASA Goddard – we’ll be excited to see it for ourselves!

    See the full article here.

    Blueshift is produced by a team of contributors in the Astrophysics Science Division at Goddard. Started in 2007, Blueshift came from our desire to make the fascinating stuff going on here every day accessible to the outside world.

    NASANASA Goddard Banner

    ScienceSprings is powered by MAINGEAR computers

  • richardmitnick 7:52 am on February 15, 2014 Permalink | Reply
    Tags: , , , , NASA Blueshift   

    From NASA/BlueShift: “Happy Valentine’s Day!” 

    NASA Blueshift

    February 14, 2014
    Maggie Masetti

    Happy Valentine’s Day from NASA Blueshift. We spotted this image go by on social media this morning and Rick Wiggins was kind enough to grant us permission to repost it. This is the Heart Nebula, or IC 1805. It’s about 7500 light years away from Earth, and can be located in the constellation Cassiopeia. The nebula actually sits in the Perseus arm of our galaxy, while the Sun is nearby (astronomically speaking, anyway) in the Orion Arm.


    This nebula, made of dusty dark clouds and hot glowing gas, has a cluster of newborn stars near “heart” center, called Melotte 15.

    [The Heart Nebula, IC 1805, Sh2-190, lies some 7500 light years away from Earth and is located in the Perseus Arm of the Galaxy in the constellation Cassiopeia. This is an emission nebula showing glowing gas and darker dust lanes. The nebula is formed by plasma of ionized hydrogen and free electrons. Wikipedia]

    milky way
    Observed structure of the Milky Way’s spiral arms.

    See the full article here.

    Blueshift is produced by a team of contributors in the Astrophysics Science Division at Goddard. Started in 2007, Blueshift came from our desire to make the fascinating stuff going on here every day accessible to the outside world.

    NASANASA Goddard Banner

    ScienceSprings is powered by MAINGEAR computers

Compose new post
Next post/Next comment
Previous post/Previous comment
Show/Hide comments
Go to top
Go to login
Show/Hide help
shift + esc

Get every new post delivered to your Inbox.

Join 453 other followers

%d bloggers like this: