I’m slowly getting back to a normal schedule after spending two weeks in Green Bank, West Virginia, in the Radio Quiet Zone. What’s that, you ask? Well, I wrote a two-parter all about radio astronomy’s own version of “light pollution” and the great, great lengths we take to keep our sensitive telescopes from interference.

The first week, I spent my time with collaborators on the PAPER project. For quite possibly the first time ever, we had almost all of our group together in one place. Of course, we recorded this on film for posterity:

Don, Pat, Aaron, Rich, James, Jonathan, Chris, Danny, me, and Erin!

That is one of our 32 antennas that we have working together as an interferometer in Green Bank. We have a matching set of 32 out in South Africa being hooked up right now! The goal is to have up to 128 of these to detect hydrogen from the very early universe so we can learn more about the first stars and galaxies. These strange looking telescopes work from 100 to 200 MHz (just above the FM radio band!) I have recently been poking at the astronomical data from our telescope, looking for and identifying problems caused by the ionosphere, or the charged particles in the Earth’s atmosphere that can refract these signals before they reach us.

Once the PAPER team left, a group of undergraduates in various STEM fields arrived for the first ever Green Bank May Term. This 10-day program gave these students a chance to learn about astronomy, the NRAO, research, and STEM careers. We had, seriously, the brightest, most interesting, coolest students I have ever seen. Okay, maybe I’m a little biased. They got a tour of the GBT, various NRAO facilities in Charlottesville and Green Bank, and completed research projects with the 40-foot telescope under the guidance of graduate student mentors. By guidance, I mean, they survived us never answering a question directly so that they could get to the answer by their own means! I’m sure that drove them a little crazy, but they handled it well. They also asked incredibly probing and thoughtful questions, whether observing, on a tour, or during Tom Troland’s astronomy lectures (which are hilarious, by the way.)

Sue Ann shows us the feedhorns on the GBT on a very foggy day.

Finally, I took a day trip to be a fangirl around Frank Drake, the man behind the first SETI experiment, as he recreated his experiment on the GBT for a BBC film crew. Though I didn’t get a chance to actually hang out with him and pester him endlessly on the topic of SETI in prep for my Life Beyond Earth class, I’m hoping to be back there for a SETI conference in September.

Okay, now back to working my butt off so I can then keep up my blogging and start packing for my move to Lake Monticello next week and actually get some research done before my class takes over my life in less than a month! Agh!!

An image of the most central part of the radio jet of 3c273, made with the Very Long Baseline Array by Zavala & Taylor (NRAO/AUI.) Also, the subject of my very first research project, where I could see superluminal motion and measured polarization in the jet!

The term blazar encompasses two subclasses of astronomical objects: optically violent variables (OVVs) and BL Lac objects, named after the prototype of the class which distinguished itself with variability and polarization. Many of these objects were first identified as irregularly variable stars, and others as strange “radio stars.” But as it was slowly uncovered that quasars were really the active nuclei of distance galaxies, the true power of blazars was finally understood.

Famous blazar 3C273, taken in the optical with the Kitt Peak 4m. This is one of the rare cases where the jet is visible in the optical! The previous image would fit well within a pixel here.

A picture of active galactic nuclei has emerged that unifies many of the different types. The supermassive black hole is accreting material in the center, sometimes ejecting powerful radio jets, and always ionizing some of the surrounding material. However, there is also a dusty torus surrounding it, and this torus blocks some of the AGN emission, depending on your viewing angle. The variability of the blazar means that you are seeing emission from very near the (relatively) small black hole itself. You are, in fact, looking right down the throat of the beast, along the line of sight of the jets. This allows for the appearance of superluminal motion as well!

Cartoon of the unified theory of AGN, by Urry, C. M., & Padovani, P. Blazars are the “OVV” and “BL Lac” at the top.

Blazars encompass 80% of gamma ray point sources, which are being monitored now by a space telescope called Fermi. At the same time, very high resolution maps of the radio jets can be made withe the Very Long Baseline Array. The Atacama Large Millimeter Array is also expected to discover many fainter blazars during the normal course of calibrator searches. Although these weird and cool objects have been studied for sometime, they still hide some of their secrets. For example, is the variability that some show on a timescale of mere hours due to intrinsic and very powerful changes in flux, or is it an effect imposed by the interstellar material within our own Galaxy along the line of sight? Astronomers aren’t exactly sure how a supermassive black hole blasting away material can make such narrow jets, but maybe one day blazars will tell us how.

A couple of years ago, I picked up Nan’s memoirs, “Two Paths to Heaven’s Gate” which was published by the National Radio Astronomy Observatory. It is a really beautiful memoir, like a conversation over tea. So many of her impressive feats are explained quite humbly, or with an almost childish glee. It is the path of her life, not a great epic tale. She shares nuggets of wisdom, inspiration, and kindness from her mentors, collaborators, and friends throughout her life. I believe that she must also be a good teacher, as her explanation of astronomical terms and processes are quite thorough and accessible and don’t detract from the flow of her story.

Her love affair with astronomy began in college. She was greatly inspired by one teacher, Dr. Helen Dodson, who inspired her to want to do her own research. Nan eventually took her astronomy knowledge to the Naval Research Lab in 1951 to get a job with their brand-new 50-ft radio telescope, just as the field of radio astronomy was finding its feet. Her “male colleagues had no hesitation in working with a young woman.” She began studying solar flares and worked on her first published paper. Her home life was not entirely peaceful as her husband was asked to leave seminary, and they had their first baby. She was lucky enough to find help to raise the little girl so she could continue her career. However, she left with her daughter on her own in 1953, while continuing to work, she says, “not only for the money, but for my sanity.” She went on to co-discover HI (neutral hydrogen) absorption along the line of sight to the center of our Galaxy. She began to long, once again, to direct her own research, which would mean returning for graduate school. Her second husband moved with her to Massachusetts where she got her PhD in astronomy at Harvard, the home of many female astronomy pioneers. And in case getting a PhD isn’t hard enough, she finished her HI studies while being barred from the main observatory due to a false accusation of a fellow student, and she defended her thesis while five months pregnant in 1958. But finally, she could do her own astronomical research.

She went on to continue her contributions to radio astronomy in mapping hydrogen disks in nearby galaxies. She also published a paper on a model of our own Galaxy based on HI observations, but a fundamental error (missed by reviewers) led her to leave modeling to the theorists and stick to observational astronomy. In 1961, after dealing with some troubling medical symptoms, she was diagnosed with multiple sclerosis. She decided to learn as little about the disease as possible and take her own symptoms as they came, since they can vary so much from patient to patient. As her second marriage deteriorated, she found a new life with her girls in Berkeley at the Radio Astronomy Laboratory. A 39-year-old single mother with a 13-year-old and a 6-year-old, she continued to blaze a trail in the radio skies. She and her colleagues probed the Galaxy with observations of the OH molecule, including highly variable OH masers in the star-forming Orion Nebula, with the 85-foot telescope at Hat Creek. She mapped high-velocity HI clouds in the Galaxy with 2500 hours of observing time and, seriously, data printed out on punch cards to be fed to the University’s computer! She later searched for formaldehyde in dark interstellar clouds as the Vietnam war protests of the 1970s raged around Berkeley. She also helped pioneer the technique of very long baseline interferometry, linking together the Hat Creek 85-foot antenna with the 130-foot dish at Owens Valley, 300 miles away.

Images courtesy N. Dieter-Conklin/NRAO/AUI

In 1968, she married Garret Conklin who was to be the love of her life until his death in 2002. With him she shared sailing, fabulous food, their summer house in the mountains, an apartment in Paris, and trip to the USSR. I found this part of the book particularly fascinating as Nan describes her experiences navigating a foreign and, for so many Americans, closed off country during the Cold War. The three month visit was made possible due to her status as a scientist as the trip’s primary purpose was to find out what Soviet researchers had discovered about the interstellar medium for a review article. Her recollections, interspersed with entries from her husband’s travel diary, tell a story of a trip that she describes as “profound,” and my attempt at a summary could never do it justice.

In 1977, Nan retired from astronomy at the age of 51, and set about living first on the Mediterranean island of Menorca for a short while, then Vermont for 17 years. Nan worked on pottery for as long as her MS would let her, then switched to painting. She dealt with chronic pain for a number of years until she beat it with the help of some wonderful visiting nurses, but she still lost the ability to walk. They moved to Seattle to be near Nan’s daughter when Garret’s Alzheimer’s became a strain, and they both moved into an assisted living facility where Nan met the writing group that eventually persuaded her to write the book. After Garret’s death, she moved to a retirement community where her memoirs end in 2005. Her work, however, extends beyond that, as I quickly found a short paper by her in the Astronomical Journal, dated April 2009, on high-resolution observations of interstellar clouds in absorption! (Unfortunately, behind a paywall. Sorry!)

She considered herself, and felt she was always treated like, “an astronomer who happened to be a woman.” However, no one should underestimate the strength and intelligence it took for her to take this journey. I highly recommend her memoirs as the story of a solid researcher and a fascinating woman who happily traveled her parallel paths of the personal and the professional.

I’ll leave with some really poignant observations on a career in astronomy from the conclusion of “Nan Dieter Conklin: A Life in Science,” the precursor to the book:

It is vital, of course, that you carry out the project with absolute integrity, and without emotion, although in order to invest the effort in the first place you need to believe that the project is worth doing. An astronomer, or any scientist, fights a daily battle between emotion and discipline, and the job cannot be done without both.

On the other hand, I have found in astronomy a career always satisfying and occasionally thrilling. One persists through times of routine, demanding hours with the possibility of an extraordinary reward. Make no mistake; the approval of colleagues, especially those not familiar with your work, is wonderful, but it does not hold a candle to the joy in realizing that you are seeing something for the first time. In my experience there are two ways in which real discoveries are made: stumbling on something totally unexpected while looking at something else, and searching for something because you think it might be there. In my own work I found one of each.

Nan, I’ve never met you, but in case you stumble upon this posting, I’d like to tell you that you are an inspiration to me.

Click for dinosaurian biggness!

Maybe I’m just paranoid (especially since Tim didn’t pick up on this until I pointed it out) but there were a number of displays asserting that the science doesn’t tell us the truth, or we’ll never know the answers, because the fossil evidence in incomplete or because the animals are not here to study directly. Although it’s a fair point to say that science doesn’t prove any theory beyond a shadow of a doubt, and that extracting answers from the tiny bits of fossils we do find is excruciating, tedious, and not exact, it was an odd point to be hammering home in a science display. After all, I personally marvel at what knowledge we can glean from incomplete evidence and at the self-correcting nature of science. That’s the kind of message I would send, especially in this era of mistrust and misunderstanding of science by so many people.

So, after we got our fill of dino fossils and expensive but admittedly delicious museum food, we headed to one of my other favorite areas, the Hall of Human Origins. I love to wonder what life was like for early hominids, including for those of our own species who were physically identical, but living in a totally different world 150,000 years ago. I marvel at the tenacity of Homo erectus who populated the Earth for 1.5 million years, whereas we’ve been here for a fraction of that. Anyway, as I was browsing, I noticed that the displays read differently than in the fossil halls:

Click for large version.

It asks a question, states that we don’t yet know, but that it is an area of active research. It puts forth a guess based on the best of our knowledge and leaves the reader wondering what we’ll find out next. This, I think, is far more exciting and educational and doesn’t do the whole process of science a disservice.

This was the first time that I looked beyond the information in an exhibit to the style of the presentation. It is important to know who your audience is and what message you want to send whenever doing science outreach or teaching. Students and museum patrons are probably not going to retain much specific information. Good teachers are aware of this and try to get across a general message about science and have to be cognizant of what that message is. It’s not easy to do this, but having a goal is a good start. You can tell that the designers of the different exhibits have different goals, or at least different opinions on what it is about science they want to convey. For what it’s worth, I think the latter example is going to be much more helpful in conveying the true nature of science to those who don’t live it everyday. And after all, isn’t that important? Isn’t that kind of transparency and understanding just what science needs?

This week’s jargon is one of my favorites, and it’s one that gets the most quizzical looks when it slips out in a tutoring session. AGN stands for Active Galactic Nucleus (or Nuclei). It is literally when the nucleus, or center, of a galaxy, or vast collection of stars, is active, or really, really bright.

Compare the galaxy with the AGN, or the “active galaxy” on the left with a similar galaxy on the right which is not active. From William Keel, University of Alabama Department of Astronomy & Physics.

There is a whole zoo of subclassifications within the grouping of AGN, mainly due to the various methods by which these galaxies were discovered. However, the basic principle lies with the giant that is at the heart of every major galaxy, a black hole that is millions (or billions) of times the mass of the sun! One of the fascinating results to come from the Hubble Space Telescope is that, everywhere we look, every galaxy (with an appreciable central bulge) has a black hole in its center.

Not only that, but the larger the bulge of stars, the larger the black hole! But that’s a story for another day. From hubblesite.org.

Although we don’t yet know where these super-massive black holes first came from, we do know that they can get bigger if mass falls onto them and becomes part of the black hole. Turns out, this is a really, REALLY energetic process. Black holes have a lot of mass packed into a (relatively) tiny space, so any gas that gets close enough to fall in doesn’t do so right away, but settles into a disk around the black hole to spin around a bunch of times before finally crossing the “point of no return.” The material in the disk gives off a LOT of energy, thus powering the active galactic nucleus.

Artist’s conception of a black hole, disk, and jet. M. Weiss, Chandra X-Ray Observatory

How much energy? A moderate AGN gives off approximately 20 times the light output of a galaxy like the Milky Way! And the light is spread out over all wavelengths, from x-ray and ultraviolet through visible and infrared, and even some in the radio. Because they are so bright, they are powerful probes of the universe at large distances. They may also be intimately involved in the life history of a galaxy, as this bright light from the galaxy’s center has an impact on the environment around it. Also, powerful jets of particles moving at almost the speed of light may be generated near the black hole and affect the galaxy and the galaxy’s environment in a violent way.

One of my favorite radio sources, 3C84 (pink) has jets that have carved out a hole in the x-ray gas (blue) in the Perseus Galaxy Cluster. (Chandra image by A. Fabian, VLA image by G. Taylor)

There are so many cool and interesting subclasses of AGN, and so many structures within and related to the AGN, that it’ll probably take a whole sub-series itself! But I hope this introduction gives a clearer picture of what astronomers means when they say, “That’s my favorite AGN!”

Wow. Yeah, what they said.

Don’t forget to check out the first four: A Glorious Dawn, We Are All Connected, Our Place in the Cosmos, and The Unbroken Thread.

(via Bad Astronomy)

LEGO SDO, designed by spectacular SpaceTweep John Knight

SDO’s EVE instrument (Extreme-ultraviolet Variability Experiment) is particularly interesting to me since these EUV photons from the sun are what drives the Earth’s ionosphere. The ionosphere is the outermost layer of the Earth’s atmosphere and consists of ionized, or charged particles. As new low frequency radio telescope capabilities have been coming online at the VLA, GMRT, LOFAR, LWA, MWA, and, my home, PAPER*, the ionosphere is gaining more attention, and not the good kind. Just as the lower levels of the atmosphere cause all kinds of scintillation and “twinkling” to annoy visible light observers, the ionosphere refracts and distorts light coming in at low radio frequencies. (Well, low for astronomers, that is… less than a few 100 MHz!) This is particularly troubling since all of these telescopes are interferometers, or systems of multiple radio antennas linked together to make one telescope. Images are made by measuring the difference between the arrival of light at different antennas, and this difference can be skewed by a turbulent ionosphere. And the ionosphere changes in density and turbulence, based on the solar output! See, it all ties together.

As the sun rises over a part of the world, the UV light ionizes particles in atmosphere, making the ionosphere more dense, and for a short period of the morning, more turbulent. Click for animated goodness!

I have to admit, of course, there are more pressing concerns than radio astronomy. The ionosphere will also have an effect on GPS signals. As we start the upswing in the solar cycle, more turbulence in the ionosphere will mean larger position errors and even times when the signals cannot propagate at all. Monitoring systems can do their best to account for changes in the ionosphere, but an early warning system will help those who have to make very precise GPS measurements (not just you and your TomTom) plan their activities. EVE will measure the extreme-ultraviolet output of the sun on 10-second time scales, 30 times better than previous instruments could. Therefore, solar physicists will be able to better understand the signs and signals of a sun that is about to make our ionosphere dance around.

That’s it, for now, for my sciencey SDO posts. I can’t wait to see what new discoveries start rolling in when science operations begin. I’ll probably have one more SDO post soon, about the TweetUp itself!

*Yeah, NASA, we can play alphabet soup, too!

A few people got this shot, but George is sitting right next to me!

And there’s video of it as well. I haven’t seen an embeddable version yet, but click to see this one hosted on spaceweather.com, taken by 13-year-old Anna Herbst from California. The ripples were seen in the clouds as a result of a shockwave just after the craft went supersonic and as it hit “max-Q” or the point at which the pressure on the craft is at its maximum. (I didn’t keep track of the timing, but Nancy Atkinson of Universe Today did!)

Such a shockwave occurs when an object is moving through a medium faster than the speed of sound in that medium (the atmosphere, in this case). The speed of sound sets the limit of how fast information about the gas can travel within that gas in the atmosphere. Sharp discontinuities in temperature, pressure, and density can occur. We could “see” these discontinuities as it reached the cirrus clouds. For whatever reason, it appeared to bust up the cloud material that was creating the sundog.

Little SDO put on quite a show in its first few minutes as a spacecraft! I’ll be writing more on SDO science and our amazing TweetUp adventure, once I get some darn sleep…

As part of the Kennedy Space Center #SDOisGO TweetUp event, we attended the Guest Mission Briefing for the Solar Dynamics Observatory. (The wha? This!) Since I couldn’t share some of the interesting tidbits inside the signal-less room, here’s a bit of what I picked up! Elizabeth Citrin, project manager for SDO at Goddard, gave a pictorial overview of much of the assembly. The 15-foot tall, three ton spacecraft was carefully put together and integrated (while all held their breath that it would fit!) after the three science instruments had been developed by their home institutions. We also watched a cool launch simulation video, which is also on YouTube:

Dean Pesnell, project scientist gave a great talk highlighting the science goals and instruments of SDO. And I have to really commend him for that. I complain at times that not enough scientists know how to give public talks, but he nailed it, even when his video simulations didn’t work. So bravo for that! I already touched on much of the science that he discussed in my last post, but I did not yet talk about the specifics of the HMI, or Helioseismic and Magnetic Imager. Pesnell showed us some example dopplergrams, which will help probe the interior of the sun. A dopplergram shows the line-of-sight velocities across the surface of the sun, so you can see individual regions moving in and out. This is done by measuring the Doppler shift of a spectral line of iron with a resolution on the disk of the sun of 1 arcsecond. (1 arcsec = 1/3600 degrees, and the sun is about half a degree across in the sky!) So, that’s technically impressive, and it gives us information about the dynamics underneath the sun’s surface. The measurements will be so accurate that you can “see” sunspots on the opposite side of the sun! (That is, you can detect the motion pattern even while the sunspots are rotated away.) THAT is pretty amazing. The instrument simultaneously measures the polarization or orientation, of the light at these wavelengths, which is determined by the magnetic field orientation. The spectral lines themselves are “split” into two by magnetic fields, so this measures their strength, as well. With the HMI, we can “see” invisible magnetic fields and peer into the sun. This is a really exciting instrument and a step up from previous technology onboard SOHO.

As I predicted, I’m getting a bit rambly… but that’s ok. The last two talks were by Stephen Francois, launch services program manager, and Vernon Thorpe, program manager for United Launch Alliance. These focused more on the rocket systems, with which I am much less familiar. For example, I did not know that Launch Services works with each NASA mission to find the best rocket for its journey. The Atlas V was chosen for SDO back in 2004 because of its larger size and high orbit. The Atlas design goes back 53 years and is probably most famous for lifting astronaut John Glenn into orbit for his Mercury flight. I am pretty excited to see the 191-foot rocket takeoff tomorrow from what will probably be a VIP vantage point. The first stage will burn for 4 minutes, then switch to the Centaur second stage for 11 minutes. Then, it will switch into “coast” mode for 87 minutes until it reaches somewhere over the east coast of Australia. Then, a three minute burn is needed to push the spacecraft into an elliptical orbit with apogee (furthest point) at geosynchronous orbit. The next two months will be spent commissioning the spacecraft and moving it to it’s circular, geosynchronous orbit above New Mexico. And then will come the science!

That’s all for now… be sure to tune in to NASA TV for the 10:26am launch! I’m sure I’ll be back with a little more about EVE (my other favorite SDO instrument), the launch itself, and the TweetUp people and events!

UPDATE: It launched successfully on the second attempt!

SDO stands for Solar Dynamics Observatory. This is the first mission of NASA’s Living With a Star program. We may think that Earth is the most important place in the solar system, but the Sun is the real powerhouse. We who live on this tiny rock in orbit about its fiery bulk must learn to live with what is, in its own way, a variable star.

The sun in extreme UV, as captured throughout one cycle by SOHO

The sun goes through a cycle of high and low activity. This manifests itself in a greater number of sunspots, solar flares, and coronal mass ejections about every eleven years. Sunspots are darkened, cooler areas of the sun, but they tell a tale of force and violence underneath. They are often linked with solar flares, which are explosions in the atmosphere of the sun that occur when magnetic energy is released. In an extremely energetic event, a coronal mass ejection can hurl electrons and protons away from the sun at incredible speeds, averaging 500 miles per hour kilometers per second! If a CME or flare is directed at Earth, these can cause power failures and disrupt satellites. As we become increasingly dependent on our power grids, cell phones, GPS, and yes, even your satellite radio, better forecasting is needed to predict such events. Enter SDO.

SDO has three instruments that will send back data on the Sun simultaneously and 24 hours a day. The Atmospheric Imaging Assembly (AIA) has four telescopes, looking at a total of ten bands, or colors, with super-high definition quality. Continually imaging the Sun’s surface and atmosphere, it will allow scientists to track the evolution of surface features and flares with a time resolution as small as 0.75 seconds. The Helioseismic and Magnetic Imager (HMI) will probe deeply into the sun and map the magnetic field structure. (How? Well, that’s so cool, I’ll devote a whole post to it later this week.) My favorite instrument of the bunch is the Extreme Ultraviolet Variability Experiment (EVE). This does just what the name says, measure the variability of the output of the sun at far-UV wavelengths. Why is that so important? UV light from the sun creates and shapes the ionosphere of the Earth. The ionosphere is the outermost layer of the Earth’s atmosphere, and although it has many beneficial effects on life, it’s a pain for low frequency radio astronomers such as myself. (So, let’s just say this will get a devoted post as well.)

SDO will sit in a geosynchronous orbit above Las Cruces, New Mexico, where a dedicated radio station will be ready to gobble up the 130 Mbps of data that this mission will send back. Project scientists are calling this an “avalanche of data.” This fits in with the trend of many modern telescopes, such as the EVLA and ALMA, producing much more data than astronomers have ever dealt with before. New techniques for handling and distributing these data are always needed.

But, don’t just take it from me. Here’s an official SDO video!

Want to get involved in solar research right now? The premier site for citizen science in astronomy, Zooniverse, has a project called Solar Stormwatch. You learn how to look for and identify solar flares, and then look at some real data from previous missions and discover solar flares better than any automated image recognition software can.

Stay tuned for more updates from KSC as we begin our adventure, and join in at a local or virtual TweetUp for the launch! I’ll be blogging here and posting pictures on Flickr. George is posting his gorgeous (and silly) photos as well!

And while we’re wrapped up in all this spacey goodness, won’t you also check out the most recent Carnival of Space at Mama Joules!

SDO Spacecraft Image