Radio bursts from Jupiter (and beyond)

Jupiter is actually an extremely bright radio source, and NASA has a pretty impressive program that lets you build your own radio telescope and observe Jupiter for yourself - and other sources as well I imagine. Go here for more information. Enjoy!

Past Interview: Dr. Tod Strohmayer (NASA/GSFC)

As a compliment of the description of the December 3rd radio show on black holes, here is my interview with Dr. Tod Strohmayer of NASA's Goddard Space Flight Center. The original post, with links to his webpage and other resources, is located here.

Description of December 3rd Radio Show: Black Holes

Long available here, below is a description of the 2008 December 3rd episode of this radio show with focused on black holes. On this program, I discussed the following:

• Black Holes: Black Holes are objects believed to be so dense that light can not escape if it gets to close (i.e., past the "event horizon"). Additionally, its gravity is so strong that material that makes up a black hole can not arrange itself into a structure that can withstand its own gravity, so this material is thought to collapse into a point. But if one can't see too close to a black hole, how does one know? Well, it the above is correct, that black holes should not have a surface, unlike a neutron star. If a neutron star or a black hole is close enough to a normal star, its gravity is so strong that it will rip material off the surface of the normal star and cause it to fall on itself. This process is called "accretion", and as discussed previously on this radio show by Dr. Tod Strohmayer, this has process have been observed for many neutron stars and black hole candidates. In the case of a neutron star, this material will pile up on the surface of the neutron star, and this pile will got hotter and denser until it is so hot and dense that the hydrogen in this material fuses into helium, releasing a burst of heat and light which is observable by X-ray telescopes such as the Rossi X-ray Timing Explorer. One would not expect such bursts from material falling onto a black hole - which is more massive than a neutron star - since their is no surface for the material to collect. These X-ray bursts have been detected from neutron stars (for example this link), but not from any black hole candidates. Therefore, even there seems to be evidence that black holes indeed do not have surfaces. Additionally, black holes appears to have a mass either a few times that of the Sun (called "stellar-mass black holes"), or millions to billions times that of the Sun - like the black hole believed to reside in the center of our galaxy, the Milky Way (called "super-massive black holes"). Why there seems to be a lack of black holes with a mass between these two extremes (for example, a thousand solar masses) isn't known. One possibility is that such black holes exist, but reside in the middle of globular clusters where they would be hard to detect. A recent survey of globular cluster RZ2109 did not find such a black hole, suggesting that if this was correct they are extremely rare (link). Studies of the super-massive black holes suggest that their may be an upper-limit to how massive they can be, around 10 billion times that of the Sun (link). Since black holes do not have any structure, they are often thought to be some of the simplest objects in the universe (really!) - according to Einstein's theory of General Relativity, in order to completely describe the properties of a black hole you need to know its mass, its spin, and its electric charge (and real black holes in the universe and expected to have zero electrical charge). If so, stellar-mass black holes and super-massive black holes should accrete matter the same way - as observed for black holes in the nearby galaxy M81 (link). As mentioned before, it a normal star passes too close to a black hole, the black hole's gravity will cause material from the star to fall towards, and eventually fall inside, the black hole. As this material falls towards the black hole, it gets hotter - so hot that it produces a lot of X-rays. By looking at the periodic flickering of this light, it is possible to estimate the mass of the black hole. This was recently done for one black hole in the Milky Way, at they estimate a mass of just 3.8 times that of the Solar Mass, the lowest mass black hole known (link). Periodic flickering has also been observed from the super-massive black holes in the centers of other galaxies, and can be used to estimate their mass as well. This was done for galaxy RE J1034+396, which has a mass a million times that of the Sun (link). What causes the light from gas falling into a black hole to flicker is not known, but a recent study of the visible light flickering and X-ray light flickering from a Galactic black hole suggests that its magnetic field plays an important role (link). As mentioned before, there is a super-massive black hole in the center of our galaxy called Sgr A*, and material falling into this black hole also produces regular flares of light (link). In fact, there is evidence that, around 300 years ago, it produced a flash of light so bright that today we are seeing some of the light reflecting off molecular clouds near the Galactic center (link). A major goal of astronomers today is to make an image of light coming from the event horizon around a black hole. The best chance to do this is using radio telescopes to observe Sgr A*, and radio astronomers have gotten down to only 3 times the expected size of the event horizon (link 1, link 2). It is possible to use to orbits of objects around black holes to test general relativity (GR), just as one does this with neutron stars. This was recently done for the two black holes believed to be orbiting each other in center of galaxy OJ 287, and the time between the closest approach of these two black holes agreed with what GR predicts. The material that flows into a black hole is believed to form a disk (called an "accretion disk") around the black hole before it passes the event horizon. Quasars are believed to be galaxies where the optical light of this disk shines much, much brighter than all the stars in the rest of the galaxy. If so, the spectrum of the quasar - how bright the quasar is at different colors - should resemble that of a disk. This is hard to measure in great detail since the light at some colors is absorbed by material between the Earth and the galaxy, but a recent study suggests that it does (link). Additionally, for some unknown reason, the presence of gas flowing into the black hole is often associated with the presence of gas flowing AWAY from the black hole with very high velocities (>60 million mph). Astronomers at UCSC and University of Florida recently observed this outflow turn on around a quasar (link). Sometimes this very collimated outflow (called a "jet) is pointed directly at the Earth, in which case the galaxy is called a "blazar." Recent radio observation of a blazar suggest that these jets are powered by the magnetic field of the black hole (link). Quasars come in very different varieties, with one class recently observed to produce many more X-ray than previously thought to be possible (link). The presence of very, young stars around super-massive black holes like Sgr A* strongly suggest that stars can form in the accretion disk around them (article, link 1). Optical observations of these accretion disk have also detected weird optical filaments around them, suggesting this gas is confined by a weak magnetic field possibly generated by the black hole (link). While all galaxies are currently thought to have a super-massive black hole in their center, very few galaxies are quasars. Why some galaxies are quasars are most are not is unknown, but it is though that quasars are the result of two galaxies recently merging together.
• Calendar of upcoming Astronomy / science events in the greater Poughkeepsie / New York City area.
• Wednesday Morning Astronomer:
• News:

James Webb Space Telescope website

NASA has just unveiled a new website for the under-construction James Webb Space Telescope (JWST), its successor to the Hubble Space Telescope. For more information on JWST (astronomers and government agencies share a love of acronyms), I encourage you to listen to this interview with Dr. Mark Clampin on NASA's Goddard Space Flight Center, one of the project scientists on JWST. Enjoy!

NASA News Feature on James Webb Space Telescope

Available here is a NASA news feature on the James Webb Space Telescope (JWST), the successor to the Hubble Space Telescope (which hopefully will survive for many years to come). For more information on JWST, listen to this interview with Dr. Clampin on NASA's Goddard Space Flight Center. Enjoy!

Swift GRB Press Conference Tomorrow

Tomorrow at 1 PM, NASA will hold a media teleconference to discuss new results regarding the gamma-ray burst GRB 080319B, which was visible to the naked eye. The burst's optical emission is the brightest seen to date and appears to have been aimed almost directly at Earth. Extensive observations from NASA's Swift satellite and ground-based observatories show the burst emission mechanism in unprecedented detail. Supporting information will be posted tomorrow at Noon EDT here, and the press conference will be streamed live here. For more information about Swift and GRBs, visit here and/or listen to my interview with Dr. Neil Gehrels of NASA's Goodard Space Flight Center and one of the lead scientists on Swift, available here. Enjoy!

Goddard Space Flight Center

This February to April, I ran a series of interviews highlighting the wide diversity of research which occurs at Goddard Space Flight Center, a NASA facility in Greenbelt, MD. I should have done this much earlier, and I apologize for my tardiness, but the Goddard scientists who were kind of enough to appear on this program were:

• Dr. Jennifer Wiseman, who talked about ongoing and future research on star formation and extrasolar planets,
• Dr. Aki Roberge, who talked about specific problems in planet formation,
• Dr. Mark Clampin, who discussed the James Webb Space Telescope, NASA's successor to the Hubble Space Telescope,
• Dr. Gary Hinshaw, who talked about the Cosmic Microwave Background (CMB),
• Dr. Tod Strohmayer on what you can learn from the X-ray emission of accreting neutron stars,
• Dr. Neil Gehrels on the Swift telescope and Gamma-Ray Bursts
• Dr. Julie McEnery on the recently launched Gamma-ray Large Area Space Telescope (GLAST),
• Dr. Dave Thompson on the importance of multi-wavelength (radio to gamma-rays) observations in understanding the physics of the most energetic objects in the night sky, and
• Dr. Ann Hornschemier on Constellation-X, an idea for the generation of X-ray telescopes to succeed Chandra and XMM

Hope you enjoy. I personally think that these are some of the most interesting interviews I've done to date, and really encourage you to listen to them if the topics interest you - many of these astronomers are people who are at the top of the fields, and it was a pleasure for me to get to talk to them. Please leave any comments or questions you might have on the above web pages or down below. Thanks a lot for listening!

Interview with Dr. Ann Hornschemeier now online

Available here is the interview I did with Dr. Ann Hornschemeier of Goddard Space Flight Center, who is Deputy Project Scientist of Constellation-X, the leading candidate for NASA's next generation X-ray satellite, the successor to the Chandra X-ray Observatory. Dr. Hornschemeier was kind enough to talk to about the science goals of Constellation-X, how it is being designed to achieve them, and the technology required to do this. I, personally, am very excited about this mission and, for more information on this project, please check out this webpage. As always, please email me or leave below any questions, comments, or concerns you might have.

This is the last interview on research at Goddard Space Flight Center, though I hope to have on as guests later others researchers at Goddard since this series really only covered the tip of the iceberg on all the work that goes on there. I'll post a summary of the interviews later, but I really hope you enjoyed this series. I had a lot of fun putting it together since it gave me an opportunity to speak to a lot of scientists whose papers and presentations I've enjoyed discussing projects I hope you found as interesting and exciting as I did. Thank you for listening.

April 16th radio show online

Sorry for the delay, but the April 16th radio show is now online and available here. This show marked the end of our ongoing series on Goddard Space Flight Center (GSFC), which I hoped you enjoyed listening to as much as I enjoyed compiling. On this program discussed:

• Calendar of upcoming science events in the greater Poughkeepsie / New York City area.
• Interview with Dr. Ann Hornschemeier of GSFC on Constellation-X, the proposed successor to current X-ray satellites Chandra and XMM.
• News: European Space Agency recruiting new astronauts, apply here; congratulations to Dr. Michael Luther for being promoted to head of NASA's Programs Office in Science Directorate; congratulation to the Stardust team for the multiple awards they have won, and good luck to them on Stardust-NExT which will flyby Comet Tempel 1 on Feb. 2011; congrats to the Cassini team for having their mission extended by two years to July 2010, and may it be extended many more times; flight path of NASA's Phoenix Mars Lander adjusted in preparation for its May 25th landing on Mars (link); final pieces of GLAST being assembled on Delta II rocket in preparation for May 16th launch; HiRISE came of NASA's Mars Reconnaissance Orbiter takes color and 3D image of Mars's moon Phobos, available here; NASA launches new science website; Stephen Hawking to speak at lecture series honoring NASA's 50th birthday; call for Italy to invest more in science and technology.
• Neutron Stars: Bursts of X-ray emission detected from a radio pulsar never seen before from a radio pulsar but similar to that observed quite often from a "magnetar," a class of young neutron stars whose emission is powered by the decay of extremely strong magnetic fields (10^14 G, Earth has a magnetic field of 0.3 G) as opposed to the loss of rotation energy believed to power the emission of "normal" radio pulsars like the Crab Pulsar. Why this radio pulsar is now behaving like a magnetar is not known, but suggests that maybe some radio pulsars can evolve into magnetars (link, paper).

Thank you very much for listening, and hope you enjoyed. Please email or leave below any comments, questions, or concerns you might have. And again, thank you.

Interview with Dr. Dave Thompson now online

My interview with Dr. Dave Thompson, multi-wavelength coordinator of the upcoming Gamma-ray Large Area Space Telescope (GLAST) is now online and available here. As he discusses, multi-wavelength observations are going to be critical in understanding the physical properties of the different types of gamma-ray sources (discussed here), as well as vital in determining the nature of unidentified gamma-ray sources, which GLAST will almost surely discover many (discussed in some more detail here).

As always, please email me any questions, comments, or concerns you might have or leave them below. Thank you for listening!

April 9th Radio Show online

Sorry for the delay, but the April 9th radio show is finally available for download here. On this program, I covered:

• Calendar of upcoming science events in the Poughkeepsie/New York City area
• Interview with Dr. Dave Thompson of Goddard Space Flight Center on multi-wavelength studies and GLAST
• News: Major shake-ups in NASA's administration - 2006 Nobel Prize Winner Dr. John Mather to focus his efforts on the James Webb Space Telescope (for more info on the successor to Hubble, listen to this.), Dr. S. Alan Stern resigns as Science Chief due to disputes with Administrator Michael Griffin over cuts to Mars rovers to fund overruns in cost of upcoming Mars Science Laboratory; NASA announces "Cassini Scientist for a Day" competition, more info available here; NASA hosted its 2008 Great Moonbuggy Race in Huntsville, AL - congratulations to all the teams who entered; Italy to help Kenya develop an Earth-observing satellite; Chinese Large Sky Area Multi-Object Fiber Spectroscopy Telesope (LAMOST) observatory approaches final technological hurdles before attempting to do an even larger and deeper survey of the sky than the extremely successful Sloan Digital Sky Survey; "Dark Matter" the movie in theaters on April 11 - science is a pretty accurate representation of Astronomical thought at the time, and character portrayals interesting for the first 2/3 of the movie.

Thank you very much for listening, and please email me or leave any questions, comments, or concerns you might have below.

Interview with Dr. Julie McEnery now online

My interview with Dr. Julie McEnergy of Goddard Space Flight Center is now online and available here. Dr. McEnery is one of the top scientists on NASA's Gamma-ray Large Area Space Telescope (GLAST), and she discusses some of the science goals of GLAST. Given how poorly the high-energy sky is understood - approximately 50% of all known gamma-ray sources are unidentified, and this isn't including the many questions remaining concerning gamma-ray bursts with Dr. Neil Gehrels talked about - GLAST will likely revolutionize our understanding of the most powerful sources in the universe. No hyperbole (I think). For more on GLAST, also check out:

• NASA's official website.
• NASA's educational webpage for GLAST.
• Introduction to gamma-ray astronomy
• History of gamma-ray astronomy.

Thank you very much for listening, and hope you enjoyed it. As always, please email or post below any questions, comments, or concerns you might have. And again, thank you!

April 2nd Radio Show online

The April 2nd edition of this radio show/podcast is now online and available here. On this week, I covered:

• Calendar of upcoming events in the greater New York City / Poughkeepsie area (link)
• Interview with Dr. Julie McEnery of Goddard Space Flight Center on the Gamma-ray Large Area Space Telescope (GLAST), NASA's next-generation gamma-ray observatory
• News: University of Toronto plans to sell David Dunlap Observatory to fund a new one, some faculty protest; European Science Foundation studying plans to build a laboratory to study stellar evolution (link); a new spacecraft designed for space tourism might be ready for testing soon, hope of first take-off in 2010 (link); the guest quarters at the Very Large Telescope - four large optical telescopes operated by ESO located in Cerro Paranal, Chile - to be featured as the villian's hideout in the next James Bond movie, "Quantum of Solace"; debate continues over International Astronomical Union's definition of a planet; three new sunspots with the magnetic field orientation of the OLD sunspot cycle detected.
• Cosmic Rays: Re-analysis of the High-Resolution Fly's Eye cosmic ray telescope confirms the GZK cutoff observed in the detected rate of the highest energy cosmic rays detected by Pierre Auger (link); Integral detected hard X-ray emission from nearby massive star binary Eta Carinae, believed to be produced by very high energy electrons accelerated where the stellar winds powered by these two massive stars collide.

Thank you very much for listening, and hope you enjoyed it. As always please email or leave below any questions, comments, or concerns you might have.

Interview with Dr. Neil Gehrels online

The interview with Dr. Neil Gehrels of Goddard Space Flight Center is now available for your listening pleasure. In this interview, Dr. Gehrels talks about Swift, an extremely successful satellite which was designed to study the gamma-ray, x-ray, and ultraviolet/optical emission from gamma-ray bursts (GRBs) and has been instrumental in furthering our understanding of what these mysterious explosions are. For more information on his research, Swift, and GRBs, check out:

• Homepage of Dr. Gehrels
• Main webpage for Swift, which also contains information on how it studies GRBs
• An introduction to GRBs courtesy of NASA

Hope you enjoy, and thank you very much for listening. Please email me, or leave below, any questions, comments, or concerns you might have. Thanks!

March 26th show online

No, this isn't an April Fool's Joke, here is the March 26th show in mp3 format for your listening pleasure. On this show, I discussed:

• Calendar of upcoming events in the greater Poughkeepsie/New York City area, available here.
• Interview with Dr. Neil Gehrels of Goddard Space Flight Center (NASA), discussing studying Gamma-ray Bursts (GRBs) with Swift, the first satellite specifically designed to study these mysterious flashes of very high-energy photons.
• News: Congratulations to Katherine Bedkowski, Pargya Kakani, and Yvette Leung, winners of a Vail Scholastic Achievement Award given by the Custer Institute and Observatory for the Astronomy science projects they presented at this year's Long Island Science and Engineering Science Fair, to former particle physicist Dr. Bill Foster for being elected to the House of Representatives, to Dr. G. Wayne Clough for being appointed head of the Smithsonian Institute which runs the Smithsonian Astronomical Observatory - one of the largest Astronomical research centers in the world, and to Vanguard I - the first American satellite - which has been observed the Earth for 50 years as of March 17th; Cassini flyby of Saturn's moon Enceladus on March 12th occurs with only a minor hitch; UK astronomers going to maintain some access to the Gemini telescopes; Large Binocular Telescope in Arizona now operational (link); sunshield for James Webb Space Telescope passes preliminary design review (related interview,link); NASA says Alpha Magnetic Spectrometer - an anti-matter detector intended to be attached to the International Space Station which has already been built - may be too expensive to launch; orientation of Saturn's rings relative to Earth causing them to disappear for a short period time.
• Interview with Dr. Neil Gehrels of Goddard Space Flight Center on gamma-ray bursts (GRBs) and the Swift satellite, the first NASA satellite dedicated to studying these mysterious flashes of high-energy radiation at all wavelengths
• Gamma-Ray Bursts: Long duration GRB detected on March 19th whose optical emission was so bright it was seen with the naked eye even though it took place 7.5 billion light years (4x10^22 miles) away; short GRB - believed to be the result of two neutron stars merging, observed occuring when the universe was only 7 billion years old (half of the current 14 billion years), earlier than expected.

Hope you enjoy, and please email any questions, comments, or concerns you might have to me or leave them below. Thank you for listening!

Interview with Dr. Tod Strohmayer online

Available here is the interview I conducted with Dr. Tod Strohmayer of Goddard Space Flight Center on what you can learn about neutron stars and black holes from precise timing of their X-ray emission using the Rossi X-ray Timing Explorer, currently the oldest working X-ray observatory. Dr. Strohmayer maintains a very nice webpage which discusses his research, which I encourage all of you to check out.

As always, please email or leave below and question, comments, or concerns you might have. Thank you very much for listening!