by Paul Gilster | Nov 14, 2005 | Exoplanetary Science
M-class red dwarf stars are of increasing interest in terms of astrobiology. If we can devise weather models that allow for regions of relative stability, a planet locked tidally to its star at a fraction of the distance from Mercury to the Sun could produce conditions suitable for life. The National Geographic show ‘Extraterrestrial,’ shown again the other night, projects just such an environment, and imagines life forms that might evolve there.
But red dwarfs are tricky because they’re flare stars. In their early lives, they spin more quickly than they will when they enter their dotage; the rapid spin can produce magnetic fields that, in turn, create flares. Life on a planet circling a younger red dwarf would have to adapt to flares that can double the star’s brightness within a matter of seconds. Some believe this makes Proxima Centauri an unlikely candidate for life-bearing planets.
And what about Barnard’s Star, so tantalizingly close (5.9 light years) to our own Sun? Study a nearby red dwarf and you can infer its age from its rate of spin. As Ken Croswell points out in A Flare for Barnard’s Star (originally published on Astronomy.com on November 11), variations in that star’s light suggest a rotation of once every 130 days. The rotation is slow, pegging the star as old enough — possibly 11 or 12 billion years — that it should no longer be emitting flares.
Fortunately, surprises are what make astrophysics such a joy. Thus the news that Barnard’s Star has indeed released a major flare, observed in July of 1998 but only analyzed four years later. Diane Paulson (Goddard Space Flight Center) and colleagues will publish this work in a future issue of Publications of the Astronomical Society of the Pacific. The team’s work indicates the flare’s temperature reached 8000 K, more than double Barnard’s usual temperature.
So are flares in older M-class stars a rarity, or do we need to revise our assumptions? Ponder this if you have an interest in amateur astronomy, for this is yet another case where regular observation over long periods of time may re-write the book on accepted theory. The Paulson paper “Optical Spectroscopy of a Flare on Barnard’s Star” is available here in preprint form. Also, be aware that the original paper written by the American astronomer Edward Emerson Barnard identifying this star as nearby is also available online, and is a key document for those of us who collect classic papers, loosely defined as those that enrich and sometimes overthrow accepted thinking.
by Paul Gilster | Nov 12, 2005 | Astrobiology and SETI, Exoplanetary Science
Two shows catch the eye tonight [Saturday] on the National Geographic Channel:
Naked Science: “Alien Contact” at 9P et/pt
Are we the only intelligent species alive in the universe? Join the
quest to separate scientific fact from science fiction in the search
for extraterrestrials.
“Extraterrestrial” at 10P et/pt
A dazzling galactic journey brings you face-to-face with fantastic
alien life-forms that scientists believe could exist in our own galaxy.
I haven’t seen the former, but “Extraterrestrial” is quite good, with sound extrapolations about life forms that could develop in such interesting environments as a planet circling an M-class red dwarf, and interviews with scientists involved in the exoplanetary hunt. For more information (and alternate program times) look here. Thanks to Larry Klaes for the tip on the re-broadcast of these shows.
by Paul Gilster | Nov 11, 2005 | Deep Sky Astronomy & Telescopes |
What can you do with 1600 detectors spread out over 3000 kilometers surrounded by an array of 24 telescopes? If you’re in Argentina’s Mendoza Province, the answer is that you can witness the arrival of high-energy cosmic rays. The ‘Cherenkov’ detectors, each containing 3000 gallons of water, detect the passage of the particles while the telescopes examine the ultraviolet fluorescence produced by their arrival in the atmosphere. The detector array covers an area roughly the size of Rhode Island.
All this is occurring at the Pierre Auger Observatory, just east of the Andes on the Argentine Pampas. Auger was the first scientist to observe the interactions between Earth’s atmosphere and cosmic rays back in 1938. The observatory named for him draws on the talent of 60 institutions in 16 countries. The presentation of the first physics results from the site took place this week in the Argentine town of Malargüe.
Image: The Andes Mountains form a snow-capped backdrop to the west of the detector array. Credit: Pierre Auger Observatory.
A news release from the Particle Physics and Astronomy Research Council (UK) synopsizes the recent work. Centauri Dreams sees more questions than answers in these studies. For one thing, we still need to learn much more about ‘primaries,’ those cosmic ray particles that strike Earth’s atmosphere first. What happens afterward is a series of collisions with air molecules that produces a particle cascade. But is the primary a proton, an atomic nucleus or a photon? Learning more about primaries should help us investigate the origins of these mysterious energy outbursts.
And perhaps they’ll lead in even more intriguing directions. From the release:
These exotic theories include hypothetical objects left over from the Big Bang, called topological defects, such as “cosmic strings,” “domain walls,” and “monopoles.” If these hypothetical phenomena existed, and then collapsed, their collapses could produce enough energy to create very high-energy cosmic rays. If so, then a certain fraction of cosmic rays would consist of photons. So far, the data is not extensive enough to prove or disprove any of these phenomena. But enlarging the data set over time will help Auger scientists narrow down the many different theories of cosmic ray origin.
Usefully, low-energy cosmic rays are more affected by galactic magnetic fields than their high-energy counterparts. This sets up the possibility of using the imbalance to track back to a point source in the sky, always one of the most difficult challenges of cosmic ray research. We are a long way from resolving the enigma of cosmic rays, but the same collaboration that funded Auger is now working to establish a northern hemisphere equivalent, probably to be situated in southeastern Colorado.
by Paul Gilster | Nov 10, 2005 | Research Tools |
Centauri Dreams sometimes laments the status of our research tools. Bibliographic coverage of the major journals online is spotty; some offer full text but only for recent issues, others are confined to abstracts, and access even at university libraries depends upon the services to which the library has subscribed. Pre-1995 items are rare online. People sometimes call the Internet a ‘digital library,’ but building the tools to make it a true library will clearly take a generation.
Nonetheless, exciting developments in spreading the news about research are happening in the digital arena, such as the heartening trend toward recording and disseminating scientific lectures in MP3 format. And even more promising is a new tool for creating audio and image slideshows to distribute conference presentations in PowerPoint and PDF format. QCShow, a freely downloadable player from AICS Research in Las Cruces, NM, synchronizes slides with audio to produce a low-bandwidth way to ‘attend’ key conferences.
What a pleasure to learn that NASA’s Institute for Advanced Concepts meetings are becoming available in this format, with the 2005 session in Colorado now available, and the 2004 meeting also archived. Those of us who couldn’t make either meeting now have the chance to hear Gerald Jackson discussing one of today’s most innovative deep space concepts, a spacecraft driven by antiprotons pushing a sail coated with uranium-238. Or Steven Dubowsky laying out the basics of his microbot concept for planetary exploration.
AICS has recorded numerous conferences, including presentations ranging from archaeoastronomy to planetary mission planning, exoplanetary studies, SETI and biomarkers. When you use its free player, what you see on the screen is the slide show prepared by the presenter, coordinated with his or her voice delivering the presentation. Needless to say, having the author’s comments available with each slide packs far more punch than a simple slideshow on its own, and makes QCShow a first-rate tool both for professional scientists unable to attend a particular meeting and members of the general public intent on learning more. The only downside: the Mac/Linux version, although in preparation, is not yet available.
For those interested in producing their own programs, details about the QCShow Author program are available at the site; although the software is designed to deliver freely distributed information, it also contains a document licensing mechanism for authors hoping to sell online audio/graphic materials. Centauri Dreams‘ hope is that tools like these will spur regular recording and archiving of conference presentations that heretofore have been available only in printed form and usually only from research libraries. A low-bandwidth solution like QCShow is a solid contribution toward making that ‘digital library’ a reality.
by Paul Gilster | Nov 9, 2005 | Administrative
Centauri Dreams was launched with the idea of providing the occasional commentary on space research with interstellar flight implications. What surprised this writer in the past fifteen months has been the fact that an ‘occasional’ schedule just doesn’t work. The news coming in, from exoplanetary discoveries to new research directions in propulsion and robotics, has kept the publication schedule fast and furious. Centauri Dreams now publishes six days a week except for rare periods when I’m traveling (I don’t carry a laptop).
The recent hosting change went much more smoothly than I had anticipated, having read horror stories from other writers who had attempted such things. In fact, it was more or less glitch-free, and by now Google has combed out many of the duplicate entries still pointing to the old pages. Only two major issues remain to be addressed.
Status of the archives. For a variety of reasons, I am transferring the articles from the old site’s archives one at a time (this plays into a current research project and also serves as a quality check). The archives are now complete save for a three-month window between mid-January 2005 and mid-April. At the present rate, I should have the complete archives transferred within about two weeks.
Comments and their uses. The comments Centauri Dreams has published so far have been of high quality and it is a pleasure to see readers’ thoughts on some of these issues. But I find the comment feature trickier to use than I would like (some readers have had trouble getting their comments in). Things would be simpler if I opened the site to anyone for comment without registration, but unfortunately the amount of ‘comment spam’ now hitting sites like these is immense. Because I don’t want to use time I could be posting here culling out spam come-ons for mortgages and imitation wristwatches, it’s necessary to keep the registration feature as is. I only hope that the next version of WordPress makes leaving comments a bit more straightforward.
As always, I thank Centauri Dreams readers for their continuing encouragement and interest in interstellar flight, a subject I think crucial for mankind’s future. Ad astra, and sooner rather than later.
