Tuesday, June 20, 2006
Sky and Telescope Tuesday! Summer Solstice Catch-Up Time. Quick Red Sox Update.
I'm back again after another unexpected absence, again to attend to family matters. For now, these matters are somewhat stable, so I'm taking advantage of the lull to update this blog for all six of you who keep screaming at the lack of recent posts.
Quick Hits: Happy Summer Solstice Eve. For we northern hemisphere dwellers, Sol marks its northernmost point in its apparent journey along the Ecliptic tomorrow morning, June 21st, at 8:26 AM EST. Conversely, this means it is the beginning of winter for my mates in Australia.
The Red Sox are, somehow, in first place by two games. This despite having been swept, then having swept two teams in back-to-back series in which both opponents had similar won-lost records going into each set of games. Oh yes, and they started last night's series with the Washington Nationals by starting a pitcher they claimed off of waivers from the KANSAS CITY ROYALS! Well, woonchanoit, but Kyle Snyder, he of the two (2) wins versus nine (9) losses career record with a 6.55 earned run average, managed to get the win in last night's 6-3 victory with five innings of mediocre (three runs allowed), but occasionally brilliant (six strikeouts) curve balls. Oh yes, Manny Ramirez launched his 18th homer of the year off of 211 centimeter (6-foot-11) pitcher Jon Rauch. The homer was Manny's 453rd career bomb that moved him past former Sox great Carl Yastrzemski. The series with the Nationals continues at Fenway park this evening.
Glenn Hughes and Edenbridge are scheduled to deliver us some new releases, and once I get my copies of their new CDs in my hands I'll spend some time at the keys detailing their merits. Now, on to the neat stuff...
Below are two excerpts from the friendly folks at Sky and Telescope. The first deals with the possibility that planets made of mostly carbon nay exist in orbit around a neighboring star, while the second hints that Native Americans may have depicted the supernova of 1006 AD in rock art.
June 8, 2006 Exotic planets, dense with diamonds and graphite, might be forming around a nearby star. Astronomers announced this week that the disk around the young star Beta Pictoris is brimming with carbon, raising the possibility that abnormally carbon-rich planets might be forming there.
The rocky planets in our solar system are made mostly of silicate minerals such as quartz and feldspar. But last year, Marc Kuchner (NASA/Goddard Space Flight Center) and Sara Seager (Carnegie Institution of Washington) presented models showing that silicate planets aren't the only possibility. If the protoplanetary disk from which planets form has more carbon than oxygen, then planets based on carbon minerals would be the norm.
Now, a team studying spectra from NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) satellite has found just such a disk. The well-studied debris disk that surrounds Beta Pictoris has almost 9 times more carbon than oxygen; whereas the Sun has only half as much carbon as oxygen. The roughly 12-million-year-old Beta Pictoris system is just 63 light-years from Earth, and has long been considered the classic example of an evolving young planetary system. But the extraordinary amount of carbon has researchers wondering how typical it actually is.
Aki Roberge (NASA/Goddard), who led the FUSE team, suggests that this disk might represent another kind of planetary system. Rocky planets in such a system would be distinctly different from Earth, and not just because the crust would be made of graphite (i.e., pencil lead) and studded with diamonds.
"Imagine a planet where water and oxygen are extremely scarce but compounds like methane, propane, butane, tar, and soot are all available in abundance," says Kuchner. "Life would be very strange on a carbon world."
Oh shit, don't let George W. Bush read this. He'll want to mount an intersteallar glider brigade to confiscate all that oil. On second thought, George Bush reading Sky and Telescope is as likely an event as me taking Jessica Alba on a Vegas vacation...
But carbon planets aren't the only possibility for Beta Pictoris. Roberge's team speculates that, alternatively, the Beta Pictoris disk might represent a carbon-rich phase that all planetary systems undergo — including ours. "Beta Pictoris could be like a time machine, offering us a glimpse of our solar system in its infancy," says Roberge.
If so, Roberge says she would expect to find other debris disks that are just as carbon-rich. Her team has only studied Beta Pictoris with FUSE so far; however, astronomers know of many more young disks that can be studied.
But if our solar system was just as carbon-rich in its youth, where did all the carbon come from – and where did it go? Conel Alexander, a cosmochemist at the Carnegie Institution of Washington, thinks asteroids and comets might be to blame. A debris disk is a particularly violent place, where asteroids and comets routinely collide. The collisions literally knock the carbon-rich gas out of them, leaving excess carbon in a system with otherwise silicate planets. Strong stellar winds might have then swept away the excess carbon over millions of years.
Astronomers find evidence for this scenario in primordial dust particles in our solar system. Some of these dust grains retain their ancient carbon, suggesting that our system once had much more carbon. "But, nevertheless, these dust particles are not carbon-rich enough to explain the composition of the gases that we see in Beta Pictoris," says Alexander. "We need to consider a more exotic explanation."
Roberge and her team, who published their results in the June 8th Nature, suspect that new instruments will be needed to further explore the carbon-rich disk around Beta Pictoris, and to hunt for more. They speculate that the Cosmic Origins Spectrograph, which may or may not be added to the Hubble Space Telescope, or the Atcama Large Millimeter Array, to be completed in Chile in 2012, will be sensitive enough to study the carbon-rich gas in detail.
"Maybe Beta Pictoris is a glimpse of our own solar system," says Kuchner. "Or maybe it's telling us about the starling variety of other kinds of planetary systems that might be out there."
I'm not as well trained as these folks, but it seems to me that our sun, as an older star, and its original nebula that eventually coalesced into the solar system, was made from "purer" stuff than the Beta Pictoris system. That is, the Beta Pictoris system resulted from the gravitational attraction of materials from stellar explosions that contained heavier elements, like carbon, than did our system. That would explain some of what this article details.
Native American Depiction of Supernova of 1006 AD?
June 6, 2006 Two astronomers have proposed that a rock carving found in the White Tanks Regional Park, north of Phoenix, Arizona, may represent the supernova of AD 1006. If true, the carving would be the oldest known Native American record of a supernova, and the only known record of Supernova 1006 in the New World.
The carving shows a star-like object hovering above a scorpion symbol, which John Barentine (Apache Point Observatory) and Gilbert Esquerdo (Planetary Science Institute) interpret as the supernova appearing near the constellation Scorpius.
Supernova 1006 was one of the brightest in recorded history, visible in mid-day and prompting astronomers in Europe, Eastern Asia, and the Middle East to record its appearance and evolution. Barentine argues that the Hohokam tribe, which lived in the White Tanks area at the time of the supernova, also recorded the event. The supernova reached magnitude –7.5, about 15 times brighter than Venus.
However, despite media reports, leading archaeoastronomers remain highly skeptical. "Having looked at the White Tanks rock art panel, I am appalled," says Edwin C. Krupp, Director of the Griffith Observatory in Los Angeles and author of Archaeoastronomy and the Roots of Science. "Panels like this are not rare. There is no reason to link it to any supernova event. There is nothing persuasive about the imagery to support the extraordinarily detailed claim. The authors say nothing about all of the other imagery on the boulder and select two details for their discussion. These two details are in themselves dubiously interpreted."
"This Supernova 1006 petroglyph interpretation is nothing but assumptions and wishful thinking," he adds. Barentine admits that his conclusions are highly speculative. "The conclusion really hinges on whether this is supposed to represent a group of stars in the sky, and not an animal," he says.
In an effort to answer that question, Barentine and Esquerdo modeled what the night sky would have looked like at the White Tanks site on May 1, 1006, when the supernova first appeared. Both the supernova and Scorpius are visible above the horizon.
Still, experts doubt that the carving represents the supernova event, arguing that the star symbol could in fact represent the Sun, and the scorpion symbol could represent an actual scorpion — or something else entirely.
"We have no reason to think prehistoric Indians of the American Southwest saw a scorpion in the stars of Scorpius," says Krupp. "In fact, in North America, the stars of Scorpius are imagined as various figures but not as a scorpion."
"[The symbol] hardly resembles our constellation of Scorpius, much less anything we know about anybody else's," says Anthony Aveni (Colgate University), a leading author on ancient astronomy in the Americas. "Color me highly unconvinced."
I hate to call "bullshit" on Krupp, but of all the constellations, Scorpius is one of the few that actually resembles that for which it is named. Besides, the little buggers are everywhere in this region. So why the naysaying?
The White Tank petroglyph is not the first Native American rock carving to arouse debate in the archaeoastronomy community. In 1973, a team of researchers proposed that a carving of a crescent moon and a star at Chaco Canyon in New Mexico might represent the supernova of AD 1054. The claim has elicited debate that continues to this day.
"I am a supernova skeptic," says Aveni. "Anthropologist Florence Hawley Ellis gave a very ethnohistorically well documented explanation of rock carvings with crescent and star: they are Sun watchers stations and what one is seeing depicted are the crescent moon and [an evening] star low in the west after sunset."
"No alleged rock art depiction of the AD 1054 supernova is either conclusive or persuasive," adds Krupp. "Very plausible alternate interpretations for these are available."
Barentine presented a poster on the White Tanks petroglyph yesterday, at the summer meeting of the American Astronomical Society in Calgary, Alberta. He plans on submitting it to a peer-reviewed journal soon.
If "very plausible alternate interpretations for these are available", then why didn't Krupp cite them? Again, I hate to call bullshit on the man, but it appears to me that he might be on the wrong side of this issue. Krupp writes a wonderful monthly column for Sky and Telescope called Rambling Through the Skies that occasionally touches on topics like this one, and he is usually very good at refining the information he has researched. I'll be following this story to see if Krupp develops any reasons to change his mind, or, if he can present evidence to back up his unusual certitude about his current stance.