by Paul Gilster | May 9, 2007 | Exoplanetary Science |
Impressive results released today show just how much we’re learning about the ‘hot Jupiters’ that comprise about a quarter of known exoplanets. The first concern HD 149026b, a distant world which the infrared Spitzer instrument has shown to be the hottest planet ever studied. It’s somewhat smaller than Saturn but more massive, and is thought to contain more heavy elements than could be found in our entire Solar System outside the Sun itself, with a core as much as 90 times the mass of the Earth.
And the odd thing about HD 149026b is that for it to reach the measured temperature — a smoking 3,700 degrees Fahrenheit, or 2,300 degrees Kelvin — it would have to be absorbing just about all the starlight reaching it. The upshot is a planet whose surface is blacker than charcoal, re-radiating incoming energy in the infrared. What a view for the nearby traveler: “The high heat would make the planet glow slightly, so it would look like an ember in space, absorbing all incoming light but glowing a dull red,” said Joseph Harrington (University of Central Florida).
You study things like this by measuring the drop in infrared light that occurs when the transiting planet moves behind its star. This is an unusual planet indeed — Drake Deming (NASA GSFC), a co-author of the paper on this work, says it’s “…off the temperature scale that we expect for planets.” HD 149026b is 279 light years away in the direction of the constellation Hercules, and it is the smallest and densest known transiting exoplanet. Its conditions sunside make the second exoplanet we have to discuss seem almost pleasant by comparison.
For HD 189733b, some 60 light years away and the closest known transiting exoplanet, shows temperatures (via Spitzer again) of 1,200 Fahrenheit on the day side (922 K) and 1,700 F at night (1,200 K), a relatively even range. We can thus deduce something more about its weather: powerful winds must be spreading the heat from dayside to nightside (assuming that this world is tidally locked to its star). These winds may be moving at more than 9,600 kilometers per hour, and the Spitzer studies show a warm spot — about twice the size of Jupiter’s Great Red Spot — 30 degrees east of the point directly below the star. From this, scientists extrapolate easterly moving winds that redistribute the intense heat.
Image: Four views of HD 189733b’s cloudtops in infrared light, each centered at a point of longitude 90 degrees from the last. A grid of longitude lines is superimposed on the map. These views clearly show a hot spot that is offset from the substellar point (high noon) by about 30 degrees. The offset may indicate fast “jet stream” winds of up to 6,000 mph (9650 km/h). Credit: NASA/JPL-Caltech/Heather Knutson (CfA)
HD 189733b is a huge planet in an extremely close orbit, circling its star every 2.2 days. With more than a quarter million data points to play with, the team was able to assemble a simple map of this distant world. “We can see the changes in brightness as features in the planet’s atmosphere rotate into and out of view,” said Heather Knutson, a graduate student at Harvard and lead author of the paper on this work.
Will the James Webb Space Telescope permit even more finely detailed work, perhaps mapping weather patterns on planets as small as Earth? It’s certainly a possibility, and one to be mindful of as we look forward to getting the Webb instrument into space around 2013. The paper on HD 189733b is Knutson et al., “A map of the day-night contrast of the extrasolar planet HD 189733b,” Nature 447, (10 May 2007), pp. 183-186 (abstract here). The HD 149026b paper is Harrington et al., “The Hottest Planet,” Nature online publication 9 May 2007.
by Paul Gilster | May 8, 2007 | Deep Sky Astronomy & Telescopes |
The thought that Eta Carinae, a star at least 100 times more massive than the Sun, is a ticking time bomb seems to infuse much of the coverage about the huge supernova recently observed by the Chandra X-ray Observatory. And you can see why. Big explosions are marketable, which is why it sometimes seems that one way to categorize many of today’s movies is by how many cars were blown up during the making of them. When you’re talking about something a hundred times larger than the typical supernova, you’re going to get attention. What if a star 100 times the size of the Sun — or larger — goes off in our neighborhood?
Adding to the comparison is the fact that the supernova, known as SN 2006gy, seems to have expelled a large amount of material before the catastrophe. Eta Carina also shows signs of expelling mass, and it’s 7500 light years away, vs. the 240 million light years of SN 2006gy. Close enough to cause us problems? I don’t know the answer, but it does seem clear that one result would be spectacular visual effects. “Eta Carinae’s explosion could be the best star-show in the history of modern civilization,” says Mario Livio (Space Telescope Science Institute).
Image: According to observations by NASA’s Chandra X-ray Observatory and ground-based optical telescopes, the supernova SN 2006gy is the brightest and most energetic stellar explosion ever recorded and may be a long-sought new type of explosion. This is an artist’s illustration that shows what SN 2006gy may have looked like if viewed at a close distance. Credit: NASA/CXC/M.Weiss; X-ray: NASA/CXC/UC Berkeley/N.Smith et al.; IR: Lick/UC Berkeley/J.Bloom & C.Hansen.
What I find interesting is the mechanism that may be at work in such giant stars, for it’s believed that explosions like these were far more common in the early universe. Instead of the core being crushed under its own gravity to become a black hole (with the outer layers blown off as the visible supernova), supernovae like SN 2006gy may be the result of intense gamma ray radiation producing particle/anti-particle pairs, creating an energy drop that causes swift and violent stellar collapse. That, in turn, would trigger thermonuclear reactions fueling the explosion.
The consequences for the local environment are huge, since a mammoth explosion spreads elements cooked inside the star out into the cosmos, while a black hole seals some of this material off forever. Is SN 2006gy an example of this new kind of explosion? Whatever the case, it took seventy days to reach full brightness, and eight months later it remains as bright as a typical supernova at its peak. “Of all exploding stars ever observed, this was the king,” says Alex Filippenko (Lick Observatory).
Results are slated for The Astrophysical Journal. Then again, you may want to revisit Richard Cowper’s 1974 novel The Twilight of Briareus, a personal favorite whose author’s real name was John Middleton Murry, Jr. (I have all kinds of things to say about Murry himself — he was the son of the well known British writer and critic — but that’s a task for another time). In the novel, a nearby supernova blows in the constellation Briareus. Here’s the protagonist, a teacher in the local school, viewing it:
It was as if a hundred filmy scarves of pastel gauze had been suspended from the zenith to curtain off the whole of the northern sky; frail webs of pendant iridescence — pink and blue and green and yellow — which seemed to wave in slow motion like ghostly battle banners. The sight simply beggared description; it was unearthly. Next day I set it as a subject for a poem and one of the bright specks in the third form came up with — “slow waving fronds of winter weed. In rainbow rippling tropic seas” — which caught a faint fragrance of the magic but that’s about all.
Talk about visual effects! But as they unfold, the Earth is being bathed in a shower of particles that changes everything and produces an unforgetable kind of mutation. This guy could flat out write — I wonder if any of you share my enthusiasm for Murry’s work, which ranged from straightforward Ballard-era British disaster fiction to memorable fantasy, with interesting stops in between. The Twilight of Briareus is a wonderful book to return to, even if Eta Carinae isn’t likely to supply us with a modern day equivalent of the supernova in question.
by Paul Gilster | May 7, 2007 | Culture and Society |
History teaches that when big operations falter, small upstarts often rise to the challenge. In the case of NASA, the process may already be at work, and the upstarts are emerging: SpaceX, Blue Origin, Virgin Galactic. Out in the wilds of Las Cruces, New Mexico is building a spaceport. In fact, says Russell Saunders, Jr., the time has come to consider contingency plans. ‘Saunders’ is a pseudonym for a space scientist who works for a major aerospace organization. His essay appeared this afternoon on the NASA Watch site.
Saunders believes NASA is fixated on an iconography that’s half a century old, referring back to the spectacular space series that ran in Collier’s magazine in the early 1950’s. These were glorous, von Braunian visions of enormous rockets and flotillas of spacecraft pushing outward to Mars, but they’re an uncomfortable fit with today’s realities. Here’s what Saunders is talking about:
Imagine what the artists and pioneers behind the Colliers vision might have done with our current situation; knowing the ease and effectiveness of robotic exploration, the potential for citizen joyrides into space, the shift from cold war to global economics, the societal impact of seeing our Pale Blue Dot from space, the interconnectedness across the world via the Internet, the revelation that an asteroid impact killed the dinosaurs, and the implications of global warming.
And now he gets into the telling specifics:
For example, picture a future where you can tune into live video and sound from rovers on Mars; the Saturn moon Titan; or swimming in the oceans of the Jovian moon Europa. Imagine taking your turn at driving a lunar rover, remotely. Imagine booking a one-nighter in an orbiting hotel. Imagine the security from knowing that your home planet is under constant watch to protect its environment and to deflect incoming asteroids. There is plenty of good stuff from which to cast new, inspiring, and productive visions.
Image: Wernher von Braun’s article in the March 22, 1952 issue of Colliers, which kicked off a series of articles on the conquest of space. A lunar expedition followed by a landing on Mars was outlined along with impressive images of hardware developed at every stage along the way. But is this centralized vision a good match for today?
Be sure to read this. It’s an inside view of a tectonic shift occurring within the space industry as witnessed by an accomplished professional who has a clear-eyed view of where this is going. The creation of a new vision is never easy, but we need one to move us firmly into the digital, entrepreneurial era of space exploration. Part of that means recapturing the fascination of a public that once cheered every scrap of news from our early space missions. Saunders thinks this can be done and so do I.
by Paul Gilster | May 7, 2007 | Culture and Society |
The news that NASA intends to close its Institute for Advanced Concepts has many in the space community concerned, and Centauri Dreams‘ comment on the matter was but one of many to fill the Net when the news broke in March. Now, however, there appears to be at least an attempt to keep the Institute alive. People who have had some connection with NIAC are being asked to step in with demonstrated benefits from its activities. That news comes via this post on the Space Elevator Blog, as passed along by Joseph Mahaney. I’ve just confirmed it with sources inside NIAC.
Here are the areas for which contributions are solicited:
- Subsequent investment by NASA, other government agencies, or the private sector.
- Intellectual contributions that have resulted in an agency putting resources into its own studies of a concept. For example, prompted by the success of a Phase I or Phase II concept, an agency convenes panels to study the work or otherwise funds studies of its own.
- Unexpected spin-off technologies. For example, some NIAC studies have resulted in new medical applications.
- The production of technical PhD and Master’s level students.
- The production of new jobs.
- Enhancement of public understanding of agency missions (for most of you, this would be beneficial PR for NASA, or NRO, or DARPA).
Evidence of such contributions can’t hurt, and if you’ve had involvement with NIAC, now is the time to step in with a statement of its benefits. The best way to contact NIAC on these matters is via questions@niac.usra.edu. It would be a positive development indeed if such input could help save the Institute from extinction, but barring that, a record of its impact on space research is worth compiling. It could provide valuable lessons for other such attempts in the future.
by Paul Gilster | May 5, 2007 | Culture and Society |
I wish I had something profound to say about Wally Schirra. But when I think about him, what I get instead are moments. Great moments. I remember watching Schirra’s Atlas booster muscling Sigma 7 downrange that day in 1962. A space-struck kid, I thought the astronaut was as cool and unflappable as any man who would ever ride a rocket.
His sense of humor was irrepressible, especially in the context of hazardous early space missions. Thus the ‘Jingle Bells’ moment on the harmonica, and his sighting of the ‘UFO’ — Santa Claus and his reindeer. “We have an object, looks like a satellite going from north to south, probably in polar orbit… I see a command module and eight smaller modules in front. The pilot of the command module is wearing a red suit…”
Tom Stafford was in on that gag on Gemini 6 (he would later go on to command Apollo 10). I was in college when Apollo 7 flew and recall the squabbles with controllers on the ground. To be fair, Schirra had a cold, a famous one that he treated with Actifed (he later did TV commercials for the product). But it’s also true that, cold or not, the astronaut had a rough edge; he seemed to yearn for space when on the ground but to dislike it thoroughly once aloft, a deeply human trait that made me admire him the more.
Indeed, Schirra always seemed to me the most likable of the Mercury 7. His straightforward, no-nonsense manner made him ideal as a CBS commentator (usually with Walter Cronkite), bringing the space program to life during the thrilling era of the later Apollo missions. These are great memories, none of them profound, but the realization that he was 84 when he died made me re-think those days that seem so fresh to me still. How does the guy who flew Sigma 7 become 84, when I can still hear the thunder of that booster as it pushed for black sky?
