Thursday, September 28, 2006

Dry Neptunes and Dusty Galaxies's preprint server delivers a bumper crop of interesting papers this morning:

Star-forming galaxies:

  • Murphy et al combine the Spitzer Infrared Nearby Galaxies Survey (SINGS) and the Westerbork Synthesis Radio Telescope to study the nature and origin of Radio-Far Infrared correlation within the galaxies. They find that in the galaxies with the hifger star formation rates the radio emission is dominated by cosmic ray electrons that have diffused less far from their natal star forming regions (i.e. are presumably younger).
  • Hirashita and Hunt find that the the average radio energy emitted per SNR over its radiative lifetime is very different in the active and passive blue compact galaxies SBS 0335-052 and I Zw 18, being roughly tens times higher in SBS 0335052 than in I Zw 18. I would have expected the opposite (as total energy losses per SN should be less for higher supernova rates per unit volume), so I'll have to read this one a bit more carefully...
  • Buat et al compare galaxies selected from far-infra red (FIR) and far-ultraviolet (FUV) surveys (IRAS and GALEX respectively). The luminosity functions of the two samples differ, even in bolometric luminosity, but the bulk of the bolometric luminosity from FUV or FIR-selected galaxies in the local universe is emitted by galaxies with log10 (Lbol/Lsun) ~ 10. They also have specific star formation rates (total star formation rate/galaxy mass) significantly higher than the average SSFR from the optically-selected SDSS sample.

  • Wiktorowicz and Ingersoll consider whether liquid water oceans exist at any level within ice giants like Neptune or Uranus. The answer: probably not (sorry SciFi authors) now (but maybe in the future as it cools. Hot extra-solar neptunes also won't have water oceans unless the lose a lot of their hydrogen and/or helium.
  • Marley et al point out that existing models of gas giant thermal evolution (i.e. how hot they are with time, which translates into how bright they'd be) start off with initial conditions NOT based on modern planet formation models. Correcting this leads to young Jupiters that are fainter than the older predictions.
  • Lecavelier des Etangs (that must be an interesting family history!) considers the evaporation of extra-solar planets by their parent stars. Interestingly the prediction is that the Neptune-mass planets recently found must contain a significant amount of rock (or water, I wonder?) if they're to have survived evaporation for long.
  • Last but not least: X-rays from Jupiter! Branduardi-Raymont et al analyze an XMM-Newton observation of Jupiter. They conclude "The XMM-Newton observations lend further support to the theory that Jupiter's disk X-ray emission is controlled by the Sun, and may be produced in large part by scattering, elastic and fluorescent, of solar X-rays in the upper atmosphere of the planet." What gives me cause for concern (about my science, not theirs) is that the spectra are pretty much indistinguishable from the thermal hot plasma models I fit to the diffuse X-ray emission from star forming galaxies and superwinds.

Friday, September 22, 2006

Torture: not effective

Hidden from view by the superficial media arguments over what how much ill-treatment to allow in the interrogation of suspected terrorists and the sophistry of those "ticking time bomb" arguments is an issue as important as the oft-discussed moral dilemma: is torture effective?

Talking Points Memo points to an old (Dec 2005) Op-Ed in the Washington Post by a former Soviet dissident, Vladimir Bukovsky.

Here is a quick history lesson for John Yoo and other neocons: Before the "Axis of Evil" there was the "Evil Empire." This empire collapsed because of the waste and inefficiency inherent in a totalitarian state (frankly it was doomed from the start, so forget about that BS about the blessed Gipper's being responsible for bringing down Communism). The good reasons for the West opposing the old Soviet Union were because it tortured, killed and oppressed its own people, and frankly wanted to export that brand of inhumanity to other countries.

Back to Bukovsky. As a Soviet dissident who spent over a decade in Soviet prison camps he might just know a thing or two about state-implemented torture, and his argument (one echoed by many western intelligence experts) is that torture simply isn't effective. Worse than that: Its not going to save lives, if anything its going to exacerbate problems within the US intelligence gathering apparatus.

[What has this got to do with astrophysics? Nothing. But even purely as exercise of reason this dimension of the issue is something that should be asked and answered. Not to mention that this is probably the most pressing moral issue facing the Western world, so it deserves at least one post in this blog]

Friday cat blogging: Piper

20 lbs of pure male catness: Piper, aka Pooper, when he is being bad.

Too much emphasis on manned space flight (?)

The current WH-ordered emphasis on manned space flight is not capturing the (liberal) public imagination, at least in terms of DailyKos readers. As of 11am EST (with 203 votes) 54% think more emphasis should be placed on unmanned missions (you know, the ones that actually produce useful results and also cost vastly less than manned mission).

This is from DarkSyde's science friday article, which is is pretty damn clear as to the cost/benefit outcomes of manned missions (the shuttle, the international space station) and unmanned missions (e.g. Hubble, Cassini).

What is a little disturbing (at least to me) is that despite his rather clear discussion 16% believe the current balance (i.e. running NASA's science capability into the ground) is acceptable, and 26% believe more manned space flight should be done.

Just for fun lets basically recap the facts, the numbers are rough but are qualitatively correct:

International Space Station:

  • Reason for construction: Congress, after deciding GHWB's Mar's plan was too expensive.
  • Total cost: $100 billion dollars?
  • Unique science accomplished: None. Microgravity experiments can be done on planes.
  • Unique advances/development of space technology: ?

Space-based (unmanned) observatories: example, the Hubble Space Telescope
  • Reason for construction: Scientific need to determine the expansion rate of the Universe (the Hubble Constant) by detecting Cepheid variables in galaxies further away than possible with any ground-based observatory.
  • Total cost: At about $5 billion HST is one of the most expensive science missions of the last 2 decades.
  • Unique science accomplished: Determined Hubble constant, distant SNe show Universe is expanding, presence of Dark Energy, deepest observations of the Universe to date, etc etc.
  • Unique advances/development of space technology: Multiple successful upgrades performed in space by astronauts.
The problem, and the cause of wasted tax-payer money, is not manned space flight itself, it is any form of space mission driven by narrow political or financial reasons. NASA does (did?) science well because missions were chosen based on apolitical scientific need as prioritized by the entire scientific community.

Thursday, September 21, 2006

A planet burnt beyond recognition

The two bright stars right at the center of this image form the binary star system ADS 16402. Binary star systems are common, maybe even to the extent that the majority of stars are part of a binary.

What makes ADS 16402 particularly interesting is a discovery announced only a few days ago. ADS 16402 b (the star on the left of the two) has a planet. What is even more astounding is that it was discovered using a network of telescopes little bigger than a SLR camera: HATnet.

Extra-solar planets (planets outside of our own Solar system) are nothing new. Starting with the first robust discovery a decade ago there are now 206 extra-solar planets known to astronomy (as of today, visit the Exoplanets Encyclopedia to find the latest details). Most are Jupiter-like gas giants.

This planet, named HAT-P-1b, is nevertheless something special. It weighs in at about half of Jupiter's mass, but its radius is approximately 40% larger than Jupiter's. Put those two things together and you have a planet with a density of ~0.4 g/cc, i.e. its less dense than water.

So what you might say? Well, this is an unusually low density for a planet, in fact standard planetary structure theory would say you can't have a gas giant planet with such a low density.

The figure on the right comes from the discovery paper of HAT-P-1b (Bakos et al 2006, E-print: astro-ph/0609369). Its a plot of the mass vs radius for the known exo-planets, and its clear that HAT-P-1b and the similarly weird HD 209458b are well outside the norm.

Why is HAT-P-1b so weird? Well, it orbits very close to its parent star. Its average distance from its star is only 5% of the distance between the Earth and the Sun, and about 1% of the distance between Jupiter and the Sun. This itself is not that unusual: many giant exo-planets, in particular the first ones to be found, orbit close to their stars despite having almost certainly formed much further out (which is a fascinating topic in its own right).

One possibility to explain the bloated puffed up nature of HAT-P-1b is that its being cooked by its parent star. IF some fraction of the stellar energy falling on the planet gets transported deep down in the atmosphere then the atmosphere could be puffed up. Its not enough just to heat the very surface layers though. This is a cool-sounding idea, and I liked the idea enough to title this post along those lines (paraphrasing from a Mentallo & the Fixer album). However the problem is that other close-in exo-planets aren't puffed up.
What are the other options? Tidal heating, either from an eccentric orbit, or from a Cassini State (its rotation axis lying close to its orbital plane, unlike the Earth where they're about 90 degree apart), might heat the planets interior sufficiently to alter the atmosphere drastically enough. But these hypotheses, as Bakos et al write, are "ad hoc; they require unusual circumstances for which there is no independent evidence." Ad hoc solutions are bad form in science, as they so often turn out ot be wrong.

So the mystery of HAT-P-1b remains, for now.

Wednesday, September 20, 2006

SciAm review of Owen Gingerich's book

The September 2006 issue of Scientific American has a review of Prof. Owen Gingerich's new book: "God's Universe". Owen Gingerich is or was an Astrophysicist and still is a noted Historian of Science at Harvard - previously mentioned in this blog regarding the Pluto redefinition furore.

Scientists write popular books all the time, but this one is likely to have a different readership from the average popular science book, and get a bit more press too. Why? Well, Prof Gingerich is one of the approximately 40% of scientists who manage to reconcile holding spiritual beliefs while still practicing the methodological/philosophical naturalism required for science. He is part of the smaller (sub)set holding theistic religious beliefs (i.e. believes in God).

Shame on him for violating the stereotype of souless atheistic scientists fiendishly plotting the moral and metaphysical downfall of the West, or whatever it is we're supposed to be doing. I forget now, must have deleted the last memo from SASFPTMAMDOTW from my inbox.

This kind of thing, the apparent oxy-moron of a religous scientist, really gets the media excited. NPR happily interviews Francis Collins (human genome project, whose book is also reviewed in the same SciAm article), in fact just about anyone who appears to break the science vs. religion theme perpetuated by the media seems to be of great interest to the same media. What is annoying is the implicit appeal to authority inherent in such attention: "Tell us about your religious beliefs o wise one. How tolerant and open minded you must be compared to your non-religious fellow scientists."

Why should we view a scientist Joe OverEductated reasons for believing supernatural thing X any more seriously than Joe Redneck's reasons for believing supernatural thing X?

And is Joe OverEducated's vision of what God is anything like Joe Rednecks. Deism, probably the most common form of religious belief by scientists, is so far from your average Southern Baptist's view of Christianity as to be irreconcilable. Yet all these cases of religious scientists are inevitably portrayed as support for Christianity (yes, some fraction are Xtian, but they're can hardly be a majority). I feel that if these interviewers did their job properly and actually probed these issues maybe we'd see less enthusiam for this sort of religious apologetics.

Hopefully our library will get a copy so I'll be able to read Gingerich's book myself, but in the mean time I'll content myself with a few choice quotes from George Johnson's review in SciAm.

... its premise survives: that there are two ways to think about science. You can be a theist, believing that behind the veil of randomness lurks an active, loving, manipulative God, or you can be a materialist, for whom everything is matter and energy interacting within space and time. Whichever metaphysical club you belong to, the science comes out the same.

In the hands of as fine a writer as Gingerich, the idea almost sounds convincing. "One can believe that some of the evolutionary pathways are so intricate and so complex as to be hopelessly improbable by the rules of random chance," he writes, "but if you do not believe in divine action, then you will simply have to say that random chance was extremely lucky, because the outcome is there to see. Either way, the scientist with theistic metaphysics will approach laboratory problems in much the same way as his atheistic colleague across the hall."

Mmmh, thats not promissing - sounds like the standard "materialism is just as much a matter of faith as religion" argument.

The reviewer, moving onto Francis Collin's book which employs a very similar rhetorical devices, remains firmly grounded in reason:

But what sounds like a harmless metaphor can restrict the intellectual bravado that is essential to science. ... Whether they are right or wrong is not a matter of belief but a question to be approached scientifically. The idea of an apartheid of two separate but equal metaphysics may work as a psychological coping mechanism, a way for a believer to get through a day at the lab. But theism and materialism don't stand on equal footings. The assumption of materialism is fundamental to science.

Steve Irwin Tribute

Animal Planet aired the Steve Irwin Tribute show last night (Tuesday September 19th, 2006). It was at the main croc enclosure (Crocoseum) at Australia Zoo, a mix of eulogies, taped tributes by media personalities, clips of Steve in action, and live music.

I know it doesn't sound all that great from my poor description, but it was probably the best send-off/tribute/funeral-type-thing I've even seen televised. I watched in bed, dampness in my eyes (Keli was sniffling too). It was sad, yet uplifting. Lighthearted, even comedic, yet deeply serious.

I won't describe the details, you can go here for an ozzy paper review with details the tribute service, just the thoughts I had about the service.

  • It was incredibly well produced. Someone put a lot of time and effort into producing it and they did an amazing job. Good on ya mate!
  • Bindi (Steve and Terri's nine-year-old daughter) gave a great (and quite deep) send off to her father. No hesitation, no umming and ahing. The kid has talent, and maybe quite a future taking over from Steve?
I kept wondering why didn't I feel like it was cheezy, superficial and painful-to-watch, like so many other stage-managed memorial services? I think it must be that the feelings expressed by the people who knew Steve were so sincere. It was clear they felt deeply, sorrowful, yet the viewer could relate to how much they'd enjoyed knowing Steve. Maybe that you were also feeling the same things, the bittersweet mix pleasure of remembering the Steve you enjoyed watching with the pain of loss. Someone said people like the croc hunter because he was so clearly himself on camera that you felt you really knew him, that he was your friend.

Bah, I can't explain it. Just watch it if you have the opportunity and if you liked watching the croc-hunter, you'll feel better for it.

Switch over to Beta Blogger

I've switched this blog over to Google's "beta" version of the new blogger service. Some nice drag-and-drop layout options, and of course the labels feature. Expect more cosmetic changes to the blog in the next few days.

Tuesday, September 19, 2006

There will be no loyalty, except loyalty towards the Party.

Remember the flap a while back about a unqualified (but Bush-loyal) hack at NASA editing press-releases and denying the press interview with climate scientists? Merely a bad-apple, you might say, not part of a deliberate and concerted effort to weaken and sideline science.

Well, this time it seems the plausible deniability is wearing thin. CNBC's request for an interview with NOAO scientist Dr. Tom Knutson gets vetted by none-other than Commerce department press secretary Chuck Fuqua...

"What is Knutson's view on global warming vs. decadal cycles?" Fuqua asked his subordinate.

He's "a bit of a different animal" than the higher-ups at the NOAA, the aide responded.

"Why can't we have one of the other guys on then?" Fuqua emailed back.

NOAA ultimately denied CNBC the interview.

The ever vigilant Henry Waxman (D-CA) is on the case, but until the house and/or senate fall under Democrat control I doubt any investigation will get anywhere.

The "There will be no loyalty, except loyalty towards the Party." quote is (of course) from 1984.

Thursday, September 14, 2006

Pluto's big cousin: Eris

The IAU has released the official names for the dwarf planet that caused Pluto's downfall: Eris (who in mythology caused a quarrel among the goddesses that lead to the Trojan War. Who says scientists don't have a wry sense of humor?). Eris's large moon is Dysnomia, the daughter of Eris and the spirit of lawlessness (sounds like Bush).

See the IAU resolutions here, or perhaps more the readable BBC news article here.

OK, that's enough blogging about planets for a while.

[Update 07/26/2016: Latest figure show Plut to be slightly larger but Eris to still be more massive]
Eris's properties

Mean radius1163±6 km[8][9]
(1.70±0.02)×107 km2[c]
Volume (6.59±0.10)×109 km3[c]

Pluto's properties:
Mean radius
Flattening <1 class="reference" id="cite_ref-Stern2015_7-1" sup="">[5]
  • 1.77×107 km2[c]
  • 0.035 Earths
  • (7.006±0.071)×109 km3[d]
  • 0.00647 Earths

Tuesday, September 12, 2006

Pluto redux has an interesting interview with the new president of the IAU, Catherine Cesarsky, regarding the redefintion of Pluto as a minor planet. She says several things worth repeating here:

"We knew in advance that no matter how this decision would come out, a part of the astronomical community would be disagreeing. The intense debate at the 2006 General Assembly was very healthy and exactly intended to make as large a fraction of the community as possible, agree with the decision. In this we succeeded.

It also has to be said that the - now very visible - "splitting" of the community in the issue of where to make the delineation between planets and other solar system objects is not new. It is a debate that has existed for several years."

Going back to calling Pluto a planet will NOT solve anything. Its hard to see what the either the scientific or public naysayers believe they will achieve.
Has the intense debate strengthened or weakened the authority of the IAU? What does the group need to do to keep its position as a governing body?

It is too early to tell. The IAU has a rigorous set of Statutes, Bylaws and Working Rules. These have been followed carefully in this process of developing the planet definition Resolution and in the voting process.

A controversial subject such as this merits debate as we had during throughout the General Assembly. The astronomers present could ponder on the arguments expressed and prepare for voting. Our Statutes state that Resolutions can only be passed by a majority of those IAU members present and voting. Resolution 5A was passed with a wide majority. There is therefore, from our perspective, little reason to question the authority of the IAU [emphasis mine].

The established rules were followed and the result was that by majority vote Pluto was redefined to be a minor planet. The IAU is a conservative body (conservative with a little "c", in the old [positive] sense that it is slow to change and acts with care, which I note is now diametrically opposite to Conservative in the political sense). This change in Pluto's status was long needed, and not taken lightly.

Monday, September 04, 2006

Sad news: Steve Irwin, Crocodile Hunter, is dead.

Steve Irwin, conservationist and wildlife ambassador, has died at the age of 44, still doing what he loved. It appears he got hit with a stingray barb in the heart while filming. News accounts here and here.

My sincerest condolences to Terry, Bindi Sue and Bob, and all the staff of the Australia Zoo.

Behind his zany persona there lived a consumate professional with amazing and effortless skill with animals and with conveying his love for them to the public. I'll never look at a croc again without thinking about what wonderful animals there are.

Crikey, but we'll miss you mate!

Friday, September 01, 2006

Pluto is not a planet, so deal with it!

Pluto's demotion from planet to minor planet is not a big deal, but a lot of people are making fools of themselves over it. Earth to Yuggoth: Get OVER it!

The small blurry pictures at the top left of this image are Hubble images of pluto. The larger smoother nicer looking images are a model fit to the data.

Its been clear for a long time that Pluto was not like the other planets, and including it was pushing the definition into dangerously ambiguous waters. The was a lot of discussion and finally a vote at the Prague general assembly of the IAU (the only organization allowed to officially name astronomical bodies, by the way) and that is that. So what is all this fuss?

Let start with the supposed hijacking of the vote.

He [Owen Gingerich] added: "There were 2,700 astronomers in Prague during that 10-day period. But only 10% of them voted this afternoon. Those who disagreed and were determined to block the other resolution showed up in larger numbers than those who felt 'oh well, this is just one of those things the IAU is working on'."


Professor Gingerich, who had to return home to the US and therefore could not vote himself, said he would like to see electronic ballots introduced in future.

Alan Stern agreed: "I was not allowed to vote because I was not in a room in Prague on Thursday 24th. Of 10,000 astronomers, 4% were in that room - you can't even claim consensus.

So the vote is somehow not valid because Stern and Gingerich all the others didn't bother turning up to vote, a vote they knew when and where was going to occur. Oh puuuullleeease.

If couldn't attend then that is tough. Valid reasons for complaining about a vote result are fraud, or disenfranchisement, but lets face it: any astronomer who wanted to go could have gone.

Secondly there is this (fine bit of journalism: a classic "some say") from the BBC article linked to above.

A fierce backlash has begun against the decision by astronomers to strip Pluto of its status as a planet.

Where is this backlash - most of it that I've seen is purely media-driven self-referential 24-hour cable news talking head nonsense. The "I was taught its a planet in school, so how dare you change it" mentality.

Yeah, so the leader of the New Horizons mission to Pluto is pissed [disclaimer: the Applied Physics Lab is somehow vaguely connected with JHU where I am currently employed]. That's hardly surprising (and it doesn't mean Pluto isn't interesting, or that his mission will suddenly disappear on route), but that is one person. Personally all the professional astronomers I spoken to about seem pleased Pluto has been demoted. That's 3-1. By MSM rules there should be an article "Astronomers overwhelming mandate Pluto's destruction" or something ;).

Anyway, in more petty silliness 300 or so astronomers have signed a petition saying they won't use the new IAU definition. If you cared that much then why did n't you bother going to the damn IAU and voting on a definition you liked then, instead of creating a bunch of bad publicity for astronomy?

The newly-adopted definition of planet has it own weaknesses. But so will any definition, because there really isn't a physical cut-off that can be made with non-fusion-burning astronomical objects planets, asteroids, comets. What should not be ignored in all this unnecessary fuss is that the new definition is BETTER than the old one. And that is the way science works, by incremental improvements. Don't expect a PERFECT solution.

And as for naming the icy minor planets "Plutons" - well, it was a nice try, I like the idea of having a new name (I would have preferred Yuggoths). This was one of the suggestions. A bit of background from the Nature web site we have this article (this is from before the IAU-vote).

On 16 August the International Astronomical Union (IAU) floated a proposal for a definition of the word 'planet', in part to end the confusion about whether Pluto is a planet or not. But their solution, which assigns Pluto and its neighbor's to a subset of planets called 'Plutons', is so far just creating more confusion and angst.

Scientists have pointed out that the word 'pluton' is already taken by geology, making at least one geologist hopping mad. Furthermore, astronomers have argued that the definition just doesn't fit with their intuitive sense of what a planet is — leading, already, to a second proposed definition. The confusion will probably continue until this Thursday, at least, when IAU members will put the proposals to a vote.

IANAG (I am not a geologist) but I knew pluton was a rather widely-used geological term. Apparently some exalted ones did not:

Owen Gingerich, an astronomer at Harvard University in Cambridge, Massachusetts, and chair of the IAU committee that created the definition, says that they were aware of its usage amongst geologists, but unaware of its importance to the field. "Since the term is not in the MS Word or the WordPerfect spell checkers, we thought it was not that common," Gingerich wrote in an e-mail to The geologic definition of the word does appear in common dictionaries, including the Oxford English.
I hate to point out to Prof Gingerich that almost all astronomical terms are not to be found in dictionaries, even good ones like the OED, let alone bad ones like MS word's atrocious spellchecker. This is not a good excuse for messing up with pluton.

You can always tell when an astronomer has ceased doing astrophysics research and has become more of an administrator or retiree, and that is when they start using Microsoft products like Word all the time instead of LaTeX running on a *nix system. I am not being snide, Gingerich is an senior astronomer emeritus, and his primary current interests are the history of astronomy (for which he is well known), see his bio here. Computer whizz he may not be, but someone please show him wikipedia!

Friday cat blogging

Macio in a playful mood.