Anthonares

In my undergraduate cosmology class my professor introduced this satellite as having brought about quantitative cosmolgy. While that’s probably just a bit of an exaggeration, this little craft definitely revolutionized the science. Prior to the launch of the Wilkinson Microwave Anisotropy Probe (WMAP) (and to a much smaller degree its predecessor, COBE), cosmology, the study of the evolution of the universe, was a mess of theories and ages. But after a series of papers published in 2003 detailing the first year of data collection from WMAP, the universe suddenly had a definite age, 13.7 billion years, and was shown to be dominated by dark energy.

Since then, WMAP has been the darling of the astronomy community and has undoubtedly led hundreds of eager young undergraduates into cosmology. The science community knew that WMAP was still collecting data, but I’m not sure that anyone really expected the news released last week (discussed at Cosmic Variance and at Bad Astronomy, here are the technical publications). The age of the universe was left unchanged at 13.7 billion years, but the date of first star formation was moved to 400 million years in better agreement with theory. Also, the first true evidence for cosmic inflation was presented as well.

It was an exciting announcement from a team that has already done so much for the field of cosmology. To better understand just why the WMAP mission is so important, I’ve put together this relatively brief summary of the study of the Cosmic Microwave Background in the last decade. These three missions have changed our prospective and refined our vision. Cosmology is now a field of true quantitative prediction that bears little resemblance to the unorganized conjecture of two decades ago.
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Almost two weeks ago, Cassini mission scientists published a host of results pertaining to Saturn’s tiny moon Enceladus. The world had been given a hint of what to expect from the image on the right released last November that revealed a geyser of material spewing away from the south polar region of the moon. We were treated to a literal feast of fantastic results, summarized in this perspectives article by Jeffrey Kargel (a hydrologist at University of Arizona). Because of the importance of these new papers, the journal Science is offering free access to the 11 articles published in the March 10th issue relating to Cassini and Enceladus. You can spend $10 to buy the newsstand edition, gotta love free and open science!

As much as I would love to review all of the Enceladus science, so many important discoveries could not receive the attention or care they deserve in a single blog entry. Instead I will focus just on the discovery of watery geysers emanating from Enceladus’ south polar region. I will focus on the two papers detail the discovery of water ice in that jet of material, though two additional papers provide the important linkage between that jet and relatively warm surface features. The so-called tiger-stripes seen on Enceladus occur on a geologically very recent portion of the moon’s crust (Porco and others), and are shown to be about 70 degrees warmer than the surrounding crust. This makes the tiger stripes about 145 Kelvin, or -128 Celsius, while the surrounding crust is a chilly 70 Kelvin (Spencer and others).

Citations

• Hansen, CJ, and 7 others (2006). “Enceladus’ Water Vapor Plume.” Science 311(5766), pp. 1422-1425. [online at CiteULike.org]
• Waite, HJ, and 13 others (2006). “Cassini Ion and Neutral Mass Spectrometer: Enceladus Plume Composition and Structure.” Science 311(5766), pp. 1419-1422. [online at CiteULike.org]

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One of the reasons that astronomy appeals to so many people are the stunningly beautiful photographs of nebulae throughout our galaxy. Tomorrow’s edition of the journal Nature features a paper that explains just how a cloud of gas was twisted and formed into a double helix shape. NASA’s Spitzer Infrared Telescope took this color-enhanced image of the nebula.

Twisting and interacting magnetic fields near the center of the galaxy are probably the culprit here, according to the article (see the citation below). When viewed in this broader-context image (taken using the Midcourse Space Experiment satellite), the twisting double helix nebula appears to be emerging nearly vertically out of the galactic plane. This fact, combined with the temperature of the gases and their proper motions provide strong evidence that the galaxy’s central magnetic field has sculpted this nebula.
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Paul Gilster at Centauri Dreams writes about a potential replacement for Terrestrial Planet Finder Coronagraph (TPF-C) that would be “faster, better, and cheaper.” The basic idea is that the Coronagraph part of the TPF-C would be an independent, free-flying “Occulter” that would be combined with the upcoming James Webb Space Telescope (JWST) to recreate the scientific mission of the TPF-C. The best part is that the Occulter could fit within the budget of NASA’s Discover class of vehicles, for which it currently has solicitations for proposals.

In light of the pressure being applied to NASA because of TPF and Europa Orbiter delays, it seems to me that this potential Occulter mission has risen to a very high scientific priority. Also, combining the effective budget of the TPF mission with the JWST would help stop the slide in its launch date. While I can hardly wait until April when the proposals are due, I am buoyed by the prospect of TPF proceeding after all. Thanks Paul!

The image on the right is an artist’s conception of the view of the Pluto/Charon system from the surface of P2, one of Pluto’s recently discovered moons (credit: NASA). While we’ve known for a month or so that Pluto has two “new” moons the paper announcing the discovery was just published Thursday. Their discovery is a truly fine example of observational astronomy, and I thought I would share some top-rate science with you all. Here I examine a pair of papers, one announcing and detailing the discovery of P1 and P2, the other speculating on their genesis and implications for the nature of the Pluto/Charon system.

Citations

• Weaver, H.A. and 8 others (2006), “Discovery of Two New Satellites of Pluto”, Nature 439(7070), pp. 943-945 [online at CiteULike.org]
• Stern, S.A. and 8 others (2006), “A Giant Impact Origin for Pluto’s Small Moons and Satellite Multiplicity in the Kuiper Belt”, Nature 439(7070), pp. 946-948 [online at CiteULike.org]

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In a press conference this morning, astronomers announced the discovery of a planet with a likely mass of 5.5 times that of the Earth orbiting a red dwarf star some 21,500 light years away. This is not the lowest mass exoplanet discovered thus far, but it is the first one that is both near Earth mass and near Earth orbital distance. I’m sure you’ve all heard the news, but now read on and hear the science (I’ll note that the Bad Astronomer did a science explanation too, but mine has pictures and graphs in it, so it must be better! Okay, also Centauri Dreams has done a summary as well, but again, mine has more pictures and graphs, plus an original analysis in the Context section below.). Also, I made a cool graph of all of the exoplanets we’ve found so far, that’s below too. So, here’s a second bonus published research synopsis in as many weeks:

Citation (online at CiteULike.org):
Beaulieu, J.-P. and 72 others (2006). Discovery of a cool planet of 5.5 Earth masses through gravitational microlensing. Nature 439(7075), pp. 437-440.
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Gamma Ray Bursts (GRBs) are the most energetic discrete events we observe in astronomy. Far more powerful than supernovae (exploding massive stars), they are also extremely short events, lasting between a few seconds and a few hours. Recently, with the advent of the SWIFT satellite (the image to the right is an artist’s rendering of the SWIFT satellite, credit: NASA) that can locate GRBs to a reasonable precision, the so-called “afterglow” of these events have been detected across the electromagnetic spectrum. This week’s Published Research Synopsis details the results of a single detection event, GRB 050724 belonging to the short-hard GRB class (very short gamma-ray emissions in the “hard”, or highly energetic, range of the gamma ray spectrum) and finds, among other things, that the GRB probably resulted from the collision of a neturon star with a black hole, or of a star with a neutron star.

Citation (online at CiteULike.org):
Berger, E. and 24 others (2005). The afterglow and elliptical host galaxy of the short γ-ray burst GRB 050724. Nature 438 (7070), pp. 988-990.
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Today’s Astronomy Picture of the Day gives us the great picture to the left of Asteroid Itokawa taken by the currently status-unknown Japanese probe Hayabusa. This picture is simply astounding because it is completely unlike any picture of an asteroid, moon, or planet we’ve seen so far. It totally lacks craters, first of all. This must mean either whatever hits it merely knocks a bunch of rocks around which subsequently reorganize themselves, or that there is some dust layer that somehow moves everything about.

Personally, I think that it looks like two separate asteroids that collided very slowly, resulting in a bit of crushed rocks and debris, but leaving the two parent bodies largely intact. Anyway, whatever it is, hopefully Hayabusa will return to functionality and enlighten us all!

I just finished submitting my first for-publication journal article entitled “The Origin and Physical Properties of Cometary Knots in the Helix Nebula NGC 7293.” I am second author, after my Astronomy Senior Thesis advisor, Dr. Eugene Capriotti. We submitted it to the Astrophysical Journal, one of the more prestigious journals in the Astronomy community. The review process, if all goes well, should take between 6 months and 1 year, though it varies greatly by journal and discipline. Either way, it ought to get published in mid-late 2006 if it’s accepted by the scientists that review our work. Anyway, it’s a very interesting paper, enough so that perhaps I can explain the basics here:
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